1. Mid-Miocene C4 expansion on the Chinese Loess Plateau under an enhanced Asian summer monsoon.
- Author
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Dong, Jibao, Qiang, Xiaoke, Lu, Fengyan, An, Zhisheng, Zhou, Weijian, Liu, Weiguo, and Liu, Zhonghui
- Subjects
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CARBON 4 photosynthesis , *MIOCENE stratigraphic geology , *CARBON isotopes , *OXYGEN isotopes , *SOIL formation , *MONSOONS - Abstract
Atmospheric CO 2 starvation, aridity, fire and warm season precipitation have all been proposed as major contributors to C 4 plant expansion during the Late Miocene. However, the driving factors responsible for the distribution of C 4 plants in the early and mid-Miocene still remain enigmatic. Here we report pedogenic carbon and oxygen isotope data (δ 13 C pedo , δ 18 O pedo ), along with magnetic susceptibility (MS) results, from the Zhuang Lang drilling core on the Chinese Loess Plateau (CLP). Elevated δ 13 C pedo values (>−5‰) signal a prominent C 4 expansion and substantially increased δ 18 O pedo and MS values indicate enhanced Asian summer monsoon (ASM) precipitation. Both of these conditions are observed during the Mid-Miocene Climatic Optimum (MMCO), 14.5–17 million years ago. The marked increase in C 4 plants, associated with warm temperatures and increased precipitation, strongly suggests the control of an enhanced ASM on C 4 expansion on the CLP during the MMCO. This finding contrasts with the late-Miocene C 4 expansion associated with cooling and drying conditions observed in low latitudes and argues for regionally specific control of C 4 plant distribution/expansion. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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