SHAPE RESPONSE OF PLEiSTOCEN-E -_ AND RECENT SEDIMENT--CHUKCH| SEA: A FOURIER ANALYSIS Thesis for the Degree of M. S. MICHIGAN. STATE UNIVERSITY JAMES WATON KENNEDY 1972 . LIBRA. Y 1 “55:! Michigan State University 83331146 BY HUAG & SUNS’ BflUK BINDERY INC. LIBRARY BINDEBS ABSTRACT SHAPE RESPONSE OF PLEISTOCENE AND RECENT SEDIMENT--CHUKCHI SEA: A FOURIER ANALYSIS BY James Waton Kennedy A Fourier analysis of grain shape was performed to determine if sand grain shape is a variable which will display some general utility in making inference about provenance, transport and deposi- tional environment of Holocene sediments in the Chukchi Sea. The shape, expressed as amplitudes of a Fourier series, was analyzed using both a pattern recognition-clustering program, ISODATA, and a complex analysis of chi-square contingency tables. The results indicate that the shape variable is extremely sensitive to changes in provenance, transport and depositional envir- onment o SHAPE RESPONSE OF PLEISTOCENE AND RECENT SEDIMENT-- CHUKCHI SEA: A FOURIER ANALYSIS BY James waton Kennedy A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Geology 1972 ACKNOWLEDGMENTS I gratefully acknowledge Dr. Joe S. Creager, of the University of'Washington Department of Oceanography, and National Science Found- ation Grant GA 28002, for providing me with the samples on which this research was based. Dr. Creager's comments, criticisms and suggestions were invaluable to the success of this project. I also extend grateful appreciation to Dr. Robert Ehrlich, my thesis advisor, for his tireless effort and enthusiasm throughout the entire project. Without his constant encouragement and helpful discus- sions this project would have taken considerably more time. Dr. Bernhard Weinberg, of the Computer Science Department at Michigan State was extremely helpful in working out and assisting in many of the computer programs used. Thanks also go to Drs. Sam Upchurch and Robert Anstey, my committee members, whose criticisms were quite helpful. Last, but not least, I wish to express my sincere gratitude to my wife, Sharon, for her patience and understanding throughout the entire period, during which the project often took precedence over the family. ii TABLE OF CONTENTS Contingency Tables LIST OF TABLES . . . . . . . LIST OF FIGURES . . . . . Chapter I. INTRODUCTION . . . . . II . GENERAL STATEPENT OF THE PROBIEM III. METHODS . . . . . . . IV. RESULTS . . . . . . . Hierarchy I . . Hierarchy II . V . CONCLUSIONS . . . . . LIST OF REFERENCES . . . . . .APPENDICES A. ISODATA Cluster Center Analyses B. Numerical Values for Chi-Square C. Locality Maps . . . . iii Page iv 11 18 18 21 24 26 27 32 34 LIST OF TABLES Page Results of contingency tables for hierarchy I. . . 15 Results of contingency tables for hierarchy II . . 16 Sample designations as related to contingency table hierarchies and sample locations . . . . . . 17 Numerical values for chi-square contingency table (hierarchy I). . . . . . . . . . . . . 32 Results of contingency tables (hierarchy II). . . . 33 iv LIST OF FIGURES Figure Page 1. General location map of Chukchi Sea region . . . . 2 2. Modern bathymetry of Chukchi Sea . . . . . . . 6 3. Pre-B sand bathymetry of Chukchi Sea . . . . . . 7 4. Schematic current pattern with south wind . . . . 9 5. Schematic current pattern with north wind . . . . 10 6. Map showing core locations . . . . . . . . . 14 7. ISODATA cluster center analysis (harmonic 2; all locations except location 1). . . . . . 27 8. ISODATA cluster center analysis (harmonic 10; all locations except location 1). . . . . . 28 9. ISODATA cluster center analysis (harmonic 14; all locations except location 1). . . . . . 29 10. ISODATA cluster center analysis (harmonic 18; all locations except location 1). . . . . . 30 11. ISODATA cluster center analysis for harmonics 2, 10, 14 and 18 at location 1 . . . . . . . 31 12. Map showing locations of most rounded (x) and most angular (o) B sands . . . , , , , , , 34 13. Map showing locations of most rounded (A) and most angular (*) B sands. . . . . . . . . 