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Robert H. Goldstein1, Evan K. Franseen2
(1) University of Kansas, Lawrence, KS
(2) Kansas Geological Survey, Lawrence, KS

Abstract: Control of original basin geomorphology on sequences and sediment dispersal in adjacent basins

Marked differences in fill and sediment dispersal across adjacent Upper Miocene-Pliocene sedimentary basins of SE Spain reflect the control of original basin geomorphology created by earlier tectonism. Prior to Upper Miocene sediment deposition, the Agua Amarga basin (~4 by 8 km) was a shallow basin, whereas the adjacent (north) Carboneras basin (~3 by 4 km), was deeper with steeper relief, and bounded to the northwest by a strike-slip fault and metamorphic-cored uplift (950 m high). The Agua Amarga basin contains thick successions (~60-85 m) of Upper Miocene marine carbonates, filling this shallow basin to a present elevation of ~80-155 m. Deep exposures of the Carboneras basin reveal only a thin cover (6 m) of Upper Miocene deposits on volcanic basement. Mostly, the top of the Miocene section is below present-day sea level. Apparently, most sediment had been bypassed to the deep, unexposed floor of the basin. After a regional exposure event, Early Pliocene (Zanclean) sea level rose over the two basins. In the Agua Amarga basin, only a few meters of Pliocene marine carbonates drape a marine planation surface at ~80 to 155 meters above present sea level. However, a thick sequence (80-100 m) of Pliocene marine carbonates is deposited up to similar elevations in the Carboneras basin. These deposits filled basin relief in the Carboneras basin, which allowed bypass of metamorphic clasts, from the northwest, into the Agua Amarga basin. These data show that sedimentary basin fill during times of relative tectonic quiescence may be controlled by earlier tectonism.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana