A QUANTITATIVE CHEMICAL TEST FOR THE ORIGIN OF THE GRANITIC PORTION OF THE POUDRE CANYON MIGMATITE Dissertation for the Degree of Ph. D. MICHIGAN STATE UNIVERSITY PHILIP ARNO MARIOTTI 1 9 7 5 LIBRARY Michigan Sta t0 Unjversitv This is to certify that the thesis entitled A QUANTITATIVE CHmICAL TEST FOR THE ORIGIN OF THE GRANITIC PORTION OF THE PGJDRE CANYON MIGMATITE presented by Philip Arno Max-Lotti has been accepted towards fulfillment of the requirements for Ph D dpgppm Geology WW U Major professor Irmafik BOOK JIIDEBY LIIMRV BINDER: ABSTRACT A QUANTITATIVE CHEMICAL TEST FOR THE ORIGIN OF THE GRANITIC PORTION OF THE POUDRE CANYON MIGMATITE By Phi lip Arno Mariotti Density corrected volume percent measurements show that the Poudre Canyon Migmatite contains an average of 26 weight percent granitic rock. Mincralogies of the metamorphic rocks are compatible with upper amphibolite facies level of metamorphism. Statistical analysis of granitic rocks and metamorphic rocks show no significant elemental interactions on the scale of samples collected 30 inches apart. If such inter- actions are present but were net seen because of too large a sampling interval. re-sampling would have to be done on the scale of inches. Looking at the region as a whole. some of the meta- morphic rocks can be seen to be granitized when compared with the main population. They show increases in biotite normative Or relative to the ungranitized population. Twenty-six of the 41 granitic rocks (63%) fit a magmatic fractionation.trend that could be expected at pressures of l to 2 kilobars. Since generally accepted estimates of amphibolite facies pressures are in the neigh- borhood of 5 to 8 kilobars. it is concluded that these 26 granitic rocks are the result of igneous intrusion that post-dates the main episode of metamorphism. By forming a biotite (annite-phlogopite) prior to the calculation of normative orthoclase. a biotite norm has been developed to adjust the normative mineralogy of aluminous and siliceous metasediments so that it more closely resembles the mode in amphibolite grade rocks. To the degree to which the profound lithologic and chemical heterOgeneity found in this study are represent- ative of sedimentary and metasedimentary piles in general. melts forming from such rocks. if they are considered to be sources of plutonic masses of granitic rocks. must be thoroughly homogenized after separation from the pile. Melting of sediments and metasediments should bring about granitic magmas that first precipitate quartz during fractionation. This is in opposition of the trends normally observed in plutonic masses of granitic rock. A QUANTITATIVE CHEMICAL TEST FOR THE ORIGIN OF THE GRANITIC PORTION OF THE POUDRE CANYON MIGMATITE By Philip Arno Mariotti A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Geology 1975 ACKNONLEDGMENTS I would like to thank Dr. Harold Stonehouse. my adviser. for his intellectual generosity and helpful suggestions during the course of this study. Tom Vegel and Duncan.Sibley critically read the early drafts of the manuscript and aided greatly the clarity of the presentation. John Hilband “saved the day" more than once with suggestions for the handling of data and its presentation. Without the generosity of Dr. Richard wars. who made the samples and raw field data available. this work could not have been done. I would also like to thank Steve Ewald. Michigan State University's reactor operator. for lending his expertise to the rapid and facile neutron.activationu determination of sodium. ll TABLE OF CONTENTS INTRODUCTION ........................................... LOCATION OF AREA ....................................... LITHOLOGIES AND FIEID OCCURRENCE ....................... SAMPLING AND FIELD MEASURDIENTS ........................ SAMPLES USED ........................................... STATISTICAL ANALYSIS OF CHBdICAL DATA .................. ESTIMATION OF THE BULK ““1110" OF mEMImTITE OOOOOOOOOO0.0000000000000IO TEST FOR COIPOSITIONS. EXPECTED mm mg PARTIAL MELTIm HwEL .OOOOOOOOOOOOOOOOOO..0... THE ORIGIN OF THE GR‘NITIC ROCKS eeeeeeeeeeeeeeeeeeeeeee DISCUSSION eeeeeeeseeseeoeseseeesssceasesoeeseesoseosose REFERENCES CITED esssseeaseooeseesssseeesesoeesesessseee APPENDIX A I SCBPIC Preparation assessessssesseeeseeeeeeeesesees ‘HQIYtICCI TCChnLque. aseessesesssseseeseeeeeeeeeee APPENDIXB . R.'Chmtc‘1 Data 00.0.0000...OOOOOOOOOOOOOOOOOOIOO APPENDIXC correl.c1°n "‘1':th eeeeeeaeeeeeeeeeeeeeeeqeeee‘eeeee APPENDIX D Results of Stepwise Multiple Regression . . . . . . . . . . . APPENDIX E C.ICUIat10n Of the bLOCAt. Horn eeeeeessesseesesese iii 1 9 10 ll 12 15 18 18‘ 24 26 31 33 35 40 46 47 49 Table 1. Comparison of the average composition of all metamorphic rocks with the average comp- osition of the line average metamorphic rocks. Table 2. Comparison of the average composition of the granitic rocks and the line average meta- morphlc rwk. s Table 3. The average bulk composition of the migmatite. Table 4. Comparison of CIPH norm and Biotite norm with actual micrometric mode of a biotite- sillimanite schist. Table A-l. Correlation coefficients and stan- dard errors of estimates of regression lines LIST OF TABLES obtained for the standard rocks. Table A-2. Comparison of the results of chem- ical analysis of this study with the USGS reco- mmended values. iv 14 16 19 22 36 39 LIST OF FIGURES Figure 1. Expected phase relations in anorthite containing 'granite“-water systems under amphibolite facies conditions. Figure 2. a & b. Biotite normative and CIPW norm- ative projections of the bulk composition of the migmatite and the average granitic rock composition. Figure 3. a &.b. Biotite normative and CIPH norm- ative projections of the granitic rocks. Figure 4. a s b. Biotite normative and CIPW norm- ative projections of the line average metamorphic rock. a Figure 5. Schematic illustration of the fraction- ation trend of the granitic rocks and the graniti- aatlon trend of the metamorphic rocks. .0. 8 0.. 23 ... 25 .0. 27 ... 28 INTRODUCTION Migmatites are megascopically heterogeneous rocks composed of portions that are granitic in character and portions that are metamorphic in character. They may be highly folded and contorted or occur as alternating layers of granitic rock and metamorphic rock. They dif- fer frcm what would be called gneissic rocks in that the granitic portion. if separated. is a granitic rock and the metamorphic portion. if separated. is a metamorphic rock. The segregations observed are lithologic while in gneisses the segregations are mineralogic. “...one of the most firmly established facts of metamorphic geology is the close association in the field of highest grade metamorphic rocks and migmatites (Read. 1940).” This world-wide association suggests a causal relationship between granitic rocks and high levels of metamorphic activity. and two alternative hypo- theses--- one being that the granitic material is the result of the metamorphism. the other. that the meta- morphism is the result of the presence of the granitic material. The former suggests an origin of the granitic material in,a closed system. the pre-migmatization.meta- morphic rock by selective fluidization and segregation. l 2 while the latter suggests that the system was open to ad- dition of granitic material. Both hypotheses should