Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean
Sediments spanning a 5 meter section across the Cretaceous-Tertiary boundary at ODP holes 689B and 690D, Maud Rise, Wedell Sea and hole 527, Walvis Ridge, are being analyzed for shock deformation, PGE's and other trace elements (including REE's). Mineral separates from each sample were stu...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19890011962 2023-05-15T18:21:13+02:00 Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean Crocket, James H. Carter, Neville L. Huffman, Alan R. Unclassified, Unlimited, Publicly available JAN 1, 1988 application/pdf http://hdl.handle.net/2060/19890011962 unknown Document ID: 19890011962 Accession ID: 89N21333 http://hdl.handle.net/2060/19890011962 No Copyright CASI OCEANOGRAPHY Lunar and Planetary Inst., Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality; p 82-82 1988 ftnasantrs 2015-03-15T05:57:13Z Sediments spanning a 5 meter section across the Cretaceous-Tertiary boundary at ODP holes 689B and 690D, Maud Rise, Wedell Sea and hole 527, Walvis Ridge, are being analyzed for shock deformation, PGE's and other trace elements (including REE's). Mineral separates from each sample were studied with optical microscopy to determine the distribution and microstructural state of quartz and feldspar present in the sediments. Samples from Maud Rise were taken of the K/T transition and at about 50 cm intervals above and below it. These samples consist of carbonate-rich sediments, with the K/T transition marked by a change from white Maastrichtian oozes to a greenish ooze with higher concentrations of altered volcanic clay and vitric ash. The Walvis Ridge site is characterized by more clay-rich sediments with average carbonate content about 60 to 70 percent. Initial results from RNAA studies indicate that iridium is present in all the Maud Rise samples in concentrations equal to or greater than 0.01 ppb (whole-rock basis). Preliminary results from optical microscopy indicate the occurrence of shock mosaicism in quartz and feldspar in all of the samples studied. The pervasiveness of shock mosaicism and presence of planar features to 2 meters from the K/T boundary indicates that a single impact or volcanic explosion 66 ma may be ruled out as responsible for the K/T event. A similar conclusion may be drawn independently from the distribution of iridium and other trace elements. Regardless of the source of the shock waves and sediment contamination, multiple events are required over a ca.0.5 my timespan; currently we favor endogenous sources. Other/Unknown Material South Atlantic Ocean NASA Technical Reports Server (NTRS) Maud Rise ENVELOPE(3.000,3.000,-66.000,-66.000) |
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collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
OCEANOGRAPHY |
spellingShingle |
OCEANOGRAPHY Crocket, James H. Carter, Neville L. Huffman, Alan R. Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
topic_facet |
OCEANOGRAPHY |
description |
Sediments spanning a 5 meter section across the Cretaceous-Tertiary boundary at ODP holes 689B and 690D, Maud Rise, Wedell Sea and hole 527, Walvis Ridge, are being analyzed for shock deformation, PGE's and other trace elements (including REE's). Mineral separates from each sample were studied with optical microscopy to determine the distribution and microstructural state of quartz and feldspar present in the sediments. Samples from Maud Rise were taken of the K/T transition and at about 50 cm intervals above and below it. These samples consist of carbonate-rich sediments, with the K/T transition marked by a change from white Maastrichtian oozes to a greenish ooze with higher concentrations of altered volcanic clay and vitric ash. The Walvis Ridge site is characterized by more clay-rich sediments with average carbonate content about 60 to 70 percent. Initial results from RNAA studies indicate that iridium is present in all the Maud Rise samples in concentrations equal to or greater than 0.01 ppb (whole-rock basis). Preliminary results from optical microscopy indicate the occurrence of shock mosaicism in quartz and feldspar in all of the samples studied. The pervasiveness of shock mosaicism and presence of planar features to 2 meters from the K/T boundary indicates that a single impact or volcanic explosion 66 ma may be ruled out as responsible for the K/T event. A similar conclusion may be drawn independently from the distribution of iridium and other trace elements. Regardless of the source of the shock waves and sediment contamination, multiple events are required over a ca.0.5 my timespan; currently we favor endogenous sources. |
format |
Other/Unknown Material |
author |
Crocket, James H. Carter, Neville L. Huffman, Alan R. |
author_facet |
Crocket, James H. Carter, Neville L. Huffman, Alan R. |
author_sort |
Crocket, James H. |
title |
Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
title_short |
Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
title_full |
Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
title_fullStr |
Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
title_full_unstemmed |
Iridium, shocked minerals, and trace elements across the Cretaceous/Tertiary boundary at Maud Rise, Wedell Sea, and Walvis Ridge, South Atlantic Ocean |
title_sort |
iridium, shocked minerals, and trace elements across the cretaceous/tertiary boundary at maud rise, wedell sea, and walvis ridge, south atlantic ocean |
publishDate |
1988 |
url |
http://hdl.handle.net/2060/19890011962 |
op_coverage |
Unclassified, Unlimited, Publicly available |
long_lat |
ENVELOPE(3.000,3.000,-66.000,-66.000) |
geographic |
Maud Rise |
geographic_facet |
Maud Rise |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
CASI |
op_relation |
Document ID: 19890011962 Accession ID: 89N21333 http://hdl.handle.net/2060/19890011962 |
op_rights |
No Copyright |
_version_ |
1766200368822222848 |