Chronostratigraphy of the Baringo-Tugen Hills-Barsemoi (HSPDP-BTB13-1A) core – 40Ar/39Ar dating, magnetostratigraphy, tephrostratigraphy, sequence stratigraphy and Bayesian age modeling

The Baringo-Tugen Hills-Barsemoi 2013 drillcore (BTB13), acquired as part of the Hominin Sites and Paleolakes Drilling Project, recovered 228 m fluvio-lacustrine sedimentary rocks tuffs spanning a ~3.29–2.56 Ma interval highly fossiliferous hominin-bearing Chemeron Formation, Tugen Hills, Kenya. Here we present Bayesian stratigraphic age model for core employing chronostratigraphic control points derived from 40Ar/39Ar dating outcrop, calibration related outcrop diatomaceous units, magnetostratigraphy. reveals three main intervals with distinct sediment accumulation rates: an early rapid phase 3.2–2.9 Ma; relatively slow 2.9–2.7 highest rate 2.7–2.6 Ma. correspond to periods high Earth orbital eccentricity, whereas corresponds low eccentricity at Ma, suggesting that astronomically mediated climate processes may be responsible observed changes in rate. Lacustrine transgression-regression events, delineated using sequence stratigraphy, dominantly operate on precession scale, particularly within periods. A set erosively based fluvial conglomerates interval, which could either depositional response or development unconformities due local tectonic activity. Age magnetic susceptibility gamma density logs indicates close temporal correspondence between shift high- low-frequency signal variability ~3 approximately coincident end mid-Piacenzian Warm Period, beginning cooling world leading initiation Northern Hemispheric glaciation c. 2.7 BTB13 Baringo Basin records thus provide evidence connection high-latitude equatorial terrestrial toward Pliocene.