be testable employing standard petrologic and geochemical techniques. The open system hypothesis leads to two generally accepted mechanisms for the origin of the granitic por- tion. One involves the direct injection of granitic mag- ma. the other. that the metamorphic rocks have been per- meated by what have been variously described as magmatic Juices. ichor or hydrothermal fluids escaping from a subjacent magma. Such permeation should lead to feld- spathization and blastesis of the metamorphic rocks. If the amount of granitic rock is locally variable. it would be expected that the surrounding metamorphic rocks should be more granitic in character when associated with larger amounts of granitic rock than with smaller a- mounts. This mode of origin should then show either porphyroblasts of feldspar in the field or strong pos- itive correlations between the amount of granitic rock locally present and the $102. A1203. Nazo and K20. the granitOphile elements. in the surrounding metamorphic rocks. Forceful intrusion of a dry granitic magma might show little interaction with the intruded rocks. or. if wet. could produce granitization of the intruded rocks due to vapor transport of alkalis and silica (Tuttle and Bowen. 1958 and Burnaham. 1967). It would 3 be expected that. owing to restricted solubilities of granitic material in a vapor phase (Burnham, 1967). attendant feldspathization and granitization of the surrounding rocks might be of less magnitude than for the magmatic “juice hypothesis. However. since the ef- fects of permeation of such juices are unknown. an estimation of magnitude is not possible. It still might be possible to distinguish which of these two mechanisms has operated if the compositions of the gran- itic rocks themselves are in agreement with experi- mentally established fractional crystallization paths of liquid descent in magmatic systems. Field evidence for the intrustion of magma would include distortion of the foliation at the granitic rock-metamorphic rock contacts and possible crushing of the surrounding rocks. neither of these tests could be interpreted as conclusive since either could conceivably be produced by post-migmat- ization.deformation. Major element correlation analyses of the granitic rock and the surrounding metamorphic rocks could show no correlation. if the magma contained little vapor. or strong positive correlations similar to those expected for the permeation by magmatic juices hypothesis if the magma were wet. Possible mechanisms for in situ origin are metamor- phic differentiation and partial melting. Metamorphic differentiation. whereby the granitic material in the 4 metamorphic rocks becomes segregated into veins. lenses and pods of granitic rock has been suggested by Loberg (1968) and White (1967) however. the process by which this differentiation occurs is unknown. Field evidence for metamorphic differentiation would be the presence of mafic selvedges surrounding the granitic p0rtions (white. 1967) with the selvedge having formed from the selective removal of the granitic component of the rocks. The thickness of the selvedge should be proportional to the amount of granitic rock it surrounds. Chemically. one would expect that there should be inverse correlations between the amount of granitic rock and the granitophile elements in the metamorphic rocks. and therefore the metamorphic rocks should show evidence of de-granitization. Partial melting should show essentially the same ef- fects as for the case of metamorphic differentiation. The only real difference between the two hypotheses is that partial melting indicates that the granitic por- tion formed from a silicate melt of granitic composition that had been derived from the adjacent rocks. The other difference between the two in situ models is that metamorphic differentiation has never been exper- imentally demonstrated on the scale of a few feet under geologically reasonable conditions. while partial melting has been heavily investigated experimentally (Tuttle and '\v 5 Bowen. 1958: Winkler and Von Platen. 1957. i960. 1961. 1962; Luth. g;_§l.. 1964: Von Platen. 1965: Von Platen and Holler. 1966; Piwinskii and Wyllie. 1968; James and Hamilton. 1969: Piwinskii. 1970; Brown. 1970; Brown and Fyfe. 1970; Robertson and Wyliie. 1971: Huang and Wyllie. 1973s and Steiner. g; 31;. 1975). Therefore. one may test the granitic and metamorphic rocks to see if they are in agreement. lgg‘. if the phase relationships suggested by their compositions are consistent with those for the experimental “granite”-water systems. Since the phase relationships in the experimental granitic systems are not as straightforward as it is generally held and because of this one frequently sees erroneous conclusions based on misunderstandings of these relationships (King. p. 231. 1965). a brief sum- mary of the compositional constraints within this system follows. The phase relationships in.the'granite'-water (Q-Ab-OrJn-HZO) system approximate those of a simple binary eutectic with the exception that. in a simple binary eutectic. a liquid with the composition of the eutectic is always presentueither at the end of crystalliz- ation or at the beginning of melting. In the ”granite”- water system a liquid with the composition of the minimum is only to be expected for fractional crystallization of melts already having the composition of the minimum. For melting. liquids will have the composition of the minimum 6 'gnlz if the rocks undergoing melting have nearly the same Or/Ab ratio as that of the minimum itself. The composition of the minimum becomes increasingly Ab rich and 8102 poor as the pressure increases from 1 to 10 kilobars (Tuttle and Bowen. 1958 and Luth g; 31;. 1964). An anorthite component in the plagioclase tends to shift the minimum toward the Q-Or side of the phase diagram relative to its position in an anorthite free system (Von Platen. 1965: Winkler. 1967 and James and Hamilton. 1969). A recent study by Steiner g;_gl.. (1975) at 4 kilobars indicates that the minimum also mi- grates toward the Q-Or side in water undersaturated . 'granite“ewater systems. The location of the minimum is only important in that it determines the path on the cotectic that a liquid pro- duced from partial melting will take as melting progres- ses. For example. for a bulk composition lying to the left of a given.minimum. the melt will begin to form on the cotectic and will proceed to rise up (thermally) on the cotectic away from the minimum with the liquid composition becoming richer in Ab and 0. Under a dif- ferent set of physical conditions. however. the same bulk composition could lie to the right of the minimum. The liquid formed in this case would then migrate away from the minimum toward the Q-Or join. It is clear that the composition of the initial melt could largely be a func- tion of the P. T conditions during the formation of the “a at.“ r. ‘0 ‘. ‘. U ’ , ..1 . I I l . . 4 3 . 