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Title: Organic geochemical investigation of sediments in the Japan Sea : tracking paleoceanographic and paleoclimatic changes since the mid-Miocene
Author: Wittkopp, Frederike
ISNI:       0000 0004 6423 544X
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2017
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The mid- to late Miocene marks one of the last warm periods of the Neogene, before the descent in to the ice house climate of the late Pliocene and Pleistocene. The mid- to late Miocene climate was long overlooked, but receives increasingly more interest. This study used organic geochemical biomarker distributions and their isotopic signatures in sediment samples from the Japan Sea, recovered during IODP Expedition 346 and ODP Leg 127/128. It was the aim to reconstruct paleoceanographic and paleoclimatic changes over the last 18 Ma. Reconstructed sea surface temperatures revealed declining temperatures since the Mid-Miocene Climatic Optimum, possibly driven by a long-term decline in atmospheric CO2. Reconstructed pCO2 using alkenone paleobarometry, revealed a late Miocene decline from circa 520 μatm to 380 μatm. A decline in this range is required to trigger the onset of the late Miocene C4 plant expansion, which was also fully detected in the sedimentary record from the Japan Sea. Stable isotope analysis of n-alkanes (δD and δ13C) revealed an intensified summer monsoon from 5-3 Ma, which also led to a freshening of surface waters in the Japan Sea. Overall, the Japan Sea is a suitable study area for the late Miocene climate change.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: GE Environmental Sciences ; QE Geology