Lithological and Geochemical Characteristics of Miocene Lacustrine Stromatolites from the Wudaoliang Formation in the Hoh Xil Basin, Northern Tibetan Plateau: Implications for the Paleo-environment

Abstract

Miocene is an important period for the development of global stromatolites. The petrological and geochemical characteristics of stromatolite (dense and porous) laminae record the changes in paleo-environment, from a drilling hole, ZK-1 at Wudaoliang in the Hoh Xil Basin, Northern Tibetan Plateau. Based on the drilling core observations, these lacustrine stromatolites are hummocky, stratiform, or domelike in shape. The stromatolites consist of dense laminae (microspar-rich) and porous laminae (microcrystalline). The oxygen isotopes suggest that these stromatolites in the Wudaoliang Formation formed in a relatively warm environment which was suitable for stromatolite growth. The isotopic variation of lacustrine stromatolites indicates the periodic hydrological closure and opening of the Miocene Hoh Xil Basin. Most of the trace elements (Ba, Pb, Th, U, Hf, Y, V, Cr, Cu, Co, Ni, and Zn) are relatively depleted in the upper continental crust. And, the rare earth elements (REE) show a slight negative Eu anomaly. The Sr/Ba and B/Ga ratios are used as paleo-salinity proxy as well, together with the results of X-ray diffraction (XRD), showing that the stromatolites tended to exist in the condition of decreased salinity. Meanwhile, the arid-dominated climate of the Miocene is more suitable for stromatolite development during the Cenozoic.

Keywords:

• Miocene
• Tibetan Plateau
• lacustrine stromatolite
• Wudaoliang
• paleo-environment

Acknowledgments

We appreciate Prof. Wu Zhenhan at the Institute of Geomechanics, Chinese Academy of Geological Sciences for his permission and kindness to our sampling from the cores of ZK-1. We appreciate Jian Li for his patient advice. We appreciate the editors and reviewers for their constructive comments which greatly improved our manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by Chinese NSFs (Nos. 40872082 and 41572085).