7 melt. even at constant bulk composition. The location of the cotectic between the quartz and feldspar fields is of greater importance than the loca- tion of the minimum because liquids forming from any bulk composition must have compositions that lie somewhere on the cotectic -- regardless of the location of the mini- mum. The minimum only serves to indicate which way the composition of the melt will change with continued temper- ature increase. Figure 1 shows the expected phase relationships in granitic systems having an anorthite component in the plagioclase for conditions expected in upper amphibolite facies environments -- temperatures from 5000 to 700°C and pressures from S to 8 kilobars. Since a plagioclase around An30 would be expected in high grade metamorphic rocks (Hinkler. 1967). the minimum would be located in the region of the letters 'ic” in the word cotectic in Figure i. In addition to the preceding compositional re- strictions for liquids produced from partial melting. it should be added that these liquids cannot migrate across the cotectic zone into the field not contain- ing the bulk composition of the source of the melt. Liquids produced from source rocks lying in the quartz field mug;,migrate into the quartz field and similarly. liquids from source rocks in the feldspar field must migrate from the cotectic zone into the feldspar field. Corectic Zone Feldspar Field Ab Or Figure 1. Expected phase relations in anorthite containing 'granite'-water systems under amphibolite facies conditions (after Hinkler. 1967). Minima would be located in the area of the letters 'ic“ in the word cotectic. 9 An additional chemical test for rocks suspected of having undergone partial melting is suggested. It stems from the fact that liquids must originate in the cotectic zone regardless of the composition of thesource rocks. Namely. that the granitic rocks produced from partial melting should show less variability with respect to the granitophlle elements than.do the source rocks. To test the various models for the origin of granit- ic rocks. the Poudre Canyon Migmatite. Larimer County. Colorado (Hard and Werner. 1962) was chosen because a good estimate of the volume percent granitic and metamor- phic rock could be obtained from thousands of lithology thickness measurements (Hard and warmer. 1962) and be- cause the metamorphic portion of the migmatite is not granite gneiss. but rather. clear cut metasediments. This avoids intuitive notions as to the prior state of the non-granitic portion of the migmatite. LQQAIIQE_QE_ABEA. The area under study lies 8 miles northwest of Fort Collins. Colorado in the northern Front Range. Lithology thickness measurements and samples were collected along the course of the Cache La Poudre River from the mouth of the Poudre Canyon to Stove Pririe Landing-~a straight line distance of 8 miles The canyon affords excellent fresh exposures produced by blasting during the widening of Colorado Route 14. the ll 10 highway that goes up the canyon. W Structurally. the granitic rocks are dominantly concordant to the metamorphic host. Those granitic rocks that are not concordant were not included in the sampled population because it is believed that they have a great- er chance of representing a post-metamorphic event. A dominant characteristic of the granitic rocks is that they occur as ellipsoidal pods and lenses from one inch to 12 inches in thickness. the average thickness being 1.75 inches. Mineralogically. they range quartz rich (80-90%) to 100% potash feldspar. While thin aect‘ionanalys is was not undertaken. potash feldspar and plagioclase feldspar stained slabs and megascoplc examination showed most of them to be one feldspar granites withmnat of the feldspar being a potash feldspar perthite. The metamorphic rock. and in fact. the migmatite as a whole_is not highly contorted but rather appears as lay- ered rocks. Evidences of folding. on the scale of an outcrop. are lacking. It appears as if one were looking at the limbs of tight isoclinal folds. Petrologically. the metamorphic rocks range from biotite-sillimanite schists to quartzo-feldspathic bio- tite gneisses. Amphibolites. though present. are minor in amount. The general character of these rocks is that ll of straightforward metasediments--there is no evidence of feldspathization. blastesis or mafic selvedge devel- opment. Petrography of potash feldspar stained thin sections shows that the mineralogy of these pelites and psammites is quartz + biotite + plagioclase (ca. An30) : potash feldspar :,sillimanite : garnet : muscovite :_ruti1e or sphene 1,0paque oxides. Blue-green to green-brown horn- blende + plagioclase + opaque oxides and sulfides t,an epidote mineral are found in the amphibolites. All of the mineral assemblages are characteristic of rocks having undergone upper amphibolite facies level (Silli- ' manite-Almandine-Orthoclase subfacies) of metamorphism (Winkler. 1967 and Turner. 1968). Detailed mapping of the region was not undertaken so that the lithologic and structural relationships of the migmatite and the rocks in the vicinity are not known. Therefore. it is not yet possible to put the migmatite into the geological context of the region as a whole. SMPLINQ AER FIELD MEASUREENTS Prior to the collection of samples and lithology thickness measurements. an outcrop was defined as one hundred feet of continuous exposure measured perpendic- ular to the foliation.(Ward and Werner. 1962). Expos- ures were measured and’those fitting the above definition 12 were numbered. From these numbered outcrops. a group was randomly selected for sampling and lithology thick- ness measurements. At each of the selected outcrops (20 in all). four ten foot lines with random starts were measured -- also perpendicularto the foliation -- to determine the volume percent of granitic and metamorphic rock. Rocks classie fied as granitic were defined as unfoliated quartz and feldspar rich rocks greater than or equal to one-quarter inch in thickness. Metamorphic rocks were rocks greater than or equal to one-quarter inch in thickness not fitting the definition of granitic rock. Pure quartz veins. when encountered. were counted as metamorphic rocks. Three rock samples were collected at each ten foot line. The granitic rock nearest the 23 foot mark on the measuring tape and the metamorphic rocks nearest the 5 foot and 73 foot marks on the tape were collected. This random scheme was adhered to for the collection of all samples. W In all. the major element chemistry and densities of 46 granitic rocks and 85 coexisting. by line. meta- morphic rocks were determined. ( Techniques used with stat- istical reliability estimates are given in Appendix A. Raw chemical data is given in.Appendix B). Five of the granitic rocks occurred within amphibolites and were dI Cl Br In l3 deleted from further analysis since the amphibolites are chemically much different from the main body of the meta- morphic rocks. This could lead to spurious correlations due to tight clusters of deviate points. Forty-one gran- itic rocks and their coexisting 75 metamorphic rocks remain. Since the amount of each of the two metamorphic rocks per line is not known. their chemical compositions were averaged. The means. standard deviations and the variance ratios for each of the oxides of the 75 metamorphic rocks and the 41 line average metamorphic rocks are shown in Table 1. It is clear from Table 1 that there is no significant difference between the average of all 75 meta- morphic rocks and the 41 line average metamorphic rocks -- at the 99.9% level. This suggests that there is a very high level of chemical heterogeneity within lines as well as between lines. In this light. the use of the line av- erage metamorphic compositions seems justified. The con- clusion that there is small scale lithologic heterogen- eity was also reached by Ward and Werner (1962) on the basis of nested analysis of variance of lithologic thickness distributions between lines. outcrops and groups of out- crops. Similar small scale lithologic and chemical het- erogeneity in a metamorphic terrane has also been found in the Moine metasediments (Butler. 