Geology of the Cretaceous sedimentary basins of the Western Pontides

The southern passive margin of the oceanic Western Black Sea Basin consists of two tectonic units, the istanbul Zone and the Central Pontides. These u nits are delimited by a Fundamental, north-south Arac-Daday shear zone juxt aposing totally different basement rock groups and covering later Mesozoic sedimentary rocks. To the west of this shear zone the istanbul Zone is cove red by a sedimentary succession deposited in a southerly deepening continen tal margin basin. This basin was bisected lengthwise during the Maastrichti an forming the Zonguldak Basin in the northwest and the Ulus Basin in the s outhwest. Both of these basins were deformed in the Early Cainozoic. To the east of the Arac-Daday shear zone, the northerly deepening Sinop Basin dom inates the architecture of the Pontides in the north. It began forming by e xtension in the Barremian and was destroyed by a single-phase north-south c ompression in the Late Eocene-Oligocene. After the juxtaposition of the Cen tral Pontides and the istanbul Zone, an E-W trending extensional magmatic a re was established on these sedimentary basins in response to northward-sub ducting Neotethys to the south. This magmatic are, which began during the T uronian, gave rise to the Western Black Sea oceanic back-are basin, None of the basins in the Pontides is simple. They show a complex evolution responding to different rifting and closure events with much, as yet unspe cified, strike-slip movement. Copyright (C): 1999 John Wiley & Sons, Ltd.