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LIBRARY

Michigan State
University

 

This is to certify that the

thesis entitled
Neogene Flysch Provenance
Variations, Sea of Japan

presented by

Kevin J. Pentony

has been accepted towards fulfillment
of the requirements for

Master—degree in Geology

Ma r professor

Dmfi Novegber 34 1977

0-7639

NEOGENE FLYSCH PROVENANCE VARIATIONS,
SEA OF JAPAN

By

Kevin John Pentony

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements

for the degree of
MASTER OF SCIENCE
Department of Geology

1977

ABSTRACT

NEOGENE FLYSCH PROVENANCE VARIATIONS,
SEA OF JAPAN

By

{evin John Pentony

Mineralogical analyses were done on Neogene flysch sediments from
the Yamato and Japan Basins in the Sea of Japan in order to : 1) de—
lineate provenance variations both within each basin and between the
two basins; and 2) determine if the silt in flysch sands and clays
differed in composition. Point-counts of the light mineral fraction
and microprobe chemical analyses of feldspars were performed.

Complex provenance variations were deciphered in this manner and
supporting evidence was obtained for the rifting hypothesis for the
origin of the Sea of Japan. No compositional differences were detected

between the silt in flysch sands and clays.

ACKNOWLEDGEMENTS

Many thanks to my thesis adviser, Duncan Sibley, for suggesting
an interesting problem, providing assistance when it was needed and
allowing me license in seeing the problem through to a favorable con-
clusion. Critical reading of the thesis together with many helpful
comments and suggestions by the other members of my committee, John
Wilband and Thomas Vogel, was much appreciated. Technical assistance
in sample preparation and microprobe analysis was provided by Craig
Tingey and Mr. Viv Shull respectively. Samples were supplied by the
Deep Sea Drilling Project, Scripps Institution of Oceanography, through
the assistance of the National Science Foundation.

Finally, I am eternally grateful to my wife, Carol, for her love
and devotion during the course of my graduate studies, something worth

more to me than any thesis.

ii

TABLE OF CONTENTS

Section

List of Tables . . . . . . . . . . . . .
List of Figures. . . . . . . . . . . . .

INTRODUCTION . . . . . . . . . . . . . .
FLYSCH PROVENANCE. . . . . . . . . . . .
SEA OF JAPAN . . . . . . . . . . . . . .
SAMPLE COLLECTION AND PREPARATION. . . .

DATA COLLECTION AND ANALYSIS . . . . . .

Petrographic analysis . . . . . . . .
Electron microprobe analysis. . . . .
Summary of point—count and microprobe

VERTICAL CHANGES IN SEDIMENT COMPOSITION

Site 299. O O O O O O O O O O O I O 0
Site 301 O O O O O O O O O O O I O 0 O

LATERAL CHANGES IN SEDIMENT COMPOSITION.

Late Miocene. . . . . . . . . . . . .
Early Pleistocene . . . . . . . . . .

VERTICAL PROVENANCE VARIATIONS . . . . .

Site 299 C O O O O O O O O O O I O O 0
Site 301. . . . . . . . . . . . . . .

LATERAL PROVENANCE VARIATIONS. . . . . .
FLYSCHSANDSANDCLAYS . . . . . . . . .

CONCLU S ION S O O O O O O O O O O O O O O 0

APPENDIX: Compositional plots of feldspar grains

REFERENCES . . . . . . . . . . . . . . .

iii

in samples 1-48

10

11
13
18

24

24
29

30

31
31

31

33
36

37
38
38
41

82

10.

11.
12.

LIST OF TABLES

List of samples from Site 299, DSDP, leg 31. . . . . . . .
List of samples from Site 301, DSDP, leg 31. . . . . . . .
Point-count data for Site 299 samples. . . . . . . . . . .
Point-count data for Site 301 samples. . . . . . . . . . .
Microprobe data for Site 299 samples . . . . . . . . . . .
Microprobe data for Site 301 samples . . . . . . . . . . .

Summary of point—count and microprobe data for
samples at Sites 299 and 301 . . . . . . . . . . . . . . .

Summary of point-count and microprobe data for Early
Pleistocene and Late Miocene samples at Sites 299 and 301.

Summary of point-count and micrOprobe data for clay and
sand samples, core-section 18—3, E. Pleistocene, Site 299.

Significant correlations of point-count and
microprObe data 0 O O O O O O O O O I I O O O O O O O O O 0

Vertical changes in sediment composition at Site 299 . . .
Vertical changes in sediment composition at Site 301 . . .

iv

12
14
16
17

20

21

22

24
28
30

Figure

1.

A-7.
A-8.

A-lO.
A-11.
A-12.
A—13.

LIST OF FIGURES

Major physiographic features of the Japan Sea
showing locations of Sites 299 and 301. . . . .

Plot of the average ZAn (and ZOr) values of the

total feldspar in each sample . . . . . . . . . . .

Histograms illustrating petrographic data (including
altered feldspar grains) and microprobe data (for all

the feldspar grains analyzed) for Sites 299 and 301

samples . . .

Diagram illustrating the correlations of depth with
Q and L, H with L and Q, and L with Q at Site 299 .

Diagram illustrating the correlations of Q with H

and L at Site

301

Generalized geologic map of the regions bordering
the Sea of Japan showing igneous and metamorphic
rock types; locations of Sites 299 and 301 are

also illustrated.

Generalized geologic map of the Toyama region of

Honshu, Japan showing

igneous and metamorphic

r0 Ck types 0 O O O O O O O O C O O O O O O O O O O

Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional

plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot

of 27 feldspar grains in sample
of 24
of 27
of 29
of 30
of 25
of 26
of 25
of 34
of 27
of 25
of 15

of 25

feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample
feldspar grains in sample

feldspar grains in sample

V

1.
2.
5.

Page

19

23
25

26

32

34
41
42
43
44
45
46
47
48
49
50
51
52
53

Figure
A—14.

A-15.
A-16.
A-17.
A—18.
A-19.
A-ZO.
A-21.
A-22.
A-23.
A—24.
A-25.
A—26.
A-27.
A-28.
A-29.
A-30.
A-31.
A-32.
A-33.
A—34.
Ar35.
A-36.
A-37.
A-38.
A-39.
A—40.
A-41.

Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional
Compositional

plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot
plot

of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of
of

16
18
16
30
17
19
27
27
28
20
2O
23
18
26
18
29
24
26
21
26
24
27
29
16
27
27
27
28

feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar
feldspar

vi

grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains
grains

grains

in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in
in

sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample
sample

sample

16
17
18
19
20
21

22 .

23
24
25
26
27
28
29
3O
31

32 .

33
35
36
37
38
41
42
43
44
45
48

INTRODUCTION

Two of the holes drilled in the Sea of Japan on leg 31 of the Deep
Sea Drilling Project (Site 299 in the Yamato Basin and Site 301 in the
Japan Basin) penetrated unconsolidated Neogene flysch sequences. The
purpose of this investigation is to determine whether changes occurred
in the sediment source through time (vertically within each hole) and
space (laterally between basins) for the flysch sediments at Sites 299
and 301 and to determine if compositional differences between silt
fractions in muds and sands exist. Hopefully, this provenance study
will lend its support to one or another of the proposed models for the
origin of the Sea of Japan outlined below.

A detailed mineralogical analysis using the petrographic microscope
and electron microprobe was the method used for determining these
provenance variations. Due to its chemical variability, feldspar is
a valuable provenance indicator, and therefore the determination of its
composition was stressed in this study. Another reason for concentrat-
ing on feldspars is that they are an important constituent in shales
(the dominant flysch.lithology) averaging about 4.5% of the total min-
eralogy (Shaw and weaver, 1965). Feldspars also comprise a large portion
of the minerals in the sediments from DSDP Sites 299 and 301 (plagio—
clase is especially abundant). X-ray data indicate that 28% of the bulk
sample mineralogy is feldspar (Cook et al., 1975); point-counts show

feldspar to compose 23% of the sands (Harrold and Moore, 1975).

FLYSCH PROVENANCE

Turbidity currents play a major role in the deposition of flysch,
although arguments have been presented in favor of oscillatory currents
(Grossgeym, 1972) and contour following currents (Heezen et al., 1966)
for flysch formation. Most inferences as to sediment dispersal patterns
and provenance of turbidites have been based on paleocurrent analyses
from sedimentary structures. This method is useful in the determination
of the provenance of the graywacke interbeds of ancient flysch sequenc-
es. However, provenance determination by use of lineated sedimentary
structures has its drawbacks: 1) it has limited application for recent
deep—sea sediments which can be sampled only by drilling and coring;

2) these structures are usually confined to the undersides of the tur-
bidite sandstones (unit a of Bouma (1962) sequence) and are exposed

only if the underlying shales have been eroded away; 3) since these sole
marks are restricted to the sandstones, they therefore say nothing of
the provenance of the hemipelagic shales; 4) distal turbidites (low sand/
shale ratio) may contain only the upper portion of the Bouma sequence
(units c-e) suggesting that the depositing medium of the basal unit did
not possess the energy or elasticity necessary to produce sole markings;
and 5) paleocurrent analysis by use of these structures may be difficult
in areas where severe tectonic events inhibit plausible palinspastic
restoration.