1965). Table l. 14 Comparison of the average composition of all metamorphic rotks with the average composition of the line 0 average metam phic rocks. in parentheses. F 001.7‘.40 i 2.51. Qxide. $102 T102 A1203 FeO MnO "30 CaO NaZO K20 Total All Metamorphic Basssiszléi 69.18 (7.98) .76 (0.36) 13.64 (3.07) 6.69 (2.74) .08 (0.04) 1.50 (0.85) 1.39 (1.06) 1.74 (0.96) 3.45 (1.62) 98.43 Line Average Metamorphic ngkg£nu41) 69.33 (7.46) .75 (0.31) 13.61 (2.94) 6.60 (2.60) .08 (0.04) 1.525(o.82) 1.42 (0.99) 1.72 (0.87) 3.35 (1.48) 98.37 Standard deviations: are given Variance 85:12.. 1.14 1.34 1.09 1.11 1.00 1.07 1.15 1.22 1.20 15 s L 1.88 I The average granitic rock composition and the line average metamorphic rock composition are given in Table 2. along with the standard deviations. The granitic rocks show greater variability with respect to $102. A1203. K20 and NaZO than the line average metamorphic rocks. This is clear evidence against the origin of the granitic rocks by partial melting of the adjacent rocks. Anatectic melts should show less variation for these elements than the source rocks which produced them. This is especially striking in that those elements show- ing less variation in the granitic rocks than in the line average metamorphic rocks are T102. FeO. Mgo and CaO which are generally held to be granitophobe elements. A 10 by 10 correlation.matrix was obtained giving the correlations for each oxide and theiuight percent granitic rock between the granitic rocks and the line average metamorphic rocks. (The whole matrix is given in Append ix C) . Of the 100 correlation coefficients. 12 were sig- nificant at the 95% level (two-tailed). Of these. the highest was r- .4501. This means that at best. only 20% of the variability is explained by regression. High positive correlations between granitophile elements in the line average metamorphic rocks and the amount of granitic rock or the composition of the grani- tic rock expected in both the magmatic “juices" and hydrous- 16 Table 2. Comparison of the average composition of the granitic rocks and the line average metamorphic rocks. Standard deviations are given in parentheses. All Line Average 9:11: Gragitic4 Metamorphic 8102 75.38 (8.07) 69.33 (7.46) T102 .14 (0.12) .75 (0.31) A1203 13.63 (4.20) 13.61 (2.94) Foo 1.39 (1.46) 6.60 (2.60) Mac .03 (0.05) .08 (0.04) MgO .31 (0.44) 1.52 (0.82) CaO .94 (0.94) 1.42 (0.99) Nazo 1.96 (1.09) 1.72 (0.87) K20 6.71 (3.94) 3.35 (1.48) Total 100.49 98.37 l7 silicate magma models are not present. Neither are high negative correlations expected for the partial melting or metamorphic differentiation models. The results of stepwise multiple regression analysis obtained (see Appendix D) by regressing the weight percent granite per line with the oxide composition of the gran- itic rocks and the weight percent granitic rock per line with the compositions of the line average metamorphic rocks gives lines with coefficients of determination of rZ- .3045 and r2- .2131 respectively. Neither the chemi- cal composidxn1of the of the granitic rocks nor the comp- ositions of the line average metamorphic rocks are good _ predictors of the amount of granitic rock present in a I given line. The total lack of correlation between the line average metamorphic rocks and the granitic rocks indicates either that tmre was no interaction between the two. or. more like- ly. that. owing to the high degree of local variability. differences could not be detected between samples collected 25 feet apart even if they were present. The area would have to be re-sampled on the scale of inches to detect inter- actions. Because of this high local variability. the continued treatment of data at the level of a line will be abandoned. I Further analysis will be concerned with averages of all rocks and the regional picture rather than the local. 18 -14; 0N F I- BU 01303-0 o 1.. r1... E Since the volume percent of each rock type per line is known from thickness measurements and the density of each rock sample is also known. it is possible to mathe- matically ”mix” the chemical compositions according to weight percent and thereby obtain an estimate of the homogenized line bulk compositions. The average of all 41 homogenized line bulk compositions then gives a good estimate of the bulk composition of the whole migmatite. i&3.. what the original bulk composition of the migmatite was‘ig the granitic material now present had been de- rived in place. This average bulk composition of the migmatite as it now exists is given in Table 3. TEST EUR COMPOSTIONS EXPECTED FROM THE PARTIAL.MELTING MODEL Even though an in place by partial melting origin of the granitic portion seems unlikely in the light of the preceding statistical analyses. it is desirable to test the observed compositional relationships with those expected from experimental systems. As was done earlier. much use of CIPH normative Q-Ab-Or projections has been made for the interpretation of lines of liquid descent during fractional crystalliza- tion of granitic magmas as well as estimating compositions of early formed liquids during episodes of melting. Bowen.and Tuttle (1958) were careful in demonstrating the similarity of their experimentally determined phase 19 Table 3. The average bulk composition of the migmatite. Standard deviations are given in parentheses. O Higmatite 0:11: 3102 “ 70.65 (5.74) no2 .59 (0.22) 11203 13.76 (2.44) Peo 5.28 (2.05) Mno .07 (0.03) "80 1.21 (0.62) Cao 1.31 (0.39) Nazo 1.81 (0.77) K20 4.22 (2.08) Total 98.90 20 relationships with natural rocks in that they only chose rocks that contained 80% or more CIPW normative Q+Ab+0r. This means that the rocks so cited were already granite to quartz diorite in composition. It has become fashionable since 1958 and especially since the establishment of a viable plate tectonic model to derive granitic melts from sedimentary rocks. These rocks. however. are not already granitic in composition -- which should live some doubts about continued usage of CI?" normative composition.estimates. The chief reason being that. while the CIPW norm is a good approximation of the mode in granitic mocks. it is not a good approx- imation of the mode in sedimentary rocks undergoing pro- grade metamorphism during burial or subduction. For example. depending upon the K20. FeO and Mgo content of the sediment. biotite is almost certain to appear during prograde metamorphism. Furthermore. the amount of biotite would be expected to be proportional to the Eco and MgO content of the rock -- assuming suf- ficient K20 is present. A biotite so formed would be expected to be stable until the onset of granulite facies conditions. The K20 in the biotite could not con- tribute to an Or component in a melt forming under amphib- olite facies conditions -- conditions in which biotite is stable. 