35 CHAPTER I INTRODUCTION The Chukchi Sea is located to the north of the Bering Strait, between Alaska and Siberia (Figure 1). As shown by Creager and McManus et al. (1969), the surface dispersal mechanisms and charact- eristics are markedly influenced by the strong northward flowing Bering Strait Current, which introduces silts and sands from a Yukon River source to the south into the Chukchi Sea. During the last glacial maximum, sea level was lowered sufficiently to expose all of the Chukchi Sea south of wrangel Island permitting a subaerial erosion surface to deveIOp. As sea-level rose, a transgressive sedimentary sequence was deposited over this surface. Initially the sediment available for dispersal and inclusion in the transgressive sequence was the reworked surface sediment and detrital sediment from the sur- rounding land mass. The main sediment source was the Kobuk and Noatak rivers and their drainage basins (Creager and MeManus, 1965). This sedimentary regime must have changed dramatically after the sill at Bering Strait was breached by rising sea level, permitting establish- ment of the Bering Strait Current and the introduction of its sediment load. The significant change in sediment source should produce a marked change in sediment character within the transgressive sediment .Auowmouu noummv seamen mum “noxaeo no use nowuuooH Managua.-.a mmpuHm 3 sequence north of Bering Strait that identifies the time of intro- duction of first Yukon River sediment. Ehrlich and Weinberg (1970), have shown that grain shape, if characterized exactly, can carry important information concerning both the provenance of sediments and their response to various processes. Assuming this method is effective, then a powerful tool exists for objectively interpreting the sedimentary record in this area. It was toward this end then, that the Chukchi Sea samples were evaluated. CHAPTER II GENERAL STATEMENT OF PROBLEM As part of a more comprehensiVe study of the Holocene history of the Chukchi Sea, a detailed stratigraphy of the last transgressive sedimentary sequence has been formulated (Creager et al., in prepar- ation). 0n the basis of texture, mineralogy, microfauna, subbottom profiles, and radiocarbon dates, the type stratigraphy of the trans- gressive sequence north of the Bering Strait and west of Point Hape consists from the base upwards of a) z-clay--a barren, compacted pre- Holocene sediment separated unconformably from an overlying; b) B-sand-- a basal sand presumably deposited near sea-level along the shores of a large Kobuk-Noatak estuary; c) A' c1ay--an upward fining sediment deposited in gradually deepening water; d) A" silt overlain by A' silt-~upward coarsening sediments postulated as resulting from intro- duction of silt from the south; e) A sand--a sand deposited under fairly stable sea-level conditions. Immediately north of Bering Strait the A sand is interpreted as part of a northward moving depositional front associated with Bering Strait Current. Elsewhere the A sand is believed to be reworked basal sand or of local derivation. Clearly, sediment in the Chukchi Sea has been affected by a variety of provenance, transport and depositional effects. The sedi- ment emanating from the Kobuk-Noatak and Yukon drainages have different S provenances. In addition these sediments have undergone differing degrees of ice action (perms-frost, sea or glacial ice). During transport much of these sediments suffered transportation abrasion on beaches and in rivers. Sediments affected by some or all of these factors, some of which involve the Opening of the Bering Strait, are now present in the Chukchi Sea. Thus, if Fourier shape analysis results indicate a lack of significant difference between samples, this will tend to reflect more upon the adequacy of the method, rather than a high degree of homogeneity in the provenance and history of the samples. Alternatively, the presence