Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska
Oxygen and hydrogen isotope ratios were measured on coexisting minerals from quartz diorites and quartz monzonites from a section across the Coast Range batholith in the Skagway area, Alaska, including a variety of outlying plutons west of the batholith in the Yakutat Bay-Mt. St. Elias region (latit...
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1976
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Online Access: | https://doi.org/10.1016/0012-821x(76)90244-2 |
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ftcaltechauth:oai:authors.library.caltech.edu:gmbfv-dt245 2024-06-23T07:56:45+00:00 Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska Magaritz, Mordeckai Taylor, Hugh P., Jr. 1976-05 https://doi.org/10.1016/0012-821x(76)90244-2 unknown Elsevier https://doi.org/10.1016/0012-821x(76)90244-2 oai:authors.library.caltech.edu:gmbfv-dt245 eprintid:116686 resolverid:CaltechAUTHORS:20220908-192610772 info:eu-repo/semantics/closedAccess Other Earth and Planetary Science Letters, 30(2), 179-190, (1976-05) Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Geochemistry and Petrology Geophysics info:eu-repo/semantics/article 1976 ftcaltechauth https://doi.org/10.1016/0012-821x(76)90244-2 2024-06-12T03:48:59Z Oxygen and hydrogen isotope ratios were measured on coexisting minerals from quartz diorites and quartz monzonites from a section across the Coast Range batholith in the Skagway area, Alaska, including a variety of outlying plutons west of the batholith in the Yakutat Bay-Mt. St. Elias region (latitudes 59–60°N). The extremely low and variable δ18Oand δD results indicate widespread meteoric-hydrothermal alternaiton of the Coast Range batholith, and to a lesser extent, of the Yakutat Bay plutons as well. In the Yakutat Bay area, the plutons with K—Ar ages younger than 50 m.y. have widely varying δD values of −72 to −148, compared to δD = −69to−90 for all but one sample in the 50–225 m.y. age grouping (one biotite has δD = −109). This suggests that the major meteoric-hydrothermal episodes in this area occurred during the Eocene and Miocene. This involved relatively small meteoric water/rock ratios(<0.1), as none of the δ18O values show any clear-cut evidence of alteration (δ18Oquartz= 7.4 −11.8; δ18Ofeldspar= 5.7−10.0). However, in the section across the Coast Range batholith, 85% of the plutonic rocks have very low δD values of −100 to −167, and the δ18O values are extremely variable δ18Ofeldspar= + 10.3to−4.0 and Δ18Oquartz-feldspar= 0.4−10.5. These data indicate that a major portion of the batholith, particularly the quartz monzonite-rich eastern part, but also including many of the quartz diorite plutons as well, interacted with meteoric-hydrothermal convective systems that involved water/rock ratios of about 0.3–1.4. The quart diorite plutons are most depleted in18O near their northeast contacts against the younger quartz monzonite intrusions. The primary igneous δ18O values of the quartz diorites were apparently higher than those of the quartz monzonites; they are also unusually high in18O compared to most other analyzed quartz diorites, suggesting derivation from, exchange with, or assimilation of high-18O metasediments or altered volcanic rocks. These data and ... Article in Journal/Newspaper Skagway Yakutat Alaska Caltech Authors (California Institute of Technology) Earth and Planetary Science Letters 30 2 179 190 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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unknown |
topic |
Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Geochemistry and Petrology Geophysics |
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Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Geochemistry and Petrology Geophysics Magaritz, Mordeckai Taylor, Hugh P., Jr. Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
topic_facet |
Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Geochemistry and Petrology Geophysics |
description |
Oxygen and hydrogen isotope ratios were measured on coexisting minerals from quartz diorites and quartz monzonites from a section across the Coast Range batholith in the Skagway area, Alaska, including a variety of outlying plutons west of the batholith in the Yakutat Bay-Mt. St. Elias region (latitudes 59–60°N). The extremely low and variable δ18Oand δD results indicate widespread meteoric-hydrothermal alternaiton of the Coast Range batholith, and to a lesser extent, of the Yakutat Bay plutons as well. In the Yakutat Bay area, the plutons with K—Ar ages younger than 50 m.y. have widely varying δD values of −72 to −148, compared to δD = −69to−90 for all but one sample in the 50–225 m.y. age grouping (one biotite has δD = −109). This suggests that the major meteoric-hydrothermal episodes in this area occurred during the Eocene and Miocene. This involved relatively small meteoric water/rock ratios(<0.1), as none of the δ18O values show any clear-cut evidence of alteration (δ18Oquartz= 7.4 −11.8; δ18Ofeldspar= 5.7−10.0). However, in the section across the Coast Range batholith, 85% of the plutonic rocks have very low δD values of −100 to −167, and the δ18O values are extremely variable δ18Ofeldspar= + 10.3to−4.0 and Δ18Oquartz-feldspar= 0.4−10.5. These data indicate that a major portion of the batholith, particularly the quartz monzonite-rich eastern part, but also including many of the quartz diorite plutons as well, interacted with meteoric-hydrothermal convective systems that involved water/rock ratios of about 0.3–1.4. The quart diorite plutons are most depleted in18O near their northeast contacts against the younger quartz monzonite intrusions. The primary igneous δ18O values of the quartz diorites were apparently higher than those of the quartz monzonites; they are also unusually high in18O compared to most other analyzed quartz diorites, suggesting derivation from, exchange with, or assimilation of high-18O metasediments or altered volcanic rocks. These data and ... |
format |
Article in Journal/Newspaper |
author |
Magaritz, Mordeckai Taylor, Hugh P., Jr. |
author_facet |
Magaritz, Mordeckai Taylor, Hugh P., Jr. |
author_sort |
Magaritz, Mordeckai |
title |
Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
title_short |
Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
title_full |
Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
title_fullStr |
Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
title_full_unstemmed |
Isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the Yakutat Bay and Skagway areas, Alaska |
title_sort |
isotopic evidence for meteoric-hydrothermal alteration of plutonic igneous rocks in the yakutat bay and skagway areas, alaska |
publisher |
Elsevier |
publishDate |
1976 |
url |
https://doi.org/10.1016/0012-821x(76)90244-2 |
genre |
Skagway Yakutat Alaska |
genre_facet |
Skagway Yakutat Alaska |
op_source |
Earth and Planetary Science Letters, 30(2), 179-190, (1976-05) |
op_relation |
https://doi.org/10.1016/0012-821x(76)90244-2 oai:authors.library.caltech.edu:gmbfv-dt245 eprintid:116686 resolverid:CaltechAUTHORS:20220908-192610772 |
op_rights |
info:eu-repo/semantics/closedAccess Other |
op_doi |
https://doi.org/10.1016/0012-821x(76)90244-2 |
container_title |
Earth and Planetary Science Letters |
container_volume |
30 |
container_issue |
2 |
container_start_page |
179 |
op_container_end_page |
190 |
_version_ |
1802650069465300992 |