5 CIPW normative calculation of such a rock would show all of the K20 in an orthoclase molecule and thereby lead to inflated estimates of the amount of orthoclase 21 actually available during amphibolite facies conditions. A biotite norm (see Appendix E for the formula for calculation) has been developed wherein a biotite --annite- phlogopite--is calculated prior to the calculation of normative orthoclase. Table 4 gives the composition of a biotite-silliman- ite schist along with the mircrometric mode and both the CIPN and biotite normative minerals. Noteworthy is that the amount of orthoclase in the CIPW norm is 18%. the bio- tite norm calculates 6% while the actual rock contains none. The biotite norm gives a more realistic picture of the actual amount of orthoclase present in amphibolite facies level rocks. Subsequent discussions of the Q-Ab-Or projec- tion will be limited to those obtained from biotite norm- ative calculations. CIPW normative projections are pre- sented only for comparison since they are so well estab- lished in the literature. Figure 2a shows the biotite normative Q-Ab-Or pro- jection of the bulk composition of the migmatite and the average granitic rock composition. along with the por- tion of the cotectic zone in which liquid should form under amphibolite facies conditions for this bulk com- position. Liquids produced from this bulk composition should lie either in the portion of the cotectic zone or between this area and the bulk composition of the migmatite. The average composition of the granitic rocks lies well out- side this region being more othoclase rich than can be 22 Table 4. Comparison of CIPW norm and Biotite norm with actual micrometric mode of a biotite-sillimnaite schist. Outcrop 33 line 04 Spec. No. 39 0:11: Sioz 57.28 T102 1.06 61203 20.37 Feo 10.84 Mno .06 Hgo 2.36 Cao .28 Nazo .32 K20 3.96 rate 96e13 CIPH 8.9m 11 1.98 bi or 17.73 ab 2.62 an 1.39 cor 24.69 hyp 24.12 sill q 26.76 Biotito 8222... 1.98 31.45 5.56 2.62 1.39 23.33 30.84 Mode 0.00 46.66 0.00 10.94 27.36 23 EM: Ab (a) Or X Ab (b) Or FigureZ. a & b. (a) biotite normative and (b) CIPW norm- ative projections of the bulk composition of the migmatite (x) and the average granitic rock composition (dot). The dotted area corresponds to the part of the cotectic zone expected to be important in amphibolite facies conditions. The ”M“ is the location of the minima under these conditions. 24 explained by means of an anatectic model. This sug- gests that. on the average. the granitic rocks were not derived from in situ partial melting of the bulk composition of the migmatite as it now exists. Some other mechanism(s) must have been operating. [fig Ofilfilfl QE IE3 QBAEIIIQ BQQES Figure 3a is the biotite normative Q-Ab-Or projection of the granitic rocks. There is a trend of granitic com- positions beginning on the Ab-Or join near the Dr corner and extending approximately half-way to the Q apex. Ex- perimental studies in plagioclase containing ”granite”- water systems at l to 2 kilobars total pressure indicate that location of the minimum is about 040Ab20°r40 and that there is a path of liquid descent beginning on the Ab-Or Join near the Or corner terminating at the minimum (Von Platen. 1965: Winkler. 1967 and James and Hamilton. 1969). The trend seen above for the granitic rocks in this study coincides with this experimentally determined line of fractional crystallization. This means that 26 (63%) of the 41 granitic rocks could be explained as belonging to a series of liquids. fractionally derived. from a nearby pluton that was crystallizing both plagioclase and potash feldspar at pressures of 1 to 2 kilobars -- pressures well below those indicated by the mineral assemblages in the metamorphic rocks. These 26 granitic rocks must post- date the metamorphism -- they could not have been formed 25 Ab (a) Or Figure 3. a & b. (a) biotite normative and (b) CIPW norm- ative projections of the granitic rocks. 26 during the high levels of metamorphic intensity exper- ienced by the metasediments. Figure 4a. the biotite normative Q-Ab-Or projection of the line average metamorphic rocks. shows a trend of compositions away from the main body of compositions toward the Q-Or join. This trend would intersect the trend of the 26 granitic rocks in the area of the 1 to 2 kilobar minimum. This suggests that some of the metamor- phic rocks have indeed been made more granitic in compo- sition and furthermore. that the composition of the gran- itic material added was that of the minimum for the in- truding granitic rocks. This is indicated schematically in Figure 5. The metamorphic rocks thereby confirm that 63% of the granitic rocks formed from injection of sili- cate magma. The origin of the remaining 15 (37%) granitic rocks cannot be explained as the result of this study. Perhaps this is due to too few samples and to the high level of variability exhibited by these rocks. QISQQSSLON The local chemical and lithologic variability found in the Poudre Canyon Migmatite.is so high that. even with sampling at 2% foot intervals the interactions between the granitic rocks and the metamorphic rocks is obscured. Only when the rocks are examined in the context of the 8 mile long region does it become clear that there has 27 Ab ('1) Or Ab (b) Or Figure 4. a & b. (a) biotite normative and (b) CIPW norm- ative projections of the line average metamorphic rocks. 28 Ab Or Figure 5. Schematic illustration of the fractionation trend of the granitic rocks(1arge dots) and the graniti- zation trend(small dots) of the metamorphic rocks. The “M” is the location of the l to 2 kilobar minimum (after Hinkler. 1967 and James and Hamilton. 1969). 29 been interaction. Had not 116 samples been analyzed. even this regional picture might have been obscured by the heterogeneity observed. Those 26 granitic rocks that can be explained are members of a fractionating series of liquids derived from a nearby pluton. They were injected into the meta- sedimentary rocks after they had been metamorphosed to amphibolite facies4level. Geologic implications of this study must deal with the high level of chemical and lithologic variability that can be expected in metamorphic terranes. To the degree to which these rocks. and the rocks of the Moine series (Butler. 1965). are representative of metasediments in general. use of descriptive terms such as "pelitic" or ”psammitic' grossly oversimplifies the true nature of the real variability -- both chemical and lithologic. In this context. use of chemical data to show that a giv- en sample has been granitized or de-granittzed relative to ”normal” 'pelitic“ or “psammitic” rocks can have no meaning unless a good estimate of the total chemical var- iability naturally inherent in the given rock pile can be made. ‘ If sedimentary rock piles are. in general. as heter- ogeneous as this study indicates. anatectic melts produced from such rocks should also show a high degree of local variability. To produce a homogeneous granitic pluton from melts so produced would require complete homogenization 30 of these melts after separation from the source rocks. Another generally overlooked phenomena come to light while examining the consequences of the partial melting of sedimentary rocks. This is that sedimentary rocks are usually expected to concentrate silica -- especially as quartz. Extensive melting of such silica rich rocks should produce liquids which lie in the quartz field of the ternary ”granite'-water system. If such a melt were intruded into higher levels of the crust. quartz should be the stable crystalline phase on the liquidus. Fraction- ation of such liquids should produce a series of granitic rocks that have quartz as the first precipitating mineral phase and show liquid descent paths from the quartz field toward the cotectic. Tuttle and Bowen (Fig. 41. p. 78. 