Cretaceous Planktonic Foraminifera from the Eastern Indian Ocean

Abstract

Cretaceous planktonic foraminifera occur at four sites drilled on Leg 26: on the Broken Ridge (Site 255), in the Wharton Basin (Sites 256 and 257), and on the Naturaliste Plateau (Site 258). In the Wharton Basin only assemblages of Albian age were found. These differ from each other in preservation and in their specific composition. The sequence on the Naturaliste Plateau ranges from upper Albian to Santonian. Rich and well-preserved faunas were found in the Albian, Cenomanian, Coniacian, and Santonian. The main features of all Cretaceous assemblages from this part of the Indian Ocean are the low diversity and the predominance of nonkeeled forms of the genera Hedbergella, Globigerinelloides, Whiteinella, and Archaeoglobigerina. This indicates a cool paleoenvironment for this area during the Cretaceous. Range charts for Sites 257 and 258 are given, and most of the species are discussed in the systematic part of this report.

Upper Cretaceous Benthic Foraminifers and Paleoenvironments, Southern Kerguelen Plateau, Indian Ocean

“…This form has been recorded from the Indian Ocean by Herb (1974), who used it as a basis for age determination. It is rare in the samples studied here.…”

Data Report: Studies into the Paleontology of the Cretaceous of the Indian Ocean Basin

“…The Campanian-lower Senonian age is based on poor calcareous nannoplankton recovery. Cretaceous foraminifers were recovered at four sites on Leg 25: Sites 255, 256, 257, and 258 (Herb, 1974).…”

“…The Cretaceous at Site 250 is very poorly preserved, and Herb (1974) did not even bother to incorporate the site in his review of DSDP Leg 26 Cretaceous planktonic foraminifers. The Cretaceous/Tertiary boundary is taken at about 690 mbsf within lithologic Unit IV, a Semilithified detrital brown clay.…”

“…Deposition was not below the CCD but more likely on the outer continental shelf or continental slope. Herb (1974) discussed the foraminifers briefly.…”

“…Only a few samples yielded well-preserved faunas. Herb (1974) referred to the faunas throughout these sites as being of low diversity and took them to be cool-water assemblages. Keeled globotruncanid content was highest (higher than 20%) in the Santonian.…”