A more universal technique for determining sediment dispersal patterns
and possible source terrains in both ancient flysch and recent deep-sea
sediments is analysis of mineralogical composition. Much work has been
done on the mineral composition of ancient flysch sequences to infer

provenance, mostly in the form of point-counts of the light mineral
2

3
fraction (Bokman, 1953; McBride, 1962; Ojakangas, 1968, 1972; Gilbert
and Dickinson, 1970; Swe and Dickinson, 1970; Dickinson and Rich, 1972;
Keighin et al., 1972; Gilbert, 1973; Hein, 1973; Moore, 1973; Murray
and Condie, 1973; Lajoie et al., 1974; Ataman and Gokcen, 1975; Eis-
bacher, 1976; and Graham et al., 1976). There are some comparable
studies also on modern equivalents (Hubert and Neal, 1967; Duncan and
Kulm, 1970; Vallier et al., 1973; Nelson and Nilson, 1974; Harrold and
Moore, 1975; Stewart, 1976; and Campbell and Clark, 1977). Almost all
of this petrographic work.has been confined to the arenite (graywacke)
interbeds. A detailed mineralogical analysis of the clays and shales
in flysch deposits is important because: 1) they are more ubiquitous
than the sand and sandstone interbeds in both recent and ancient de-
posits; 2) sandstones may contain a larger percentage of altered mineral
grains than do adjacent shale beds (apparently due to the greater per-
meability of the sandstones); this suggests that shales rather than
sandstones should be used for petrographic analyses (Blatt and Suther-
land, 1969); and 3) conclusions as to flysch provenance, sediment
transport mechanisms and paleogeographic-tectonic setting based only

on flysch sandstone mineralogy must be confirmed.

SEA OF JAPAN

The Sea of Japan is a marginal sea or back.arc basin, and there are
varied explanations for its origin. Unpopular "sinking landmass" ideas
are propounded by Minato (1973) and Beloussov (1968). Sychev and Sne-
govsky (1976) believe that the sea represents a relict oceanic crust

which was separated from the Pacific when the Japanese islands were

formed by subduction of the Pacific plate. The predominant view holds
that the sea originated by tensional subsidence and rifting during the
Oligocene-Early Miocene interval (Karig et al., 1975). Uyeda and Miya-
shiro (1974) postulate that the Japan Sea opened up as a result of col-
lision and subduction by a hypothetical Kula-Pacific ridge. Hasebe et
a1. (1970) and Matsuda and Uyeda (1971) consider that magmas generated
along the upper surface of the descending oceanic plate rise through
the upper mantle and create the new oceanic lithosphere of a marginal
sea with a resultant oceanward drift of the crust to form an island arc.
Karig (1971) has a similar view but emphasizes the periodic diapiric
rise of mantle.materials from the upper surface of the descending slab
instead of the steady rise of a magma.

The Sea of Japan is divisible into a southeastern area of complex
bathymetry characterized by major basins and rises and a northern and
western area of simple bathymetry termed the Japan Basin or Abyssal
Plain (Figure 1). Recent Soviet and Japanese refraction measurements
in the Japan and Yamato Basins indicate that the crust is typically
oceanic (Ludwig et al., 1975). The Yamato Basin has a shallower sea
floor, thinner sediments, a shallower basement surface and a thicker
basement layer when compared with the Japan Basin (Ludwig et al., 1975)
which may indicate that the eastern part of the sea is younger than the
western part. The fact that sediments are thickest on the west side
of the Japan Basin may be a result of differential sedimentation rates
rather than a decrease in crustal age toward the east. However, there
are no large rivers along the Asian coast of the Sea of Japan and the
sediments of the Japan Basin have a large biogenous component; hence a

greater part of the terrigenous input to that basin is probably derived

 

 

  

 

 

 

 

 

 

l = Yamato Basin
2 = Tshushima Trough (Basin) g
3 = Toyama Trough 5
4 = Genzan Trough -;
5 = Yamato Trough a
6 = Oki Trough :
7 = Mogami Trough ‘—
8 = Kits-Yamato Ridge __ :
[HID = other ridges =
@= continental 43’ ___-‘:" —
slope $9 =— l' n_.
‘3" 5" i ‘- —
: :l E— o
: g = 5:55“)
L‘;==" E 5' 99
S“X ' I}
m ‘55 _..

 

 

 

 

ll -
SOUTH a: :3 ii
KOREA, g’ .i.::

\v.?

  

 

Figure 1. Major physiographic features of the Japan
Sea showing locations of Sites 299 and 301
(from Hilde and Wageman, 1973, figure 2).

 

6
from Japan (Karig and Moore, 1975). Terrigenous sedimentation is in
the form of turbidites which are distributed by channelized turbidity
currents passing through Tartary trough, Genzan trough, Toyama trough,
Mpgami trough and to a lesser extent Tshushima trough (basin), Yamato
trough and numerous submarine canyons on the steep continental slope
adjacent to Primorye.

Site 299 in the Sea of Japan was drilled in an extension of the
Toyama trough within the northeastern Yamato Basin; 532 meters of Recent
through Late Miocene sand, silt and clay deposits were penetrated and
172.3 meters of cored sediment were recovered. These sediments have
been interpreted as predominantly distal turbidites or alternatively
as levee deposits on a deep—sea fan complex ( Karig et al., 1975).

Site 301 was drilled in the east central portion of the Japan Basin: a
location selected so that it would be the furthest possible distance
from any of the major channels feeding the abyssal plain (Bouma and
Mbore, 1975). The hole penetrated 496.5 meters below the sea floor and
183.5 meters of cored sediment were recovered. The section consists

of 240.5 meters of Holocene to Late Pliocene distal turbidites, sands,
silts and clays underlain by 256 meters of Late Pliocene to Late Miocene
pelagic and hemipelagic diatomaceous oozes with a few terrigenous inter-
beds.

Data regarding source areas for the sediments drilled at Sites 299
and 301 are rather limited and interpretations vary. X-ray data are
qualitative because of the large biogenous, amorphous and lithic com-
ponents in some samples. Only a few analyses were performed: 7 for Site
299 and 9 for Site 301 (Cook et al., 1975). Harrold and Moore (1975)

point-counted 28 deep—sea sand samples from leg 31 of the Deep Sea

7
Drilling Project (including 6 from Site 299 and 4 from Site 301) in
order to delineate source areas for the sands. Their compositional
analyses were similar in approach to others which have been performed
on deep—sea sands and ancient graywackes and have the same drawbacks
(see Flysch Provenance section). In addition, the large percentage of
rock fragments (72% for Site 299 and 24% for Site 301) in this tectonic
setting may preclude comparison of Harrold and Meore's data to ancient
rocks because diagenesis and low-grade metamorphism may quickly reduce

the percentage of lithic fragments (Cummins, 1962).

SAMPLE COLLECTION AND PREPARATION

Samples from Sites 299 and 301 in the Sea of Japan were obtained from
the Deep Sea Drilling Project and are listed in Tables 1 and 2. For
Site 299, these include 33 one cc samples from 8 cores and for Site 301,
8 one cc samples from 4 cores. The lithology of the sediments is dom-
inantly silty clay and silty sand.

The very fine sand—coarse silt size fraction was separated out from
each sample and used for the compositional analysis. Fan (1976) has
shown that the silt fraction is more representative of total sediment
composition than either the sand or clay fraction in Recent silts in
the Santa Clara drainage basin. Sufficient material was present within
this size class for all but 5 of the samples (3,4,40,46 and 47) and
these five were therefore not included in the analysis. Samples 34 and
39 were excluded from the study because they contained only volcanic
rock.fragments and volcanic glass respectively.

Use of the same size fraction in different lithologies effectively

eliminated the effects of textural sorting which have been shown to

Table 1.

Sample
no.

*indicates depth.below sea floor to top of sample

List of

Core—
section

1-1

2-3

5-5

I!
16-3

M

II

18-3

24-2
M
II
30-5
M

36-1
n

Interval

gem.) '

53-54
64-65
75-76
100-101
53-54
80-81
98—99
1-2
30-31
49-50
2-3

5-6
9-10
30-31
35-36
39—40
60-61
65-66
69-70
75-76
80-81
84-85
120-121
125-126
129-130
100-101
113—114
124-125
54-55
78-79
96-97
110—111
125-126

8

Depth*

"(m.‘)

.53
.64
13.25
13.5
44.53
44.8
44.98
145.51
145.8
145.99
164.52
164.55
164.59
164.8
164.85
164.89
165.1
165.15
165.19
165.25
165.3
165.34
165.7
165.75
165.79
221
221.13
221.24
329.54
329.78
329.96
495.1
495.25

samples from Site 299, DSDP, leg

Ase

L.PlSt 0-1-1010
'I

H
L.Plst.

II

II
E.Plst.

H

I!

L.Mioc.

H

Lithology

silty clay
H

sandy clay
1|

sandy silty clay
II

"
silty clay
H
H
II

clayey silty sand
H

silty clay
clay
ll

silty clay
I!

II

clayey silty sand
I!

silty clay
H

sandy clay
H

9

Table 2. List of samples from Site 301, DSDP, leg 31.

Sample Core— Interval Depth*

no. section (cm.) gm.) Agg_ Lithology

37 4-4 54—55 160.04 E.Plst. silty clay

38 " 76-77 160.26 " "

41 5—3 85—86 ' 177.85 " "

42 " 144—145 178.44 " "

43 11-1 56-57 317.06 L.Plioc. sandy silty clay
44 " 96-97 317.46 " "

45 " 140-141 317.9 " "

48 19—5 139-140 485.39 L.Mioc. clay

*indicates depth below sea floor to top of sample

occur in turbidites (Shideler et al., 1975).

The samples were heated for 20 minutes in full strength HNO3 to re-
move carbonates and grain coatings and to oxidize any organic matter
present. They were then heated for another 20 minutes in .lM KOH to
dissolve oxidized organic matter. The residue was then completely dis—
persed by treating the samples for 20 minutes with a .05M sodium hexa-
‘metaphosphate (Na6P6018) solution in an ultrasonic bath. After each
‘was washed and centrifuged 3 to 5 times after each intermediate step,
the samples were subjected to a final set of washings and were wet-
sieved using 200 and 325 mesh sieves. This procedure was generally ef-
fective in achieving its objectives and in order to assure that no
apparent chemical or physical alteration occurred, the same treatments
were first carried out on orthoclase, microcline, albite, labradorite
and bytownite grains of equivalent size.

The sediment within each size fraction was dried and stored and the
‘material retained on the 325 mesh sieve was weighed. The average weight
in the very fine sand—coarse silt size class (the size fraction used
in the study) was .19-grams with a large variation: ranging from 1.5

grams (in a sand unit) to .002 grams (in a clay unit).

10

Part of the material was mounted on a glass slide with Lakeside 70
(n=1.54) and used for the petrographic microscope work. Another split
was retained for a polished grain mount necessary for the electron
microprobe. For this purpose, k inch lengths of 3/4 inch diameter glass
tubing were glued to frosted slides on which a grid had been drawn.
A—271 epoxy (Armstrong Products Co.) was then mixed with the sample in
this receptacle and centrifuged for 12 minutes at 1800 RPM on a model
K International Centrifuge with an attachment device develoPed specifi—
cally for this purpose. This technique insured that each grain of sed-
iment lay on the glass slide with its long axis parallel to the slide
and came to rest on a cleavage plane (if present). The preferred orien—
tation of the cleavage plane and axis is useful in optical studies
where a specific mineral orientation is desired. Finally, the epoxy-
filled glass tubing was cut off slightly above the slide and polished
grain mounts were prepared using the procedure outlined by WOodbury and

Vogel (1970).

DATA COLLECTION AND ANALYSIS

Because certain minerals and mineral suites may be more predominant
in a particular size range, use of different size fractions in different
lithologies may introduce.mineralogical sorting. Also, Shideler et a1.
(1975) demonstrated the occurrence of mineralogical sorting in cases
where no textural differences exist between the top and bottom of a
sandstone bed. Such sorting would be controlled by the specific grav-
ity and shape of the various mineral constituents. The mineralogical
sorting possibly introduced by these factors was probably not signifi-

cant in this study because quartz and the various feldspars do not

11
differ markedly in shape or specific gravity (the lowest - microcline
has an SG of 2.54; the highest - anorthite has an SG of 2.76; quartz

is intermediate at an SG of 2.65).

Petrographic analysis

 

Point-counts were made of the 41 Lakesidedmounted slides until ap-
proximately 250 monocrystalline quartz, feldspar: n<1.54 and feldspar:
n>1.54 mineral grains were identified on each slide; the actual average
is somewhat lower (i=241, s=24) because some samples did not contain
enough grains. Feldspar: n<1.54 includes the alkali feldspars as well
as plagioclase between AnO and An30; feldspar: n>1.54 includes plagio-
clase between An30 and AnlOO. A large percentage of the feldspar:
n<1.54 (greater than 50% in each sample) is altered, probably a result
of albitization of originally calcic plagioclase. The point-counts
for each of the above categories were converted to percentages and var-
ious ratios were computed: feldspar: n>1.54/feldspar: n<1.54, monocrys—
talline quartz/feldspar and monocrystalline quartz/feldspar: n<1.54
(Tables 3 and 4). The means and standard deviations were computed for
each of the above categories for all the samples at Sites 299 and 301
(Table 7); in addition, i and s were computed for the samples in each
category within the Early Pleistocene and Late Miocene time intervals
(Table 8). The Chi-square test (corrected for continuity) was used to
determine if statistically significant differences could be detected
in %monocrystalline quartz, %fe1dspar: n<1.54 and %fe1dspar: n>1.54 for
a particular sample and the sample immediately under it. If a signif—
icant difference exists (#-.05) an asterisk (*) is shown next to the
percentage; a highly significant difference ($=.01) is indicated by 2

asterisks (**). Finally, i and s were computed for each category for

12

Table 3. Point—count data for Site 299 samples.
Spl.
ELASE _“;__B__C__P__§__F__G___
1 L.Plst.— 183 44.3 40.9 14.8 55.7 .36 .80 1.08
H01.
2 " 247 43.7 40.1 16.2 56.3 .40 .78 1.09
5 " 250 36.8** 43.2** 20.0 63.2 .46 .58 .85
6 " 249 20.5** 59.8** 19.7 79.5 .33 .26 .34
7 L.Plst. 176 34.1 41.5 24.4 65.9 .59 .52 .82
8 " 136 38.2* 36.8 25** 61.8 .68 .62 1.04
9 " 249 26.1* 29.3 44.6** 73.9 1.52 .35 .89
10 E.Plst. 251 36.7 36.7 26.7 63.3 .73 .58 1
11 " 247 29.6* 37.2 33.2 70.4 .89 .42 .80
12 " 247 40.5 30 29.6 59.5 .99 .68 1.35
13 " 249 40.6 32.5 26.9 59.4 .83 .68 1.25
14 " 249 35.3 30.1 34.5 64.7 1.15 .55 1.17
15 " 249 41 31.7 27.3 59 .86 .69 1.29
16 " 250 40.8 32.8 26.8 59.6 .82 .68 1.24
17 " 249 41.4 24.9* 33.7 58.6 1.35 .71 1.66
18 " 248 39.5 33.5 27 60.5 .81 .65 1.18
19 " 248 41.9 33.9 24.2 58.1 .71 .72 1.24
20 " 217 46.1 35.9 18 53.9 .50 .86 1.28
21 " 212 45.3 35.8 18.9 54.7 .53 .83 1.27
22 " 248 46.4 30.6 23 53.6 .75 .87 1.52
23 " 248 44.8 37.5 17.7 55.2 .47 .81 1.19
24 " 248 41.5 35.9 22.6 58.5 .63 .71 1.16
25 " 248 43.1 36.3 20.6 56.9 .57 .76 1.19
26 " 248 42.3 34.3 23.4** 57.7 .68 .73 1.23
27 " 248 33.5* 26.6* 39.9** 66.5 1.50 .50 1.26
28 " 248 44 35.5 20.6 56 .58 .79 1.24
29 " 250 38.8 36 25.2 61.2 .70 .63 1.08
30 " 250 38* 36.8** 25.2 62 .68 .61 1.03
31 " 250 48 24.4* 27.6* 52 1.13 .92 1.97
32 " 250 47.2 33.2 19.6 52.8 .59 .89 1.42
33 " 250 49.6 36 14.4* 50.4 .40 .98 1.38
35 L.Mioc. 251 49 28.3 22.7 51 .80 .96 1.73
36 " 251 53.4 25.1 21.5 46.6 .86 1.15 2.13
A - total monocrystalline q artz + feldspar
B - %monocrystalline quartz
C - %fe1dspar: n<1.54
D - %fe1dspar: n>1. 4
E - %total feldspar
F - feldspar: n>1.54/feldspar: n41.54
G - monocrystalline quartz/feldspar
H - monocrystalline quartz/feldspar: n<1.54

H

sum of %monocrystalline quartz, %feIdSpar: n<1.54 and %fe1dspar: n>1.54

is approximately 100% for each sample.

2altered feldspar grains are included in the point-count data.

13

Table 3 (contd.).

*indicates a significant difference Ox=.05) in this component for this
sample and the one immediately under it

**indicates a highly significant difference («=.01) in this component
for this sample and the one immediately under it

the clays and sands of core-section 18-3 from Site 299 (Table 9).

Electron microprobe analysis

Analyses of K, Ca and Na were performed on 993 feldspar grains in
41 polished grain mounts (§=24, s=5) using a 3-spectrometer ARL model
EMX—SM electron microprobe. Each grain was analyzed in 5 places at a
beam current of 40,000 microamps (constant) and voltage of 15 kV for
approximately 10 seconds per analysis. The composition of each grain
was determined in terms of Wt% Anorthite (An), Wt% Albite (Ab) and Wt%
Orthoclase (Or) using the formulae:

Wt% An =

CPSca
1.1
Ca Ca
An Std ° An Std x 100
CPSca CPSNa CPSK
u u
Ca Ca Na Na K K
An Std ' An Std CPSAb Std ° B CPS 30: Std

 

CPS

 

 

 

CPS Ab Std Or Std '

Wt% 0r =

CPSK
11
K K
Or Std ' 0r Std x 100

CPSK CPSca CPSNa
u u
+
CP

“ +
K K Ca Ca SNa BNa
An Std Ab Std ' Ab Std

 

CPS

 

 

 

B CPS B

CPSOI Std ' Or Std An Std '

where CPS is counts per second, u is the unknown and the B's are correct-

ion factors computed according to Sweatmen and Long (1969) for the

14

Table 4. Point-count data for Site 301 samples.

Spl.

