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E . , . r T L 0 A .. .. a... .. . 2‘ m% mma . ..¢-_ m m . -V D . run.“ ' “ 5" LIBRARY 3 Michigan State University alumna av "DAG 8r SUNS' BOOK BINDERY INC. l.! " RARY BINDER! ’-°- “-3-“ "RT, fiiCiiSifl 1.3—:M9h ABSTRACT DIFFERENTIATION AND ALTERATION OF THE CALDWELL SILL, ONTARIO BY Eugene Himie Shannon The extent of chemical differentiation and alter- ation of nine major elements and twelve trace elements in a vertical section of the Caldwell sill, Ontario, was conducted to determine variation in major and trace elements through differentiation in a vertical section of the Caldwell sill, and propose a crystallization model for their origin. An attempt is made to evaluate the effects of chemical weathering on this suite. Analytical determinations of major and trace ele- ments were done by emission spectrographic analysis, and rapid chemical analysis. The analytical values obtained were compared with those of the Logan sills, Karoo dolerites, Palisades sill, and other sills of the world to see if any similarities existed. It was found that in all the sills, calcium and magnesium showed a decrease from bottom to top. The chemical percentage plots versus height Eugene Himie Shannon of the sill, the mafic index, and MgO do not show smooth trends possibly because of the high degree of deteuric alteration of this sill. FKM and other distribution diagrams are drawn to show the degree of variation from the normal trend in basaltic differentiation. The author concludes that the Caldwell sill is composite, and that the associated granophyric rocks, the so-called red rocks resulted from the end product of a normal differentially fractionated basaltic magma, subjected to a high degree of deteuric alteration. DIFFERENTIATION AND ALTERNATION IN THE CALDWELL SILL, ONTARIO BY Eugene Himie Shannon A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Geology 1973 ACKNOWLEDGMENTS Appreciation is extended to Dr. Charles Spooner, my major advisor for his suggestions and patience during the research and preparation stages of this thesis; Dr. Harold B. Stonehouse, Dr. Thomas A. Vogel, and Dr. M. Mortland for their suggestions and proof reading. Further appreciation is extended to Mr. Irvin May, Chief of the Branch of Analytical Laboratories, U.S.G.S., Anthony Dorrzaph, William Crandell, Cathy Thomas, spectro- graphers, and z. S. Altschuler, David Gottfried, George Phair, geologists, of the U.S.G.S. Last, but not the least, appreciation is extended to my beloved wife, Loris Mardia Shannon for her encouragements during those periods of frustrations. ii TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . . . . . LIST OF FIGURES. . . . . . . . . . . . . INTRODUCTION 0 I O O O O O O O O O O O I 1 GEOLOGIC SETTING . . . . . . . . . . . . 2 PREVIOUS INVESTIGATION . . . . . . . . . . 3 PRESENT INVESTIGATION OF THE CALDWELL SILL. . . . 4 THE DIABASE-GRANOPHYRE . . . . . . . . . . 7 Petrography . . . . . . . . . . . . . 10 Mineralogy. . . . . . . . . . . . . . 13 Feldspars . . . . . . . . . . . . . l4 OliVine O O O O O O O O O O O I O O 14 Pyroxenes . . . . . . . . . . . . . 14 Amphiboles . . . . . . . . . . . . . 14 Biotite . . . . . . . . . . . . . . 14 Magnetite and Ilmenite . . . . . . . . . 15 Quartz . . . . . . . . . . . . . . 15 Chemical Data. . . . . . . . . . . . . 15 Major Elements. . . . . . . . . . . . 15 Trace Elements. . . . . . . . . . . . 21 Strontium . . . . . . . . . . . . . 24 Barium O O O O O O O O O O O O O O 28 Chromium. . . . . . . . . . . . . . 29 CObalt O O O O O O O O O O O O O O 30 NiCkel C O O O O O O O O O O O O O 31 Zirconium . . . . . . . . . . . . . 32 Niobium . . . . . . . . . . . . . . 33 Copper . . . . . . . . . . . . . . 33 iii Beryllium . Molybdenum. Lead. Zinc. Petrology. Discussion of Errors Precision and Accuracy of Rapid Analysis. CONCLUSION REFERENCES APPENDIX iv Page 34 35 35 36 42 45 45 55 56 59 LIST OF TABLES Samples of the Caldwell Differentiated Sill, 8-1 to 8-12 (Collected by Dr. C. Spooner) Estimated Model Composition Per Cent of the Caldwell Sill . . . . . . . . . Analytical Results of Rapid Silicate Analysis of the Caldwell Sill, Caldwell, Ontario, Canada. . . . . . . . . . . . Analytical Results: Rapid Analysis and Trace Analysis, 100 Per Cent Water Free (CIPW Norm, Weight Per Cent) . . . . Analytical Results: Emission Spectro- graphic Analysis . . . . . . . . Concentration Ranges of Elements Determined by Computerized Spectrographic Analysis of Silicate Rocks . . . . . . . . . Comparisons of the Results of the Analyses of 149 Samples and 682 Comparisons . . . Comparison of Semiquantitative Spectro- chemical Results With Quantitative Results by Other Methods for 10 Elements in 80 Samples of Vein Material and Mineralized Metamorphic Rocks From the Front Range, Colorado . . . . . . . . . . . Concentration Ranges of Reported Semi- quantitative Spectrographic Results Based on One-Third Order of Magnitude . . . Page 12 16 17 27 47 49 51 54 Figure l. 10. 11. LIST OF FIGURES Index map (Fort William and Port Arthur, and Thunder Cape map areas, Thunder Bay District, Ontario, Department of Mines) showing the location of the Caldwell sill and the Logan sills . . . . . . . . . . % CaO and MgO lost during differentiation of the Caldwell sill . . . . . . . . Graph illustrating the variation in chemical composition of the Caldwell sill with respect to elevation . . . . . . . Graph illustrating variation in chemical composition of the Caldwell sill with respect to elevation . . . . . . . Graph illustrating the chemical composition of the major elements of the Logan sills with respect to MgO . . . . . . . . . Graph illustrating the variation in chemical composition of the Logan sills magma. . Graph illustrating the variation in chemical composition of the trace elements of the Caldwell sill with respect to elevation. Sr/Ca plotted with respect to height in the Caldwell sill and Logan sills . . . . Ba/K plotted with respect to height in the Caldwell sill and Logan sills . . . . Pb/K plotted with respect to height in the Caldwell sill and Logan sills . . . . Co/Ni plotted with respect to height in the Caldwell and Logan sills. . . . . . vi Page 11 19 20 22 23 25 37 38 39 40 Figure Page 12. Graph illustrating iron and alkali enrichment during crystallization of the Logan sills and the Caldwell sill . . . . . . . . 43 13. Comparison of semiquantitative spectro- chemical results with chemical and stpectrochemical quantative results . . . 50 14. Schematic diagram for the rapid analysis of rocks . . . . . . . . . . . . 60 vii INTRODUCT ION The Caldwell sill which is within the area of the Logan sills, crops out between 89°30' and 89°00 West longitude and 48°00; 48°15' North latitude. Chemical analysis of the Logan sills are reported by Blackadar (1956). From the petrographic and mineralogical studies of the Logan sills, it is concluded by Blackadar (1956) that many of these sills are composite, and that the associated hybrid rocks, the so-called red rock, resulted from the assimilation of granite or rarely chert and quartzite. Differentiation was limited by the small size of the individual units composing multiple intrusions. However, there are no analyses reported on the Caldwell sill, which shows a vertical gradation from a diabase to a granophyre in a vertical section of approximately 90 feet. These latter rocks represent the last stage of a fraction- ated basaltic magma. Owing to the overprint of alteration the liquid line of descent has been obscured. However, this sill fits a model of a late stage tholeiitic differ- entiation sequence reminescent of the hornblende gabbro of the Duluth complex to the south, Cornwall (1951). GEOLOGIC SETTING Towards the close of the Precambrian time, the Lake Superior basin was subjected to the intrusion of vast amounts of basic magma. This activity gave rise to dikes, sheets, sills of diabase, one group of which is known as the Logan sills. From the similarity in petrology, mineralogy and field relations, the writer believes that the Caldwell sill is also the result of this intrusion. The large, differentiated, basic sill which outcrops in the vicinity of Duluth, Minnesota is thought to be derived from the same source. The Rove formation, a succession of interlayered shales and graywackes, underlie these sills. T Caldwell region ha farlane, the fielc memoir 1e Departme: MOorehou during t‘ Out Chem PREVIOUS INVESTIGATION There has been no previous work carried out on the Caldwell sill, but the Logan sills which are within the region have been studied by Sir William Logan, T. Mac- farlane, E. D. Engall, and A. C. Lawson. The results of the field work by T. L. Tanton were published in 1951 as memoir 167 of the Geological Survey of Canada. An Ontario Department of Mines field party headed by Dr. W. W. Moorehouse carried out further geological investigation during the field seasons of 1950. Blackadar (1956) carried out chemical analysis of the Logan sills. PRESENT INVESTIGATION OF THE CALDWELL SILL In this study, twelve samples of the Caldwell sill, ranging from 5 feet to 90 feet, above the contact with the Rove formation, were collected by Dr. Charles Spooner (Table l). The writer studied the extent of chemical differentiation during fractionation of nine major and twelve trace elements of eleven of these samples over a short vertical section of about 71 feet of this composite sill. Chemical values are reported in Tables 3, 4, 5, and 6. It was found that the possibility for end stage vapor phase reactions increases the closer one gets to the roof. The chemical values of the Caldwell sill in Tables 3, 4, 5, and 6 are compared with values determined from the Logan sills, the rocks of Duluth, the Keweenawan Series to see if these rocks, of basically the same mineralogical composition, follow the normal differentiation trend. The normal trend is a strong concentration of Na, K, Si, P, S, Ti, Cu, and Mn in the residual magma, or last stage of differentiation, and a decrease of Ca, Mg, and Al in the magma during differentiation and solidification. It is TABLE l.--Samp1es of the Caldwell Differentiated Sill, S-l to S-12 (Collected by Dr. C. Spooner). SUITE Differentiated Sill 62 4804 25 174 Air Photo # Coll: C. M. Spooner S 1 5' above base of cliff (probably 5' above contact with Rove) S 2 7' above base of cliff S 3 10' above base of cliff S 4 12.5' above base of cliff S 5 15' do 8 6 20' do S 7 25' do S 8 38' do S 9 48' do S 10 56' do 30' lateral displacement to west between S 10 and S 11 S 11 71' do S 12 90' above base considered that SiO2 and Nazo increase gradually, MgO and CaO decrease, A1203 declines in latter stages, FeO, T102, P205, and Cu increase to a peak and fall off. If the above statements are true, it would be expected that the chemical analysis of the Caldwell sill will show the same trends. THE DIABASE--GRANOPHYRE The general geology of the area is given by Tanton (1931). According to Tanton, the Logan sills which are also within this area are most commonly found in the shaly members of the Rove formation. Fig. l is an index map showing the locations of the Logan sills and the Caldwell sill. These rocks represent the last stage of a basaltic magma differentiate which has been extremely altered deuterically. This type of alteration was brought in by late stage water-rich fluids, presumably residual solutions from the granophyre precursor. These water-rich liquids superimposed a new low temperature mineralogy on the rocks with some change in bulk chemistry composition, especially magnesium and calcium. Such alteration the author assumes affected parti- cularly the upper parts of the sill (such as the section studied) owing to the tendency of this volatile-rich late fraction to rise in the partly consolidated crystal mush. The evidence for making this extensive alteration deuteric includes: AJ— 4" .'""‘~W_I_‘:§ 0‘ VI - .' . Wilt-una- - N'I'c‘ “13.-LI." "f I III'II In I \'.II“ a. ’ I ‘v ' fl — p—d _ —— |—— I. . I I— — — ——_ —- Index map (Fort William and Port Arthur, and Thunder Cape map areas, Thunder Bay District, Ontario, Department of Mines) showing the location of the Caldwell sill and the Logan sills. The trend of major element enrichment shown by the variation diagrams parallel the known magmatic trends in basalts; hence the alteration probably took place during the later stages of, and as a direct consquence of the consolidation of the magma. The fact that the data points are co-linear and deviation from the curve is small suggests similar degree of deuteric alteration throughout the sequence. The fact that the minerals of the late stage granophyre are much less altered than the earlier minerals of the diabase indicate that the altering fluids were nearly in equilibrium with the early formed diabase minerals. Many of the analysed altered rocks from the Logan sills contain up to 7.0% water total and 1.0% CO2 and are even more extensively altered than the Caldwell sill. In spite of this alteration, the Logan rocks are co-linear, and show only moderate scatter, and fit the pattern of magmatic FeO enrichment followed by alkalic enrichment. This suggests that (l) the alteration is deuteric, and (2) the deuteric alteration is provincial in character affecting in some degree all diabase sills in the region. 10 In Fig. 2 the contents of CaO and MgO in the Caldwell and Logan sills and their differences have been plotted against FeO throughout the differentiation history of these Sills. By looking at the FKM diagram in Fig. 12 it appears as though the FeO content of both the Caldwell sill and the Logan sills is constant. Assuming that this is true throughout differentiation, the amount of CaO and MgO of the Caldwell sill decrease as those of the Logan sills remained constant. The curves of these diagrams explain the offset in the alkali lines of decent shown in the FMK diagram of Fig. 12. The interpretation of this offset of the Caldwell sill curve from the Logan sill curve is due to the continu- ous removal of MgO and CaO contents as FeO remained constant throughout differentiation. This type of alteration which the author has termed deuteric was brought about by late stage water rich fluids which superimposed a new low temperature mineralogy on these rocks causing some change in bulk chemistry, mostly in the MgO and CaO contents. Petrography Eleven thin sections of the sill were examined. The modal compositions are given in Table 2. The texture which is similar to the rocks of Duluth, Grout (1918), varies from sugary to very coarse. It is micropegmatitic, varying to granitic in some large mases. The chief red mineral is feldspar stained with considerable hematite, %CaO %Mg0 5 %FoO Fig. 2. NOIhuOflat no 0| «5 (I (3 <3 ”OI-500N040 ll — . f . Ill"? _ 000 Logan Sills” )- 5" I- I o- x 7 )— 4/ r” 2 Jr "' ' 3‘ i 'L/ \J “‘1’ . .- I / CaO ColdwollSlll I I _ g” I 1 6I l 4 L l l J l J l l I 2 3 4 5 6 7 8 9 l0 ll l2 %FoO P o s 5 6 lie _ Mg Logan Ill: 2 2. L015"1 17 . "WV )9 - f [by t 5 ALLA—Air MgO CaldonISlll j I l l L L J l l l l l L I 2 3 4 5 6 7 8 9 IO ll l2 %Foo " / §(Mg0) (CaO) ' L 4\\ l P \‘K‘k \ ‘N\ h— : \ : > ‘V \o r LA, 1 1 1 1 l 1, l 1 l l l 1 -5 -4.5 -4 -3.5 -3 -2.5 -2 -I.5 -l -.3 O 96 000 and M90 Loot During Differentiation of tho Caldwoll Sill. (Tho 96 ot 000 and MgO are conoldorod Conot. In tho Logan Slllo.) 12 TABLE 2.