1958) show that the path of liquid descent of natural granitic rocks lies in the feldspar field and moves toward the cotectic from that side. Examination of natural granitic batholiths in- dicate that a feldspar is usually the first mineral phase to crystallize. It would appear that batholithic masses of gran- ite do not originate from partial melting of sedimentary rocks both because of their homogeneity and because quartz is seldom the first mineral to crystallize. REFERENCES CITED REFERENCES CITED Brown. G.C.. 1970. A comment on the role of water in the partial fusion of crustal rocks. Earth Plan. Sci. Letters. Vs 9. ps 355'358s Brown. 6.6. and Fyfe. W.S.. 1970. The production of granitic melts during ultrametamorphism. Contr. Mineral. and Petrol.. v. 28. p. 310-318. Burnham. C. W.. 1967. Hydrous fluids at the magmatic stage. in.H. L. Barnes (ed. ). "Geochemistry of Hydrothermal Ore Deposits.“ Holt. New'York. Butler. B.C.M.. 1965. A chemical study of some rocks of the Moine Series of Scotland. Quart. J. Geol. Soc. Lon.. Vs 121. pa l63’208s Flanagan. F.J.. 1973. 1972 values for international geo- chemical reference samples. Geochim..et Cosmochim. Acta. Vs 37. pe 1189-1201s Huang. W.L. and Wyllie. P.J.. 1973. Melting relations of muscovite-granite to 35 kbar as a model for fusion of metamorphosed subducted oceanic sediments. Contr. Mineral. and Petrol.. v. 42. p. 1-14. James. R. S. and Hamilton. D. L.. 1969. Phase relations in the system NaAlSi 3O -KA1SiO -CaAl Si 20 ~SiO at l kbar water vapor pressur8.Cont3.08Miner12a Pe rol.. v. 21. p. 111 l 1. King. 8.0.. 1965. The nature and origin of migmatites: Metasomatism or anatexis. in.N.S. Pitcher and G. W. Flinn (“219 Egzntrols of Metamorphism.” Oliver 6. Boyd. London. pe s Loberg. 8.. 1963. The formation of a flecky gneiss and similar phenomena in relation to the migmatite and vein gnegsiogroblem. Geol. Foeren. Stockholm Foerh.. v. 85. p. . 31 32 LUth. W.C.. J‘hfl‘o R.H. and TUttle. Ost. 1964. The granlte water system at pressures of 4 to 10 kbars. Jour. Geophys. R680. Vs 69. ps 759’773s Piwlnskii. A.J. and Nyllie. P.J.. 1968. Experimental studies of igneous rock series: A zoned pluton bn the Hallows Batholith. Oregon. Jour. Geol.. v. 76. p. 205-234. Piwinskil. A.J.. 1970. Experimental studies of igneous rock series: Felsic body suite from the Needle Point Pluton. Hallows Batholith. Oregon. Jour. Geol.. v. 78. p. 52-76. Robertson. J.K. and Hyllie. P.J.. 1971. Rock-water systems with special reference to the water-deficient region. Amer. Jaurs sets. Vs 271. pa 252’277s Steiner. J.C.. Jahns. R.H. and Luth. W.C.. 1975. Crystalli- zation of alkali feldspar and quartz in the haplogranite system NaAlsi3OB-KAlSi3OB-Sioz at 4 kbars. Bull. Geol. Soc. Amer.. v. 86. p. 83-98. Turner. F.J.. 1968. “Metamorphic Petrology.” McGraw-Hill. New York. ‘ Inttle. 05F. and Bowen. N.L.. 1958. Origin of granite in the light of experimental studies in the system NaAlSl308- KA181308'8102‘H20. GeOle Soc. Amer. Meme 7‘. p. l‘lSSs Von Platen. H.. 1965. Experimental anatexis and genesis of migmatites. in w.s. Pitcher and G.w. Flinn (ed.). "Controls of Metamorphism.“ Oliver & Boyd. London. p. 203-218. ward. R.F. and Werner. 8.1... 1962. Analysis of variance of thegggmgggition of a migmatite. Sci.. v. 140. no. 3570. P. ' s Helday. 3.8.. Baird. A.K..‘Mc1ntyre. D.B. and Madlem. K.W.. 1964. Silicate sample preparation for light-element analyses by X-ray spectrography. Amer. Miner.. v. 49. p. 889-903. white. A.J.R.. 1966. Genesis of migmatites from the Palmer Region of South Australia. Chem. Geol.. v. 1. p. 165-200. "inkler. H.G.F. .nd Von Pl‘tans He. 1957‘1962. Experimental Gesteinmetamorphose I-V. Geochim. et Cosmochim. Acta. v. 13. (1957). p. 42-69: v. 15. (1958). p. 91-112: v. 18. (1960). {é0294-316' v. 24. (1961). p. 48-69: v. 26. (1962). p. 145- Winkler. H.G.F.. 1967. ”PetrOgenesis of Metamorphic Rocks.” 2nd edition. Springer-Verlag. Berlin. A PPEND IX A 33 APPENDIX A Sample Preparatiog All rocks were cut into one-quarter inch thick slabs on a water-cooled diamond saw to avoid the possibility of including granitic stringers in metamorphic rocks and vice- versa. This is consistent with the field definitions used during the lithology measurements. After the slabs were used for density determinations. they were ground for five minutes in a steel ring-and-puck disc mill. In preparation for X-ray fluorescence analysis. one gram of rock powder was mixed with two grams of lithium metaborate(LiBOz) and then fused in graphite crucibles for ten.minutes at 1000°C (after Welday. g; g;;. 1964). The glass beads were ground for three minutes in the disc mill. The rock-borate powders were then pressed at seven tons/in.2 in aluminum Spex Caps using boric acid filler. For neutron activation analysis. one gram of each rock powder was weighed into a polyvial that had been cleaned in reagent grade methyl alcohol. The polyvials were hand led with rubber gloves to avoid fingerprint contamination. 34 APPENDIX A ngpig Eggpggation All rock were cut into one-quarter in thick slabs on a water-cooled diamond saw to avoid the possibility of including granitic stringers in metamorphic rocks and vice- versa. This consistent with the field definitions used during the lithology measurements. After the slabs were used for density determinations. they were ground for five minutes in a steel ring-and-puck disc mill. In preparation for x-ray fluorescence analysis. one gram of rock powder was mixed with two grams of lithium metaborate(LiBOZ) and then fused in graphite crucibles for ten minutes at 1000°c (after Welday. g; 51.. 1964'). The glass beads were ground for three minutes in the disc mill. The rock-borate powders were then pressed at seven tons/in.2 in aluminum Spex Caps using boric acid filler. For neutron activation analysis. one gram of each rock powder was weighed into a polyvial that had been cleaned in reagent grade methyl alcohol. The ployvials were handled with rubber gloves to avoid fingerprint contamination. 35 APPENDIX A Wm Densities of the rock slabs were determined on a Jolly balance apparatus. Replicate determinations on some of the samples yielded densities that agreed to 1_0.01 gm/cma. In.addition. a rose quartz standard was used throughout the weighings of the unknowns. The average density of the standard. form all eight determinations. was 2.649 gm/cma. the standard deviation. 0.0064 gm/cma. and the coefficient of variation.was 0.00242 of the mean. The densities are believed to be accurate tel: 0.01 gm/cma. 8102. T102. A1203. total iron as FeO.‘MnO.