Abstract

Clay fabric of selected Mississippi Delta sediment and a red clay from the eastern equatorial Pacific is related to void ratio and depth of burial. Relatively high-void-ratio, naturally consolidated delta sediment is characterized by a fabric of randomly oriented domains and short linking chains with particles in edge-to-face and face-to-face contacts. Lower intermediate-void-ratio sediment showed greater particle-to-particle packing but a consistent predominance of randomly oriented domains with a few chains and a slight development of larger domains than observed in the high-void-ratio sediment. The deeply buried, very low-void-ratio sediment has highly oriented domains and thin, long voids. The red clay sample is characterized by flocs connected by long linking chains and a very high void ratio. Domains and "turbostratic-type" clay fabric are characteristic of high-porosity (high-void-ratio) Mississippi Delta sediments. Highly oriented domains and long chains are diagnostic of the deeply buried, very low-porosity delta muds. The clay fabric of natural (undisturbed) samples was compared with laboratory remolded samples for comparison with models suggested by earlier researchers. Observations using the transmission electron microscope (TEM) support the proposed fabric models for remolded sediment. Selected samples were studied using the scanning electron microscope (SEM). Tentative clay fabric models for undisturbed submarine sediment are proposed and related to void ratios.

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