Abstract
The 2008 Tanzania Drilling Project (TDP) expedition recovered common planktonic foraminifera (PF), calcareous nannofossils (CN) and calcareous dinoflagellates with extraordinary shell preservation at multiple Cenomanian-Campanian sites that will be used for paleoclimatic, paleoceanographic, and biostratigraphic studies. New cores confirm the existence of a more expanded and continuous Upper Cretaceous sequence than had previously been documented in the Lindi and Kilwa regions of southeastern coastal Tanzania. This TDP expedition cored 684.02. m at eight Upper Cretaceous sites (TDP Sites 28-35) and a thin Paleocene section (TDP Site 27).TDP Sites 29, 30, 31 and 34 together span the lowermost Turonian to Coniacian (PF Whiteinella archaeocretacea to Dicarinella concavata Zones and CN Zones UC6a-9b), with TDP Site 31 being the most biostratigraphically complete Turonian section found during TDP drilling. A discontinuous section from the Santonian-upper Campanian (PF D. asymetrica to Radotruncana calcarata Zones and CN Zones UC12-16) was collectively recovered at TDP Sites 28, 32 and 35, while thin sequences of the lower Cenomanian (PF Thalmanninella globotruncanoides Zone and CN subzones UC3a-b) and middle Paleocene (Selandian; PF Zone P3a and CN Zone NP5) were cored in TDP Sites 33 and 27, respectively. Records of δ 13C org and δ 13C carb from bulk sediments generated for all the Cretaceous sites show largely stable values through the sections. Only a few parallel δ 13C org and δ 13C carb shifts have been found and they are interpreted to reflect local processes. The δ 18O carb record, however, is consistent with Late Cretaceous cooling trends from the Turonian into the Campanian. Lithologies of these sites include thick intervals of claystones and siltstones with locally abundant, finely-laminated fabrics, irregular occurrences of thin sandstone layers, and sporadic bioclastic debris (e.g., inoceramids, ammonites). Minor lithologies represent much thinner units of up to medium-grained, massive sandstones. The %CaCO 3 (~5-40%) and %C org (~0.1-2%) are variable, with the highest %CaCO 3 in the lower Campanian and the highest %C org in the Turonian. Lithofacies analysis suggests that deposition of these sediments occurred in outer shelf-upper slope, a setting that agrees well with inferences from benthic foraminifera and calcareous dinoflagellates.
Originalsprog | Engelsk |
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Tidsskrift | Journal of African Earth Sciences |
Vol/bind | 70 |
Sider (fra-til) | 36-57 |
Antal sider | 22 |
ISSN | 1464-343X |
DOI | |
Status | Udgivet - 2012 |
Udgivet eksternt | Ja |
Bibliografisk note
Funding Information:The Tanzania Petroleum Development Corporation and the Tanzania Commission for Science and Technology are acknowledged for logistical support and permission to carry out this research in the field. We appreciate the generous hospitality and valuable technical assistance of Ephrem Mchana, the late Michael Mkereme, and Elvis Mgaya (Mr. K). Field work and drilling were funded by a USA National Science Foundation grant to KGM and BTH (EAR 0642993) and a Smithsonian Walcott Fund grant to BTH. JAL was funded by the NERC (Grant NE/G004986/1). Financial support to MRP was provided by MIUR-Prin 2007-2007W9B2WE 001. The PhD program of the Università degli Studi di Milano is acknowledged for funding FF. All authors participated in the 2008 drilling season. AJB did the sedimentological and facies analysis. BTH, MRP, HC, FF, HB and LC did the planktonic foraminiferal biostratigraphy. JAL and PRB did the calcareous nannofossil biostratigraphy. IW and JW did the benthic foraminiferal and dinoflagellates analyses, respectively. KGM and SH carried out the chemostratigraphic measurements. AJB, BTH, KGM, MRP, JAL, HC, HB, IW, JW, PRB and SH collaborated on writing the manuscript.