4-D Distribution of Deepwater Mass-Transport Deposits (Late Cretaceous Upper Gosau Subgroup, Muttekopf Area, Northern Calcareous Alps, Austria): Implications for Syndepositional Structural Reconstruction
Growth basins are common in constructional regions on many of Earth’s continental margins, including Angola, Brazil, and the Gulf of Mexico. 4D outcrop analysis of the distribution and internal features of mass-transport deposits (MTDs) integrated with stratigraphic, sedimentological, and structural data of deepwater, carbonate-rich, siliciclastic deposits provides significant insight into the syndepositional structural history of a thrust sheet piggyback basin. Across the approximately 2 km by 8 km study area, the basin morphology changed considerably over an 11.6-16.9 my period. The depocenter narrowed, forming an east-west elongate basin, and shifted eastward and northward through time. The primary drivers of these changes were relatively continuous folding about a generally east-west synclinal axis and diachronous folding above dextral, northwest-southeast-striking strike-slip faults active along the southern basin margin.
The areal distribution of MTDs within a given stratigraphic interval is a function of the location of the depocenter and of the rate and location of tectonic deformation, as determined from stratal thickness patterns. MTD concentrations roughly follow lateral shifts in the depocenter through time and the average thickness of MTD intervals generally decreases through time, following the overall stratal pattern. 4D analysis of the distribution and characteristics of MTDs in deepwater basins may contribute significantly to successful modeling of such deposits and in reducing uncertainty in the interpretation of a basin’s syndepositional structural history.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009