--Estimated Modal Composition Per Cent of the Caldwell Sill. S-l S-Z S-3 5-4 5-5 5-6 S-7 S-8 5-9 5-10 5-11 Height 5' 7' 10' 12.5' 15' 20' 25' 38' 48' 56' 71' Plagioclase 4O 4O 30 15 10 5 5 10 10 10 3 K-spar - - 10 15 37 35 4O 4O 41 40 43 Pyroxene 20 20 l l l 1 l l — - - Amphibole 10 10 19 21 15 5 6 3 3 4 2 Biotite 3 3 3 4 S 5 4 - — - - Chlorite 3 3 3 3 - - - - - - - Quartz 5 16 25 20 25 4O 4O 40 40 40 42 Muscovite 2 2 2 2 Tr Tr Tr - - - - Sericite 15 15 20 15 15 10 5 5 5 3 3 Magnetite 3.5 5 5 2 1 1 1 l l l Tr Ilmenite 5 2 3 2 l l l 1 l l Tr Pyrite Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Leucoxene Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Apatite 1 1 1 Tr Tr Tr Tr Tr Tr Tr Tr Epidote Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Spinel Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr Tr 13 often badly kaolinized. Probably most of the red rocks contain two feldspars, orthoclase and plagioclase. Zoning is especially common in the phases grading into the diabase. Quartz, though abundant is rarely visible except with the microscope as an intergrowth. Hornblende is the chief ferromagnesian mineral, but it is fibrous and mixed with secondary minerals as if itself secondary. Biotite is secondary. Mineralogy The rocks of the Caldwell sill are relatively simple mineralogically though extremely altered. Feldspar, and pyroxene comprise about 65 per cent of the mineral content in most thin sections examined. Olivine is absent through- out the sill due to extreme alteration. Biotite, Chlorite, amphibole are abundant in most sections. Magnetite, ilmenite, pyrite, apatite, potash feldspar, carbonate and micropegmatite are found in variable amounts. This precambrian diabase sill, similar to the Mamainse diabase in the Canadian shield studied by Friedman (1954) has been greatly altered by hydrothermal deuteric action as the composition of pyroxenes and feldspars cannot be determined. Major and trace elements have been analysed by the writer to provide a tool for studying differentiation trends of basaltic magma, and to evaluate effects of differentiation. 14 Feldspars Because of the high degree of alteration of the plagioclase feldspars to sericite and clay their com- positions cannot be determined. In thin sections of the granophyre untwinned alkali feldspar forms extensive intergrowths with quartz displaying a graphic texture. Olivine Crystals of olivine are absent from these samples. Because of the extent of alteration, relict structures of olivine are not discernible. Pyroxenes Unfortunately, the pyroxenes like the plagioclase are extremely altered to serpentine, hornblende, clay minterals, etc. In thin sections where gragments could be seen the pyroxenes were mainly diopside and hypersthene. Amphiboles Almost all of the amphiboles are hornblende. They are replacement products of the pyroxenes. Biotite The author believes that the biotite present is also a replacement product of the amphibole since it appears to be forming around the outer rims of the amphibole. 15 Magnetite and Ilmenite Magnetite and Ilmenite are mostly concentrated in the diabasic part of the section. Higher in the more felsic part of the section the opaques seem to decrease considerably. Quartz Quartz though abundant, is rarely visible except with the microscope as an intergrowth in the granophyre. Pyrite, leucoxene and apatite are only found in trace amounts . Chemical Data Major and trace elements analyses were done by the writer through the courtesy of the U.S.G.S. The procedures used were those outlined by Leonard Shapiro (Rapid Analysis of Silicate, Phosphate and Carbonate Rocks), Helz, Walthall and Berman (Spectrographic Computer Analysis of the U.S.G.S. chemical laboratory), W. Slavin (Atomic Absorption Spectro- scopy). The chemical values are reported in Tables 3, 5, and 6 and in Table 4 as dry weight per cent. Major Elements The MnO content of the sill ranged from .11 per cent to .20 per cent (1.02%). According to Deer Howie and Zussman (1963) both the dark silicates which contain the hydroxyl groups, and the pyroxenes are the probable carriers of this element. The chemical analysis of these l6 Lnllmrnnanuuar. OOH OOH OOH OOH OOH OOH OOH OOH OOH OOH OOH OOH sum OO.v OO.v NH. OO.v OO.v OO.v OO.v OO.v NH. OO.v OO.v OO.v moo mm. HH. NH. HH. OH. OH. OH. OH. OH. OH. HO. OH. 0:: Ha. OO. OO. OO. OO. an. Om. Om. HO. OO. OO. HO. OONO O.~ OO. OO. OO. OO. H.H H.H H.H O.H O.~ O.~ O.N NOHH HO. OO. HO. OO. OO. OO. OO. OO. OO. HO. he. OO. -me H.H A.H O.~ O.H O.N H.H O.m m.N O.~ O.~ O.~ O.~ +O~m O.~ N.O O.O O.O m.O H.m H.H O.m a.m H.H O.H m.~ OHM m.m O.m O.m O.m O.m O.m O.n H.m O.N O.~ O.m m.m ONOz O.m O.H m.H m.H H.H H.H O.” O.m O.m O.m O.O O.O omu O.~ OO. OO. «O. OO. OO. H.H H.H O.H O.m O.m O.~ om: O.OH O.m m.O O.O O.O 0.0 O.O O.O O.O «.OH 0.0H O.m OOH O.~ O.m O.N O.~ H.H m.m O.m n.H O.H O.~ O.~ H.H memos O.mH O.~H O.NH O.~H H.HH O.~H O.~H m.~H O.NH O.~H O.OH 0.0H mONHH O.OO O.OO O.OO O.OO O.OO e.mO O.~O O.NO O.OO O.OO ~.mm m.mm NOHO .OO .HO .OO .OO .OH .ON .OH .OH .O.~H .OH .O .O uanmm «Hum HH-O OH-O mum Oum elm OlO Olm elm mum mlm Hum .02 OHOHO .apmcmu .OHHmuso .HHmscho scum mememm HHHHmO mmmano UHmHmm NH mo mwmaHmcc HOUHEmno onmm .Oomcmu .oHHOucO .HHO3OHOO .HHHO HHszHOO Ono Oo mHmsHmca OOOOHHHO OHOOO Oo OHHOmmm HOOHusHmcall.m OHOOH 17 OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouHeoano OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouHuHmo OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OOHHHO OO.O OO.O OO.O O0.0 O0.0 OO.O OO.O OO.O OO.O OO.O OO.O ouHuosHm OO.O OO.O OO.O OO.O OO.O OO. OO. «H.H OO.H HH.H Om.H ouHqu< OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O oHHuOm OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O oume>ouoa OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O oconam OO.H OH.H OO.H OH.H OH.~ OO.O OO.~ OO.O OH.O HO.O HO.O ouHcosHH OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O muHumewm OO.. OO.v OO.O «H.H OO.O H~.. HO.~ OH.~ OO.O OO.O OO.O muHuocOmz OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouOuHHHmosouo esHuHau OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ocH>HHo OO.O ~H.O OO.O OO.O OO.O OA.OH OO.OH OO.OH OH.OH OO.OH OO.OH oconumamasm OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouHcoumaHHoz OO. OO.O HO. OO.O OO.O OO.H OO.O OO.O HO.H OO.O O0.0 ouHmOoHO OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O oumoHHHmOumz Eddmmmuom OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OHOOHHHOOHOz esHooO OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O muHEO< OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouHHmm OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O O0.0 OO.O O0.0 «unconuao EOHOoO OO.O OO.O OO.O OO.O O0.0 OO.O OO.O OO.O O0.0 OO.O OO.O ouHoumcose OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ocHHonsz OO.O OO.O O0.0 OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O ouHHHOOoHHOx O0.0 O0.0 OO.O OO.O O0.0 OO.O OO.O O0.0 OO.O OO.O O0.0 ouHoOOH ~H.O OO.O HH.O OO.O H~.O OO.O OO.O ~O.OH OO.OH HN.AH OO.OH oanouoc< O~.Hm OO.OH OO.O~ OO.OH OO.OH ~H.~m OO.ON HO.ON OO.OH OO.~H OO.ON OOHOHO OO.OH OO.ON OO..