Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The
2015 Fall. Includes illustrations (some color), maps (some color). Includes bibliographical references. The Bornite Cu-Zn-(Co-Ge) deposit is located in the Cosmos Hills of the southern Brooks Range of northwest Alaska, approximately 260 km east of Kotzebue and 460 km north of Fairbanks. The deposit...
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ftcolostateunidc:oai:mountainscholar.org:11124/20143 2023-05-15T15:46:59+02:00 Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The Conner, Douglas Tynan Hitzman, Murray Walter Leach, David Humphrey, John D. 2015-08-27T03:55:34Z born digital masters theses application/pdf application/zip http://hdl.handle.net/11124/20143 English eng eng Colorado School of Mines. Arthur Lakes Library 2015 - Mines Theses & Dissertations T 7836 http://hdl.handle.net/11124/20143 Copyright of the original work is retained by the author. bornite cobalt zinc carbonate Alaska copper Text 2015 ftcolostateunidc 2021-07-14T20:04:45Z 2015 Fall. Includes illustrations (some color), maps (some color). Includes bibliographical references. The Bornite Cu-Zn-(Co-Ge) deposit is located in the Cosmos Hills of the southern Brooks Range of northwest Alaska, approximately 260 km east of Kotzebue and 460 km north of Fairbanks. The deposit contains an indicated resource of 14.1 Mt of 1.08% Cu and an inferred resource of 165.2 Mt of 1.57% Cu. The deposit is hosted within late Silurian to middle Devonian limestones, argillaceous carbonate rocks, and highly graphic carbonate rocks as well as several carbonate debris flows. The carbonate rocks underwent an early stage of replacive alteration and a later stage of dolomite-calcite veining, dedolomitization, and sodium metasomatism that was temporally and spatially associated with copper mineralization. The hydrothermally altered rocks were metamorphosed to greenschist facies during the Jurassic-Cretaceous Brookian orogeny. Early replacive alteration utilized apparently permeable debris flow breccias as fluid conduits. Limestone in both the debris flow breccias and adjacent wallrock was converted to dolostone. Three major dolostone bodies were created at Bornite during this alteration stage. Each is zoned with respect to iron with an outer normal dolostone fringe that is gradational inwards with ferroan dolostone and in the basal dolostone body a siderite core. The later alteration stage produced normal dolomite-(calcite) veins and locally resulted in dedolomitization of dolostone wallrock. Sulfides often occur within dolomite-calcite veins and are zoned from pyrite and sphalerite along the upper fringes of the dolostone bodies, inward to chalcopyrite and bornite. Along the edges of the dolostone bodies stockwork dolomite-calcite veins and intense dedolomitization of dolostone wallrock are spatially associated with massive sulfides. The massive sulfides may be dominated by pyrite or chalcopyrite that replaced pyrite. The massive sulfide bodies and are zoned with increasingly copper-rich sulfide assemblages inward. The most copper-rich assemblages of bornite-chalcocite-digenite replaced dolostone wallrock and were associated with calcite precipitation. Tan-green phyllite beneath the dolostone bodies displays intense sodium alteration and pervasive dedolomitization that is zoned around high-grade copper orebodies within adjacent dolostone bodies. The timing of alteration and mineralization at Bornite is poorly understood. Published Re-Os dates of approximately 400 Ma and 384 Ma, from pyrite, chalcopyrite, and bornite at the deposit suggest that alteration and mineralization occurred in the Paleozoic relatively soon after sediment deposition. New textural evidence demonstrates generally simultaneous growth of copper sulfides phyllosilicate minerals, and albite that preserves a relict -Cretaceous deformational fabric, suggesting that copper mineralization occurred during or after metamorphism. Cymrite, a low temperature and pressure metamorphic barium aluminosilicate mineral, is intergrown with replacive dolostones, copper sulfides, and albite, also suggesting that alteration and mineralization at Bornite occurred during the Jurassic-Cretaceous metamorphic event. Text Brooks Range Alaska Digital Collections of Colorado (Colorado State University) Fairbanks |
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Open Polar |
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Digital Collections of Colorado (Colorado State University) |
op_collection_id |
ftcolostateunidc |
language |
English |
topic |