E’s—5:39. Liiiiiii
37 E.Plst. 250 64** 23.6 12.4 36 .53 1.78 2.71
38 " 250 50* 29.6 20.4 50 .69 1.0 1.69
41 " 250 40.4 36 23.6 59.6 .66 .68 1.12
42 " 250 43.6 38.4 18 56.4 .47 .77 1.14
43 L.Plioc. 232 48.7* 34.9 16.4* 51.3 .47 .95 1.40
44 " 251 38.6 35.9 25.5 61.4 .71 .63 1.08
45 " 250 45.2 33.6 21.2 54.8 .63 .82 1.35
48 L.Mioc. 250 47.2 34.4 18.4 52.8 .53 .89 1.37

- total monocrystalline q artz + feldspar
- %monocrystalline quartz

- %fe1dspar: n<1.54

- %fe1dspar: n>1. 4

%total feldspar

- feldspar: n>1.54/feld3par: n<1.54

- monocrystalline quartz/feldspar

- monocrystalline quartz/feldspar: n<1.54

WQ'QMUOflP
l

1sum of %monocrystalline quartz, %fe1dspar: n<1.54 and %fe1dspar: n>1.54
is approximately 100% for each sample.

2altered feldspar grains are included in the point-count data.

*indicates a significant difference («=.05) in this component for this
sample and the one immediately under it

**indicates a highly significant difference («8.01) in this component
for this sample and the one immediately under it

15
mineral standards used. Wt% Ab was found by subtracting Wt% An +
Wt% Or from 100% to insure that no rounding error occurred. It should
be noted that only unaltered feldspar grains were analyzed with the
microprobe, whereas many of these altered grains were included in the
petrographic analysis. Therefore a literal comparison of microprobe
and point—count data cannot be made.

The composition of each.grain was plotted in the ternary system of
An, Ab and Or; the feldspar grains in each sample are illustrated in
this manner in 41 separate triangular diagrams (see Appendix). In order
to evaluate the microprobe data quantitatively, the points in each dia-
gram were arranged in certain compositional groups which consistently
contained significant numbers of grains (Tables 5 and 6). The means
and standard deviations were computed for each compositional group for
all the samples at Sites 299 and 301 (Table 7); in addition, 2 and s
were computed for the samples in each.category within the Early Pleis-
tocene and Late Miocene time intervals (Table 8). The Fisher exact
probability test (Siegel, 1956) and the Chi-square test (where applic-
able) were used to determine if statistically significant differences
could be detected in any of the compositional groups for a particular
sample and the sample immediately under it. If a significant difference
exists (g=,os), an asterisk.is shown next to the percentage; a highly
significant difference (#=.01) is indicated by two asterisks.

The.average.%An values of the plagioclase in each.sample and the av-
erage %An values of the total feldspar in each.sample are listed in
Tables 5 and 6; their means and standard deviations for total and age
(as described above) are listed in Tables 7 and 8. Differences in

these two groups were not evaluated using the Fisher test or Chi-square

16

 

O.HO O.OO OO NO On On On O OH ON ON O O A A ON
O.ON NO OO OO O O OO O NO NO NN O O OH «Om OH
w.nm o.~q mm Hm «smq «*0O «NH o m O ON seam O O «O om
A.ON 0.00 «O AAO ON OO ON O ON O «O As O As O OH
O.ON O.NO ON «NN ON OO OO O OH OH O NN O O NN ON
0.0N N.OO ON ON O Am OO OH OO ON O OO O ON ON ON
O.ON O.ON ON OH OH ON on O On O OH OH OH O OO ON
0.0N 0.00 ON ON A ON NO O NO OH HO O On A «A ON
O.HO N.OO HO HO AOO OO ON O ««O OH NN «ON OH O O AN
0.00 A.OO ON NN NN AO OO O OH ON A On OH O ON AN
0.00 OO NO NO as NO AO O as On On an ON On On On
OO 0.00 ON ON ON ON ON O OH ON O On O O ON AN
A.OH N.ON On A ON OO OO O ON «O O OH On A OO OO
mm 0.00 ON OH OO On OH O ON O OH ON OH O O ON
O.ON O.OO ON AS AN NN OO O AS HO O as O O AON OA
0.00 0.00 OO OO O O OO O O On On O O ON On ON
A.ON HO On On On OtOO OO O *ON OH *O O ON «O On ON
H.OO H.OO AN ON ON AO OO O tO A OH OH AN A ON OH
NO N.OO NO OO ON ON OOO O ON *OO NA NH «O O O ON
0.00 0.00 OO HO NN ON OH O A OH NN A O O as AN
N.OO 0.00 mm ON HO OO O O O O OH ON O O O OO
0.00 N.NO NO ON OO Om ON O O O ON ON NH O O ON
m.o~ N.OO mm mm «sq «smfi ma «tam w w ma sq m w m mm
O.AO 0.00 OO OO OH ON On tO ON ON Os O O O O ON
0.00 0.00 AO AN ON OO AH ON tam On AH On A O OH OO
N.OO A.OO HO ON On An OH HO On A OH O O A O ON
0.00 H.OO OO OO NN OO «Am two A NH OH an A On OOH AN
0.0N O.NO OO ON AO AH OO O ON ON O O As O O ON
O.AO A.OO AO NN OOH AO OO O OH On A HO OH O A AN
.OHOO .OONN, ANO, Ase aNO Asw, ANO‘ ANO ANO ANO NNO ANO NNO, N ANO .Ommm
Nduou OO-OO OAIOO OmuOO OO-ON OOlO OOIOO OOnumO OA-OO OOuom OO-OO OmnON ON-OH OauO «o A
.Imawlcwzw d< d< OO OO d< NO to ma q< ca d< c< d<

.moamamm amN oufim wow

sump onoumouowx

A

.umam.m

.—
=
=
.—
.—
~—
.-
.—
.—
=
=
=
.-
=
.-
.-
.-
.—
=
.-

.OONO

—-
:
.OOHO
.—

.m

=
.Hom

'oumHmoA
mam

an
on
mm
mm
AN
0N
mm
«N
mm
mm
HN
ON
mg
mg
NH
ca
mH
OH
mH
Na
AH
OH

NLnOl‘wCh

 

.Ofi
.NOO

.m maan

7
1

pmwsaoxo ouoz chme Hmamvamm monoudm umnu muoz
Houumn mucoaowcmuum :Omuuoo monsoon mmaum>o meaouw Hmaowuamomaoo ummmwaom maom
on amo sump mnoueouowa ouoaeaou

.mOOOHmam weoueouofia ecu scum

.muonuo amsu moamamm N amozuon mooaouommwp use uaomoseou

.Nfivcoee< one aw venom
.moanmu omega Boum waammfia mum mHm>hmucO HmcoOuHmoeaoo maom whomouonu
no can m moanma aO popsaoafi mum wouoouov on mac mowcmso Hmnoaufimoeaoo Hmofiuuo> unmoOwOawOm OHHmoOumO
lumuw :oOSB GO was mawmuw mo oneness mamoamwawfim dOmucoo £oa£3 mesoum HmcoHuHOOQSoo opoueouofia omocu ease

H

uH Home: %Houm
IOmeEH oco men was maaamm manu How usmsomaoo mfisu :O AHo.uuv mommHmMMOp unmofimaawfim haswwe m mmumofiwcfiss

 

 

uO Hops:
%Hmumfiwmsaa mco mew was mamamm mane How unmaomfioo mafia SO Amo.uuv modemmwwap unmowmacmwm m mmumofivsfls

 

 

O.ON O.OO HN HN OH HN OO O HH OH O A A OH OH ON .OOOz.H OO
O.ON H.OO HH HH OO OO ON HH OH O A OH HH O HH AN = OO
OH O.ON O O OH AO ON OH OO O O OH OH A O AN = OO
N.ON O.ON HH HH NN OO AO OO OO A O HH HH A OOH AN .OOHHO.H OO
A O.AH O O OO OH OO O OO O O O OH O OH OH = NO
A.AH O.OO A A «ON OO OH A OO O O OH OH O O ON : HO
O.NN O.OO NN NN A NN OO O ON OH A O OH A A AN = OO
0.0H A.HN OH OH O AH OO O ON O O O O O OOO ON .OOHO.O AO
.OHOO .OOHO, HNO ONO ANO. HNO HMO NOV NOO HNO HOO, AOO (NAM, HNO HNO .Odsw .OOO. .oa
Hmwmw.u .I OO-OO OAIOO OOnOO OOuON OOIO OOuOO OOHIOO OA-OO OOIOO OOnOO OOION ON-OH OHIO O0 A .HOO
OON OOOO dO tO q< OO n< NO NO :4 OO d< OO d4 OO
.mmamamm fiom ouOm you Hmumw maoumouowz .o oHan
0.00 A.HO OO OO OH AN NH O OH AN NH O O O O ON : OO
N.OO O.OO OO OO OH OH ON O OH OH OH OH O O OH HN .OOO2.H OO
O.AN H.OO OO OO NH OH HO O ON OH OH NH O O OH ON = OO
0.00 0.00 OO OO O AH ON O OH ON ON O OH O OH ON .OOHN.O NO
.OHOO JOE HNO 8 QM HNO NOV ONO ONO NNO 8 H5 8 NNO ONO .mfim m3 .8
Hmuou OOuOO OAIOO OOIOO OOION O0-0 OOnOO OOHnOO OAuOO OOnOO O0-00 OO-ON ONIOH OHnO OO O .HOO
.lquuamxfl OO q< OO d< OO no no q< OO OO :< :< OO

.A.OOOOOO O OHOOO

18
since these tests require specific counts rather than percentages.
The average %An values of the total feldspar in each sample are plot-
ted in a triangular diagram (Figure 2).
The means and standard deviations were computed for each composi—

tional group for the clays and sands of core-section 18-3 from Site

299 (Table 9).

Summary of point-Count and microprobe data

In order to facilitate the comparison of appropriate sets of data,
the means and standard deviations of the foregoing analyses are listed
in Tables 7, 8 and 9. Means were compared using the t-test and where
applicable, the Fisher test or Chi-square. Significant differences
(d-.05) and highly significant differences («=.01) are indicated by
one and two asterisks respectively. The histograms in Figure 3 illus-
trate the petrographic and microprobe data at Sites 299 and 301.

Certain correlations between compositional groups and between com-
positional groups and depth below the sea floor were evaluated. The
simple correlation coefficient (r) was computed for each correlation
and tested for significance. Those correlations judged to be signif—
icant (d=.05) and highly significant (fi-.01) are listed in Table 10
for each site. Figure 4 illustrates the correlations of depth with
%monocrystalline quartz and %fe1dspar: n<1.54; %fe1dspar: n>1.54 with
%fe1dspar: n<1.54 and %monocrystalline quartz; and %fe1dspar: n<1.54
with %monocrystalline quartz for Site 299. Figure 5 illustrates the
correlations of %monocrystalline quartz with %fe1dspar: n>1.54 and
%fe1dspar: n<1.54 at Site 301.

Since each.point-count and microprobe compositional group is pre-

sented as a percentage out of 100, a lack of independence between the

19

AV
AV ,1
AV
AV I, ..,., :Site 301
AV '

 

 

 

Figure 2. Plot of the average %An (and %Or) values of the total
probe-analyzed feldspar in each sample. Note that Site
299 is more basic or conversely that Site 301 is more
acidic.

20

Table 7. Summary of point-count and microprobe data for samples at
Sites 299 and 301.

Point-count

 

%monocrystalline quartz
%fe1dspar: n<1.54
%fe1dspar: n>1.54
%total feldspar
feldspar: n>1.54/
feldspar: n<1.54
monocrystalline quartz/
feldspar
monocrystalline quartz/
feldspar: n<1.54

Microprobe

%An0-10
%An10-20
%An20-30
%An30-4O
%An50-60
%An60-70
%Or85-100
%Or40-60
%An0-30
%AnZO-SO
%An30-50
%An50-70
%An50-90
Ayg. %An
-plagioclase
-tota1 feldspar

 

SITE 299

i. 5.
40.7* (6.8)
34.6 (6.5)
24.7* (6.8)
59.3* (6.8)
.75 (.30)
.71 (.18)
1.22 (.33)
i. .e
13 (10)
7 (5)

9 (8)
11 (8)
14 (8)
14 (8)
14* (9)

3 (8)
29 (13)
28 (14)
18 (12)
28** (12)
34** (12)
4o.2** (7)
32.7** (6.5)

SITE 301
i; a.
47.2 (7.8)
33.3 (4.7)
19.5 (4.1)
52.8 (7.8)
.59 (.10)
.94 (.36)
1.48 (.53)
i. .e
14 (12)
7 (5)
13 (5)
10 (7)

5 (3)

6 (7)
31 (15)
6 (7)
33 (11)
29 (10)
16 (11)
11 (8)
11 (8)
29.2 (6.7)
18.1 (5.9)

*indicates a significant difference («=.05) in this component between

this mean and the equivalent mean at Site 301

**indicates a highly significant difference (&=.01) in this component

between this mean and the equivalent mean at Site 301

Table 8.

21

tocene and Late Miocene samples at Sites 299 and 301.

Point-count

%monoxln. quartz
%fe1dspar: n<1.54
%fe1dspar: n>1.54
%total feldspar
feldspar: n>1.54/
feldspar: n<1.54
monoxln. quartz/
feldspar
monoxln. quartz/
feldspar: n<1.54

Microprobe

%AnO-lO
%An10-20
%An20-30
%An30-40
%An50-60
%An60-70
%0r85-100
%0r40-60
%An0-30
%An20-50
%An30—50
%An50-70
%An50-90
Avg. %An
-plagioclase
-total feldspar

 

EARLY PLEISTOCENE

Site 299

i. .2
41.5 (4.7)
33.3 (3.8)
25.3* (6)
58.5 (4.7)
.79 (.27)
.72 (.14)
1.27 (.23)
i. .e
15 (11)
7 (6)
10 (8)
12 (9)
14 (9)
14 (8)
15** (9)

1 (2)
31 (14)
29 (15)
20 (13)
28 (13)
33** (14)

38.2* (6.9)
32.2**(7.1)

Site 301

i. .2
49.5 (10.5)
31.9 (6.7)
18.6 (4.7)
50.5 (10.5)
.59 (.11)
1.06 (.50)
1.67 (.75)
i. .e
15 (16)
4 (3)
13 (5)

6 (6)

5 (4)

6 (7)
39 (14)
4 (3)
33 (15)
24 (10)
11 (12)
11 (9)
11 (9)
28.3 (9.9)
15.7 (6.4)

LATE MIOCENE

Site 299
i. .9
51.2 (3.1)
26.7* (2.3)
22.1 (.9)
48.8 (3.1)
.83 (.04)
1.06 (.13)
1.93 (.28)
i. .e
7 (10)
5 (1)
7 (2)
9 (7)
13 (1)
23 (6)
19 (o)
0 (0)
18* (9)
23 (6)
17 (4)
36 (4)
45 (2)
48.2 (5)
38.1 (2.6)

Summary of point-count and microprobe data for Early Pleis-

Site 301

X

47.2
34.4
18.4
52.8

.53

*indicates a significant difference («8.05) in this component between
this mean and the mean of equivalent age at Site 301

**indicates a highly significant difference (98.01) in this component
between this mean and the mean of equivalent age at Site 301

22

Table 9. Summary of point-count and micrOprobe data1 for clay and
sand samples, core—section 18-3, E. Pleistocene, Site 299.

 

 

CLAYZ SAND3

Po int-count i §_ it: _s
%monocrystalline quartz 42.5 (3.5) 40.1 (3.5)
%fe1dspar: n<1.54 33.8 (2.7) 31.4 (4.6)
%fe1dspar: n>1.54 23.7 (5.4) 28.6 (7.1)
%total feldspar 57.5 (3.5) 60 (3.5)
feldspar: n>1.54/

feldspar: n<1.54 .71 (.22) .96 (.38)
monocrystalline quartz/

feldspar 75 (.11) .67 (.09)
monocrystalline quartz/

feldspar: n<1.54 1.26 (.11) 1.29 (.18)
Microprobe i s i _s_
%AnO-IO 15 (10) 21 (12)
%AnIO-ZO 5 (4) 11 (8)
%AnZO-BO 16 (9) 7 (5)
%An30-40 12 (5) 11 (11)
%An50-60 10 (7) 10 (6)
%An60-7O 17 (10) 12 (6)
%Or85-100 16 (10) 16 (10)
%Or40-60 0 (0) 2 _ (4)
%An0-30 35 (14) 38 (12)
%AnZO-SO 35 (10) 22 (17)
%An30-50 19 (7) 16 (14)
%An50-70 27 (13) 22 (8)
%An50-90 29 (12) 29 (11)
Avg. %An - plagioclase 36.6 (7.9) 35 (4)
Avg. %An - total feld. 30.6 (7.5) 29.4 (5.9)

1Note that no statistically significant differences were found between
the clay and sand samples.

2Number of samples = 9 (samples 13-15 and 19-24).

3Number of samples = 6 (samples 16-18 and 25-27).

SITE 299

Petrographic data

10% 20% 30%

40%

llJLJlllJLlLJLJJJilLI

 

 

 

 

 

 

 

 

Total=100%

.T-‘L—UO

Microprobe data

5% 10% 15%

1111111114111111

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J

Total=100%

 

Or85-100

Or60-85
Or40-6O
Or10-40
AnO-lO

An10-20
An20-30
An30-40
An40-50
An50-60
An60-70
An70-80

An80-90

An90-100

23

SITE 301

10% 20%

30% 40% 50%

L11lililllllllllllllllull

 

 

 

 

 

 

 

 

Total=100%

%monocrystalline quartz
%fe1dspar: n<1.54
%fe1dspar: n>1.54

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5% 10% 15% 20% 25% 30%
llllllLllLlLlllLJlllllLlLLlllll
TotalleO%

Figure 3. Histograms illustrating petrographic data (including altered
feldspar grains) and microprobe data (for all the feldspar
grains analyzed) for Sites 299 and 301 samples. Note that
altered feldspars were excluded from the micrOprobe analysis.

 

24
Table 10. Significant correlations of point—count and microprobe data.

SITE 299 (Number of samples = 33)

 

 

Correlation "r"

depth and %monocrystalline quartz .634**
depth.and %fe1dspar: n<1.54 -.571**
depth and monoxln. quartz/feldspar: n<1.54 .777**
%fe1dspar: n>1.54 and %fe1dspar: n<1.54 -.483**
%fe1dspar: n>1.54 and %monoxln. quartz -.534**
%fe1dspar: n<1.54 and %monoxln. quartz -.482**
%0r85—100 and %monocrystalline quartz .422*

SITE 301 (Number of samples = 8)

 

 

Correlation "r"

%fe1dspar: n>1.54 and %monoxln. quartz -.876**
%fe1dspar: n<1.54 and %monoxln. quartz -.903**
%An0-10 and %monocrystalline quartz .913**
%An0-30 and %monocrystalline quartz .755*

*indicates a significant («=.05) value of "r".
**indicates a highly significant QK=.01) value of "r".

variables may result; this may be especially true for the point-count
data because there are only three components. In this circumstance,
there is a strong bias toward negative correlation between the varia-
bles of the closed array (Chayes, 1962). To remedy this situation,
Chayes suggests the use of the Fisher 2 transformation (Steele and
Torrie, 1960). The z transformation was done on the correlation coef-
ficients of Table 10 and the subsequently performed t-tests confirmed

the statistical significance of the "r"'s listed.

