Fluid evolution in CM carbonaceous chondrites tracked through the oxygen isotopic compositions of carbonates
Fluid evolution in CM carbonaceous chondrites tracked through the oxygen isotopic compositions of carbonates
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通过碳酸盐的氧同位素组成追踪 CM 碳质球粒陨石中的流体演化
DOI：
10.1016/j.gca.2017.01.048
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发表时间：
2017
影响因子：
5
通讯作者：
Lindgren P
中科院分区：
文献类型：
--
作者：
Lindgren P
四个CM碳质方解石的方解石颗粒的氧同位素组成已被确定的NanoSIMS，结果表明，水溶液演化的母体区域之间以类似的方式与不同强度的水蚀变。两种类型的方解石被确定在默奇森，Mighei，冷Bokkeveld和拉巴斯冰原031166的岩石学性质和氧同位素值的差异。1型方解石是在蚀变的最早阶段，通过充填陨石基质中的孔隙空间而形成的小等长颗粒。平均而言，第1类颗粒的δ 18 O为32-36‰（VSMOW），Δ 17 O在32 ‰和-1 ‰之间。大多数2型方解石颗粒在1型之后沉淀。它们含有微孔和包裹体，并取代了铁镁硅酸盐矿物。第二类方解石的平均δ 18 O值为21-24‰（VSMOW），Δ 17 O值介于21 - 1‰和-3 ‰之间。这两种方解石类型之间一致的同位素差异表明，它们形成于离散的事件中，并且来自其δ 18 O和δ 17 O值通过与母体硅酸盐反应而发生变化的溶液，正如水蚀变的封闭系统模型所预测的那样。温度很可能在方解石沉淀的时间跨度内增加，可能是由于放热蛇纹化作用。蚀变程度最高的CM方解石通常除方解石外还含有白云石。在两个先前研究的CM白云石中，白云石颗粒的δ 18 O范围很窄（VSMOW为25-29‰），Δ 17 O范围为−1‰至−3‰。这些颗粒可能在1型和2型方解石之间沉淀，并且响应于瞬时加热事件和/或流体镁/钙比率的短暂增加。尽管有局部温度和/或溶液化学漂移的证据，碳酸盐氧同位素记录表明，流体演化是许多母体区域之间的可比性。因此，这里研究的CM碳质小行星样本要么是几个具有非常相似的初始组成和演化的母体，要么更可能是一颗C型小行星。
The oxygen isotopic compositions of calcite grains in four CM carbonaceous chondrites have been determined by NanoSIMS, and results reveal that aqueous solutions evolved in a similar manner between parent body regions with different intensities of aqueous alteration. Two types of calcite were identified in Murchison, Mighei, Cold Bokkeveld and LaPaz Icefield 031166 by differences in their petrographic properties and oxygen isotope values. Type 1 calcite occurs as small equant grains that formed by filling of pore spaces in meteorite matrices during the earliest stages of alteration. On average, the type 1 grains have a δ18O of ∼32–36‰ (VSMOW), and Δ17O of between ∼2‰ and −1‰. Most grains of type 2 calcite precipitated after type 1. They contain micropores and inclusions, and have replaced ferromagnesian silicate minerals. Type 2 calcite has an average δ18O of ∼21–24‰ (VSMOW) and a Δ17O of between ∼−1‰ and −3‰. Such consistent isotopic differences between the two calcite types show that they formed in discrete episodes and from solutions whose δ18O and δ17O values had changed by reaction with parent body silicates, as predicted by the closed-system model for aqueous alteration. Temperatures are likely to have increased over the timespan of calcite precipitation, possibly owing to exothermic serpentinisation. The most highly altered CM chondrites commonly contain dolomite in addition to calcite. Dolomite grains in two previously studied CM chondrites have a narrow range in δ18O (∼25–29‰ VSMOW), with Δ17O ∼−1‰ to −3‰. These grains are likely to have precipitated between types 1 and 2 calcite, and in response to a transient heating event and/or a brief increase in fluid magnesium/calcium ratios. In spite of this evidence for localised excursions in temperature and/or solution chemistry, the carbonate oxygen isotope record shows that fluid evolution was comparable between many parent body regions. The CM carbonaceous chondrites studied here therefore sample either several parent bodies with a very similar initial composition and evolution or, more probably, a single C-type asteroid.
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影响因子：
3.2
作者：
Emery, J. P.;Fernandez, Y. R.;Ziffer, J.
通讯作者：
Ziffer, J.
Nogoya CM 球粒陨石中碳酸盐的氧和碳同位素比率
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
W. Fujiya;K. Fukuda;M. Koike;A. Ishida;Y. Sano
通讯作者：
Y. Sano
CM2 碳质球粒陨石 LON 94101 中方解石的微观结构：对水蚀变期间和/或之后变形历史的影响
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
P. Lindgren;Martin R. Lee;M. Sofe;M. Burchell
通讯作者：
M. Burchell
高反照率 C 复合体小行星的特征
DOI：
--
发表时间：
2021
期刊：
影响因子：
--
作者：
Hasegawa;S.;Kasuga;T.;Usui;F.;and Kuroda;D
通讯作者：
D
冷 Bokkeveld CM 碳质球粒陨石中硫酸钙的岩相学、矿物学和起源
DOI：
--
发表时间：
1993
期刊：
影响因子：
--
作者：
Martin R. Lee
通讯作者：
Martin R. Lee