Seismic Facies, Processes, and Evolution of Miocene Inner Fan Channels, Indus Submarine Fan
The large size of inner fan channel-levee complexes of the Indus Fan permits the recognition on multifold seismic profiles of distinct seismic facies and depositional and erosional features. The depositional history of inner fan channels is reconstructed based on the relative ages of features within each channel-levee complex. Typically, immediately following avulsion and initiation of inner fan channels, dramatic lateral migration allowed the accumulation of extensive lateral accretion deposits that resemble large versions of meandering fluvial systems. Subsequently, channels aggraded, lateral migration diminished, and levees encroached toward the channel axis. Interpretations suggest that during aggradation, the lateral connectedness of sand bodies, the lateral extent of sand deposition, and the thickness of sand bodies decreased.
The main seismic facies recognized in the Indus Fan are (1) H-C, high-amplitude continuous convergent reflections that occur within wedge-shaped levees, especially away from the channel margin; (2) L-C, low-amplitude continuous convergent reflections that occur within some wedge-shaped levees immediately adjacent to the channel margin; (3) H-D, high-amplitude discontinuous.
This pattern of channel evolution is interpreted to be a response to waning flow volumes and velocities through time. Waning flow is attributed to allogenic events such as small-scale fluctuations of relative sea level, tectonism, and climate.
KeywordsSand Body Channel Axis Lateral Migration Seismic Facies Channel Fill
Unable to display preview. Download preview PDF.
- Bouma, A.H., Coleman, J.M., Stetting, C.E., and Kohl, B., 1989: Influence of relative sea level changes on the construction of the Mississippi Fan; Geo-Marine Lett., v. 9, p. 161–170.Google Scholar
- Damuth, J.E., Flood, R.D., Kowsmann, R.O., Belderson, R.H., and Gorini, M.A., 1988: Anatomy and growth pattern of Amazon Deep-Sea Fan as revealed by long-range side-scan sonor (GLORIA) and high-resolution seismic studies; Am. Assoc. Petrol. Geol. Bull., v. 72, p. 885–911.Google Scholar
- Damuth, J.E., Kolla, K., Flood, R.D., Kowsmann, R.O., Monteiro, M.L., Gorini, M.A., Palma, J.J.C., and Belderson, R.H., 1983: Distributary channel meandering and bifurcation patterns on the Amazon Deep-sea Fan as revealed by long-range side-scan sonar (GLORIA); Geology, v. 11, p. 94–98.Google Scholar
- Kolla, V., and Coumes, F., 1987: Morphology, internal structure, seismic stratigraphy, and sedimentation of Indus Fan; Am. Assoc. Petrol. Geol. Bull, v. 71, p. 650–677.Google Scholar
- McHargue, T.R., and Webb, J.E., 1986: Internal geometry, seismic facies, and petroleum potential of canyons and inner fan channels of the Indus Submarine fan; Am. Assoc. Petrol. Geol. Bull., v. 70, p. 161–180.Google Scholar
- Stelting, C.E., Bouma, A.H., and Coleman, J.M., 1987: Depositional characteristics of channelized deposits in a passive margin submarine fan: Mississippi Fan; Soc. Econ. Paleont. Mineral. Annual Midyear Mtg. Abstr., v. 4, p. 80.Google Scholar
- Weimer, P., and Buffler, R.T., 1988: Distribution and seismic facies of Mississippi Fan channels; Geology, v. 16, p. 900–903.Google Scholar