~ OO.ON O0.0H O0.0H .O.m~ OO.ON OO.OH HO.HH OO.OH ommHoosouo OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O coouHN OO.O ON. OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O OO.O esocauoo OO.OH OO.ON OO.ON OO.ON OO.H~ OO.OH OO.OH ~H.OH OO.HH H0.0 OO.O spouse HH-O OHum Olm O-O hum Oum mum elm mum «um Hum macaw owaam .Aucmo you unOHoz .suoz 3OHuO oouu nouns acoo you OOH .OHOHqum ooaue can OHOHHOO< OHmmm unuasmam HaOHUhHac¢I1.v wands 18 rocks shows that the content of manganese varies very little from the bottom to the top of the sill. This means that both the primary pyroxenes and secondary hydroxyl minerals carried the oxide (Fig. 3). P205 is mainly tied up with the mineral apatite. Generally speaking about 95 per cent of the P205 content of igneous rocks is in this form. P205 ranges from .08 per cent-.68 per cent. This oxide gradually increased during the earlier stages of differ- entiation, then it decreased and remained constant up to the top of the sill (Fig. 3). TiO2 is present in amounts up to 2.8 per cent. Undoubtedly, this is mainly tied up with illeminite or titaniferous magnetite. This oxide ranges from .54 per cent to 2.8 per cent. It shows a steady trend during the early stages of differentiation, then it decreases a little, and therefore remained almost constant up to the top of the sill (Fig. 4). SiO2 is exceedingly high in this sill, ranging from 53.3 per cent (bottom) to 67.9 per cent (top). The SiO2 content in this sill is higher than the values of the Logan sills and other diabase sills throughout the world. This high content of SiO2 is due to the presence of an acid residum which is dominantly quartzo-feldspathic, and charged with soda and lime. Kennedy (1933) classifies these rocks as the last differentiate of a tholeiitic basalt. 19 80'— O . 75'~ C3 C2,. C3 8' 9., 2 2 U 2 x 7|‘(s-m 76- ? r 2 65'- l I I .' E . I . , .' T"50-11. I : - .5 55% | -. . : 56(S-IO) § 50.v- ' \ I . I n = , 48(3-9) 2 45'— ' I I 13 4m I = l c l . se'ts-el 9 35— I ' \ 5 30'- ' \ ' _ V '. m 25'L \ \ \\ 2515-?) s? l '1 i 20' 3-6 20 ‘ \ \‘ V§<\x ( 1 l5' -— ' z . .35 l5'(S-5) \\ \_.___-', -HI mists-4) IO'- \. /\. IO (5-3) I “-. \- I .. } ,- ~ 7 (s 2) 5.__ \ x \ 5' (S-l) P05 'L_ I J l l l l l l l l l l A .5 I. l.5 2. 2.5 3. 3.5 4. 4.5 5. 5.5 6. 6.5 Percent Fig. 3. Graph illustrating the variation in chemical composition of the Caldwell sill with respect to elevation. 20 80w- ..Mgo Fe203 Al 0 2 3 7O'ri/Ti02 , F30 . 7|‘(s-u) _ I \ : t I I I \\ : : 60 '—| ' X l U I ' t O I l . : o 50.F- I ' 8 ‘L I 1 1 43'(s-9) D "'" I \ ‘l E; 40' l I \ l .o h 1 ' ' _ o l \ ‘\ '1 38 (S 8) 5 A \ “ " g 30'— K . \ ,' 3 l \ - " 25'(s 7) a . '. ,/ \ : . 20 X f T‘ I. —" 20 (3'6) . I Y: \.. ( 15'(§-5) . \ X“ k l2.,5(S-4) I0 4‘ - no (5-3) I I .l “fi 7'(S‘2) . I . . 5' (3-1) 0 l 1 1 J l J 41 .L l 1 1 1 :1 1.1I J I 2 3 4 5 6 7 8 9 IO ll (2 l3 l4 l5 l6 Percent Major Oxides Fig. 4. Graph illustrating variation in chemical compo- sition of the Caldwell sill with respect to elevation. 21 CaO and MgO decreased with differentiation from bottom to the top of the sill (Fig. 3). These elements are mostly concentrated within pyroxenes, olivine and plagio- clase, which come out very early in a differentiated basaltic sill. A1203 decreased during the early stages of differentiation and thereafter remained almost steady to the close of differentiation (Fig. 4). K20 and Nazo increased with differentiation from the bottom of the sill to the top (TOp.). The alkalies are mobile and travel upwards, tending to concentrate in the valatile phases becoming enriched during the later stages of differenti- ation. Unlike the Caldwell sill, the Logan sills though lower in K20 and NaZO, are higher in M90 and CaO. Combined water is more abundant in these granophyric rocks. Figs. 5 and 6 are variation diagrams showing the chemical compo- sition of the Logan sills. Trace Elements The results of the trace element studies are presented according to element behavior during differ- entiation (Fig. 7). The trace elements tend to follow the major elements in their distribution. They enter the sites that might normally be occupied by major cations in the lattice structure. This means that the trace cation successfully competes with the major cation for the available site. The cation of a trace element tends to enter the mineral lattice site normally occupied by a 22 l5? II?‘ F80 l \\ /A\\ IOL ’1'" \VT, }_j_ _____ 5P /’ O- 5»— //"\\_F:293_‘,-.‘ -- ”””” 8 (Dr ‘0 tg I5b 5- IO- cog"j\ ,’\‘\ .2 ,’-1-'r’/ \ I \‘\4 U 5- / \I E ’ \I E h- 8 5" “ N020 C) "p" ---- .1”\\’_1-_____4 O. L .1 lot 51.. —-'\‘P_--_KEO /‘~ -~ ______ 01 5'1 ’r. ‘ T302- ’,1\\ . 0. Fl \",.— ‘4 -1.-— 1 1 1 ML 1 1 1-1 3 456789l0|l|2 PercentMgO Fig. 5. Graph illustrating the chemical composition of the major elements of the Logan sills with respect to MgO. “0 Fe, 0, so, CaO N330. noa Fig. 6. 23 fg‘» #J“*“1$ 10 1' l \ 1‘3‘ 51 I i D 15 * 1(50/0 "_"" *0 5T O p 19 I i ‘P—‘m w 55 d s ib n F. o + ‘0: 01 M30+Fe O+Fez 0, Graph illustrating the variation in chemical composition of the Logan sills magma. 24 major cation whose chemical properties are closest; for example, where Rb+(l.48A) enters a K+ (1.33A) site. Some trace elements are only accommodated with difficulty in the lattice sites of the major elements in minerals, and these tend to behave independently; for example Zr and Cu. Thus, where trace elements have no similar major elements with which they can associate, they tend to concentrate in the magma until they can form a separate mineral phase, i.e., Zr. Their behavior then switches from that of a trace to that of a major mineral-forming element, with which other suitable matched trace elements may then associate (Kenneth R. Walker, 1969). Distribution trends of trace elements of the Caldwell sill are shown in Fig. 7. Strontium Some recent estimates of the strontium content of basaltic rocks are 440 ppm Faure and Hurley (1963), 440 ppm, Vinogradov (1962), 461 ppm, Gast (1960), and 300 ppm, Fairbairn and others (1953). The Sr within the rocks of the Caldwell sill as reported by the author ranges from 882 ppm in the more basic samples to 144 ppm in the more felsic. There is an average of 376 ppm for both felsic and basic samples of this diabase-granophyre. It appears as though most of the strontium was contained within the 25 I Q 3 o 39* o\° E e e . E ’ 80 23%;; g g g 75- §2§’z E5 2 z 2 £0 .12 i; 8 70 u, y _.-— _---_——— (s-um' , T TI 5 65- l I / 3 1 ”2 (some 1;, 3 .-_-___1_ lS-QMB‘ s C 3 ls-elsa' 0 § uJ . ___--_,..__. ls-‘nzs' " —-— --——~ ls-elzo' 7 ,. ,. -...__-— (s-sns', _ _....\_....__ (54112.5 f. :21 ' l*”fl -— so "5' (3")5 l 1 l 1 1 l l_L J 90 400 600 000 lOOO IZOO Trace elements in parts per million Fig. 7. Graph illustrating the variation in chemical composition of the trace elements of the Caldwell sill with respect to elevation. 26 Ca-rich minerals such as plagioclase and clinopyroxene which have been extremely altered. In the Palisades sill, Walker (1969), Sr content shows a steady increase with fractionation in the middle and late fractionation stages, whereas the Ca content progressively decreases. This might be true because of the early removal of Ca in Ca- bearing phases. In the Caldwell sill, Sr does not show a steady increase with fractionation. This might be due to the depletion of Sr as fractionation proceeded or the lack of available sites, like (K + Ca) for Sr. Another possibi- lity could be the early removal of Sr in Ca rich phases. Hier (1962) shows that the ratio of Sr in K feldspar to plagioclase is close to unity and ranges from 0.5 to 2.0. Heier and Taylor (1964) have noted that high Ba and Sr contents of many alkaline rocks. Wager and Mitchell (1951) found that Sr increased in the residual magma until about 60 per cent solidification, and then dropped off. The present day study shows that alkali basalts contain much ~54 more Sr than do tholeiites. The enrichment of Sr in alkali basalts may be due to higher average K contents. Variation diagram with respect to height is drawn to show the trend of Sr with differentiation. Sr showed an in- crease during the initial stages of differentiation, then it began to fluctuate during later stages of differenti— ation. It shows an overall decrease (Fig. 7). 27 now mvw Hmo mmo mvm Hmo Hov awn owv ham wNN 5&0 Nu «2 9: m2 3 HS mma 63 «2 m3 SN m3 and an «3 MS 65 m2 9: m2 8N om... Sm moo «mm and um a. on 3 a. o a. m m S K. m and no 3 v m S v v m o 2 on «N and Hz So mom 5... Now 2m owe 3... 