of significant differences between samples would permit useful interpretations relative to the deposi- tional history postulated in the stratigraphic sequence presented above. Significant differences do, in fact, exist. However, because of the small number of samples, a detailed explanation for these differences cannot now be undertaken. Samples were collected to test hypotheses concerning past and present sedimentary provenance and transport hypotheses. Bathymetry, Paleobathymetry and Currents Comparison of the present bathymetry (Figure 2) with the paleobathymetry of the pre-Holocene transgression surface (Figure 3) clearly indicates the significance of the Bering Strait Current derived sediment in changing the bathymetry of the Chukchi Sea conti- nental shelf surface north of Bering Strait. The paleobathymetric sill had depths of 50-52 meters but the modern sill is at depths of .Auowmmuo nouns «mucous a“ mu30ucoov mom wsoxsnu mo muuuahnuwn vase nuoumuu.m umDUHm 46-48 meters. The filled valley south of Cape Thompson (Figures 2, 3) is related to a previous lower sea level--Kobuk-Noatak delta (Creager and McManus, 1967). In deciphering the transgressive history of the Chukchi Sea sediments it is of permanent importance to: (1) specifically identi- by, if possible, each sand unit as either a wave reworked shallow- water transgressive sand or a deeper-water current transported advancing depositional front sand; and (2) identify characteristics of a sedi- ment which can place its source and hence identify the onset of sedi- ment contribution by the Bering Strait Current (Figures 4 and 5). It is of interest, then, to examine two separate analytical hierarchies in the contingency tables, in order that both an overall A-B contrast and overall between A and between B comparisons can be made. Addition- ally, individual A-B comparisons and between-core contrasts are use- ful. I79)" I76' I74’ 172' I79' I6? I66’ l64' ICE" 160' |58° l56’ I, I I I I I I I I I I 72-- . 1 72' WRANGE L ' ISL mo 1 I». I .- "- ' I ALASKA .,\. II .0"! 911/!" 5011M? 4.. we.“ {MINCE C: \‘chJ'U av .6“. 5T. LAWRENCE ISLAND ,7, .30 ::_.> WIND 02*- -—-‘I'-' SURFACE CURRENTS —~ '1'.) BOTTOM CURRENTS _J l l L i l ,. I71)“ I76" I74. |?l‘. I 7"” N-‘i' Hui)" It, 3“ H 1'" 9|..." 159' .56. K'LOML— 1L- RS FIGURE 4.--Schematic current pattern with south wind (after Creager). 10 178° 176’ ”I." l?2’ I T {o‘i’t‘Eu'GFL v I LAN t: 35/ A I | l. C’r'JG S TAM/7' :\ \ ,1 / 13./wrap SHOAL p I“ r. '— 5") - UWA 72. ALASKA {S .: 70 ".‘:.-':- .: . , ."'r""r‘(’(£/[ .c',).’//I'0 :. e' ;/ M156;- )4"- ~64) SI. LAI’JF'JENC . ISLAIIS. m s 1 _—1 ~_.,> WI 1.49 K'LC'."'L I ERL.‘ “2'? -—-T.‘* SURFACE CURREi-éTS ‘ m, '16? ,.... ”4. -- -:> sorrow CURRERTS .5335. J 1 I L l 1 "or ° 1 L I710 I i.’ 174’ :7?” “'3' ~15" “' m:- Iih" I56' ! FIGURE 5.--Schematic current pattern with north wind (after Creager). CHAPTER III METHODS In evaluating the grain shape of the Chukchi Sea samples, quartz was chosen as the mineral to be analyzed. The reason for choosing quartz, vis-a-vis some other mineral was two-fold. First of all, quartz is ubiquitous. Secondly, quartz shape, because of its presumed lack of cleavage control, was thought to carry a more uniform response history to the processes at work in eroding, trans- porting and ultimately depositing the sediment. The size of the grains analyzed ranged from medium silt to medium sand. In preparing samples for analysis, they were first thoroughly washed, in order to remove most of the fine, organic rich muds holding the grains together. After filtering and drying, the grains were mounted on petrographic slides using a mounting oil. The grains, when strewn on the slide, would then theoretically position themselves in their area of maximum projection. In order that the shape would be characterized as exactly as possible, a camera lucida was used which projected the image of the grain onto a starburst pattern, consisting of 48 radial lines of equal angular spacing, upon which