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ABSTRACT: Quantitative Determination of Geological and Tectonic Development Under Complex Geological Settings--Thrace Area, Turkey

L. Tufan Erdogan, M. Arif Yukler

Thrace area is composed of several subbasins, formed during the middle Eocene, overlying the metamorphic and granitic rocks of the Istranca Massif. Syndepositional fault patterns and variations in sedimentary thicknesses indicate that the subbasins evolved tectonically by northeast-southwest extension from the middle Eocene to early Paleocene. From the early Paleocene to early Miocene, the northern part of the area underwent northeast-southwest extension, whereas in the middle Miocene, northwest-southeast wrench-fault assemblage resulted in a clockwise rotation of the extension axes. Consequently, the right-lateral motion of the transform faults resulted in a north-south extension, which prevailed until the late Pleistocene. During the last 1 m.y., the area was subjected o a major compression leading to rapid erosion in the central part of the area.

A deterministic three-dimensional basin analysis model has been applied to quantify the geological and tectonic evolution of the subbasins. A total of 72 wells were simulated to determine compaction, pressure, and temperature histories of the sedimentary sequences to set up the conceptual model. The validity of the conceptual model was then checked with the simulation of six seismic profiles before the full three-dimensional simulation of the area.

The trends from the computed subsidence and uplift, heat flow, and compaction maps as a function of time were checked against the observed stratigraphic and sedimentological data. The excellent match between the

computed trends and observed isopachs, and erosions as determined from seismic data and depositional environments, aided in the quantification of the regional stratigraphy and tectonics. The combination of the computed heat flow and uncompacted isopach maps was used in determining stress-strain relationships in the subbasins as a function of time. The fracture patterns determined also showed an excellent match with the available pressure, volume, temperature, and core data.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990