The evolution of Earth's surficial Mg cycle over the past 2 billion years

Zhiguang Xia; Shilei Li; Zhongya Hu; Or Bialik; Tianyu Chen; Mebrahtu F Weldeghebriel; Qishun Fan; Junxuan Fan; Xiangdong Wang; Shichao An; Feifei Zhang; Haoran Xu; Jiayang Chen; Zhihan Ji; Shuzhong Shen; Tim K Lowenstein; Weiqiang Li

doi:10.1126/sciadv.adj5474

The evolution of Earth's surficial Mg cycle over the past 2 billion years

Sci Adv. 2024 Mar;10(9):eadj5474. doi: 10.1126/sciadv.adj5474. Epub 2024 Mar 1.

Authors

Zhiguang Xia^{1

2

3

4}, Shilei Li^{2

5}, Zhongya Hu^{1

6}, Or Bialik⁷, Tianyu Chen^{1

2}, Mebrahtu F Weldeghebriel^{8

9}, Qishun Fan¹⁰, Junxuan Fan¹, Xiangdong Wang¹, Shichao An^{1

2}, Feifei Zhang¹, Haoran Xu^{1

2}, Jiayang Chen^{1

2}, Zhihan Ji^{1

2}, Shuzhong Shen¹, Tim K Lowenstein⁸, Weiqiang Li^{1

2}

Affiliations

¹ State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, Jiangsu, China.
² Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing 210023, Jiangsu, China.
³ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China.
⁴ International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu 610059, China.
⁵ Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences, Nanjing University, Nanjing 210023, China.
⁶ State Key Laboratory of Marine Geology, School of Ocean and Earth Science, Tongji University, Shanghai 200092, China.
⁷ Institute of Geology and Palaeontology, University of Muenster, Corrensstr. 24, 48149 Münster, Germany.
⁸ Department of Earth Sciences, Binghamton University, NY 13902, USA.
⁹ Department of Geosciences, Princeton University, NJ 08544, USA.
¹⁰ Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China.

Abstract

The surficial cycling of Mg is coupled with the global carbon cycle, a predominant control of Earth's climate. However, how Earth's surficial Mg cycle evolved with time has been elusive. Magnesium isotope signatures of seawater (δ²⁶Mg_sw) track the surficial Mg cycle, which could provide crucial information on the carbon cycle in Earth's history. Here, we present a reconstruction of δ²⁶Mg_sw evolution over the past 2 billion years using marine halite fluid inclusions and sedimentary dolostones. The data show that δ²⁶Mg_sw decreased, with fluctuations, by about 1.4‰ from the Paleoproterozoic to the present time. Mass balance calculations based on this δ²⁶Mg_sw record reveal a long-term decline in net dolostone burial (NDB) over the past 2 billion years, due to the decrease in dolomitization in the oceans and the increase in dolostone weathering on the continents. This underlines a previously underappreciated connection between the weathering-burial cycle of dolostone and the Earth's climate on geologic timescales.