Stable isotope (C, O, H) characteristics and genesis of the Tazheran brucite marbles and skarns, Olkhon region, Russia
Stable isotope (C, O, H) characteristics and genesis of the Tazheran brucite marbles and skarns, Olkhon region, Russia
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DOI：
10.1007/s00710-016-0477-8
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发表时间：
2017-06
影响因子：
1.8
通讯作者：
A. Doroshkevich;E. Sklyarov;A. Starikova;V. Vasiliev;G. Ripp;I. Izbrodin;V. Posokhov
中科院分区：
文献类型：
--
作者：
A. Doroshkevich;E. Sklyarov;A. Starikova;V. Vasiliev;G. Ripp;I. Izbrodin;V. Posokhov
对俄罗斯奥尔洪地区塔热兰地块南部的水镁石大理岩和镁矽卡岩的稳定同位素组成进行了检查。与国内白云石同位素组成（+2.0 至 +2.4 ‰）相比，水镁石大理石的 δ18O 范围较窄，为 +23.3 至 +26.2 ‰，碳同位素贫化为 -1.9 至 -4.4 ‰，这可以通过脱碳过程和贫化流体的参与来解释。水镁石大理岩的侵位伴随着正长岩和水镁石大理岩接触处内、外卡岩的形成。整个接触面的 δ18O 剖面显示出朝向正长岩一侧的典型减少，这被解释为流体/岩石相互作用和岩浆流体流入的结果。最后，我们讨论了水镁石大理岩的侵位机制，并考虑了产生这些岩石的三种可能的方式：（1）注入白云石，随后转变为方镁石大理岩，然后转变为水镁石大理岩； (2)注射方镁石大理石，然后用水镁石代替方镁石或注射水镁石大理石； (3)地壳富水碳酸盐熔体。我们倾向于模型 2 和 3，并讨论它们的优点和缺点。
Stable isotope compositions are examined for brucite marble and Mg-skarn that occur in the southern part of the Tazheran massif, Olkhon region, Russia. Brucite marble exhibits a narrow range in δ18O of +23.3 to +26.2 ‰ and shows carbon isotope depletion of −1.9 to −4.4 ‰) as compared with the country dolomite isotope compositions (+2.0 to +2.4 ‰) which is explained by both decarbonation processes and participation of fluids depleted in13C. The emplacement of brucite marble was accompanied by the formation of endo- and exoskarn at the contact between syenite and brucite marble. δ18O profiles across the contact show a typical decrease towards the syenite side interpreted as the result of fluid/rock interaction and influx of magmatic fluids. Finally, we discuss the mechanisms of brucite marble emplacement and consider three possible ways of producing these rocks: (1) injection of dolomite with subsequent transformation to periclase marble and then to brucite marble; (2) injection of periclase marble with a following replacement of periclase by brucite or injection of brucite marble; (3) crustal water-rich carbonate melt. We favor models 2 and 3 and discuss their strengths and weaknesses.