3m 83 o? 2... and am cm X” 2 an an 8 R S 2 2 m in n2 m K. o a. o a. m e h v v and 0: 2m omm mg 08 32 on: 8: 2.3 or; 83 8.: son a: m Z Z 2 S «N 8 mm H2 om 8 En so 2 S 2 3 m S Q m , 2 2 3 BE no N a m m m s m S R on R can co n v n a. n m n m m N a and on film 07m mim mlm Tm mum Tm vim Tm mum Tm 538on «8373 382.: 2.82.: $82-3 $82-: $82.... $82.... $82-: $02.73 $82.: $02.73 295m .oz 3on 63.323 cwnmuumouuoomm sound—um spanned 303305716 mamas 28 Barium Recent estimates of Ba in basaltic rocks include 300 ppm, Vinogradov (1962), 330 ppm, Turekian and Wedepohl (1961), 33 ppm, Gast (1960), 310 ppm for one activation analysis, Hamaguchi and others (1957), and 280 ppm, Fair- bairn (1953). The wide range of values of Ba may partly reflect poor inter-laboratory correlation. The Caldwell sill is very high in barium. The value range from 430 ppm to 1000 ppm, with an average of 720 ppm. This high content of Ba is due to the presence of a high amount of feldspar present as intergrowth. K-feldspars are richer in Ba (2000-3000) than coexisting plagioclase owing to a strong coherence of K and Ba. Heier (1964) shows that alkalic rocks are usually rich in Ba, indicating high barium content in feldspathoids. The high content of Ba could also be due to the high degree of alteration that these rocks have suffered. The present study shows that alkale basalts have about twice as much barium than do tholeiites. The coherence of K and Ba is reflected in the increase of Ba in alkali basalts that have more alkalies. The sharp increase in the barium content in the barium content in the late fractionation stages probably resulted from the increase in the K content of the orthoclase with fraction- ation. Variation diagram with respect to height is drawn to show the trend of barium with differentiation (Fig. 7). Barium shows a steady increase during differentiation of the Caldwell sill. 29 Chromium Fleischer and Stevens (1962), Ahrens and Fleischer (1960), and Fleischer and Chao (1960) find only fair agreement in Cr content of W-l (+50% and -33%) from vari- ous laboratories. There is a great deal of uncertainty about absolute values of chromium. Recent estimates of chromium content in basaltic rocks are: 172 ppm Turekian and Carr (1963), 200 ppm, Vinogradov (1962), 170 ppm, Turekian and Wedepohl (1961), 100 to 400 ppm, Goldschmidt (1954). Chromium usually shows the greatest dispersion of all the spectrographically determined elements, which reduces the significance of an average value. The study of basalt gives an arithmetic mean of 162 to 168 ppm and a median value of 140 ppm for 245 analyses (Poldervaart and Hess, 1968). The range of accepted values from the study of basalt was between 0-550 ppm, Poldervaart and Hess (1968). The author assumes that most of the chromium was separated from the magma with the olivines and pyroxenes. Early pyroxene incorporates great amounts of chromium causing chrome spinels to cease crystallization. Later pyroxenes and magnetite usually have lesser amounts of chromium because the magma is now depleted in chromium. Carstens (1958) finds that feldspar, feldspathoids, ilmenite and other minerals in basaltic rocks contain little or no chromium. Alkali basalts are therefore 30 usually low in chromium. Variation diagram is drawn with respect to height is drawn to show the trend of chromium with differentiation (Fig. 7). Chromium does not show a continuous decreasing trend as expected during differ- entiation. This might probably be due to Spectrographic dispersion of chromium. Chromium was determined in nearly all of the analysis made, although in amounts never exceeding 42 ppm. According to Rakama and Sahama (1950) chromium occurs in trace amounts in many silicates. It has been detected in augite, hornblende and olivine. Mason (1952) states that 1.2 per cent of some augites may be CR203. It is particularly abundant in magnesian-olivine. In the Caldwell sill, it ranges from 8.05—29 ppm. In this sill chromium shows a random trend with differentiation. Cobalt Some recent estimate of cobalt in basaltic rocks included 45 ppm, Vinogradov (1962), 48 ppm, Turekian and Wedepohl (1961), Carr and Turekian (1961), and 35 ppm, Unksov and Lodochinikova (1961). The cobalt of the Caldwell sill as reported by the author ranges from 1.6 ppm to 30.3 ppm. Co tends to follow the pyroxenes and olivines which have Fe+2 and Mg+2. These cations provide appropriate sites for cobalt. Since the pyroxenes and olivines are almost completely absent from this late stage differentiate, it is not surprising that cobalt is this 31 low. Cobalt decreases with differentiation as expected (Fig. 7). Nickel Nickel enters the same minerals as cobalt. Turekian (1963) and others show that nickel is enriched in early olivine and to a lesser extent in early orthopyroxene. It is also present in lesser amounts in magnetite, clinopyroxene, amphibole, and biotite. Since nickel enters most abundantly into the olivine structure, this mineral has a marked influence on the nickel distribution in basaltic rocks. In general nickel is rapidly depleted by early ferromagnesian silicates and opaque ores and has low abundance in late-stage basalts. The author therefore believes that the low amount of nickel is due to its early extraction from the magma with olivine, and pyroxenes. The author reports that nickel ranges from 2.39 ppm to 22 ppm in the Caldwell sill. There appears to be no systematic decreases with differentiation as expected. This is probably due to the extreme alteration of the olivines and pyroxenes of these rocks, and the removal of certain cations, like Fe and Mg which act as favorable lattice sites for nickel. The distribution trend of nickel is shown in Fig. 7. Nickel shows an overall decrease with differentiation. 32 Zirconium Recent estimates of zirconium in basaltic rocks include 110 ppm, Vinogradov (1962), 140 ppm, Turekian and Wedepohl (1961), and 110, Degengardt (1957). In the Caldwell sill as reported by the author, the value of zirconium ranges from 226 ppm to 681 ppm (from bottom to top). The average value of 498.4 ppm is much higher than any other result reported in the literature. However, this high value of zirconium in the residual magma could be due to the fact that zirconium has its highest concentrations in products of residual fractionation; the granophyre. According to Chao and Fleischer (1960), zirconium increases rapidly from mafic to silicic compositions. The main feature of zirconium behavior as reported by Walker (1969) is that it forms its own silicate phase, zircon, rather that entering other mineral lattices. This accounts for its somewhat irregular distribution in the whole rock. The size of Zr+4 (0.80A), in addition to the problem of charge balance, makes entry into major cations sites of minerals difficult. Ringwood (1955b) has indicated that zirconium may also form complexes. As (ZrO4) is large with respect to (Si04), it concentrates in residual melts. The distribution trend of zirconium is shown in Fig. 7. Zirconium shows a great increase from the bottom of the sill to the top. 33 Niobium Niobium was detected in the Caldwell sill to range from 9 ppm to 34 ppm (from bottom to top). This means that niobium increased from bottom to top during magmatic differentiation. One of the most important features of the geochemistry of niobium and tantalum are their strong coherence with titanium (Rankama, 1944, 1948; Fleischer gt‘gl., 1952). Quantitative studies of the distribution of niobium in minerals in some basalts (Huckenholtz, 1965; Cornwall and Rose, 1957), and in gabbroic rocks (Gottfried, unpublished data) indicate that the iron-titanium oxides (magnetite and ilmenite) contain most of the niobium in major rocks. This means that the content of niobium depends on the concentration of titanium. The distribution trend of niobium is shown in Fig. 7. Niobium increases from bottom to the top, while titanium decreases with differentiation. This trend might be due to the fact that a 1 perhaps niobium followed other cations as titanium was depleted from the magma. Co er Recent estimates of copper in basaltic rocks include 100 ppm (Vinogradov, 1962), 88 ppm (Wedepohl, 1962), 87 ppm (Turekian and Wedepohl, 1961), 56 ppm for gabbros, 87 ppm for basalts (Monita, 1955), and 72 ppm (Fairbairn and others, 1953). Present day studies show an arithmetic mean of 119-123 ppm and a median of 100 ppm 34 for 156 analysis. Copper ranges from 5.97—131 ppm in the Caldwell sill. It has an average of 44.3 ppm. Copper decreases from bottom to top in these rocks. The author believes that this decrease is due to the fact that copper might have separated earlier as a sulphide phase. The dominant characteristic of copper behavior is its tendency to complex in the magma rather than form independent ions if enough sulfur is available. When sufficiently concen— trated, copper forms an immiscible liquid, which in turn separates as a sulphide phase. At low concentration copper can be camouflaged by olivine, pyroxene or biotite. This behavior was identified in the Skaergaard intrustion by Wager and Mitchell (1951). Avariation diagram of copper with respect to height is shown in Fig. 7, and chemical values in Table 5. Beryllium E[ The author did not encounter any literature on the » chemical analysis of beryllium in basaltic rocks. However, from the periodic chart, beryllium, with a valence of 2, )r might behave like some of the other alkaline earth metals. In the Caldwell sill, beryllium ranges from 1.81-4.39 ppm. Though slightly irregular, it shows an overall increasing trend from bottom to top. It drops slightly in S-ll to 2.79 ppm. This slight irregular trend with differentiation of beryllium could be due to the presence or absence of available cation sites, or insufficient amount of beryllium 35 in the original magma. Distribution trend of beryllium is shown with respect to height in Fig. 7. Spectrographic results are recorded in Table 5. Molybdenum M0 in the granophyre-disbase of the Caldwell sill range from 3 ppm to 7 ppm. It has an overall average of 6 ppm. According to Walker (1969) Mo enters the opaque iron minerals, and its presence in these minerals show a progressive, but irregular increase in concentration with fractionation. Molybdenum shows a strong tendency to complex and concentrate in residual magmas, as the complexes formed are larger than SiO4 (Ringwood, 1955b), Zr (0.80A), or Fe (0.64A), which is consistant with its presence mainly in the opaque iron minerals. The irregular increase in concentration of molybdenum could also be due to its early separation from the magma as a sulphide phase. The distri- bution trend of molybdenum with respect to height is shown in Fig. 7. £639 Lead distribution in the Caldwell sill is irregular. Lead shows a slight general increase in concentration with differentiation. The average composition is 10 ppm. It ranges from 4 ppm to 30 ppm. Distribution trend is given in Fig. 7, and values are given in Table 5. Lead tended to concentrate in the residual melt as expected, though 36 some of it might have entered crystal lattices, such as the K-feldspars proxying for potassium ion, or might have separated earlier as sulphide phases. Zinc The distribution of zinc, like beryllium in basaltic rocks are not reported in any recent literature that the author has read. However, from the geologic occurrence of zinc the author believes that zinc crystal- lizes out as a sulphide mineral similar to lead. Zinc ranges from 226 ppm to 681 ppm. It seemed to be mostly concentrated in the residual magma. Zinc also shows a slight irregular trend with differentiation, but overall it seems to increase in concentration from bottom to top. The distribution trend of zinc is shown in Fig. 7, and spectrographic values are reported in Table 5. Comparisons of the ratios of Sr/Ca, Ba/Ca, Pb/K and Co/Ni of the palisades sill and Caldwell sill are shown in Figs. 8, 9, 10, and 11. The curves were made to see whether the trace elements were controlled by differ- entiation, favorable lattice sites, or whether trace elements followed major elements because of their chemical sililarities. These curves were also drawn to see if alternation played a significant role in the differentia- tion of these elements. According to the Sr/Ca ratio curves of both the Palisades sill and the Caldwell sill, it seems that Sr follows Sr very closely up to a point in 550 500 450 400 350 300 250 200 I50 mo 50 Sr/Co Fig. 37 Sr/Co (in the Caldwell Slll) l L 1 L l l l l L l 1 l l l l l l J 5 IO I5 20 25 50 35 4O 45 5O 55 60 65 TO 75 80 85 90 Ft. (Height) Sr/Co (Palisades Sill) L l _1 l l l l 1 l l 50 ICC 200 300 400 500 600 700 800 900 Ft. (Height) 8. Si/Ca plotted with respect to height in the Caldwell sill and Logan 3 113. 38 500 r- 400'- 3°° ’ Ba/K Caldwell Sill 20(’_. “ __...o---—-n two times, each time by different analysts. Results of 1 per cent or higher are reported to the nearest tenth of a per cent; results below 1 per cent are reported to the nearest hundredth. Major elements that are 10 per cent or above are plus or minus 1 per cent relative. Constituents that are 1-10 per cent are plus or minus .1 per cent absolute, 46 e.g., 6.7 per cent and 6.6 per cent are about the same. Constituents that are below 1 per cent are plus or minus .02 per cent absolute, e.g., .60 per cent or .62 per cent are about the same (Dr. Leonard Shapiro and W. W. Brannock, 1959). For complete analysis, the averages of the sum- mations are expected to be between 99.0 and 101.0. These methods are designed to give results that are comparable to those obtained by conventional gravimetric method. Two studies (Fairbairn and others, 1951, and Stevens and others, 1960) of the results of conventional analyses made by a number of laboratories show the range of results obtained for each constituent in two silicate rock samples. The Rapid methods described here provide data well within these ranges (Shapiro, 1959). Accuracy and precision of concentration ranges of elements determined by computerized spectrographic analyses of silicate rocks are at least equal to the visual semi- quantitative spectrographic analysis previously used (50%, ~33%) (W. W. Helz, F. G. Walthall, and S. Berman, 1969). A routine analysis includes all elements listed in Table 6 with limits. Values obtained by visual methods are supplied when possible for those listed above without limits. The standard deviation of any single answer is taken as plus 50 per cent, and minus 33 per cent. 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I omnw l J - J l ' --_..-l._----L_-l. - -- -._ J--:- - - .-- _ -l._-l...-..(--- l_._ 2" .9; 32 .2 z: :2 a: '5 :2 m. “1 0. C. 3 23 £1 a :3 g g; e s; 0 ‘9 “ " " '“ g 0' d 0 QUANWAIIVL 01111110111 Ann Sl'ECTROCHfMECM. lawns; IN PHCC'LHl ‘ Figure 13. Comparison of semiquantitative spectrochemical results with chemical and Spectrochemical quantitative results. Elements determined: Ag, Co, Cr, Cu, M0, M0, Ni, Pb, Th, Ti, U, V, and Z. Source of samples analyzed veins, mineralized metamorphic rocks, igneouis minerals, and soils. Total number of paired results, 682 in agreement, 478; missed by one- third, 204; missed by more than one-third order, 5. 51 TABLE 8.