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Abyssal benthic Foraminifera in the eastern Equatorial Pacific (IODP Exp 320) during the middle Eocene

Hiroyuki Takata, Ritsuo Nomura, Akira Tsujimoto, Boo-Keun Khim and Ik Kyo Chung
Abyssal benthic Foraminifera in the eastern Equatorial Pacific (IODP Exp 320) during the middle Eocene
Journal of Paleontology (November 2013) 87 (6): 1160-1185


We report on the faunal transition of benthic foraminifera during the middle Eocene at Site U1333 (4862 m water depth, 3,560-3,720 m paleo-water depth) of Integrated Ocean Drilling Program Expedition 320 in the eastern equatorial Pacific Ocean. During the period approximately 41.5-40.7 Ma, which includes carbonate accumulation event 3 (CAE-3), the benthic foraminiferal accumulation rate (BFAR) increased gradually and then it declined rapidly. In contrast, BFAR was considerably lower during approximately 40.7-39.4 Ma, corresponding to the middle Eocene climatic optimum (MECO), and then it increased during approximately 39.3-38.4 Ma, including CAE-4. Diversity (E [S (sub 200) ]) was slightly lower in the upper part of the study interval than in the lower part. The most common benthic foraminifera were Nuttallides truempyi, Oridorsalis umbonatus, and Gyroidinoides spp. in association with Globocassidulina globosa and Cibicidoides grimsdalei during the period studied. Quadrimorphina profunda occurred abundantly with N. truempyi, O. umbonatus, and G. globosa during approximately 39.4-38.4 Ma, including CAE-4, although this species was also relatively common in the lower part of the study interval. Virgulinopsis navarroanus and Fursenkoina sp. A, morphologically infaunal taxa, were common during approximately 38.8-38.4 Ma, corresponding to the late stage of CAE-4. Based on Q-mode cluster analysis, four sample clusters were recognized and their stratigraphic distributions were generally discriminated in the lower and upper parts of the study interval. Thus, there was only a small faunal transition in the abyssal eastern equatorial Pacific during the middle to late-middle Eocene. The faunal transition recognized in this study may be related to recovery processes following intense carbonate corrosiveness in the eastern equatorial Pacific during MECO.

ISSN: 0022-3360
EISSN: 1937-2337
Serial Title: Journal of Paleontology
Serial Volume: 87
Serial Issue: 6
Title: Abyssal benthic Foraminifera in the eastern Equatorial Pacific (IODP Exp 320) during the middle Eocene
Affiliation: Pusan National University, Marine Research Institute, Busan, South Korea
Pages: 1160-1185
Published: 201311
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 114
Accession Number: 2014-000636
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 8 plates, sketch map
N10°31'00" - N10°31'00", W138°25'10" - W138°25'10"
Secondary Affiliation: Shimane University, JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, The Paleontological Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201401
Program Name: IODPIntegrated Ocean Drilling Program
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