Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous sediments from southern Tanzania: Tanzania drilling project sites 21–26

Early Cenomanian “hot greenhouse” revealed by oxygen isotope record of exceptionally well‐preserved foraminifera from Tanzania

“…It is a sedimentary package characterized by thick accumulations of mainly fine‐grained sediments deposited in an evolving passive margin basin formed through the breakup of Gondwana and rifting away of Madagascar from Africa [ Jiménez Berrocoso et al , ]. The depositional environment has been generally interpreted as upper slope to outer shelf based on Turonian foraminiferal assemblages and sedimentological criteria [ Jiménez Berrocoso et al , , 2012]. This study provisionally limits the depositional setting to upper slope, taking into account new information from the planktonic foraminiferal assemblage (see section 3.1.2).…”

“…The mid‐Cretaceous (Albian‐Coniacian) marine strata widely distributed in the southeastern coastal surface/subsurface area of Tanzania (Figure ) have recently been named the Lindi Formation [ Jiménez Berrocoso et al, ]. It is a sedimentary package characterized by thick accumulations of mainly fine‐grained sediments deposited in an evolving passive margin basin formed through the breakup of Gondwana and rifting away of Madagascar from Africa [ Jiménez Berrocoso et al , ]. The depositional environment has been generally interpreted as upper slope to outer shelf based on Turonian foraminiferal assemblages and sedimentological criteria [ Jiménez Berrocoso et al , , 2012].…”

“…Drilling reached a total subsurface depth of 74 m and recovered cores representing a 65 m long sequence of dark gray siltstones underlain by coarse‐grained sandstones. Initial on‐site biostratigraphic study of this rock unit, based on the consistently occurring microfossils (planktonic foraminifera and nannofossils), documented a 50 m thick Cenomanian interval (Cores 24 to 4) with short intervals of Turonian sediments above and upper Albian sediments below [ Jiménez Berrocoso et al , ].…”

“…The ranges of selected age‐diagnostic species are reported herein, while the detailed assemblage characterization and taxonomy will be reported elsewhere. As described below, foraminifera and nannofossils provide the biostratigraphic results that are internally consistent at the substage level, and the new information has led to revisions of the initial interpretations on the stage boundaries and biozonation schemes of Jiménez Berrocoso et al [].…”

Untitled

“…Over the past few years, study of Cretaceous intermediate and deep-water circulation patterns has been galvanized by an increase in published neodymium (Nd) isotopic data (e.g., Jiménez Berrocoso et al, 2010;Robinson et al, 2010;MacLeod et al, 2011;Martin et al, 2012;Murphy and Thomas, 2012;Jung et al, 2013;Moiroud et al, 2013;Voigt et al, 2013;Zheng et al, 2013). Nd isotopic values (expressed as εNd) have emerged as a promising proxy for reconstructing past circulation and are applicable across a wide range of water depths, including abyssal samples deposited below the carbonate compensation depth.…”