The first well logs collected below the Antarctic circle were obtained during Leg 113 at Site 693 on the Dronning Maud Land Margin (Antarctica) in the Weddell Sea. Gamma-ray, resistivity, and sonic logs were collected between 108.0 and 439.0 mbsf. The downhole logs show good agreement with the data...
Main Authors: | , , |
---|---|
Other Authors: | |
Format: | Text |
Language: | English |
Subjects: | |
Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.5277 http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf |
id |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.485.5277 |
---|---|
record_format |
openpolar |
spelling |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.485.5277 2023-05-15T13:46:37+02:00 Xenia Golovchenko Suzanne B. O'connell Richard Jarrard The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.5277 http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.5277 http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf text ftciteseerx 2016-01-08T08:09:47Z The first well logs collected below the Antarctic circle were obtained during Leg 113 at Site 693 on the Dronning Maud Land Margin (Antarctica) in the Weddell Sea. Gamma-ray, resistivity, and sonic logs were collected between 108.0 and 439.0 mbsf. The downhole logs show good agreement with the data collected from cores and provide a con-tinuous measurement of the sedimentary record. These continuous log records show that the rather uniform Tertiary li-thology seen in cores is characterized by high-frequency variability in the log data. Several thin hard streaks are identi-fied, the largest of which coincides with a major Miocene hiatus. Associated with this hiatus is a change to lower illite content (and correspondingly lower gamma-ray counts) and to a significant increase in diatom content. Spectral analysis of the logs was performed on the lower Pliocene through upper Oligocene interval (108.0-343.0 mbsf). Between 108.0 and 245.0 mbsf, average sedimentation rates (50 and 26 m/m.y.) are high enough to show that variance is present in the orbital eccentricity ( — 95 k.y.) and obliquity ( — 41 k.y.) bands. Between 253.0 and 343.0 mbsf, the sedimentation rate (8 m/m.y.) is too low to resolve high frequency variations. The Milankovitch frequencies are best developed in the resistivity logs. Resistivity is responding to changes in porosity, which in these sediments is controlled by the abundance of biosiliceous sediments, particularly diatoms. The orbital forcing suggested by the Milankovitch frequencies may be influencing diatom productivity by inducing oscillations in upwelling, ice coverage, pack ice, and/or polynya. Although variations in diatom abundance were observed in the cores, they were not attributed to a Mi-lankovitch signal, and therefore in this environment, downhole logs are an important contribution to the detection and understanding of orbitally influenced changes in sedimentation. Text Antarc* Antarctic Antarctica Dronning Maud Land Weddell Sea Unknown Antarctic Dronning Maud Land The Antarctic Weddell Weddell Sea |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
ftciteseerx |
language |
English |
description |
The first well logs collected below the Antarctic circle were obtained during Leg 113 at Site 693 on the Dronning Maud Land Margin (Antarctica) in the Weddell Sea. Gamma-ray, resistivity, and sonic logs were collected between 108.0 and 439.0 mbsf. The downhole logs show good agreement with the data collected from cores and provide a con-tinuous measurement of the sedimentary record. These continuous log records show that the rather uniform Tertiary li-thology seen in cores is characterized by high-frequency variability in the log data. Several thin hard streaks are identi-fied, the largest of which coincides with a major Miocene hiatus. Associated with this hiatus is a change to lower illite content (and correspondingly lower gamma-ray counts) and to a significant increase in diatom content. Spectral analysis of the logs was performed on the lower Pliocene through upper Oligocene interval (108.0-343.0 mbsf). Between 108.0 and 245.0 mbsf, average sedimentation rates (50 and 26 m/m.y.) are high enough to show that variance is present in the orbital eccentricity ( — 95 k.y.) and obliquity ( — 41 k.y.) bands. Between 253.0 and 343.0 mbsf, the sedimentation rate (8 m/m.y.) is too low to resolve high frequency variations. The Milankovitch frequencies are best developed in the resistivity logs. Resistivity is responding to changes in porosity, which in these sediments is controlled by the abundance of biosiliceous sediments, particularly diatoms. The orbital forcing suggested by the Milankovitch frequencies may be influencing diatom productivity by inducing oscillations in upwelling, ice coverage, pack ice, and/or polynya. Although variations in diatom abundance were observed in the cores, they were not attributed to a Mi-lankovitch signal, and therefore in this environment, downhole logs are an important contribution to the detection and understanding of orbitally influenced changes in sedimentation. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Xenia Golovchenko Suzanne B. O'connell Richard Jarrard |
spellingShingle |
Xenia Golovchenko Suzanne B. O'connell Richard Jarrard |
author_facet |
Xenia Golovchenko Suzanne B. O'connell Richard Jarrard |
author_sort |
Xenia Golovchenko |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.5277 http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf |
geographic |
Antarctic Dronning Maud Land The Antarctic Weddell Weddell Sea |
geographic_facet |
Antarctic Dronning Maud Land The Antarctic Weddell Weddell Sea |
genre |
Antarc* Antarctic Antarctica Dronning Maud Land Weddell Sea |
genre_facet |
Antarc* Antarctic Antarctica Dronning Maud Land Weddell Sea |
op_source |
http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.485.5277 http://www-odp.tamu.edu/publications/113_SR/VOLUME/CHAPTERS/sr113_19.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766244622049214464 |