‘MgO. CaO and K20 were determined with a General Electric XRD-6 helium path spectrometer. A flow proportional counter with P-lO gas and pulse height discrimination.was used for all runs. Only fixed clock time was used for counting. The particular time chosen was based on count rates for the uses standard rocks o-z. ass-1. AGV-l. son-1, DTS-l and FCC-1. estimated sample concentrations for the element to be determined and the desirabiAity of holding the counting error to one percent or less. The correlation coefficients and the standard errors of estimate for the regression lines obtained for each of the elements are given in Table A-1. 36 APPENDIX A Table A-1. Correlation coefficients and standard errors of estimates of regression lines obtained for the standard rocks. 92:499- gcii‘éfiag'iéfig" SQE‘E‘S‘JL...‘ :28: z) 8102 .9994 .493 T102 .99999 .005 A1203 .9988 .411 Foo .9996 .151 Mac .9999 .002 MgO .9954 .135 CaO .9997 .078 K20 .9993 .078 37 APPENDIX A NaZO was determined with Michigan State University's Triga reactor. 0868 standard rocks G-Z. GSP-l. AGV-l. BCR-l and w-l were used in.addition to one standard of reagent grade NaC1 such that its concentration of Nazo was equal to that contained in one gram of 689-1. The unknowns (up to 37) and three standards were placed in the reactor's lazy susan sample holder. which was rota- ted during irradiation. and irradiated for 15 minutes at 250 kilowatts. The samples were allowed to “cool“ over- night--- 12 to 15 hours. The 2.75 Mev Na27(n.gamma) peak was counted for 100 seconds live-time with a lithium drifted germanium (GeLi) detector maintained at the boiling point of liquid nitrogen. Absolute peak heights were deter- mined and the average ratio of peak height to weight percent NaZO of the standards was used to calculate the weight per- cent NaZO of the unknowns. The counting error. expressed as the relative standard deviation is given by 100/JN. where N - the number of counts. Since the number of counts is proportional to the concen- tration of NaZO. the counting error can be related to the concentration. The lowest concentration of Nazo measured in this study was 0.54 weight percent and the highest. 4.68 weight percent. The associated counting error for these two samples is 1_2.45% and 1 0.83%. respectively. The 38 APPENDIX A counting error for the other unknowns will lie within this interval. A comparison of the values for the oxide concentrations of BCR-l. AGV-l. GSP-l. and G-Z obtained by this study with those recommended by Flanagan.(1973) is given in Table A-2. 39 Table A-2. Comparison of the results of chemical analysis of this study with the USGS recommended values (Flanagan. 1973). All values are in weight percent. This This This This .Qsids. 1393.31212, 0395.33242. u§§§.§tadx. Q§0§.§tudx 3102 54.50 54.77 59.00 53.99 67.38 67.27 69.11 69.19 no2 2.20 2.23 1.04 1.19 .66 .77 .50 .53 11203 13.61 12.97 17.25 16.98 15.25 15.40 15.40 15.69 FeO 12.06 12.03 6.03 6.30 3.90 3.33 2.39 2.39 MnO .18 .23 .10 .12 .04 .05 i.03 .04 MgO 3.46 3.03 1.53 1.50 .96 .93 .76 .78 Geo 6.92 6.89 4.90 5.08 2.02 2.00 1.94 1.92 N320 3.22 3.40 4.26 4.35 2.80 2.85 4.07 ND [(20 1.70 1.66 2.89 2.95 5.53 5.52 4.51 4.43 16:.1 97.39 97.53 96.93 96.95 93.35 99.26 93.99 93.61* *NaZO equal to that of the USGS recommended value added. A PPEND IX 8 40 APPENDIX B Raw Chemical Data The raw chemical data is listed on the following pages as it appeared on the IBM cards used for computer analysis. Each row gives the outcrop number. the line number. the specimen number. rock type. the results of the chemical- analysis. the weight percent granitic rock in the line(abb- reviated to "Gran) and the density of the specimen(abbreviated "Dens”). The columns containing the oxide concentrations. the weight percent granitic rock and the density of the sample are appropriately labeled. The key to the first 8 columns is as follows: 1. The first two columns (1-2) give the outcrop number. 2. The next two columns (3-4) give the line number. 3. The next three columns (5-7) give the specimen number. 4. The next column (8) gives the rock type-- ”G" for granitic and "M" for metamorphic. S. If columns 5 through 8 are all M's. the row represents the line average metamorphic rock. For example. 02173946 would mean-- outcrop No. 2. line No. 17. specimen No. 394 and that the rock is granitic. If the first 8 columns contained the designation 0610MMMM. it would mean-- outcrop No. 6. line No. 10 and that the row represented the line average metamorphic rock compo- sition. APPENDIX B Raw Chemical Data Granitic Rocks associated with psammo-pelitic rocks 2700001 2708004 5015118 5302121 5700145 5703148 5709151 5802157 5804160 5805163 5906175 d76.53 72.67 8102 T102A1203 FeO‘MHOMROO C80 N820 6.54 1.0 2.2 .02 .61.01 69.19 65.39 76.62 79.62 69.62 .0.29 .07 .20 .06 .08 .28 0.12 0.06 0.11 .08 .06 .08 .11 .10 0.13 7.9 5.01 5.4 6.9 05.7 14.5 13.03 10.62 13.5 16.29 15.03 13.14 13.55 13.72 0.33 0.50 .30 .08 .19 .12 .25 .21 .37 .52 .11 13.75 15.91 16.02 12.48 15.34 16.74 18.0 18.1 15.30 03.93 s0 15.15 .1 18.97 .0_10.46 .1112.14 .0 15.33 .0 19.74 .0 17.75 18.72 14.0 17.1% 19.5 13.67 13.52 12.52 17.44 .0 e0 .0 .1 .1 .0 41 3.3 4.5 01.3 01.0 00.8 .8 1.1 .8 1.1 1.6 02.9 02.0 2.4 1.2 1.0 5.3 1.8 3.3 3.6 .0 03.2 05.0 .3 .1 .1 .6 .2 15.92 .00. .0 e0 .01 .01 .01 .01 .01 .01 .01 .04 .040.5 .07 .08 .02 .02 .22 .02 .03 .03 .01 .03 .04 .01 0.0 0.2 .5 .641078 .7 1.54 .24 .6 e8°1s0 .61 .81 0.170e7 0.5.2.6 0.9-3.4 .311e31 1.1‘ .5 .81‘06 .9"‘.O e4-1s20 0.43 s11 .331.90 .4 1.91 1.101.09 e601s24 1.121003 1.651.03 .71 .96 3.03’.34 ;‘.34 .6 1.81 e943s16 .4'1s11 e7? .14 1.141.42 e501s72 .501e41 -36.-s73 .504.15 e5-le91 .611s9 .431031 .432.1010.20 0. K20 GranDens .71. 2.63 2.5 12.02.61 2.4 l3.‘2s60 1.8 19.:2.62 2.6018.°2.64 2.5 13. 2.63 6.8 19s‘2e58 3.9 11.'2s61 5.71 8..2.59 2.4 19.02.63 “2.59 2.4 9.‘2s65 2.0 19.62.65 7.9 -0.-2e61 06.7 14.‘2.61 7.17 8.19 12.05 6.21 8.32 10.19 1.86 7.76 b1.oe 01.22 9.58 11.19 6.58 5.78 10.63 13.79 11.57 12.5 3.56 11.29 17e“2s66 12.n2.62 2.32s57 0.02.70 28. 2.64 41. 2.66 23.0 .71 15.- .69 12..2s65 08.: .69 38.‘ s59 26.02.58 16.02.61 22.42.60 18. .59 72.’ s55 24.: .59 13.; .59 38.02.65 29.12.58 13.5 8.7 e741s1 e4 1s3 .5‘1s6 4.4 2s6 9.2 7.1 11.7 3.0 38.'2e57 10. 2.61 15. 2.60 26. 2.60 29.12.59 34.‘2s57 42 APPENDIX B Line average metamorphic rocks $102 TiOZAlZO3 FeO‘MnOMgO CaO NaZO K20 GranDens 0217MMMM 9.5 .9 12.96 7.3 .041.70 .831s42 3.13‘1s s76 0505MMMM 3.7 .7 11.35 7.9 .05 .90 .751.31 2.1012.0 s76 0510MMMM58.111.0 18.3310.2 .08-.23 .821.23 4.6 13.« .32 0518MMMM67.9 .8 16.22 7.7 .0 1.91 .5 .72 2.7‘19s4 s79 0519MMMM58.6 .9418e8010e3 .08’s32 .51 .60 3.7‘18.’ .79 3207MMMM73.8.0.7111.6406.5 s101s210.5=1.26 2.5‘13. s70 3210MMMM76.9 0.6 10s8605s3 s0 1s020.5’1s4 2.6 19e' s69 3217MMMM79.2 Os6 08.9505e8-s14°s84 .571e1 2.3"11.‘2e70 3304MMMM57.011.0 20.1 10.7 .0-2s41 .2‘ .2 3.9 8.02.78 3319MMMN68.6 .8 12.81 7.7 .0-1038 .9-1s9 2.6"19.02s74 33OOMMMM54.6 1.0 20.4511.21.032.38 .4: .6 4.1 0.“ s88 3806MMMM79.0 .6 10.07 6.2 .0‘1.11 .2- .4 2.34 9.‘ s72 3812MMMM64e3 .9 15.29 7.9 .03108. .8‘1s9 3s6-19e-2s74 2814MMMN7le2 0.6 11.8305e4 .0 1.0 0.4 0.6 07.5020sa2e68 2816MMMN70.9 0.6 12.0407o1 .1'1s1 1.8'2.2 02.5—14.*2.74 3804MMMM77.8 .6 10.21 5.7 s0-1s01 .3' s8 2.7017.‘2s69 3813MMMM65.1 .9 15.51 8s2 s0°1s8 .4 1.0 2.5312.a2s76 4812MMMM69.6 .4 14.28 3.9 .0" .7 1.132.0 6.8 2.: .68 1504MMMM67.5 .7 13.3007.0 .141s3 1.542s0 4.63 0.02.72 1213MMMN65o2 .4 16.11 4.3 .O 3.5 3.632o4 2.83*8.*2.74 1214MMMM70.3 .4 12.91 5.1 .0 2s7.2.612.0 2.4“41.‘2.73 2310MMMM72.4 .6 12.17 5.01.0‘1.512.3'2.2 2.5. 3.02.72 2314MMMM75.4 .5 11.66 3.7 .00 s9 2.4 1.8 3.4’15.