the outline of the grain was traced. An automatic digitizer was then employed which would assign a four digit X, and a four digit Y co-ordinate to each point at which the grain 11 12 boundary crossed one of the 48 radial lines, and punch these co- ordinates in a counterclockwise pattern onto Hollerith cards. It has been shown empirically (Redmond, 1969; Waltz, 1972; Orzeck, 1972), that a sample size of 100 grains is sufficient to overcome any bias due to incorrect digitization of a small number of grains. Once digitized, the first twenty harmonics of a Fourier series were calculated for each grain using a computer program developed by Dr. Bernhard Weinberg (see Ehrlich and Weinberg, 1970, for a discussion A of Fourier analysis of grain shapes). Each sample, consisting of 100 grains, the shape of each des- cribed by values of 19 harmonic amplitudes, was evaluated by a pattern recognition procedure, ISODATA. ISODATA is an acronym for Iterative Self Organizing Data Analysis Technique (A) (Ball and Hall, 1967). ISODATA is a clustering technique for multi-variate data which uses an average response pattern to represent a group of patterns. The endpoint of this technique is to minimize the sum of the squared distances of each data point from the nearest cluster center (Ball and Hall, 1967). The resulting output then, has distributed the grains in each sample into clusters, the mean shape of which can be inferred from an analysis of the harmonic amplitudes of the cluster centers. In addition, a complex analysis of chi-square contingency tables was performed, harmonic by harmonic, using samples as rows, as the harmonic amplitude variation divided into six categories and the columns. The chi-square analyses were performed to identify those l3 harmonics that carried significant shape information and to locate the origin of significant variation within each such harmonic. The degrees of freedom of the total chi-square was partitioned in a manner equi- valent to Kimball's method for partitioning degrees of freedom in chi- square (Kimball, 1954). The chi-square analyses were hierarchical in character. How- ever, two different hierarchies were evaluated; one for harmonics 2- 10, and another for harmonics 11-20. The hierarchy employed for harmonics 2-10 included an overall test for A sands versus B sands, as well as breakdowns to show selected within and between A sand variations. For harmonics 11-20, the hier- archy was selected so as to test for significant variation between A and B sands within single cores, as well as to test for significant between-core variation. Admittedly this procedure injects some ambiguity into data inter- pretation. However, all comparisons must, by definition, be estab- lished before data are inspected. In the case of the Chukchi Sea sam- ples, two hierarchies were of equal interest. Both, however, could not be performed on the same set of data. Therefore, separate hier- archical analysis of harmonics 2-10, and 11-20 were performed. This procedure depends on redundancy between the two sets of data, an assumption warranted by previous studies (Redmond, 1969; Waltz, 1972; Orzeck, 1972). Tables 1 and 2 show the hierarchies employed in the contingency tables. Table 3 shows how the members of the hierarchies are related to the core locations that are dis- played on Figure 6. .AIIII IIIIIIN'IIEI‘I. l... ill-1" Ill} 14 t. FIGURE 6.--Map showing core locations (see TABUE 3 for sample designations). 15 TABLE 1.--Results of contingency tables for hierarchy I. Harmonic Source of ygriapility g,f, Z 3 4 5 6 7 8 _9 10 Total 85 X X A vs B* 5 Within A.vs B 80 X X X Between A 35 X .A 2+3+4+5+ 9+12 vs ArhAa 5 X Al vs A2 vs vs4vs5 vs9vs12 30 X A1 V8 A8 5 X Between A2 3,4,5, 9,12 25 x x A12 vs A2+ 3+4+5+9 5 Between A2,3,5,9 20 x x x A. vs A2+3 +3+5 5 x Between A2,3,4,5 15 X X Between B 45 X indicates significance at 5% level * See TABLE 3 for explanation of A and B sand subscripts. 16 TABLE 2.