--> ABSTRACT: Cenozoic Sedimentary and Deformational History of Hispaniola: 2, Cordillera Septentrional, by Ruurdjan De Zoeten, Paul Mann, James F. Dolan, and Simonetta Monechi; #91030 (2010)

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Cenozoic Sedimentary and Deformational History of Hispaniola: 2, Cordillera Septentrional

Ruurdjan De Zoeten, Paul Mann, James F. Dolan, Simonetta Monechi

Previous workers have recognized that the basement rocks of northern Hispaniola consist of structurally complex volcanic, plutonic, and metamorphic rocks that have been interpreted as a Late Cretaceous-Eocene forearc and trench complex. Questions that have remained poorly answered from the study of the basement complex include: (1) why and when did subduction end, and (2) how many arc complexes are present and how and when did accretion occur? In order to answer these questions more satisfactorily, we have conducted detailed mapping of upper Eocene-lower Miocene marine clastic and carbonate rocks that unconformably overlie the forearc and trench complex. The Cordillera Septentrional consists of a minimum of two distinct arc terranes that have been juxtaposed since the mid le Miocene by left-lateral strike-slip faulting oriented slightly oblique (315°) to the structural and geomorphic trends of the present-day plate boundary (295°). Basement types and overlying sedimentary rock types and ages vary abruptly across the linear, 100-400 m wide shear zone. Southwest of the fault, the basement is made mostly of currently undated, deep-water silty carbonates with interbedded volcanics, whereas to the northeast of the fault, basement consists of a heterogeneous volcanic, plutonic, and metamorphic complex. Fossil dating of sediments is in progress to determine the age of arc activity. The composition of turbidite basins unconformably overlying both basement types closely reflects the underlying basement lithologies. Preliminary biostratigraphic data indic te the southwestern basin (approximately 5,500 m of section) is late Eocene-early Oligocene, whereas the northeastern basin (approximately 2,500 m of section) is early Miocene. Upper Miocene-Pliocene carbonates (> 300 m thick) cap both basins and suggest post-early Miocene "docking" of the basement terranes and their associated basins.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.