Submarine slumps and slides of the Pliocene Mao Fm, Dominican Republic: significance as paleoslope indicators
Syndepositional slumps and slide are commonly used as proxy indicators of paleoslope direction in the absence of direct evidence for the direction of the depositional slope. The direct measurement of depositional slope compared with the orientations of slump fold axes allows calibration of this method of paleoslope determination. The Pliocene Mao Fm. is a 400-600 meter thick limestone and siliciclastic unit located in the Cibao Valley, Dominican Republic. The sandstone and conglomeratic basal portion of the formation contains 30 cm to 3 m high, synsedimentary, generative, recumbant folds formed during submarine slumping and sliding. The orientations of 17 fold axes in 12 different folds show a bimodal distribution with distinct modes for folds with upslope and downslope closure. The range of axes for folds with upslope closure (40/sup 0/) is smaller than that for folds with downslope closure (135/sup 0/). The mean axis orientation for all folds is N6/sup 0/W with individual means for folds with upslope and downslope closure being N41/sup 0/W and N15/sup 0/E respectively. Paleoslope is commonly taken as the normal to the mean of all fold axes, in this case, N84/sup 0/E. The directly measured paleoslope is N10/sup 0/E, a difference of 74/sup 0/ between the two methods. These data indicate that the commonly used normal to the mean is not an accurate indicator of paleoslope when all folds are considered. The normal to the mean of only those folds with upslope closure is a better indicator of paleoslope. Likely explanations for these results include: folding was initiated by a shear which did not act in the downslope direction, and/or some folds with downslope closure were emplaced as detached, freely sliding, sediment bodies, the final orientation of which may have been influenced by local topography.
- Research Organization:
- Univ. of Miami, Miami Beach, FL (USA)
- OSTI ID:
- 6613372
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CONTINENTAL MARGIN
LANDSLIDES
DOMINICAN REPUBLIC
SUBMARINE CANYONS
GEOLOGIC FORMATIONS
INCLINED STRATA
LIMESTONE
ORIENTATION
PLIOCENE EPOCH
SLOPE STABILITY
TECTONICS
TOPOGRAPHY
CARBONATE ROCKS
CENOZOIC ERA
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GREATER ANTILLES
HISPANIOLA
ISLANDS
ROCKS
SEDIMENTARY ROCKS
STABILITY
TERTIARY PERIOD
WEST INDIES
580100* - Geology & Hydrology- (-1989)
580201 - Geophysics- Seismology & Tectonics- (1980-1989)