--Resu1ts of contingency tables for hierarchy II. Harmonic Source of variability d.f. 11 12 13 14 15 16 17 18 19 20 Total 80 X. X X X X Between cores 25 . X Bet. A vs B W/cores 30 X A1 V8 B]. 5 A2 vs B2 5 X X X X X X X A3 V8 33 5 X Ag vs B4 5 A5 vs B5 5 A9 vs 39 5 Tot. bet. unpaired A and B 20 X X X X A8 vs A12 5 X B vs B 7 10 B 10 vs 11 X X A8+A12 V8 B7+B16+B11 5 X X X X X X indicates significance at 5% level * See TABLE 3 for explanation of A and B sand subscripts. 17 “flame x “HIV ae-mweHm Aoamv x Aoav A-~o-flnaa afimv x AH comm 4 coaumooa ouoo was: cannmuwaumuum nomaumasou xznoxnxmumoz m> noxsw :oaumooa ouoo .mmoaumoofi oHasmm was .mownoumuoan ofinmu moaowmwuooo ou voumaou mm mooaumamamov ofimsmmuu.n uqm I” IIIII m > m > 0 I a a o o n I I I I I I I I I I I I I I I I I l I I ’ o ;L__ III D II > a 3 o In on IIIIIIIIIIIIIIIIIIII Quins I cluster —.0 " 80 or - «I ‘. Lilly. . . . . f 39 .o'oT ooo .oos .010 .012 .014 on ma hstmonlc smplltudo FIGURE 8.--ISODATA cluster center analysis (harmonic 10; all locations except location 1). 29 .. l I .. I A3 I as I I .. I I . .. I .5 l I grains/clans: .. I I so I A12 I I sIo I I I , l .. I " I I '__A o oh oh: oh: .064 .060 .060 .607 .600 hstmonlc autumn. 8338 FIGURE 9.--ISODATA cluster center analysis (harmonic 14; all locations except location 1). 30 .. I .. I —- I .3 I s: l .._ I i .. | A5 I A0 I grains/cluster m I I I s10 I III I I .. I - so 37 - so L L -.. .IF .74 .I'. .s'c .is .s'o .54 .s's 3: human“: smpIImdo IIIOO FIGURE 10.--ISODATA cluster center analysis (harmonic 18; all locations except location 1). 31 81s I I DID .I...I...I.... Is II J. an .is is .us is .. I _._ I I II. I 010 §JIII|IIIIIIII V ' T V V V V .0“ one .003 .004 .0“ .000 .007 .000 males [cluster 34 8 O 3. e. O 2 O 9 O §JIIIIIIIIIIII __4. .1 I I 7 '° r v 1’ v V Y ‘ 00‘ .0. .‘2 s'. .20 .2‘ 02. '32 '3. harmonic amplltudo FIGURE ll.--ISODATA cluster center analysis for harmonics 2, 10, 14 and 18 at location 1. APPENDIX B NUMERICAL VALUES FOR CHI-SQUARE CONTINGENCY TABLES 32 TABLE 4.--Numerica1 values for chi-square contingency table (hierarchy I.) Harmonic Source of variability d.f. 2 3 4 5 6 7 8 9 10 Total 85 109.9 80.7 101.3 72.7 102.4 67.7 94.2 112.4 116. A vs B 5 .9 6.9 9.5 10.0 10.0 3.0 5.6 9.2 5. Within A vs B 80 107.0 73.8 91.8 62.7 92.4 64.6 88.5 103.2 110. Between A 35 47.7 37.4 42.4 26.4 39.7 20.3 44.4 46.5 60. A+34%?»- 9+12 vs AI+A8 5 19.7 .7 7.4 4.9 5.4 3.9 5.1 3.5 5. ALI-8V8 A2 vsts4vs5 vs9vs12 30 28.0 36.7 35.3 21.4 34.4 16.4 39.3 43.0 54. A1 vs A8 5 2.5 1.5 4.9 1.7 4.3 2.0 3.0 5.2 12. Between A2.3.4.5. 9,12 25 25.6 35.2 30.4 19.7 30.1 14.5 36.3 37.8 42. A12 V8 A2+ 3H4k5+9 5 1.2 5.5 3.1 4.3 8.3 4.4 2.3 5.8 7. Between A 2.3.4.5.9 20 24.4 30.0 27.3 15.4 21.7 10.1 34.0 32.0 34. A9 vs A2+3 +4+5 5 7.6 7.0 8.3 2.2 2.4 1.8 14.7 4.4 2. Between 42’3’4’5 15 16.8 23.0 19.0 13.2 19.3 8.3 19.3 27.5 32. Between B 45 59.3 36.3 49.1 36.3 52.7 44.3 44.1 56.7 50. * For significant harmonics, see TABLE 1. 33 TABLE 5.--Resu1ts of contingency tables (hierarchy II.) Harmonic Source of variability d.f. 11 12 13 14 15 16 17 18 19 20 Total 80 85.3 93.3 111.7 114.9 101.9 107.6 107.0 107.5 89.8 101.3 Between cores 25 23.3 29.8 20.6 30.4 27.4 32.7 32.9 27.6 31.7 39.5 Bet.AvsB 5 W/cores 30 38.2 43.0 55.2 42.7 36.0 35.9 32.5 36.9 32.5 17.2 A1 vs B1 5 4.3 3.4 1.9 8.7 1.4 7.0 3.5 4.2 2.0 3.5 A2vs B2 5 18.5 17.2 32.8 11.5 14.5 9.2 17.3 14.7 3.3 4.4 A3 vs 33 5 2.8 4.7 5.3. 12.1 7.3 3.6 1.9 1.8 9.7 2.3 An vs 84 5 5.3 6.9 2.0 6.6 7.5 9.6 1.9 5.6 5.7 .5 A5 vs 35 5 4.7 6.4 4.3 .8 2.8 2.0 6.5 1.7 4.4 3.9 A9 vs 89 5 2.5 4.4 8.9 3.1 2.5 4.5 1.4 8.8 7.3 2.5 Tot. bet unpaired A and s 20 13.6 25.4 21.3 25.9 28.5 25.4 33.4 36.9 24.4 33.0 A8 vs A12 5 3.2 5.6 3.7 9.0 9.4 14.1 9.3 9.4 9.3 8.6 B7 vs B10 V8 311 10 7.0 19.1 12.5 10.7 14.3 13.9 14.0 24.4 12.9 16.5 Aé+A12 vs B+B +B 7 10 11 5 3.3 .7 5.1 6.2 4.8 7.4 10.1 3.2 2.1 7.9 * For significant harmonics, see TABLE 2. APPENDIX C LOCALITY MAPS .328» < A3 ustmaw 303 new 9.0 vmvnsou umos mo 23.333 9539? muslin." 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