-2.7O 2700MMMM69.2 O.8113.0 06.3 .081.3 2.2-2.9 2.1 12.02.74 2708MMMM62o3 1.0 15s3707s5 .0:1s6.3.313s3 2.50 8.32s76 4304MMMN56o5 1.9112.7 12.6 .1-3s3 2.7-1.2 4.7‘t8.° s89 4504MMMM79.0 .3 11.93 2.6 .0 s2 1.4“2.6 2.4"6.02e68 4508MMMM75o5. .3 11.86 3.4 .14 .601o9-1.7 4.2016.02.70 4514MMMM78.2 .3 10.9 236 .0- .3 .8"1.6 5.31’2.4 .64 4811MMMM79.1 s3-10s9 2s7 .0" s2 1.4‘2s31 3s5118s” .65 SOOOMMMN56o2 1.0 17.97 9.3 .0-2.3 .5: .9 6.6- 2.- .82 5013MMMM68.4 .9 13.9 7.2 .0-105 1.0'104 3.3‘ 4.: e74 5015MMMM71.8 .8 13.16 6.9 s0-1s3 1.091e2 2s4~13e32s68 5302MMMM81.51 .44 8.59 3.5 .0. s7 1.2 .21 1.0 $8.02s70 7‘““5706MMMMW4;2" .3 11.3df3.9 .031.3 .1-1.9 3.8 r9.1*.7o 5703MMMM59.5 1.0 16.0610.3 .1-2e6 2.5-2e5 3.9-‘8.".80 5709MMMM70.01 .3 15.62 2.4 .0- s6 3.4-‘s61 s7'10. .69 5802MMMM67s1 s7 14.15 6.2 .1'2.1 e112e2 2.5015. 2.75 5804MMMM71e2 .7 11.88 7s0 s1'1s5 1.8‘1s7 2.7 '6. s77 5805MMMM58.5-1.1 18.12 9.7 .1“2s4 .7‘ .9 5.1-’9sl .83 5906MMMW75s9 .4 12.2q 4s21s1- .31 .632.9 .9“4.‘ s71 APPENDIX B 43 Psammo-pelitic metamorphic rocks 4304081 0510401 0510402 0519407 0519408 33040381 3304039 3300047 3300048 5000110 5703149 5805165 0217396 0518405 3207026 3319044 3319045 3812068 3812069 2814020 2816024 3813071 3813072 4812105 1504446 1504447 1213429 2700003 2708005 2708006 4304080 5013116 5013117 5015119 5703150 5802158 8102 T102A1203 FeO‘MnOMgO C80 N320 K20 GranDens 48.882.8813.6113.6 .1 4.31 1.2 5.0 ‘8. 7.881.0717.5810.81e022s6 1.4 4.4.13. 58.34 .9319.15 9.7 .O 1.8 1.1 4.7:13. 58.68 .9319.6310.4 .0 2.3 .4 3.5-18. 58.65 .9417s9610.3 .0 2.2 .7 3.9118. 56.741.0320.3710.7 .062.4 .1 3.9: a. ‘7.281.0619.9 10.8 .062s3 s3 3.9-’8. 54.051.2120.9011.7 s0 2.5 .8 4.3' O. -55.28 .9520.0510s6 .0 2021 s5 4s01’0s 56.241.0617.97 9.3 .0.2.3 .9 6.6- 2. 57.221.1016.4512.1 .2 3.2 3.602.70 3.71 8. 54.111.3019s1111.2 .1 2.7- 1.2 68.35 s8813.4 7.1 s0-1.5 1.86 3e0“1s 64.22 .9717.64 8.1 .0 .7 3.0 19. 67.350.8213.7 08.5 .1 1.2 02.8 13. 68.60 .8014.55 6.9 .0 152s1 2s4_19s 68.67 .9011s02 8.5 .0 1.7 2.8'19. 61.43 .9516.38 7.9 .0 2.7 3.4.190 67.241.0114s19 7.9 .0 1.0 3.9-19. 69.490.6412.4505.9 .0 0.6 07.7 20. 4.730.7813.6108.9 .1 2.4 03.0’14. :63e27 .9316.40 8.4 so .42 .8 4s9‘12s 67.01 .6614.73 8.1 .0- 1.2- 3.2.12. .2.31 .5217.14 4.8 .0- 1.9 9.0- 2. 69.33 .7113.05 6.21.0. 2.392.96 1.8"0. 65.83 .7213.55 7.8 .1 1s21 7.4040. 65.25 .4416.11 4.3 .0 2.4 2.8328. 65.700.8014.9805e8 .0 3.7 2.0412. 62.071.0015.2407.5 .1 3.1 02.1-o8. 62.601.0515.4qo7.5 .o 3.6002.8‘08. 64.25 .9411.8911.71.1 1.17 4.4. a. 07.471.0013.42 7.9 .0 2.14 2.91 4. 969.36 .9514.56 6.6 .0- .81 3.7-24. 68.46 .9914.44 7.5 .o .59 3.6 13. ‘61.881.0315.68 8.6 .1 2.1-1.522.35 4.2 ‘8. 66.66es8114.85 5.6 .0 108 3.492.50 2.2 15. 44 APPENDIX B Paammo-pellttc metamorphic rocks (cont'd) 81.02 1102A 1203 F90 MnngO C80 N820 K20 GranDens 5802159:-7.61 .7613.4 6.8 .112.4 2.7 1.94 2.7 15. 2.76 5804161 .3.151.1114.0 9.9 .1 2.0 1.5'1.92 3.9 26. 2.82 5805164 .2.99 .9717.1 8.31.1 2.1 .5. .70 4.7129.12.79 0217395 0.70 .9212.4 7.4 .0 1.8 .60 .98 3.3141. 2.76 0505399 3.72 .7511.3 7.9 .0 .9 .7"1.31 2.1 12. 2.76 0518404 1.70 .8014.8 7.31.0 1.6 .4. .67 2.4 19. 2.79 3210029 78.4 0.6610.1 05.1 .0 0.7 0.6‘1.5802.3119. 2.68 3210030 5.4 .6811.5 05.6 .o 1.2 0.5.4.3 3.0 19. 2.70 3217035 79.4 0.6909.1 05.4 .1 0.9 0.6-1.3 2.3 11. 2.70 3217036 79.11 .5108.7106.2 .1 O.7-0.4=1.0 2.3 11. 2.70 3806065 79.0 .6710.0 6.2 .0 1.11 .2. .4 2.3 39. 2.72 2814021 73.0 0.6 11.2104.8 .0 0.8 0.410.6607.3 20. 2.67 2816023 77.1 0.5 10.4 05.2 .1 0.4 1.512.1 01.9 14. 2.71 3804062‘78.7 .6 9.6 5.4 .0 .9 .33 .8 2.5 17. 2.69 3804063 76.8 .6 10.7 6.1 .0 1.0 .40 .8 2.8 17. 2.69 4812104 76.9 .3 11.4 3.1 .0 .3 1.2.2.1 4.6 2. 2.68 1214432 70.3 .4 12.9 5.1 .0 2.7 2.612.0 2.4 41. 2.73 2310461 74.4 .5 11.7 4.3 .0 1.2 1.9-1.9 2.9 23. 2.71 2310462 70.42 .7 12.61 5.6 .0 1.7 2.712.4 2.0 23. 2.73 2314464 75.26 .5 11.4 4.1 .0 .8 2.131.5 4.0 15. 2.69 2314465 75.55 .5 11.8 3.2 .0 1.0 2.7-2.11 2.8 15. 2.71 2700002 72.770.8111.2 6.91.0 1.311.582.2 2.2 12. 2.74 4504086 79.11 .3 12.99 2.6 .0 .2 1.3.3.3 1.2 26. 2.67 4504087 78.94 .3 10.86 2.6 .1 .2 1.5'1.8- 3.5 26. 2.68 4508092 77.21 .3 11.43 2.9 .1 .6 1.871.06 5.1116. 2.69 4508093 73.9 .4112.29 4.0 .0 .5 2.0-2.3 3.2 16. 2.71 4514095 77.91 .3 11.54 2.21.0 .1 1.0-2.1 4.6 22. 2.65 4514096 8.6 .3 10.30 3.0 .0 .4 .6‘1.10 5.9 22. 2.64 4811101 79.7 .3 10.73 2.61.0 .2 1.4‘2.1 3.4 18. 2.67 4811102 78.5 .3 11.18 2.9 .0 .2 1.432.4 3.5 18. 2.63 5015120 75.2 .7 11.89 6.4 .0 1.0 1.6 1.8 1.2 13. 2.67 5700146 74.9 .3 12.00 2.8 .0 .4 1.632.9 2.4129.12.67 5700147 73.4 .4 10.59 5.0 .112.3 .51 .9 5.3 29.12.73 5709152 70.01 .3 15.62 2.4 .0 .6 3.4—1.61 .7 10. 2.69 5804162 79.3 .41 9.71 4.2 .0 1.0 2.1 1.4 1.5 26. 2.72 5906176 77.5 .6111.41 3.7 .0 .4 2.34 .6 1.1 34. 2.70 5906177 74.31 .1 12.93 4.7 .21 .1 3.0 .15 .7 34.42.72 3207027 80.3 0.6 O9.52D4.5 .0 0.7 0.5 1.2 2.2 13. 2.67 5302122 81.51 .4 8.59 3.5 .0 .7 1.2 .21 1.0 38.02.70 APPENDIX B 45 Granltlc rocks and associated amphlbolitea 0610412 061441 061741 1.70 9.26 9.31 3.59 2.85 8.9 63.8 0.9711.6 52.6 .2 14.64 .8 17.43 .1 9.01 O.1315.16 .1720.14 1.4213.63 1.1312.79 1.3613.84 1.62.0 6.88.0 3.06.0 01.34.0 2.86.0 10.12.1 13.45.2 13.97.3 09.58.1 1.1813.1 12.20.3 1.2513.2 106014.0 .8812.6 1.3812.9 1.2912.5 1.4315.1 0.6110.6 1.3212.7 1.2513.1 10.06.2 10.18.1 12.80.2 14.10.3 14.01.2 13.9 .3 4.8 .0 14.2 .2 13.3 .3 1.1013.1111.0 .3 8.3 2.0 .0 00.6 .4 1.1 $102 T102A1203 F901Mn0MgO C80 NaZO K20 GradDenfl 01.5119. 01.3 19. 1.9 3. 3. APPENDIX C 46 660.. ocN. mm.. n.o. hm.- hm.. 6N..- «cNM. «Nu.- co~.- .couoN .6~. «66m. «.~n.1 o-.- 6.6.- e~..- 666.- ~66. 6N..- .~..- o~x 66..- 6.6. 666. «MNM. ~MN. 6... 666. 66.. «666. ~h~.- o~oz owe.- no.- on..- «Nun. .cmc. m.o.- 666. mm.. «wwm. ao~.- Ono we..\xoou o.u.:ouw ucmouoa unm.oa I .CQuuN mocwv.ucoo Nma undo. u. 60910.nc. Acv xo.u0u6< «own. ~6.. .o~.- 66~.- «mNn. ~m..- No.. 666. 666. ..6.- 662 ~66. and. ovo.u Nu~.- ca~.- v.6. cud.- who. 66... 006.. 0:2 mow. n~o.- saw.- «mam.- um... an..- emo. ma..- coo.- no~. 00h owo. mod. «~.v.- voN.1 .eo. mm~.- boo. aud.o .60.- owe. no~.< 6x00: 0.;auoeuuoz owoum>¢ uc.a Imauuuufiamdumquummu 66N. moo. hu~.1 uo~.1 66..- 66..- .N6. 6...- .66.- N... No.“ mo~.- as..- «man. 6mm. 666.- Nau. 666.- 666. 666.- 666.- N0.6 .cwuuN 6:: 6mm 6o~.¢ No... N6.6 0 Xanmmmc APPENDIX D 47 APPENDIX D Bgsglgs of Steggise flultiple ngggssion Dependent variable - weight percent granitic rock/line Independent variables - oxide composition of granitic rock Multiple correlation coefficient - .5518 Multiple coefficient of determination - .3045 Significance - 81% 2111.11. Em A1203 7.80 MnO 51-47 $102 4.69 MgO 20.73 C80 ..55 FOO 4.09 x20 2.10 Constant -466-32 APPENDIX E 49 APPENDIX E legulggion of the biotite norm. The biotite norm has not been generalized to work for all rocks. It was developed for siliceous and alum- inous sediments and metasediments. Prior to calculation. the following relationships must hold: (NOTE: All oxides in moles.) 1. 1120 {game + 1130 + 11110) 2. 111203 a (x20 + 0.0 + 11.20) 3. 3102 _>_ (Feo + MgO + MnO + 6K20 + 6Na20 + 20.0) The norm is then calculated as follows: 1. 2. 3. 4. 5. 6. An amount of F00 - 1102 to produce ilmenite as in the CIPW norm. The remaining FeO-‘Mgo and Mno are added together. To this amount adds a. K20 - %(Fe0 + 1150 + MnO) b. 111203 - -6l(l-‘e0 + 1130 «1 mm) c. 3102 - (Foo + 1130 + 11110) d. 1120 - §