Marius Dan Georgescu, 1997. "Upper Jurassic–Cretaceous Planktonic Biofacies Succession and the Evolution of the Western Black Sea Basin", Regional and Petroleum Geology of the Black Sea and Surrounding Region, A. G. Robinson
Download citation file:
Three planktonic biofacies successions are recognized in the Upper Jurassic and Cretaceous in the Western Black Sea, offshore Romania. Biofacies A (Oxfordian-Valanginian) contains rare Globuligerina tests in punctual occurrences. The planktonic foraminifera are recorded in carbonate inner-shelf deposits in the Upper Jurassic, and mixed (detrital, clayey, marly) shelf deposits in the Berriasian-Valanginian. The first records of the Western Black Sea opening are dated as Valanginian. Biofacies B largely corresponds to the turbiditic interval of the late Albian–Cenomanian. The planktonic foraminiferal assemblages consist of both primitive (globular chambered) and morphologically advanced taxa (keeled Rotalipora and Praeglobotruncana). The planktonic record is discontinuous, but some claystone levels accumulated under calmer water environments (very low terrigenous input) show remarkable consistency. Biofacies C is peculiar to the outer-shelf deposits of Cenomanian through Maastrichtian age. A gradual increase of the recorded taxa and group diversity is evident. Planktonics are ubiquitous.
Figures & Tables
Regional and Petroleum Geology of the Black Sea and Surrounding Region
In 1967 and 1969, two oceanographic cruises were made in the Black Sea under the guidance of the Woods Hole Oceanographic Institute: The cruises included scientists from many countries and disciplines. Their aims were to determine the recent geological and geochemical evolution of the Black Sea, to map the shallow structure of the basin, and to study the interaction between the oxidized surface waters and the anoxic waters beneath them. The results were published 23 years ago, as AAPG Memoir 20 (Ross and Degens, 1974). During the 1969 cruise, the vessel Atlantis II collected 40 piston cores, which formed the basis of most of the subsequent geological studies that were restricted to very recent sedimentation. Speculations concerning the origin of the basin and the relationship of the geology offshore to that exposed around the margins of the Black Sea were rooted in pre-plate tectonic concepts of basin formation and were in any case hampered by a lack of relevant data (Brinkmann, 1974).
In 1976, the Glomar Challenger visited the Black Sea on Leg 42B of the Deep Sea Drilling Project and drilled and cored three deep-water sites (379, 380, and 381). Well 381 north of the Bosporus encountered sediments as old as Miocene, including some apparently deposited in shallow water (Ross, 1978).
The next major volume in Western literature to deal with the Black Sea was published a decade later, collecting papers presented two years earlier at a conference in Yalta. In this volume, a number of seismic reflection lines