VERTICAL CHANGES IN SEDIMENT COMPOSITION

Site 299
Vertical changes in sediment composition at Site 299 are assumed
to occur where statistically significant differences in a compositional

group exist between a particular sample and the one immediately under

50% 60%

l J

 

 

10%
1
figs Dem
L. :53
P1st.- .64
" 13.5
44.53
L.
Plst.
44.98
145.51
E.
Plst.
145.99
164.52
M
165.79
221
" 221.24
329.54
M
329.96
L. '49501
Mioc. 495.25
Figure 4.

p
-’
"
0’

(7

 

 

 

= %mono quartz
= %fe1dspar: n<1.54
= %feldSpar: n>1.54

Diagram illustrating the correlations of depth with Q and L,
H with L and Q, and L with Q at Site 299.

26

 

 

 

 

10% 20% 30% 40% 50% 60%
L i l l l J
Age Depthgm.)
160.04 -” -L
E.
Plst.
160.26 ,,O”o
177.85
= %mono quartz
= %fe1dspar: n<1.54
= %fe1dspar: n>1.54
M
178.44
317.06 / -/’..’
L. \H \L /0
Plioc.
317.9 ,/ / \-8\Q
1" ~485 39
Mioc. ° ”

Figure 5. Diagram illustrating the correlations of Q with H and L
at Site 301.

27
it (see Tables 3 and 5). These changes are noted in Table 11 for the
sake of clarification; some unenlightening redundant data have been
omitted. Sample 1 contains 44.3% monocrystalline quartz, 40.9% feld-
spar: n<1.54 and 14.8% feldspar: n>1.54; its triangular diagram (Fig-
ure A—l) indicates Or85-100 (11%) and AnO-lO (7%) components with the
rest of the feldspar Spread from An17 to An78.

In most cases, the probe and point-count compositional changes of
Table 11 agree or at least can be rationalized; for example, in the
interval 5-6 an increase in %fe1dspar: n<1.54 can be explained by a
corresponding increase in %0r40-60 even though the increase in %feld-
spar: n<1.54 conflicts with.the decreases in %monocrystalline quartz,
%An0—10 and %An0—30. The microprobe is obviously more sensitive to
feldspar compositional changes than is the microscope (especially as
used in this study) and therefore changes in probe compositional groups
are justifiably more frequent than changes in microscope compositional
groups.

The correlations listed in Table 10 indicate that the percent of
monocrystalline quartz increases and the percent of feldspar: n<1.54
decreases with depth below the sea floor at Site 299; there is also a
negative correlation of %monocrystalline quartz with %fe1dspar: n<1.54.
One might expect a positive correlation of quartz and feldspar: n41.54.
The negative correlation may be explained by a large influx through
time of non-quartz related detrital feldspar: n<1.54 although the ef-
fect of the constant sum data may be influential also. The presence
of this feldspar may be a result of lowegrade metamorphism or spilit-
ization of basic igneous rocks in the source area causing albitization

of Ca plagioclase in the rock; rocks of this type were present in the

28
Table 11. Vertical changes in sediment composition at Site 299.

COMPOSITIONAL CHANGES

Sample

interval Increase Decrease

1-2 %An30-50

2-5 %An30-50

5-6 %fe1dspar: n<1.54; %monocrystalline quartz;
%0r40-60 %An0-10; %An0-30

6-7 %monocrystalline quartz %fe1dspar: n<1.54

7-8 %0r85-100

8-9 %fe1dspar: n>1.54; %monocrystalline quartz
%Or40—60

9—10 %monocrystalline quartz; %fe1dspar: n>1.54;
%An30-50 %0r40-60

11-12 %monocrystalline quartz

13-14 %An20-30; %An0-30 %An60-70

14-15 %0r85-100

15-16 %An10-20; %An50-60 %0r85-100; %An20-50

17-18 %fe1dspar: n<1.54 %AnO-lO

19-20 %An60-70

23-24 %0r85-100 %An30-50

24-25 %An0-10

26-27 %fe1dspar: n>1.54;
%An30-40

27-28 %monocrystalline quartz; %fe1dspar: n>1.54;
%fe1dspar: n<1.54 %An50-7O

28-29 %An50-60

29-30 %An0—10 %An30-50

30-31 %monocrystalline quartz %fe1dspar: n<1.54;

%An0-10
31-32 %fe1dspar: n<1.54 %fe1dspar: n>1.54
33-35 %fe1dspar: n>1.54

29
source area of Site 299 during Neogene time. The negative correlation
of %monocrystalline quartz and %fe1dspar: n>1.54 and the positive one
of %monocrystalline quartz with %0r85-100 are evidence that the data
themselves are legitimate. That is, these last two correlations argue
against the possibility that the negative correlation of %monocrystal-
line quartz with %feldspar: n<1.54 is simply due to the influence of
a quartz-rich, feldspar-poor source (e.g., a quartz arenite). A large
number of the feldspar: n<1.54 grains are altered and were therefore
not included in the probe data because good compositional analyses
were impossible to obtain on these grains. Therefore the lack of a
correlation of %AnO—lO or %An0—30 with.%monocrystalline quartz makes
the strongly felt presence of a sedimentary-type source conceivable

but improbable.

Site 301

No significant correlations of any compositional groups with depth
were obtained at Site 301; this was most likely due to the small num-
ber of samples (8) procured. However, highly significant negative
correlations of %monocrystalline quartz with %fe1dspar: n41.54 and
%fe1dspar: n>1.54 are present at this site also; the latter can be in-
terpreted in the same manner as at Site 299 and the former is again
evidence that the data are legitflmate. The positive correlations of
%An0-10 and %An0—3O with.%monocrystalline quartz also support the leg-
itimacy of the data.

Vertical changes in sediment composition at Site 301 are assumed
to occur where statistically significant differences in a compositional
group exist between a particular sample and the one immediately under

it (see Tables 4 and 6). These changes are summarized in Table 12.

30
Table 12. Vertical changes in sediment composition at Site 301.

COMPOSITIONAL CHANGES

Sample

interval Increase Decrease

37-38 %monocrystalline quartz

%An0-10

38-41 %monocrystalline quartz

41-42 %An30-50

42-43 %An30-50

43-44 %fe1dspar: n>1.54; %monocrystalline quartz;
%Or40-60 %An0-10

Sample 37 contains 64% monocrystalline quartz, 23.6% feldspar: n<1.54
and 12.4% feldspar: n>1.54; its ternary diagram (Figure A-34) indicates
predominant components of Or85-100 (29%) and AnO-lO (38%) with the re-
maining feldspar spread from An10 to An66.

Fewer compositional changes occur at Site 301 in large part due to
the paucity of samples and therefore the correspondence of probe-micro-

sc0pe changes cannot be properly evaluated.

LATERAL CHANGES IN SEDIMENT COMPOSITION

Table 7 presents a summary of microprobe and point-count data for
Sites 299 and 301. The large compositional variations within the sam-
ples at each.site prevent many compositional differences between the
sites from being recorded. There are however, statistically signifi—
cant differences in %monocrystalline quartz, %fe1dspar: n>1.54, %0r85-
100, %An50-90, average %An-plagioclase and average %An-total feldspar
between Sites 299 and 301 (this last difference is illustrated in Fig-
ure 2); Site 299 sediments on the average contain higher percentages

of %fe1dspar: n>1.54, %An50—90, average %An-plagioclase and average

31
%An-total feldspar and lower percentages of %monocrystalline quartz

and %0r85-100 than do Site 301 sediments.

Late Miocene

Table 8 contains a summary of point-count and probe data for Late
Miocene and Early Pleistocene samples at Sites 299 and 301. The small
number of samples of Late Miocene age (2 for Site 299 and 1 for Site
301) preclude many statistical comparisons from being made. However,
Site 299 contains less feldspar: n<1.54 and less %An0-30 than Site 301.
Some statistically non-significant differences between the two sites
are: Site 299 contains higher percentages of %fe1dspar: n>1.54, aver—
age %An—plagioclase, average %An-total feldspar and %An50—90 and a

lower percentage of %0r85-100 than Site 301.

Early Pleistocene

 

Early Pleistocene sediments at Site 299 contain less %0r85-100 and
higher percentages of %fe1dspar: n>1.54, %An50-90, average %An-plagio-
clase and average %An-total feldspar than do Site 301 sediments of the

same age (Table 8).

VERTICAL PROVENANCE VARIATIONS

The vertical changes in sediment composition that were outlined in
a previous section can be related to changes in source area with the
aid of generalized geologic maps of the areas bordering the Sea of Ja—
pan. Site 301 does not appear to be influenced by any one particular
trough.entering the Sea of Japan (see Figure 1) and not many samples
were obtained from this site. Therefore Figure 6 (small scale geologic

map) was used to infer tentative source areas for sediments at Site

 

 

 

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33
301. Sediments reach the Yamato Basin primarily through the Toyama
trough in the form of turbidity flows (Figures 1 and 6). Although
contour-following bottom currents have been shown to influence deep-
sea sedimentation (Heezen et al., 1966) they are probably not present
in the Yamato Basin. Contour—following currents (where present) are
restricted to the western sides of ocean basins and have not been re-
ported in enclosures as small as the Sea of Japan. Furthermore, the
sand deposits of contour-following bottom currents (contourites) are
well sorted, have sharp upper and lower contacts and contain less than
5% matrix (42p) (Bouma and Hollister, 1973). The sand as well as other
beds at Site 299 are poorly sorted, have gradational contacts and con-
tain greater than 10% matrix thus precluding their classification as
contourites. For these reasons and because such a large number of
samples (33) were procured from Site 299, Figure 7 alone (large scale
geologic map of the Toyama region) was justifiably used to delineate

source areas for these sediments.

