Sedimentary history and chemical characteristics of clay minerals from the Bengal Fan

The purpose of this study is to clarify the sedimentary history and chemical characteristics of clay minerals found in sediments deposited in the distal part of the Bengal Fan since the Himalayas were uplifted 17 m.y. ago. A total of seventy-eight samples were collected from three drilled cores which were to be used for the clay mineral analyses by means of XRD and ATEM. The results obtained from the analyses show that individual clay mineral species in the sediment samples at each site have similar features when the samples are of the same age, whereas these species have different features in samples of differing geological ages. Detrital clay minerals such as illite and chlorite were deposited in greater amounts than kaolinite and smectite during the Early to Middle Miocene. This means that the Himalayan uplift was vigorous at least until the Middle Miocene. In the Pliocene chemical weathering was more prevalent so that instead, in the distal part of the Bengal Fan, kaolinite shows the highest concentrations. This would accord with weaker uplift in the Himalayas. In the Pleistocene period, vigorous Himalayan uplift is characterized by illite-rich sediment in place of kaolinite. In the Holocene, smectite shows the highest concentration in place of the illite and kaolinite which were the predominant clay minerals of the earlier periods. Increasing smectite concentration suggests the Himalayan uplift to have been stable after the Pleistocene period. The smectite analyzed here is found to be dioctahedral Fe-beidellite, and it originated largely from the augite-basalt on the Indian Deccan Traps. The tri-octahedral chlorite is subdivided into three sub-species, an Fe-type, a Mg-type and an intermediate type. The mica clay mineral can be identified as di-octahedral illite which is rich in potassium. The chemical composition and morphology of each clay mineral appears to exhibit no change with burial depth in the sedimentary columns. This implies that there was no systematic transformation of clay minerals with time.

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Cite this as

Aoki, Saburo, Kohyama, Norihiko, Ishizuka, Toshio (1991). Dataset: Sedimentary history and chemical characteristics of clay minerals from the Bengal Fan. https://doi.org/10.1594/PANGAEA.759871

DOI retrieved: 1991

Additional Info

Field Value
Imported on November 30, 2024
Last update November 30, 2024
License CC-BY-3.0
Source https://doi.org/10.1594/PANGAEA.759871
Author Aoki, Saburo
Given Name Saburo
Family Name Aoki
More Authors
Kohyama, Norihiko
Ishizuka, Toshio
Source Creation 1991
Publication Year 1991
Resource Type application/zip - filename: Aoki_1991
Subject Areas
Name: Lithosphere

Name: Oceans

Related Identifiers
Title: Sedimentary history and chemical characteristics of clay minerals in cores from the distal part of the Bengal Fan (ODP 116)
Identifier: https://doi.org/10.1016/0025-3227(91)90090-Q
Type: DOI
Relation: IsSupplementTo
Year: 1991
Source: Marine Geology
Authors: Aoki Saburo , Kohyama Norihiko , Ishizuka Toshio .