東華大學圖書館 |

語系: 繁體中文

說明(常見問題)

回圖書館首頁

手機版館藏查詢

登入

回首頁

切換: 標籤 | MARC模式 | ISBD

Accessing the records of methane pas...

Martin, Ruth A.

FindBook

Google Book

Amazon

博客來

Accessing the records of methane passage in ancient sediments.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Accessing the records of methane passage in ancient sediments./
作者:	Martin, Ruth A.
面頁冊數:	226 p.
附註:	Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2267.
Contained By:	Dissertation Abstracts International71-04B.
標題:	Paleontology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3406079
ISBN:	9781109725452

Accessing the records of methane passage in ancient sediments.
Martin, Ruth A.

Accessing the records of methane passage in ancient sediments. - 226 p.

Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2267.

Thesis (Ph.D.)--University of Washington, 2010.

Along the ocean margins of the world, hydrocarbons are typically generated from organic matter within thick sediment accumulations and released into the oceans and atmosphere because of faulting, over-pressuring, and changes in depositional rates, sea level, climate, or tectonic regime. Ephemeral hydrocarbon migration in marine sediments leaves robust geological signatures including carbonates resulting from microbial and inorganic processes. The goal of this study was to utilize the calcium carbonate tests (shells) of foraminifera to develop a proxy for identifying and characterizing methane seepage in ancient sediments. Specific objectives were to: (i) assess the effects of methane seepage on foraminiferal assemblages: (ii) integrate carbon and oxygen isotopic data from foraminiferal carbonate and associated authigenic carbonate: and (ii) identify and characterize diagenetic alterations of carbonates resulting from methane seepage. Samples from fossil methane seeps of Eocene through Pliocene age were obtained from the Cascadia Margin of northwest Oregon, western Washington, U.S.A. and southern Vancouver Island, Canada. Samples from a modern analogue were recovered from the Hikurangi Margin off the east coast of New Zealand. Foraminiferal assemblages from both fossil and Recent seeps did not definitively reflect the presence of methane-influenced water. No endemic seep species were found, and assemblage density and diversity were not significantly different in seep and non-seep samples. Stable isotopes, on the other hand, reflected the influence of methane-derived dissolved inorganic carbon in their depleted and variable delta13C values. In Recent samples, however, these values are generally in disequilibrium with surrounding pore- and seawater. Combining isotope analyses with carbonate elemental ratios (Mg/Ca) revealed that the greatest value in using foraminifera for evaluation of methane seepage lies in recognizing diagenetic alteration and exploiting the record. Near seeps, foraminifera become nucleation centers for diagenetic mineralization. These alterations mimic authigenic carbonates and carry complex geochemical information about prevailing conditions and processes. Because foraminifera are small and nearly ubiquitous in marine sediments, they are present where other carbonates are absent. Thus, they facilitate fine scale measurements and reconstruction of modern and fossil methane seep environments.

ISBN: 9781109725452Subjects--Topical Terms:

518862
Paleontology.

Accessing the records of methane passage in ancient sediments.
LDR:03360nam 2200289 4500 001 1404438
005 20111205104759.5
008 130515s2010 ||||||||||||||||| ||eng d
020 $a 9781109725452
035 $a (UMI)AAI3406079
035 $a AAI3406079
040 $a UMI $c UMI
100 1 $a Martin, Ruth A. $3 1683759
245 1 0 $a Accessing the records of methane passage in ancient sediments.
300 $a 226 p.
500 $a Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2267.
500 $a Adviser: Elizabeth A. Nesbitt.
502 $a Thesis (Ph.D.)--University of Washington, 2010.
520 $a Along the ocean margins of the world, hydrocarbons are typically generated from organic matter within thick sediment accumulations and released into the oceans and atmosphere because of faulting, over-pressuring, and changes in depositional rates, sea level, climate, or tectonic regime. Ephemeral hydrocarbon migration in marine sediments leaves robust geological signatures including carbonates resulting from microbial and inorganic processes. The goal of this study was to utilize the calcium carbonate tests (shells) of foraminifera to develop a proxy for identifying and characterizing methane seepage in ancient sediments. Specific objectives were to: (i) assess the effects of methane seepage on foraminiferal assemblages: (ii) integrate carbon and oxygen isotopic data from foraminiferal carbonate and associated authigenic carbonate: and (ii) identify and characterize diagenetic alterations of carbonates resulting from methane seepage. Samples from fossil methane seeps of Eocene through Pliocene age were obtained from the Cascadia Margin of northwest Oregon, western Washington, U.S.A. and southern Vancouver Island, Canada. Samples from a modern analogue were recovered from the Hikurangi Margin off the east coast of New Zealand. Foraminiferal assemblages from both fossil and Recent seeps did not definitively reflect the presence of methane-influenced water. No endemic seep species were found, and assemblage density and diversity were not significantly different in seep and non-seep samples. Stable isotopes, on the other hand, reflected the influence of methane-derived dissolved inorganic carbon in their depleted and variable delta13C values. In Recent samples, however, these values are generally in disequilibrium with surrounding pore- and seawater. Combining isotope analyses with carbonate elemental ratios (Mg/Ca) revealed that the greatest value in using foraminifera for evaluation of methane seepage lies in recognizing diagenetic alteration and exploiting the record. Near seeps, foraminifera become nucleation centers for diagenetic mineralization. These alterations mimic authigenic carbonates and carry complex geochemical information about prevailing conditions and processes. Because foraminifera are small and nearly ubiquitous in marine sediments, they are present where other carbonates are absent. Thus, they facilitate fine scale measurements and reconstruction of modern and fossil methane seep environments.
590 $a School code: 0250.
650 4 $a Paleontology. $3 518862
650 4 $a Geobiology. $3 549918
650 4 $a Marine Geology. $3 1674685
690 $a 0418
690 $a 0483
690 $a 0556
710 2 $a University of Washington. $3 545923
773 0 $t Dissertation Abstracts International $g 71-04B.
790 1 0 $a Nesbitt, Elizabeth A., $e advisor
790 $a 0250
791 $a Ph.D.
792 $a 2010
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3406079