ISSN 1006-3021 CN11-3474/P
Published bimonthly started in 1979
碳酸盐(岩)的锂同位素组成:一种潜在的古海水pH替代性指标
  
关键词:marine carbonate rocks  lithium isotopes  boron isotopes  pH
基金项目:国家重点研发计划(编号: 2017YFC0602705);中国地质科学院矿产资源研究所基本科研业务费(编号: KK1913)
作者单位E-mail
赵悦 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室 zhaoyue0612@hotmail.com 
李延河 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室 lyh@cei.cn 
胡斌 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室  
侯可军 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室  
范昌福 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室  
高建飞 中国地质科学院矿产资源研究所, 自然资源部成矿作用与资源评价重点实验室,自然资源部同位素地质重点实验室  
摘要点击次数: 2833
全文下载次数: 1577
摘要:
Lithium Isotopic Composition of Marine Carbonate Rocks:A New Proxy for Paleo-pH Reconstruction
      The pH value of seawater has changed obviously in the evolution history of the earth. The pH value of seawater may be an important factor controlling the formation of marine carbonate rocks and the evolution of their components, which is of great significance to the genesis of early dolomite and the formation of some minerals. However, there are very few proxies for recording changes in ocean pH, with boron isotopes of carbonate (rocks) being the main proxy. Boron isotopes of ancient carbonates are often affected by diagenetic processes. During the transformation process of δ11B-pH, the uncertainty of αB, pKB* and δ11BSW needs to be based on a variety of assumptions. The analytical results are of multiple solutions and uncertainty. Multiple independent indicators are needed to limit seawater pH value, and lithium isotopic composition of carbonate (rocks) is a potential proxy. Roberts et al. (2018) found that the δ7Li of foraminifera carbonate shells and seawater pH value have significantly negative relationship, and the strength of the 6Li and 7Li hydration spheres (and hence their respective desolvation energy) is pH-dependent, resulting in a significant isotopic fractionation during the incorporation of lithium into foraminifer calcite. The δ7Li values of well preserved pristine carbonate rock range from 4.9‰ to 13.4‰ (averaging 8.03‰), significantly lower than those of the modern marine carbonate. Therefore, the δ7Licarb shows a general increasing trend since the Mesoproterozoic. Preliminary analyses of B and Li isotopes in Mesoproterozoic marine carbonate rocks from Jixian section exhibit a clear anti-correlation trend for δ7Li and δ11B values, also δ7Li and pH (δ11Bsw=25‰). The same pattern is observed in siliceous banded dolomite as well. This implies that the δ7Li of marine carbonate has the potential to be a novel pH proxy, although the mechanism behind requires further investigation. Li isotope may have great implications in the reconstruction of δ11B of seawater, if it can be used as an independent constraint on pH value.
ZHAO Yue,LI Yan-he,HU Bin,HOU Ke-jun,FAN Chang-fu,GAO Jian-fei.2020.Lithium Isotopic Composition of Marine Carbonate Rocks:A New Proxy for Paleo-pH Reconstruction[J].Acta Geoscientica Sinica,41(5):613-622.
查看全文  查看/发表评论  下载PDF阅读器
Copyright©2008 All Rights Reserved
Sponsored by:
Address:: PostCode: Tel: E-mail: