thumbnail

Microscopic character of marine sediment containing disseminated gas hydrate. Examples from the Blake Ridge and the Middle America Trench

By:

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

The presence of disseminated gas hydrate was inferred based on pore fluid geochemistry and downhole logging data, but was rarely observed at Ocean Drilling Program (ODP) Leg 164 (Blake Ridge), and Leg 170 (Middle America Trench, offshore from Costa Rica) drilling sites. Gas hydrate nucleation is likely to occur first in larger voids rather than in constricted pore space, where capillary forces depress the temperature-pressure stability field for gas hydrate formation. Traditional macroscopic descriptions of sediment fail to detect the microscopic character of primary and secondary porosity in sediment hosting disseminated gas hydrate. Light transmission and scanning electron microscopy of sediments within and below the depth of gas hydrate occurrences reveal at least four general types of primary and secondary porosity: (1) microfossils (diatoms, foraminifera, and spicules) void of infilling sediment, but commonly containing small masses of pyrite framboids; (2) infauna burrows filled with unconsolidated sand and or microfossil debris; (3) irregularly shaped pods of nonconsolidated framboidial pyrite; and (4) nonlithified volcanic ash.

Additional Publication Details

Publication type:
Conference Paper
Publication Subtype:
Conference Paper
Title:
Microscopic character of marine sediment containing disseminated gas hydrate. Examples from the Blake Ridge and the Middle America Trench
Volume
912
Year Published:
2000
Language:
English
Larger Work Title:
Annals of the New York Academy of Sciences
First page:
189
Last page:
194
Number of Pages:
6