Site 299
Late Pleistocene—Holocene

Sample
interval Provenance variations

1 - acid source: rock type 1 (tip of Noto peninsula, E side
of Toyama Bay, 35-80 km. SW of Toyama Bay); rock type 2
(large exposure 50—100 km. S of Toyama Bay, a few iso-
lated outcrops just W'of this region).

intermediate source: rock type 5 (numerous outcrops in
central and eastern part of Toyama); rock type 6 (Sado
island, Noto peninsula and numerous outcrops 30-100 km.
SW of Toyama Bay); rock type 8 (large exposures 15 km.
SE and 25—50 km. S of Toyama Bay).

basic source: rock type 9 (isolated outcrops 35 and 65
km. ESE of Sado island); rock type 10 (2 exposures 20-25
km. S of E side of Toyama Bay).

1—2 - decrease in intermediate source: rock types 5,6 and 8 (as
located in Sample interval 1*).

DWNH

O‘U‘I

 

 

 

 

 

 

 

- Neogene acid extrusives 7 - Cretaceous interm. extrusives
- Cretaceous acid extrusives 8 - Paleozoic schists and
- Miocene acid-interm. intrusives gneisses
- pre-Miocene acid-interm. 9 - Neogene basic extrusives
intrusives 10 - pre-Tertiary basic-ultrabasic
- Quaternary interm. extrusives intrusives
- Neogene interm. extrusives
(including green tuff) unnumbered - sedimentary rocks

Figure 7. Generalized geologic map of the Toyama region of Honshu,
Japan showing igneous and metamorphic rock types (modified
from Geological Survey of Japan, 1956, 1964).

Sample

interval

2-5
5-6

6-7

7-8
8-9

Sample

interval

9-10

11-12

13-14

14—15
15—16

17-18

19-20
23-24

24-25
26-27
27—28

28—29

35

Provenance variations
increase in intermediate source: rock types 5,6 and 8.

increase in intermediate source: rock types 5 and 6 (es-
pecially green tuff of 6).

influence of a sedimentary source (any of the unnumbered
regions of the map area).

decrease in quartz-poor, acid—intermediate source: rock
type 6 (especially green tuff area).

increase in acid source: rock types 1 and 2.

increase in intermediate-basic source: rock types 5,6 and
8; rock types 9 and 10.
decrease in acid source: rock types 1 and 2.

Early Pleistocene

Provenance variations

 

decrease in basic source: rock types 9 and 10.
increase in intermediate source: rock types 5 and 6.

increase in sedimentary source (as located in Sample in-
terval 6-7).

increase in acid-intermediate source: rock types 1 and 2;
rock type 3 (few isolated exposures in west-central part
of map area); rock type 4 (numerous exposures in NE cor-
ner of map area, numerous exposures 25-50 km. S and SSE
of Toyama Bay); rock types 5 and 8.

decrease in basic source: rock type 9.

increase in acid source: rock types 1 and 2.

increase in intermediate source: rock types 3,4 and 8 (as
located in Sample intervals 13—14 and 1).

decrease in acid source: rock types 1 and 2.

increase in basic source: rock type 9.

increase in intermediate source: rock types 5,6 and 8.
decrease in acid source: rock types 1 and 2.

increase in basic source: rock type 9.

increase in acid source: rock types 1 and 2.
decrease in intermediate source: rock types 5 and 6.

increase in acid source: rock types 1 and 2.
increase in intermediate source: rock types 5 and 6.

increase in acid source: rock types 1 and 2.
decrease in basic source: rock type 9.

increase in basic source: rock type 9.

36
Sample
interval ‘Provenance variations

29-30 — increase in acid source: rock types 1 and 2.
decrease in intermediate source: rock types 5 and 6.

30-31 - increase in sedimentary source (as located in Sample in-
terval 6-7).
decrease in acid source: rock types 1 and 2.

31—32 — increase in acid source: rock types 1 and 2.
decrease in basic source: rock types 9 and 10.

Late Miocene

 

 

Sample

interval Provenance variations

33-35 - increase in intermediate-basic source: rock types 5,6,9
and 10.

*locations of all rock types are given in Sample interval 1 unless
otherwise indicated.

Site 301

Turbidite sediments reach the Japan Basin Via numerous troughs (see
Figure 1). Since there are more possible source areas for Site 301
sediments, the delineation of these source areas cannot be as specific
here as at Site 299; and therefore a more general small scale geologic

map (Figure 6) was used to deduce provenance variations.

Early Pleistocene

Sample
interval Provenance variations

37 - predominant acid source: rock types 1,2,5 and 6 in the
Yamato Basin—Toyama trough area; rock types 2 and 5 in
the Mbgami trough areaCbetween Oga and Sado); rock types
6 and 7 along W margin of Tartary trough (coast of Prim—
orye); rock types 2 and 3 in the Genzan trough area (ad-
jacent to Korea).

weak intermediate-basic source: rock types 12 and 13 in
the Toyama trough area; rock types 12 and 13 in the Mo—
gami trough.erea; rock types 12 and 13 along the E mar-
gin of the Tartary trough (coast of Hokkaido); rock type
10 along W side of Tartary trough.

37
Sample
interval PrOVenanCe variatiOns
37-38 - decrease in acid source: rock types 1,2,5,6 and 7 (as lo-
cated in Sample interval 37).

38-41 - decreasing influence of a sedimentary source (any of the
unnumbered regions near the major troughs) or a quartz—
rich metamorphic source: rock type 11 in Genzan trough
area.

41-42 — decrease in intermediate-basic source: rock types 12 and
13 (as located in Sample interval 37).
Late Pliocene

Sample
interval ProvenanCe variations

42—43 - increase in intermediate-basic source: rock types 12 and
13 (as located in Sample interval 37).

43-44 - decrease in acid source: rock types 1,2,5,6 and 7 (as lo-
cated in Sample interval 37).
increase in basic source: rock types 13 and 14 in the Toy-
ama trough area; rock type 13 in Mogami trough area;
rock types 13 and 14 along the E margin of the Tartary
trough; rock.types 14 and 15 along the W margin of the
Tartary trough; rock type 14 in the Genzan trough area.

LATERAL PROVENANCE VARIATIONS

The lateral changes in sediment composition that were outlined in
a previous section were related to changes in source area with the aid
of Figures 6 and 7. Contributions from a basic source are definitely
more influential at Site 299 than at Site 301. This seems reasonable
considering that Site 299 is close to an island arc while Site 301 is
closer to a continent. Source areas for the Toyama, Mogami and Tartary
troughs are similar in nature; however, source areas for the Genzan
and Tshushima troughs contain much less basic and far more quartz-rich
rocks. Presumably, Site 301 sediments receive no preferential sedimen-

tation from any of the troughs feeding the abyssal plain. The fact that

38

sediments are more basic at Site 299 than at Site 301 may indicate
that the Genzan and possibly the Tshushima troughs contribute more
sediments to the Japan Basin than do the other major troughs. Late
Miocene and Early Pleistocene comparisons between Sites 299 and 301

follow the same trends as the overall comparisons listed above.

FLYSCH SANDS AND CLAYS

Table 9 contains a summary of data for Early Pleistocene clay and
sand samples from Site 299. No statistically significant differences

in composition could be found between the clays and sands.

CONCLUSIONS

1 — The increase of %monocrystalline quartz with depth at Site 299
indicates that sedbment contributions from a quartz-rich source
decreased through Neogene time. Since there does not appear to
be much change in acid igneous activity in the Toyama area during
Neogene time, a presumption is made that this area was closer to
a quartz-rich source in Late Miocene time and gradually was re-
moved from that source. That is, Late Miocene Japan was closer
to Asia or possibly the granitic Yamato rise acted as a source

area at this time.

2 - This increase of %monocrystalline quartz with depth would seem
to refute Sychev and Snegovsky's (1976) hypothesis that the Japan
Sea is a relict ocean basin with no relative displacement of the
Japanese islands from the Asian continent. This is consistent

with the rifting hypothesis for the origin of the Sea of Japan.

39
3 - The decrease of %fe1dspar: n<1.54 with depth at Site 299 and the
negative correlation of %monocrystalline quartz with %fe1dspar:
n<1.54 indicate an increasing contribution of a quartz-poor,
feldspar :nx1.54 source through Neogene time. This probably re-
flects the increasing contribution of the Neogene green tuff
through time. It could also reflect the increasing albitization

of Ca plagioclase in the basic igneous rocks of the source area.

4 - The negative correlation of %monocrystalline quartz and %fe1dspar:
n<1.54 at Site 301 may indicate that the Neogene green tuff of
the Toyama region served as a source area for Japan Basin sedi—

ments.

5 — The Genzan and possibly the Tshushima troughs are more effective
in delivering sediment to the Japan Basin than are the Toyama,

Mogami or Tartary troughs.

6 - Turbidity currents rather than contour-following bottom currents

are responsible for the deposition of sands in the Yamato Basin.

7 - Complex provenance variations can be deciphered if enough is known
of the geology of the source area and if specific compositional

determinations can be.made.

8 - Feldspar is a valuable provenance indicator because of its chem-
ical variability, although the albitization of Ca plagioclase may
confuse interpretations (this may be especially true in lithified

flysch).

9 - The examination of very fine sand-coarse silt size mineralogy is
worthwhile because this size class is a convenient one to work

with.and is present in sufficient quantity in both clays and sands.

40

10 - The laboratory techniques used in this study allow sufficient in-

formation to be obtained from miniscule samples.

11 - No compositional differences exist between the silt in flysch
sands and clays; therefore clays rather than sands should be used
for petrographic studies because of their greater availability

and because presumably less diagenetic mineral alteration occurs

in clays.

APPENDIX

41

 

 

   

WA,

Ab . .
a .9
‘4' t?

0 Q Q Q Q
s «9 3’ s 3’ 8’ 5°
‘1’ ‘7 v V ‘17 V9

Figure A-l. Compositional plot of 27 feldSpar grains in sample 1.

42

Or

A
AVA
Or85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
Or4 0 AVAV
AVAV
AVAV
AVAV
AVAV
AVAV
V Y

Q Q Q
s s «a p 9
c c c
v V- V’ V7

.5

 

Q
.9 4° ~° 8°
V? v v9 v

Figure A-2. Compositional plot of 24 feldspar grains in sample 2.

43

 

Figure A-3. Compositional plot of 27 feldspar grains in sample 5.

44

 

Ab AAA/\ANWWVWAAAAAAA A.

Q Q Q Q Q
s a? 3’ g 3’ 3° .9

A? e
v V we?

Figure A-4. Compositional plot of 29 feldspar grains in sample 6.

45

 

Ab .. . O .0 t a 04" An

Q Q 0
2° 9’ s s :2 g? s ,9 4°
‘2' O? '9' x9 V v V? ‘3' V?

Figure A-5. Compositional plot of 30 feldspar grains in sample 7.

46

 

Ab ’

 

o o
‘o t? ,9 3°
V9 {:7 5:

~29

:9
Y’

4040

Figure A—6. Compositional plot of 25 feldspar grains in sample 8.

An

47

 

Figure A—7. Compositional plot of 26 feldspar grains in sample 9.

48

 

Ab ‘ ' . . . ' ' ' An

0 o
s 3 9° :2 A? e 3° 3°
‘19 Q ‘1' “V v .5 v v

Q
3"
V. ‘V

Figure A98. Compositional plot of 25 feldspar grains in sample 10.

49

 

._ AA

s .9
V" 5:9

40)b

Figure A-9. Compositional plot of 34 feldspar grains in sample 11.

50

Or

A
AVA
0r85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
Or4 0 AVAV
AVAV
AVAV
AVAV
AVAV
AVAV
V V

 

Abm ' ' - An

0 Q Q Q
3' 3 3’ g
‘7 V’ V

0
8 .1? «° 8’
V’ V v; V9 T

3°
'8'

Figure A-lO. Compositional plot of 27 feldSpar grains in sample 12.

51

Figure A—ll. Compositional plot of 25 feldspar grains in sample 13.

52

 

Ab u. . - . ' An

 

<3 0
5° s g? .9 :3 g9 s a g?
y t9 ‘1' 85' V V t9 V v

Figure A—12. Compositional plot of 15 feldspar grains in sample 14.

53

 

Ab '1'.

An

 

‘Q
Q Q Q %
Q Q Q) ‘0 I\
Q Q n, V ¢ c C’
N, c xv
we ‘53" .5 v5 O O. v

3°
Y'

15.
Figure A—13 Compositional plot of 25 feldspar grains in sample

54

 

Ab 0' 1 . . 0 .0 An
o Q Q Q

8’ ~° :9 5° 3’ .‘9 5°
W 55 V” v V '6' v9

Figure A-14. Compositional plot of 16 feldspar grains in sample 16.

55

 

Ab '

An

 

O9 9 «.9 9 4° .9 o «8
o' 3? £7 3? 9' .c 3} <0
V’ v V’ v V v v 9:

3°
V

Figure A-15. Compositional plot of 18 feldspar grains in sample 17.

56

 

Ab

 

o
'3 Q a? 9 ‘0 O3 ‘3 a?
e .9 c 8 9 . 9 9
V’ v V’ v V ‘6' 949' ‘7

An

33°
V

Figure A-16. Compositional plot of 16 feldspar grains in sample 18.

57

 

 

 

WA,

3°
Y.

Q
29
v

Q Q Q Q Q
8' 9° 3’ g: £9 9° 3°
v V? v v V? V

Figure A-l7. Compositional plot of 30 feldspar grains in sample 19.

58

 

Figure A-18. Compositional plot of 17 feldspar grains in sample 20.

59

 

Ab - - " '- ' An

 

o 0 o
3‘? q? 3: v9 I? 35) 3° :59 3?
V' O? ‘V i? 'V V’ O? ‘V ‘v

Figure Ae19. Compositional plot of 19 feldspar grains in sample 21.

60

Figure A-ZO. Compositional plot of 27 feldspar grains in sample 22.

61

 

A.
“'7i'7 :.%.. ' . An

Q Q 0
9° «9 :9 v9 .59 s? «° 2° g?
V V? V’ we ‘2' v? V ‘2'

Figure A-21. Compositional plot of 27 feldspar grains in sample 23.

62

 

Ab:
Q Q
3 .9 o» \S 3’
‘7 r: ‘7 <7 v
V’ v V V'

/\/\/\ An
3?
‘2'

Figure A-22. Compositional plot of 28 feldspar grains in sample 24.

63

Or

A
AVA
Or85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
Or40 AVAV
AVAV
AVAV
AVAV
AVAV
AVAV
V V

 

Ab . ' ' ' . ° ' An
Q Q
39 re 23’ $ :2 gs? ,9 go 3‘?
v V9 V;- V? V V ‘4? V" V

Figure A-23. Compositional plot of 20 feldspar grains in sample 25.

64

 

Ab ~ ‘ '- ' ' An

0 Q o
S 3 m a w a «o co 0,0
47 o 47 1;. ‘7 c ‘7 <7
‘2' V7 Y‘ Y’ V V’ V9 ‘7 ‘2'

Figure A-24. Compositional plot of 20 feldspar grains in sample 26.

65

 

 

to O . Q 0
Ab .- Q o a? ”9 49° :9 $9 V; V;
"I W Q 0 V V v
V9 {=7 V’ v

1e 27.
feldspar grains in samp
itional plot of 23

Figure A—25. Compos

An

66

Or

A
AVA
01.85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
Or40 AVAV
AVAV
AVAV
AVAV
AVAV
GVAV

Ab WWW/WW An

0
Z?
w

 

o
'3 9 03° Q k? Q Q) o?
c 3’ q A? 47 '\ ¢ 1;
V v V w ‘3' ‘29 V’ “v

Figure A-26. Compositional plot of 18 feldspar grains in sample 28.

67

Ab 4 . . : ' : - An

 

o o
S9 ‘9 3’ «‘3 :9 o?
v V? w .5 w ‘29

4qq0

Q
3’
V!

Figure A-27. Compositional plot of 26 feldspar grains in sample 29.

68

 

Ab t. o . 0 ° . 0 An

4Q3b

:2 (e
V w?

4040

Figure A-28. Compositional plot of 18 feldspar grains in sample 30.

69

 

 

Ab .. .'
Q Q Q
g9 a? ,1.» x? :3 :9 «° :9 g?
V w? V V? V ‘v V9 V’ v

Figure A-29. Compositional plot of 29 feldspar grains in sample 31.

An

70

 

 

AAAAAAAAAAAAAAAAAAA
Ab VVVVVVVVVVV-VVVVVVV An

Figure A—30. Compositional plot of 24 feldspar grains in sample 32.

71

Or

A
AVA
Or85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
Or4 0 Av"
AVAV
AVAV
AVAV
AVAV
AVAV
V V

 

Ab "0 . . ' O 0. a An

0 0 o
S .9 ., .9 ., «9 e «c o?
47 ¢ 4*: 47 ¢ I: Q. ‘7 c:

Figure A-31. Compositional plot of 26 feldspar grains in sample 33.

72

 

 

VV
AAAAAAAAAAAAAAAAAAA
Ab WVVVVVVVVVVV An

Figure Ar32. Compositional plot of 21 feldspar grains in sample 35.

73

Figure A-33. Compositional plot of 26 feldspar grains in sample 36.

74

 

A
"" An

Ab ~-

Figure A-34. Compositional plot of 24 feldspar grains in sample 37.

75

AA
“""’ An

Figure A—35. Compositional plot of 27 feldspar grains in sample 38.

76

Figure Ar36. Compositional plot of 29 feldspar grains in sample 41.

77

 

Figure A-37. Compositional plot of 16 feldspar grains in sample 42.

78

AA
"7V"’ An

Figure A-38. Compositional plot of 27 feldSpar grains in sample 43.

79

Or

A
AVA
Or85 AVAV
AVAV
AVAV
AVAV
AVAV
Or60 AVAV
AVAV
AVAV
AVAV
0r40 AVAV
AVAV
AVAV
AVAV
AVAV
AVAV
V V

 

Ab '- - " °~ An

0 Q Q Q
3’ W 3’ 3’
v V? v V

 

o 0 o
g“? .‘9 «° 2° .9
w 7 s? V V

Figure A-39. Compositional plot of 27 feldSpar grains in sample 44.

8O

 

 

VV
AAAAAAAAAAAAAAAAAAA
Ab .VWVVVVVVVVVVVVV An

Figure A-40. Compositional plot of 27 feldSpar grains in sample 45.

81

 

Ab -' '. . . " “ An

0 Q
5? «e g? 6? :9 :9 «° 2° :9
‘7 V? V V? V ‘V V9 V" V’

Figure A-41. Compositional plot of 28 feldSpar grains in sample 48.

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