bornite cobalt zinc carbonate Alaska copper |
spellingShingle |
bornite cobalt zinc carbonate Alaska copper Conner, Douglas Tynan Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
topic_facet |
bornite cobalt zinc carbonate Alaska copper |
description |
2015 Fall. Includes illustrations (some color), maps (some color). Includes bibliographical references. The Bornite Cu-Zn-(Co-Ge) deposit is located in the Cosmos Hills of the southern Brooks Range of northwest Alaska, approximately 260 km east of Kotzebue and 460 km north of Fairbanks. The deposit contains an indicated resource of 14.1 Mt of 1.08% Cu and an inferred resource of 165.2 Mt of 1.57% Cu. The deposit is hosted within late Silurian to middle Devonian limestones, argillaceous carbonate rocks, and highly graphic carbonate rocks as well as several carbonate debris flows. The carbonate rocks underwent an early stage of replacive alteration and a later stage of dolomite-calcite veining, dedolomitization, and sodium metasomatism that was temporally and spatially associated with copper mineralization. The hydrothermally altered rocks were metamorphosed to greenschist facies during the Jurassic-Cretaceous Brookian orogeny. Early replacive alteration utilized apparently permeable debris flow breccias as fluid conduits. Limestone in both the debris flow breccias and adjacent wallrock was converted to dolostone. Three major dolostone bodies were created at Bornite during this alteration stage. Each is zoned with respect to iron with an outer normal dolostone fringe that is gradational inwards with ferroan dolostone and in the basal dolostone body a siderite core. The later alteration stage produced normal dolomite-(calcite) veins and locally resulted in dedolomitization of dolostone wallrock. Sulfides often occur within dolomite-calcite veins and are zoned from pyrite and sphalerite along the upper fringes of the dolostone bodies, inward to chalcopyrite and bornite. Along the edges of the dolostone bodies stockwork dolomite-calcite veins and intense dedolomitization of dolostone wallrock are spatially associated with massive sulfides. The massive sulfides may be dominated by pyrite or chalcopyrite that replaced pyrite. The massive sulfide bodies and are zoned with increasingly copper-rich sulfide assemblages inward. The most copper-rich assemblages of bornite-chalcocite-digenite replaced dolostone wallrock and were associated with calcite precipitation. Tan-green phyllite beneath the dolostone bodies displays intense sodium alteration and pervasive dedolomitization that is zoned around high-grade copper orebodies within adjacent dolostone bodies. The timing of alteration and mineralization at Bornite is poorly understood. Published Re-Os dates of approximately 400 Ma and 384 Ma, from pyrite, chalcopyrite, and bornite at the deposit suggest that alteration and mineralization occurred in the Paleozoic relatively soon after sediment deposition. New textural evidence demonstrates generally simultaneous growth of copper sulfides phyllosilicate minerals, and albite that preserves a relict -Cretaceous deformational fabric, suggesting that copper mineralization occurred during or after metamorphism. Cymrite, a low temperature and pressure metamorphic barium aluminosilicate mineral, is intergrown with replacive dolostones, copper sulfides, and albite, also suggesting that alteration and mineralization at Bornite occurred during the Jurassic-Cretaceous metamorphic event. |
author2 |
Hitzman, Murray Walter Leach, David Humphrey, John D. |
format |
Text |
author |
Conner, Douglas Tynan |
author_facet |
Conner, Douglas Tynan |
author_sort |
Conner, Douglas Tynan |
title |
Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
title_short |
Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
title_full |
Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
title_fullStr |
Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
title_full_unstemmed |
Geology of the Bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern Brooks Range, Alaska, The |
title_sort |
geology of the bornite copper-zinc-cobalt carbonate-hosted deposit, southwestern brooks range, alaska, the |
publisher |
Colorado School of Mines. Arthur Lakes Library |
publishDate |
2015 |
url |
http://hdl.handle.net/11124/20143 |
geographic |
Fairbanks |
geographic_facet |
Fairbanks |
genre |
Brooks Range Alaska |
genre_facet |
Brooks Range Alaska |
op_relation |
2015 - Mines Theses & Dissertations T 7836 http://hdl.handle.net/11124/20143 |
op_rights |
Copyright of the original work is retained by the author. |
_version_ |
1766381795731832832 |