--Comparison of Semiquantitative Spectrochemical Results With Quantitative Results by Other Methods for 10 Elements in 80 Samples of Vein Material and Mineralized Metamorphic Rocks From the Front Range, Colorado. Ag Cu Mn Mo Spectro- Wet Spectro- Wet Spectro- Wet Spectro- Wet Spectro- Fire Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Sample Assay cal cal2 cal2 cal4 cal2 cal1 cal2 cal3 cal2 1 0.00014 0.00015 <0.005 0.003 0.03 0.03 0.15 0.15 0.04 0.07 2 .00054 .0015 <.OOS .007 15 .15 .20 .3 .22 .3 3 .00014 .0015 <.OOS .003 .14 15 .17 .3 .038 .03 4 ------ 0 <.OOS .003 .0095 .015 1.80 3. .018 .015 S .0046 .007 .018 .015 .15 .15 .63 .7 .60 .7 6 ------ .0003 <.OOS .007 .02 .015 1.45 1.5 .060 .07 7 .0014 .0015 <.OOS .007 .09 .07 .56 .7 .18 .15 8 .00008 .0015 <.OOS .007 .08 .07 .50 .7 .072 .07 9 Tr. Tr. <.OOS .003 .03 .03 4.12 3. .062 .07 10 .00014 .0003 <.OOS .003 .03 .03 .59 .7 .060 .07 11 .0062 .007 .017 .015 .87 1.5 .08 .15 .56 .7 12 .0042 .007 .008 .015 .14 .15 .10 .07 .43 .3 13 .00014 .0007 <.005 .003 .11 .15 .05 .07 .04 .03 14 .0015 .003 .012 .015 .19 .3 .08 .15 .14 .15 15 ------ Tr. <.OOS .003 .03 .03 .12 .15 .006 .007 16 .0062 .007 .021 .015 .23 .3 .09 .15 .31 .7 17 .0048 .007 .007 .015 .09 15 .47 .7 .42 .7 l8 Tr .0015 <.OOS .003 .09 .07 1.8 3. .058 .07 19 .0178 .015 .04 .03 1.07 1.5 .22 .15 .22 .3 20 Tr. .0015 <.OOS .007 .22 .3 .09 .15 .054 .15 21 .0056 .015 .018 .015 .95 1.5 .12 .13 .21 .3 _ 22 .0095 .015 .016 .015 .62 .7 .05 .07 .15 .3 If; 23 .0012 .003 .006 .007 .46 .7 .02 .03 .07 .15 1 24 .0120 .015 .016 .015 1.16 1.5 .04 .03 .22 .3 ‘ 25 .0241 .015 .05 .03 .89 1.5 .21 .3 .84 .7 '.1 26 .0036 .007 .012 .015 .32 .3 .28 .3 .17 .15 r 27 .00068 .003 <.OOS .007 .10 .15 .18 .15 .092 .15 28 .0031 .003 .013 .015 .16 .15 .58 .7 .14 .3 29 .0016 .003 <.OOS .007 .43 .7 .41 .3 .17 .3 30 .0066 .007 .018 .015 .85 1.6 .06 .15 .95 .7 1Analyst, D. L. Skinner. 2Analyst, N. M. Conklin. 3Analysts, R. F. Dufour and Claude Huffman, Jr. 4 Analyst, W. D. 6038. 52 'TABLE 8.--Continued. Ni Pb U V Zn Wet Spectro- Wet Spectro- Wet Spectro- Wet Spectro- Wet Spectro- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Chemi- Sample cal3 cal2 cal4 cal2 cal4 cal2 cal3 cal2 ca17 cal2 1 0.0065 0.007 0.10 0.07 0.63 0.7 0.02 0.015 0.013 (0.03 2 .010 .015 .46 .7 .58 .7 .03 .07 .014 (.03 3 .0075 .007 .06 .07 .26 .3 .03 .03 .012 (.03 4 .0065 .007 .009 .007 .017 <.07 .03 .01 .020 Tr. 5 .006 .03 .81 .3 5.57 7. .03 .07 .086 .07 6 .002 .007 .21 .15 .33 .3 .04 .05 .030 <.03 7 .011 .007 .23 .3 .58 .3 .08 .03 .030 <.03 8 .0075 .007 .08 .07 .56 .7 .03 .03 .023 (.03 9 .0085 .003 .05 .015 .067 .07 .02 .015 .019 <.03 10 .008 .007 .07 .03 .684 .07 .04 .03 .022 (.03 11 .022 .03 1.05 1.5 .79 .7 .03 .03 .19 .07 12 .011 .015 .46 .7 1.95 1.5 .02 .03 .056 .03 13 .0065 .007 .11 .07 .033 .07 .01 .015 .062 .03 14 .016 .015 .63 .7 .72 .7 .02 .015 .16 .15 15 .009 .007 .03 .03 .009 (.07 .02 .015 .11 .07 16 .039 .03 .73 .7 1.59 1.5 .03 .03 .068 .07 17 .022 .03 .69 .3 4.59 7. .03 .03 .020 (.03 18 .009 .007 .13 .07 .50 .3 .03 .03 .046 Tr. 19 .035 .03 .62 .7 3.61 3. .05 .07 .11 .07 20 .0085 .015 .06 .07 .28 .3 .03 .03 .044 .03 21 .018 .015 .29 .3 .58 .7 .03 .03 .092 .07 22 .018 .03 .37 .7 1.15 1.5 .02 .03 .052 .07 23 .014 .015 .08 .15 .11 .15 .02 .03 .076 .07 24 .016 .015 .70 .7 2.79 3. .03 .03 .089 .07 25 .053 .07 .60 .7 3.70 3. .08 .07 .10 .03 26 .017 .015 .16 .3 1.11 .7 .04 .03 .045 Tr. F.£ 27 .009 .007 .10 .15 .29 .3 .03 .03 .041 .03 28 .016 .015 .28 .3 2.49 3. .05 .03 .16 .07 29 .019 .03 .73 .7 1.37 1.5 .03 .03 .16 .15 30 .011 .07 1.45 1.5 6.36 7. .06 .07 .084 .07 5Analysts, H. M. Nakacawa and C. E. Thompson. 6Analysts, H. H. Lippo J. P. Schuch, and J. s. Wahlberg. 7Analyst, J. S. Wahlberg. 53 chemical results. The author compared the emission spectrographic results of Co, Mn, Pb, and Zn of the Caldwell sill with the above analysis by A. T. Myers, R. G. Havens, and P. J. Dunton (1961). Comparisons were close enough to say that they fall within the same order of magnitude. In Table 9, the author reports a series of numbers reported (per cent) as compared with limits of concen- tration defined by standard (per cent). Error bars have been plotted at analytical points to show that the standard deviation for every single answer is taken as +50 per cent, and -33 per cent. 54 TABLE 9.--Concentration Ranges of Reported Semiquantitative Spectrographic Results Based on One-Third Order of Magnitude. Number Reported Limits of Concentration Defined (Per Cent) by Standards (Per Cent) 7 10 — 4.6 3 4.6 — 2.2 1.5 2.2 — 1.0 .7 1.0 - .46 .3 .46 - .22 .15 .22 — .10 .07 .10 - .046 .03 .046 - .022 .015 .022 - .010 .007 .010 - .0046 .003 .0046 - .0022 .0015 .0022 - .0010 .0007 .0010 - .00046 .0003 .00046 - .00022 .00015 .00022 - .00010 Note: In addition to the above the following symbols are used in reporting results: M: major consti- tuent greater than 10 per cent. Tr: barely detected and concentration uncertain. O: looked for but not found (for limits of detection see Table 2). -: not looked for. < with number: less than number shown; here standard detectabilities do not apply. nu‘r ‘. ‘1‘" i - '3- ' 41.4.11 "‘2 CONCLUSION Differentiation in the Logan sills, Palisades sill and other similar sills led to an enrichment in iron. The Caldwell sill shows a trend towards alkali enrichment. This sill represents the close of magmatic differentiation, characterized by an enrichment in alkalies and silica and a deficiency in magnesium, calcium, iron, and aluminum. The author therefore concludes that these rocks are a result of the last residue of a basaltic magma differentiate which have been extremely altered deuteri- cally by water-rich fluids. 55 ..Il‘lul' . A REFERENCES REFERENCES Blackadar, R. G. 1956. Differentiation and assimilation in the Logan sills, Lake Superior District, Ontario. Carstens. 1968. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Cornwall. 1951. Differentiation in magmas of the Keeweena- wan series. Jour. Geol, Vol. 59, pp. 151-172. Cornwall, H. R., and Rose, H. J., Jr. 1957. Minor ele- ments in Keweenawan lavas, Michigan. Geochim. Cocmochim. Acta 12, 209-224. Degengardt. 1957. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Fairbairn and others. 1953. Basalt. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Fairbairn, H. W., and others. 1951. A cooperative investigation of precision and accuracy in chemical, spectrochemical, and modal analysis of silica rocks. U.S. Geological Survey Bull. 980, 71p. Faure, G., and Hurley, P. M. 1963. The compositions of strontium in oceanic and continental basalts: application to the origin of igneous rocks. Journ. of Petrology, 4, 31-50. Fleischer and Chao. 1960. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Fleischer and Stevens. 192. Basalts. The Poldervaart treastise on rocks of basaltic composition. 56 57 Friedman, G. M. 1954. Note on the relative abundance of some trace elements near the lower and upper contacts of the Palisade sill. Jour. of Geology, v. 26, pp. 626-658. Gast. 1960. Limitations on the composition of the upper mantle. Jour. of Geophys. Res., 65, 1287-1298. Goldschmidt. 1954. Geochemistry, in muir, A., Editor, Oxford University press, 730p. Grout, F. F. 1918. A type of igneous differentiation. Jour. of Geology, v. 26, pp. 626-658. Hamaguchi and others. 1957. Basalts. The Poldervaart treatise on rocks of basaltic composition. Heier. 1962. Basalts. The Poldervaart treatise on rocks of basaltic composition. Heier, 1964. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Heier and Taylor. 1964. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Helz, A. W., Walthall, F. G., and Berman, S. 1969. Computer analysis of photographed optical emission spectra. Huckenholtz. 1965. Die verteilung des niobs in den Gesteinen and mineralen der alkalibasalt-association der Hocheifel. Geochim. Cosmochim. Acta 12, 209-224. Kennedy. 1948. Equilibrium between volatiles and iron oxides in igneous rocks. Am. Jour. Sci, 246, 529-549. Kennedy, W. O. 1933. Crustal layer and the origin of magmas: petrological aspeCts of the problem. Bull. Volcanologique, ser. 2, tome 3, pp. 24-41. Monita. 1955. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Myers, A. T., Havens, R. G., and Dunton, P. J. 1961. A spectrochemical method for the semiquantitative analysis of rocks, minerals, and ores. U.S. Geological Survey, Bull. 1084—1, 207. 