Metamorphic Evolution of the Seward Peninsula Blueschist Terrane
Blucschists and greenschists of the central Seward Peninsula (the Nome Group) crop out over an 8000 km2 area. The protolith package for the mid-Jurassic high P / T metamorphism consisted largely of Cambrian, possibly also Precambrian, to Devonian sedimentary rocks (limestones, marls, pelites, carbon...
Published in: | Journal of Petrology |
---|---|
Main Authors: | , |
Format: | Text |
Language: | English |
Published: |
Oxford University Press
1989
|
Subjects: | |
Online Access: | http://petrology.oxfordjournals.org/cgi/content/short/30/3/531 https://doi.org/10.1093/petrology/30.3.531 |
id |
fthighwire:oai:open-archive.highwire.org:petrology:30/3/531 |
---|---|
record_format |
openpolar |
spelling |
fthighwire:oai:open-archive.highwire.org:petrology:30/3/531 2023-05-15T18:19:18+02:00 Metamorphic Evolution of the Seward Peninsula Blueschist Terrane PATRICK, BRIAN E. EVANS, BERNARD W. 1989-06-01 00:00:00.0 text/html http://petrology.oxfordjournals.org/cgi/content/short/30/3/531 https://doi.org/10.1093/petrology/30.3.531 en eng Oxford University Press http://petrology.oxfordjournals.org/cgi/content/short/30/3/531 http://dx.doi.org/10.1093/petrology/30.3.531 Copyright (C) 1989, Oxford University Press Articles TEXT 1989 fthighwire https://doi.org/10.1093/petrology/30.3.531 2013-05-26T23:39:54Z Blucschists and greenschists of the central Seward Peninsula (the Nome Group) crop out over an 8000 km2 area. The protolith package for the mid-Jurassic high P / T metamorphism consisted largely of Cambrian, possibly also Precambrian, to Devonian sedimentary rocks (limestones, marls, pelites, carbonaceous siltites, quartzites) of shallow water miogeoclinal origin, which maintained a coherent lithostratigraphy during metamorphism and concurrent high-strain, noncoaxial deformation. Several experimentally and empirically calibrated geothermobarometers have been integrated with textural and microstructural observations in order to derive a pressure-temperature ( P - T ) path for the metamorphism of the Nome Group. These data, coupled with previously obtained Rb-Sr phengite-whole-rock isochron ages, yield a P - T - t path showing a steep burial segment followed by a prolonged period ({small tilde}55 Ma) of isothermal decompression. Peak pressures, obtained from the jadeite content of clinopyroxene in rare, isofacial eclogites, and from the celadonite content in phengite yield {small tilde}12 kb. Temperatures at this pressure, gained from garnet-clinopyroxene and microcline-plagioclase pairs, were 460�30�C. Decompression temperatures were essentially the same, as evidenced by calcite-dolomite and garnet-biotite thermometry. Uniformity of metamorphic conditions throughout the Seward Peninsula blueschist terrane coupled with the miogeoclinal nature of the protolith package indicate burial beneath a flat-lying (A-type) subduction zone. The derived P - T - t path is difficult to reconcile with one-dimensional thermal models of collisional blueschists, where peak P and T are not generally coincident. Text Seward Peninsula HighWire Press (Stanford University) Journal of Petrology 30 3 531 555 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Articles |
spellingShingle |
Articles PATRICK, BRIAN E. EVANS, BERNARD W. Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
topic_facet |
Articles |
description |
Blucschists and greenschists of the central Seward Peninsula (the Nome Group) crop out over an 8000 km2 area. The protolith package for the mid-Jurassic high P / T metamorphism consisted largely of Cambrian, possibly also Precambrian, to Devonian sedimentary rocks (limestones, marls, pelites, carbonaceous siltites, quartzites) of shallow water miogeoclinal origin, which maintained a coherent lithostratigraphy during metamorphism and concurrent high-strain, noncoaxial deformation. Several experimentally and empirically calibrated geothermobarometers have been integrated with textural and microstructural observations in order to derive a pressure-temperature ( P - T ) path for the metamorphism of the Nome Group. These data, coupled with previously obtained Rb-Sr phengite-whole-rock isochron ages, yield a P - T - t path showing a steep burial segment followed by a prolonged period ({small tilde}55 Ma) of isothermal decompression. Peak pressures, obtained from the jadeite content of clinopyroxene in rare, isofacial eclogites, and from the celadonite content in phengite yield {small tilde}12 kb. Temperatures at this pressure, gained from garnet-clinopyroxene and microcline-plagioclase pairs, were 460�30�C. Decompression temperatures were essentially the same, as evidenced by calcite-dolomite and garnet-biotite thermometry. Uniformity of metamorphic conditions throughout the Seward Peninsula blueschist terrane coupled with the miogeoclinal nature of the protolith package indicate burial beneath a flat-lying (A-type) subduction zone. The derived P - T - t path is difficult to reconcile with one-dimensional thermal models of collisional blueschists, where peak P and T are not generally coincident. |
format |
Text |
author |
PATRICK, BRIAN E. EVANS, BERNARD W. |
author_facet |
PATRICK, BRIAN E. EVANS, BERNARD W. |
author_sort |
PATRICK, BRIAN E. |
title |
Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
title_short |
Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
title_full |
Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
title_fullStr |
Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
title_full_unstemmed |
Metamorphic Evolution of the Seward Peninsula Blueschist Terrane |
title_sort |
metamorphic evolution of the seward peninsula blueschist terrane |
publisher |
Oxford University Press |
publishDate |
1989 |
url |
http://petrology.oxfordjournals.org/cgi/content/short/30/3/531 https://doi.org/10.1093/petrology/30.3.531 |
genre |
Seward Peninsula |
genre_facet |
Seward Peninsula |
op_relation |
http://petrology.oxfordjournals.org/cgi/content/short/30/3/531 http://dx.doi.org/10.1093/petrology/30.3.531 |
op_rights |
Copyright (C) 1989, Oxford University Press |
op_doi |
https://doi.org/10.1093/petrology/30.3.531 |
container_title |
Journal of Petrology |
container_volume |
30 |
container_issue |
3 |
container_start_page |
531 |
op_container_end_page |
555 |
_version_ |
1766196373287337984 |