Progressive change of pelagic clay microstructure during burial process; examples from piston cores and ODP cores

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doi: 10.1016/j.margeo.2004.03.016
Author(s): Kawamura, Kiichiro; Ogawa, Yujiro
Author Affiliation(s): Primary:
Fukada Geological Institute, Bunkyo, Japan
University of Tsukuba, Japan
Volume Title: Marine Geology
Source: Marine Geology, 207(1-4), p.131-144. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 35 refs.; illus., incl. sketch map
Summary: Progressive change of microstructure in pelagic clays of different three orders of burial depths, several centimeter, several meters and several hundred meter depths, was observed by measurement of anisotropy of magnetic susceptibility (AMS) and observation by scanning electron microscope (SEM) and thin section. At depths of several centimeters (void ratio >3.0), peds of several 10 µm in diameter are linked by long and narrow connectors in edge-face (EF) contact and pore sizes between the peds are large. At depths of several meters (void ratio 3.0-2.0), the shape of the connectors changes from narrow to broad. The pore size between the peds decreases with burial depth. At depths of several hundred meters (void ratio <2.0), clay flakes are arranged in wavy parallelism in face-to-face (FF) contact. The pores of intra-peds are reduced in volume. The pelagic clays are consolidated due to rotation of clay flakes composed of the connectors and peds. The AMS suggests that parallel coordination is developed strongly at 150 m depth. Below this depth, zeolite occurs around radiolarian tests, and conjugated zeolite veins are observed with a normal fault sense of displacement. Due to cementation, the rotation of clay flakes in pelagic clays ceased, and the resulting clay microstructure were further preserved through diagenesis. Abstract Copyright (2004) Elsevier, B.V.
Year of Publication: 2004
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Anisotropy; Cementation; Cenozoic; Clastic sediments; Clay; Cores; Cretaceous; DSDP Site 197; Deep Sea Drilling Project; Diagenesis; Framework silicates; Izu-Bonin Arc; Leg 185; Leg 20; Magnetic susceptibility; Marine sediments; Mesozoic; Microstructure; Miocene; Neogene; North Pacific; Northwest Pacific; ODP Site 1149; Ocean Drilling Program; Ophiolite; Pacific Ocean; Paleomagnetism; Pelagic environment; Philippine Sea; Pleistocene; Quaternary; SEM data; Sediments; Silicates; Tertiary; West Pacific; X-ray diffraction data; Zeolite group
Coordinates: N312030 N312030 E1432100 E1432100
N301726 N301726 E1474027 E1474027
Record ID: 2004059150
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands