PR0CESS-RESPONSE MODEL FOR SEDIMENTATION IN TECTONICALLY ACTIVE INTRACRATONIC BASINS APPLIED IN THE PENNSYLVANIAN PARADOX BASIN AND THE PROTEROZOIC BELT BASIN, U.S.A

In this presentation, response structures will be analyzed for fan-delta systems that aggrade during intervals of locally rapid subsidence caused by intracratonic movements and prograde during intervals of relative tectonic stability as streams continuously adjust their grade according to their evolving depositional potential, work potential, and surface potential.

Actual depositional architectures of aggradation, retrogradation, and progradation record three stream processes that control their formation. Longterm change in the fault grade adjustment cycle (F.G.A.C.) occurs through shorter term change in the eccentricity grade adjustment cycle (E.G.A.C.) and precession grade adjustment cycle (P.G.A.C.) to yield different depositional architectures. Fault response structures actually comprise the superposition of successive architectures reflecting the evolution from basin plain aggradation to shoreline progradation.

A ternary realistic framework includes the stream processes that control stream parameters as the missing links. Stream product rows classify fan-deltas and resultant system tracts as fault or eustatic dominated. Real fan-delta response structures are fault dominated in their aggrational systems tract and eustatic dominated in their progradational systems tract.

Tectonic and climatic sedimentological effects have not previously been integrated into one process-response model in tectonically active intracratonic basins in either the Pennsylvanian Period or Proterozoic Era. I as the product of my Ph.D. dissertation research at the University of Texas at Austin co-supervised by W. R. Muehlberger and R. L. Folk have documented the first such process-response model in the Pennsylvanian Paradox Basin and Proterozoic Belt Basin. Sedimentary strata in the Desmoinesian north of Molas Pass, Colorado, in the Late Middle Proterozoic west of Plains, Montana, and in the Early Middle Proterozoic south of Paradise, Montana each record by stream response the exceeding of a surface potential stream response threshold. In the Paradox Basin, the stream response structure is on the same scale as globally correlated eustatic units, registering one still frame of global lithospheric deformation.