Characteristics of Mississippi fan sediments, DSDP Leg 96
Sedimentologic, paleontologic, geochemical, and geotechnical studies were conducted on cores drilled at eight sites on the Mississippi fan during the Deep Sea Drilling Project Leg 96. Together with seismic and well log data, these studies allow development of a number of depositional facies within an overall fan-lobe model. The central middle-fan channel of the youngest Mississippi fan-lobe was an effective conduit for the transport of coarse-grained material; only clays and minor amounts of silt spilled over the channel margins. The channel fill deposit is basically an upward-fining sequence, commencing with coarse-grained sands and gravels, overlain by sands, sandy-silty muds, and muds. The basal coarse-grained sediment interval is approximately 134 m (450 ft) thick. The swale deposits, the overbank deposits, are characterized by fine-grained turbidites and hemipelagics. Basically, both sites contain a minor upward-coarsening sequence. Deposits on the lower fan, in the area where the channel shifts position frequently, show alternating sequences of channel fill, levee, and over-bank deposits. Sediments near the channel terminus have upward-coarsening sequences (i.e. channel-mouth depositional lobes) and contain 47 to 65% sand. Most of the sparse microfauna in both sands and muds are benthic species characteristic of inner and middle neritic origin. Traces of biogenic methane and other hydrocarbons were found in the underlying lobes but not in the youngest lobe. All sediments are underconsolidated, resulting from the extremely high accumulation rates of 6-12m/1000 yr (20-40 ft/ 1000 yr).
- Research Organization:
- Gulf Research and Development Co., Houston, TX
- OSTI ID:
- 6872514
- Report Number(s):
- CONF-8405216-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:4; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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ALKANES
ALLUVIAL DEPOSITS
DEPOSITION
FOSSILS
GEOLOGIC DEPOSITS
GEOLOGY
GEOPHYSICAL SURVEYS
HYDROCARBONS
METHANE
MISSISSIPPI RIVER
ORGANIC COMPOUNDS
RIVERS
SEDIMENTS
SEISMIC SURVEYS
STRATIGRAPHY
STREAMS
SURFACE WATERS
SURVEYS
WELL LOGGING