Clumped isotopes of paired dolomite and calcite constraining alteration histories of ancient carbonate successions
Clumped isotopes of paired dolomite and calcite constraining alteration histories of ancient carbonate successions
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成对白云石和方解石的团块同位素限制了古代碳酸盐岩层序的蚀变历史
DOI：
10.1016/j.chemgeo.2022.121264
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发表时间：
2022-12
期刊：
影响因子：
3.9
通讯作者：
Peter K. Swart
中科院分区：
文献类型：
--
作者：
Chaojin Lu;Huayao Zou;Guangwei Wang;Fuyun Cong;Yongbin Quan;Peter K. Swart
团块同位素测温是了解碳酸盐岩沉积后改造作用的有效工具，包括重结晶作用和固体重排序作用。然而，由于这两个过程都受温度升高的控制，区分这两个过程在深埋碳酸盐岩序列中的相对重要性(深度为5000微米或地层温度为150摄氏度)往往是一项挑战。在本文中，我们建立了一个成对的白云石和方解石的块状同位素框架，以解释固态重排序与重结晶的相对影响，从而对其中的机制有了更好的理解。所研究的物质来源于四川盆地中部中国南部两个深埋的层序(侏罗纪-埃迪卡拉纪)。用缓冲醋酸分离了这些岩心中的方解石和白云石矿物，并根据双组分混合模型测定了两个端元的碳、氧和成团同位素(Δ-47)组成。根据固体重排序模型的评价，我们得出结论：侏罗纪至寒武纪的泥晶碳酸盐(白云石和方解石)在埋藏过程中受到镜质组反射率确定的地温梯度的影响。埃迪卡拉纪泥晶白云岩记录了埃迪卡拉纪与寒武纪之间的一次热液事件。相反，埃迪卡拉纪鞍状白云岩的团块同位素温度反映了志留纪和泥盆纪的后续热液活动，并显示出受冷却速度控制的成分变化。这项研究突出了基于成对白云石和方解石记录的理论框架在解开古碳酸盐岩中团块同位素叠加信号方面的作用，并为更好地理解深埋碳酸盐岩序列中蚀变过程的复杂性提供了洞察。
Clumped isotope thermometry is an effective tool which allows to understand the post-depositional alteration, including recrystallization and solid-state reordering, of carbonate rocks. However, as both processes are controlled by elevated temperatures, it is frequently a challenge to distinguish between the relative importance of these two processes in deeply buried carbonate successions (depth > 5000 m or formation temperature > 150°C). In this paper, we have established a clumped isotopic framework of paired dolomite and calcite in order to decipher the relative influence of solid-state reordering versus recrystallization and consequently offer an improved understanding of the mechanisms involved. The material studied was derived from two deeply buried successions (Jurassic-Ediacaran) drilled in the central Sichuan Basin of South China. The calcite and dolomite minerals from these cores were separated using buffered acetic acid, and based on a two-component mixing model, the carbon, oxygen and clumped isotopic (Δ47) compositions of the two endmembers were determined. Based on an evaluation of solid-state reordering models, we conclude that micritic carbonates (dolomite and calcite) from the Jurassic to the Cambrian have been altered during burial by the geothermal gradient as determined by vitrinite reflectance. The Ediacaran micritic dolomite records a hydrothermal event in the transition between the Ediacaran and Cambrian. In contrast, the clumped isotopic temperature of Ediacaran saddle dolomites reflects subsequent hydrothermal activity during the Silurian and Devonian and shows compositional variations controlled by cooling rates. This study highlights the utility of the theoretical framework based on paired dolomite and calcite records to untangle overprinted signals of clumped isotopes in ancient carbonate rocks and gives insight to better understand the complexity of alteration processes in deeply burial carbonate successions.
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影响因子：
12.1
作者：
J. Veizer;A. Prokoph
通讯作者：
J. Veizer;A. Prokoph
影响因子：
3.7
作者：
P. Swart;S. Murray;P. Staudigel;D. Hodell
通讯作者：
P. Swart;S. Murray;P. Staudigel;D. Hodell
影响因子：
5.3
作者：
U. Ryb;M. Lloyd;D. Stolper;J. Eiler
通讯作者：
U. Ryb;M. Lloyd;D. Stolper;J. Eiler
影响因子：
3.9
作者：
Daeron, M.;Blamart, D.;Affek, H. P.
通讯作者：
Affek, H. P.
影响因子：
2.3
作者：
Huntington, K. W.;Eiler, J. M.;Came, R.
通讯作者：
Came, R.