Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada
Variations in reflectance and bireflectance of graptolites and bitumen are documented from lower Paleozoic rocks of Howard's Pass (XY) Zn–Pb deposit and adjacent portions of the Selwyn Basin. Two types of graptolite morphologies are recognized in these rocks: a nongranular type, comprising bloc...
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crcansciencepubl:10.1139/e89-169 2023-12-17T10:47:42+01:00 Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada Riediger, C. Goodarzi, F. Macqueen, R. W. 1989 http://dx.doi.org/10.1139/e89-169 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-169 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 26, issue 10, page 2003-2015 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1989 crcansciencepubl https://doi.org/10.1139/e89-169 2023-11-19T13:38:19Z Variations in reflectance and bireflectance of graptolites and bitumen are documented from lower Paleozoic rocks of Howard's Pass (XY) Zn–Pb deposit and adjacent portions of the Selwyn Basin. Two types of graptolite morphologies are recognized in these rocks: a nongranular type, comprising blocky and lath-shaped varieties, and a granular type. The nongranular graptolites generally display higher reflectance and bireflectance than granular graptolites. Bitumen (epi-impsonite to meso-impsonite) is common in these rocks and displays a wide range of reflectance and bireflectance values.At the Howard's Pass (XY) property, graptolite-reflectance values display a slight increase with depth, and anomalously high values (7.46–10.25% [Formula: see text]) are documented in the sulphide-rich, upper Active Member. In surrounding regions of the Selwyn Basin, remote from Howard's Pass, graptolite-reflectance values are lower (3.02–6.26% [Formula: see text]). Conodont colour-alteration-index values reported by others show no detectable variation in the same rocks, which indicates that graptolite-reflectance measurements are more sensitive to variations in thermal maturity, at least for overmature sediments, than conodont colour-alteration index.The anomalously high reflectance values of both the graptolites and the bitumen from the Howard's Pass (XY) property, particularly in samples from the upper Active Member, indicate that these rocks have experienced elevated temperatures compared with regional values. This study demonstrates that graptolite-reflectance measurements may be used to delineate thermal anomalies. The integration of graptolite-reflectance and biostratigraphic studies in lower Paleozoic sequences is potentially useful for determining episodes of high heat flow. Article in Journal/Newspaper Northwest Territories Yukon Canadian Science Publishing (via Crossref) Yukon Northwest Territories Canada Selwyn ENVELOPE(-138.287,-138.287,62.799,62.799) Canadian Journal of Earth Sciences 26 10 2003 2015 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Riediger, C. Goodarzi, F. Macqueen, R. W. Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
topic_facet |
General Earth and Planetary Sciences |
description |
Variations in reflectance and bireflectance of graptolites and bitumen are documented from lower Paleozoic rocks of Howard's Pass (XY) Zn–Pb deposit and adjacent portions of the Selwyn Basin. Two types of graptolite morphologies are recognized in these rocks: a nongranular type, comprising blocky and lath-shaped varieties, and a granular type. The nongranular graptolites generally display higher reflectance and bireflectance than granular graptolites. Bitumen (epi-impsonite to meso-impsonite) is common in these rocks and displays a wide range of reflectance and bireflectance values.At the Howard's Pass (XY) property, graptolite-reflectance values display a slight increase with depth, and anomalously high values (7.46–10.25% [Formula: see text]) are documented in the sulphide-rich, upper Active Member. In surrounding regions of the Selwyn Basin, remote from Howard's Pass, graptolite-reflectance values are lower (3.02–6.26% [Formula: see text]). Conodont colour-alteration-index values reported by others show no detectable variation in the same rocks, which indicates that graptolite-reflectance measurements are more sensitive to variations in thermal maturity, at least for overmature sediments, than conodont colour-alteration index.The anomalously high reflectance values of both the graptolites and the bitumen from the Howard's Pass (XY) property, particularly in samples from the upper Active Member, indicate that these rocks have experienced elevated temperatures compared with regional values. This study demonstrates that graptolite-reflectance measurements may be used to delineate thermal anomalies. The integration of graptolite-reflectance and biostratigraphic studies in lower Paleozoic sequences is potentially useful for determining episodes of high heat flow. |
format |
Article in Journal/Newspaper |
author |
Riediger, C. Goodarzi, F. Macqueen, R. W. |
author_facet |
Riediger, C. Goodarzi, F. Macqueen, R. W. |
author_sort |
Riediger, C. |
title |
Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
title_short |
Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
title_full |
Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
title_fullStr |
Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
title_full_unstemmed |
Graptolites as indicators of regional maturity in lower Paleozoic sediments, Selwyn Basin, Yukon and Northwest Territories, Canada |
title_sort |
graptolites as indicators of regional maturity in lower paleozoic sediments, selwyn basin, yukon and northwest territories, canada |
publisher |
Canadian Science Publishing |
publishDate |
1989 |
url |
http://dx.doi.org/10.1139/e89-169 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-169 |
long_lat |
ENVELOPE(-138.287,-138.287,62.799,62.799) |
geographic |
Yukon Northwest Territories Canada Selwyn |
geographic_facet |
Yukon Northwest Territories Canada Selwyn |
genre |
Northwest Territories Yukon |
genre_facet |
Northwest Territories Yukon |
op_source |
Canadian Journal of Earth Sciences volume 26, issue 10, page 2003-2015 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e89-169 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
26 |
container_issue |
10 |
container_start_page |
2003 |
op_container_end_page |
2015 |
_version_ |
1785571638337601536 |