Abstract
The Nanggulan section in south central Java comprises open marine sediments and volcanic deposits of Eocene–Oligocene age that accumulated in a marginal basin within the young Sunda Arc complex. A new borehole captures the stratigraphy and showcases the exceptional preservation of calcareous microfossils across an apparently complete Eocene–Oligocene Transition (EOT), a time interval significant for the initiation of continental-scale glaciation on Antarctica. Low-resolution benthic and planktonic foraminifera oxygen and carbon stable isotopes (δ18O and δ13C) record increasing δ18O and δ13C in the basal Oligocene, allowing correlation to global records. Isotopic values imply warm temperatures and relatively high nutrients along the SE Java margin. The Nanggulan EOT is a valuable archive for reconstructing ocean–climate behaviour and plankton evolution and extinction in the Indo-Pacific Warm Pool. The borehole also adds to understanding of the early stages of Sunda Arc volcanism.Supplementary material: Supplementary figures, tables and appendices are available at https://doi.org/10.6084/m9.figshare.c.5429453
Highlights
Miocene and younger volcanic rocks dominate much of the surface geology of the Indonesian island of Java
Characteristic features are the occurrence of disseminated carbonate grains and a ‘sugary’ texture, similar to the principal hemipelagic clay lithology of the early–middle Eocene of Tanzania Drilling Project (TDP) Sites 2 and 3 in the Kilwa area of Tanzania (Pearson et al 2004)
The studied section, which sampled the upper part of the Nanggulan Formation, spans c. 13 myr, from the middle Eocene (Lutetian) to the early late Oligocene (Chattian), and includes an apparently continuous succession through the Eocene– Oligocene Transition (EOT)
Summary
In the Nanggulan region of central Java, patches of calcareous marine and volcaniclastic sediments of Paleogene age crop out in small pockets where there has been limited burial followed by uplift and erosion (Oppenoorth and Gerth 1929; Hartono 1969; Lunt 2013a) These calcareous sediments, which comprise chalky marls, claystones and clays, and contain diverse and in places very well-preserved ‘glassy’ microfossils of middle Eocene to late Oligocene age, are renowned to palaeontologists (Verbeek 1891; Rutten 1927; Hartono 1969; Saito et al 1981; Pearson et al 2006; Lunt 2013b). If declining levels of CO2 were the dominant driver, as modelling studies predict
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