58 Poldervaart and Hess. 1968. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Rankama, Kalervo, and Sahama, Th. G. 1950. Geochemistry. Chicago, University of Chicago Press. Ringwood. 1955b. The principles governing trace element distribution during magmatic crystallization. Geochim et. Cosmochim. Acta, V. 7, pp. 242-254. Shapiro, L., and Brannock, W. W. 1959. Rapid analysis of silicate, carbonate and phosphate rocks. Geol. Survey Bulletin ll44-A. Tanton, T. L. 1931. Fort William and Port Arthur, and Thunder Cape map areas. Thunder Bay District, Ontario. Canada Geological Survey, V. 26, pp. 626-658. Turekian and Carr. 1963. The Chromium and Nickel distri— bution in basaltic rocks and eclogites. Geochim. Cosmochim. Acta, 27, 835-846. Turekian and Wedepohl. 1961. Distribution of the ele- ments in some major units of the earth's crust. Bull. Geol. Soc. Am. 72, 175-192. Unksov and Lodochinikova. 1961. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. Vinogradove. 1962. Basalts. The Poldervaart treatise on rocks of basaltic composition. Vol. 2. i .J Wager and Deer. 1939. The petrology of the Skaergaard intrusion, Kangerdlugssuag, East Greenland. Medd. Om Gr¢nland, bd. 105, no. 4, 335p. Wager and Mitchell. 1951. The distribution of trace elements during strong fractionation of basic magma--a further study of the Skaergaard intrustion, East Greenland. Geochem. et. Cosmochim. Acta, V. 1, pp. 129-208. Walker, K. R. 1969. The Palisades sill, New Jersey: A reinvestigation. The Geological Society of America, Special Paper 111. APPENDIX APPENDIX Analytical Procedures Rapid Method Analysis The methods described here are those that are currently in use by the U.S. Geological Survey for rapid rock analysis. They are an outgrowth of the scheme of analysis originally presented by Shapiro and Brannock (1952) and revised by Shapiro and Brannock (1956). Since 1956 approximately 800 samples per year have been analyzed. During this period the methods for analyzing silicate rocks have been modified and extended to include methods for carbonate and phosphate rocks. Provision is made for the determination of Sioz, i K A1203, total iron, FeO, MgO, CaO, TiOz, MnO, P O, 205' 2 Naz), H20, C02, F, and S. The complete scheme for the analysis of silicate, carbonate and phosphate rocks is shown by the flow diagram in Fig. 14. Silica and Alumina were determined spectrophoto- metrically on alliquots of a solution prepared by fusing the sample with NaOH; a molybdenum blue method was used for SiOz; and alizarin red-S was used in the determination of A1203. A second portion of the sample was digested 59 6O .UNAIXSR,OF annex“; Cguuoxxmg PHOSPHATE nocxs .A: .- -__._..- --—.._. __/\_ Ammomum \ )"r 3'03 ~._»’ molybcatc ' mac K . ...'_ "* ) ‘- ALO. -- - Alnzann rod- 5 (‘ ~ «f3 :01 L, i :ON .z..) c 7; A .J.‘ a I.‘ _.‘ . a; ‘ .1 -- 1" u“!‘u°"|\“l‘ ; NSCH k __ / Jg‘f\ulf Itt’ \‘ If;-.- I 1 .- .- :‘TeflCn C 9‘1“. ) .- -- '.- , . «hf-“We 9 i T 03' : - / . .- ----- : ...;"“".-_. “on —-——-----~--——-——-~-~— " .l .3” T . I J". H vSUd. HIVOJ '- ,’ \N‘J/ vam 1-._ SpecIra-,smzhmnctcf : L 1. . .- ..1.‘__ \’.nnadon'u!yh.lnc If. i .‘n “C”, I ~ TBA-year ..\ . 1 .1 , .3 \‘_lo'/ 1 SOLUiaox B ...-.-.. -- _ . (2“-0\ I I. , 3 “' Orlhonlzcn.‘umuomzc /' Vnrsonc 1 .'- I _‘ 3...; i‘.\ L‘.‘ ;--0 O .. Thi1v0| ye-JO\V\" ‘ “\ \ 731’. "'.'“I""‘ [3" ‘- '_...- - c-..__.1 ' '. ‘1F7-.'-‘. . 1;, '- I a [:1 1" . -: J.a’ I ' 2 I . (54:. “a \ L‘LJ as on n c \3.’ / .r‘; i : E : ._ , 3"? : .1. ...- / .' Z . l 1&1” .3 . VJ ,/ ~i1rz’ ‘ i - V C.a0 "p' ' :-- [OT/K. mzmmzh: ,5 Q d ' _ . Li- J [5’ - ~-.1\‘\ ".-' \‘u 3 : C30 '33. Photon-31m? '_ ' 6 v ‘E-I-l' EDTA. L'Ili \(JHCI; In)... tufdh" \" ...; ., :J-us - .. -— bu- ckT or --- .' a... L130 .1 1.7 | L . C ...l ”‘0 . (1' "\1 Wm.“ ' 14:0 .25" " Mnluon ,. 'Na 0 k3.) —lnlcmal Jamar“ \ '\.'-‘J\ ..--.-.‘-—.- ..---1- . |- P ‘3‘. I. I ,\'. --.! {—.I I [2],. '."‘\’I" ..’.*..1 Flame :3» 1 if- ‘..' g:¥M¥7 photometer o L .... . l0: ~ 'J i I LON C02 | l .0 i ch’aot ‘7 ' "' ‘i' ' ‘ 2‘. -~ ("M \ . J . " ’. .tf“ c 1 (3.1." :4?“ E l : -... f [I | ‘szliJQO ! n 'C‘f; i ‘. i : Ll}: {i Roan ' ‘ ’3“..ng ' ’. 1.... i ! l I '. E. [1‘ w - ' . H.150.- \ ' n V . | : o ‘ .. I ' n,’ i ‘ II ‘1 /. ’ ‘J g ""“3' “' , ,. ' I r . i i J ‘5‘“, i D U 0 l-‘D / I. . 0 'c b...” I. '«‘ K. E «mp‘*/ . ‘... J (' ' ‘23:“ u ’7." "‘ A\\." ' s’()1 K *1 Figure 14. Schematic diagram for the rapid analysis of rocks. 61 with HF - H2804 - HNO3 in teflon beakers. This solution was used for the photometric determination of total iron with orthophenathroline, TiO2 with tiron, P205 with molybdivanadophosphoric acid, MnO as permanganate after a persulfate oxidation, and low-level MgO with thiazol yellow. Automatic photometric titrations were used for CaO, MgO, and CaO-MgO. Flame photometry was used for Na 0 and K20. Separate portions of samples were used for 2 the determination of FeO by titration with K2Cr207 after decomposition with HF and H2504; H20 by its weight when evolved by heating a mixture of sample plus flux; CO2 by evolution with acid, high or low levels of CO2 being measured either by change in volume upon alkaline absorption or by direct volume measurement. Spectrographic Analysis The methods described here are those that are currently in use by the U.S.G.S. for analytical work. 15mg. of sample plus 30mg. of graphite were mixed throughly in order to make the burn smooth. The mixed samples were placed in carbon electrodes. Carbon electrode was used because of its capability in determining all elements. The elements were raised to an excited state and as they were returning to ground state, mostly ultra- violet light was given off. This light was dispersed by grating into component wave lengths which were recorded on a photographic plate. Atmosphere was used instead to 62 prevent the combination of C and N which gives cyanogen bands that make the wave length area 3500-4200A not useable. Ar/O2 enhances sensitivity of some elements and gives detectability for others. The wavelength of light (line) gave which element was present and the darkness of the line proportional to concentration compared your plate to standards of known concentrations. The advantages of this method is that small amount of sample is used, and many trace elements of low levels are detected. Computer Analysis_of Photographed Optical Emission Spectra A recording system and computer were used for the complete spectrochemical analysis of the photographed spectra. Transmission values were taken at equal intervals of travel along the spectrum. These values were trans— ferred to a magnetic tape with high precision, high speed, and in a form suitable for computer processing. This processing included wave length determination, line identification, and plate calibration. I A microphotometer moves the spectrum through a scanning beam at a velocity of 5mm per sec. At 5n inter- vals of distance traveled, the analog photomultiplier out- put is digitized and stored in a buffer. When a pre- determined number of readings have accumulated, they are transferred to a magnetic tape as a group without 63 interrupting incoming readings. The number of the reading (not recorded) determines the wave length coordinate. Transmission values are recorded in three digits. Computer line finding starts with a known strong line and an approximate value of dispersion. The position of the line in the spectrum expressed as a reading number is determined automatically and is stored with the related transmission value. Lines for chemical analysis are found by the computer using a wavelength list of such lines. An IBM 360-65 computer was used in this work with Fortran 1V language. MICHIGAN STATE UNIVERSITY LIBRARIES 3 1193 0317J 5981