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Geology of the Kiernan Quadrangle Iron County Michigan

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Geology of the Kiernan Quadrangle Iron County Michigan Geology of the Kiernan Quadrangle Iron Description............................................................. 13 Age relations.......................................................... 13 County Michigan Middle Precambrian rocks ...............................................13 By JACOB E. GAIR and K. L. WIER Randville dolomite........................................................13 Dolomite................................................................. 14 Feldspathic and dolomitic quartzites ..................... 15 GEOLOGICAL SURVEY BULLETIN 1044 Arkose.................................................................... 15 Sericite and chlorite slates and schists ................. 15 Prepared in cooperation with the Slaty graywacke .................................................... 15 Geological Survey Division of the Silicified dolomite(?) .............................................. 15 Michigan Department of Conservation Age relations.......................................................... 16 Goodrich quartzite........................................................16 Description............................................................. 17 Age relations.......................................................... 18 Hemlock formation .......................................................18 General features.................................................... 18 Metabasalt ............................................................. 19 Metamorphosed basic pyroclastic rocks ............... 20 UNITED STATES GOVERNMENT PRINTING OFFICE, Biotite-, hornblende-, and epidote-bearing schists 21 WASHINGTON : 1956 Metarhyolite ........................................................... 22 UNITED STATES DEPARTMENT OF THE INTERIOR Slate....................................................................... 23 Fred A. Seaton, Secretary Graywacke............................................................. 24 Age relations.......................................................... 24 GEOLOGICAL SURVEY Thomas B. Nolan, Director Fence River formation..................................................25 Distribution and name............................................ 25 For sale by the Superintendent of Documents, U. S. Government Description............................................................. 25 Printing Office Washington 25, D. C. - Price $1.50 (paper cover) Age relations.......................................................... 25 Michigamme Slate........................................................25 Intrusive rocks..................................................................26 CONTENTS Metamorphosed basic intrusive rocks..........................26 Abstract ............................................................................. 2 Kiernan sills ........................................................... 26 Other basic intrusive bodies .................................. 27 Introduction........................................................................ 3 Age of altered basic intrusive rocks....................... 28 Location, extent, and accessibility of area..................... 3 Quartz porphyry ...........................................................28 Topography and drainage ............................................. 4 Trachyte .......................................................................29 Relief........................................................................4 Diabase ........................................................................29 Glacial features........................................................4 Cambrian rocks................................................................29 Streams and swamps ..............................................5 Field methods ................................................................ 6 Structure ..........................................................................29 Laboratory methods....................................................... 6 Amasa oval...................................................................29 Acknowledgments ......................................................... 6 Southeastern green schist uplift...................................30 Stratigraphic terminology............................................... 6 Michigamme Mountain and vicinity ..............................31 Previous geologic work.................................................. 6 Magnetic surveys.............................................................32 General geology................................................................ 7 Aeromagnetic survey ...................................................32 Stratigraphy ................................................................... 7 Ground magnetic survey ..............................................33 Structure ........................................................................ 8 Magnetic anomalies............................................... 33 Metamorphism............................................................... 9 Geologic history ...............................................................34 Lower Precambrian rocks ................................................. 9 Economic geology............................................................35 Margeson Creek gneiss................................................. 9 Exploration ...................................................................35 Banded gneiss .......................................................10 Goodrich quartzite........................................................35 Granitic rocks .........................................................11 Origin .....................................................................12 Fence River formation..................................................36 Mylonitized granitic rock ........................................12 Magnetic green schist ..................................................36 Age relations ..........................................................13 Literature cited .................................................................37 Magnetic green schist.................................................. 13 Distribution .............................................................13 Geological Survey Bulletin 1044 – Page 1 of 37 ILLUSTRATIONS 4. Petrographic data for rocks of the Margeson Creek gneiss.............................................................................11 FIGURE 1. Index map showing location of Kiernan quadrangle, 5. Petrographic data for the Randville dolomite and the Iron County, Mich. ............................................................4 Goodrich quartzite..........................................................14 2. Map of the western part of the northern peninsula of 6. Petrographic data for rocks of the Hemlock formation ......19 Michigan showing the Kiernan quadrangle in relation to the principal geologic features..........................................4 7. Partial analyses of greenstone and metagabbros from Kiernan quadrangle and adjacent areas of northern 3. Distribution of glacial deposits in the Kiernan quadrangle. ..5 Michigan.........................................................................20 4. Outline map of Kiernan quadrangle showing approximate 8. Chemical analyses of metarhyolite and rhyolite ................23 location and trends of metamorphic zones. ......................9 9. Petrographic data for intrusive rocks in the Kiernan 5. Foliated inequigranular granitic rock of Margeson Creek quadrangle .....................................................................28 gneiss. ............................................................................10 6. Photomicrograph of typical granitic rock in Margeson Creek gneiss. ............................................................................11 ABSTRACT 7. Photomicrograph of microcline crystal partly replaced by The Kiernan quadrangle is in eastern Iron County, in the albite...............................................................................12 western part of the northern peninsula of Michigan. The area is underlain by Lower and Middle Precambrian rocks, formerly 8. Fold in Randville dolomite. ................................................14 designated as Archean and Huronian rocks, and is extensively 9. Photomicrograph of oolitic Randville dolomite...................14 covered by Pleistocene glacial deposits. An Upper Precambrian (Keweenawan) diabase dike and a few scattered 10. Photomicrographs of ferruginous cherty Goodrich quartzite remnants of lower Paleozoic sandstone are also found in the in plane light and with crossed nicols .............................16 area. 11. Photomicrograph of ferruginous cherty Goodrich The major structural feature is a north-northwest axis along quartzite..........................................................................17 which are uplifts of Lower Precambrian rocks in the 12. Photomicrograph of ferruginous cherty Goodrich northwestern and in the southeastern parts of the quadrangle. quartzite..........................................................................17 The northwestern uplift is called the Amasa oval, and the southeastern is called the southeastern greenschist uplift. In 13. Block diagram showing stratigraphic and structural the saddle between these two uplifts, particularly near relations in vicinity and northeast of Michigamme Michigamme Mountain, local cross-folding has produced Mountain.........................................................................18
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