Stratigraphy, depositional rates, and other DSDP Leg 96 conclusions: Mississippi fan
The Quaternary Mississippi fan consists of at least seven seismically mappable fan lobes. Eight sites were drilled into the youngest fan lobe during DSDP Leg 96. The Holocene (Ericson Zone Z) is capped by a marly foraminiferal ooze. Assuming an age of 12,000 yr for the Holocene/Pleistocene boundary, a minimum accumulation rate of 3-30 cm/1000 yr (1-12 in/1000 yr) is computed for the Holocene. The youngest fan lobe was deposited during the upper part of Ericson Zone Y (late Wisconsin glacial, 12,000-85,000 y.B.P.). Deposition rates for the Y Zone are extremely high for the middle fan sites, averaging 12 m/1000 yr (39 ft/1000 yr). Lower fan accumulation rates are 7 m/1000 yr (23 ft/1000 yr) for the channel sites and 6 m/1000 yr (20 ft/1000 yr) for the channel-mouth depositional lobes. These rates are not corrected for compaction. Foraminifera are scarce; the occurrence of shallow-water benthic species indicates a displaced inner and middle neritic origin for the sediments. Drilling on the youngest fan lobe shows that most of the silts and sands were transported through the upper and middle fan channel onto the lower fan, producing a 6 to 10-km (4 to 6-mi) wide, 135-m (443-ft) thick aggradational channel deposit. Much of the fine-grained sediment spilled out of the channel onto the adjacent overbank areas, constructing broad marginal plain. The channels on the lower fans are smaller and shift position frequently. Channel-mount depositional lobes are constructed at the end of the active channels and are composed of more than 50% net sand.
- Research Organization:
- Louisiana State Univ., Baton Rouge
- OSTI ID:
- 6608826
- 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
Similar Records
Seismic stratigraphic comparison of DSDP Leg 96 results with older Mississippi fan lobes, Gulf of Mexico
Lithologic characteristics of Mississippi fan
Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
ATLANTIC OCEAN
CARIBBEAN SEA
CENOZOIC ERA
DEPOSITION
DRILLING
FOSSILS
GEOLOGIC AGES
GEOLOGY
GEOPHYSICAL SURVEYS
GULF OF MEXICO
MISSISSIPPI RIVER
OFFSHORE SITES
QUATERNARY PERIOD
RESEARCH PROGRAMS
RIVERS
SEAS
SEDIMENTS
SEISMIC SURVEYS
STRATIGRAPHY
STREAMS
SURFACE WATERS
SURVEYS
WELL DRILLING