Crustal thickening and endogenic oxidation of magmatic sulfur
Crustal thickening and endogenic oxidation of magmatic sulfur
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DOI：
10.1126/sciadv.aba6342
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发表时间：
2020-07
期刊：
影响因子：
13.6
通讯作者：
Ming Tang;Cin-Ty A. Lee;Weiqiang Ji;Rui Wang;G. Costin
中科院分区：
文献类型：
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作者：
Ming Tang;Cin-Ty A. Lee;Weiqiang Ji;Rui Wang;G. Costin
地壳增厚为形成斑岩铜矿床创造了岩浆条件。斑岩矿床是地球上最重要的铜、钼和铼资源，与显示高压分异迹象的长英质岩浆密切相关，通常发现于地壳增厚的地方（>45公里）。这种模式是众所周知的，但无法解释，并且仍然是我们理解斑岩矿床形成的一个突出问题。我们通过研究岩浆硫的氧化态来解决这个问题，它控制着岩浆分异和岩浆热液转变过程中成矿金属的行为。我们利用磷灰石中的硫来重建藏南冈底斯岩基中的硫氧化态。我们发现印度-欧亚大陆碰撞后岩浆硫酸盐含量急剧增加。磷灰石硫含量和计算出的岩浆S6+/ΣS比值与全岩镝/镱比值相关，表明在增厚地壳中有利的残余石榴石对岩浆造山带中的硫氧化发挥一级控制作用。我们的研究结果将硫氧化与内部成岩过程联系起来，并暗示岩浆氧化与同岩浆地壳增厚之间存在内在关系。
Crustal thickening primes the magmatic conditions to make porphyry Cu deposits. Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding problem in our understanding of porphyry ore deposit formation. We approach this problem by investigating the oxidation state of magmatic sulfur, which controls the behavior of ore-forming metals during magma differentiation and magmatic-hydrothermal transition. We use sulfur in apatite to reconstruct the sulfur oxidation state in the Gangdese batholith, southern Tibet. We find that magma sulfate content increased abruptly after India-Eurasia collision. Apatite sulfur content and the calculated magma S6+/ΣS ratio correlate with whole-rock dysprosium/ytterbium ratio, suggesting that residual garnet, favored in thickened crust, exerts a first-order control on sulfur oxidation in magmatic orogens. Our findings link sulfur oxidation to internal petrogenic processes and imply an intrinsic relationship of magma oxidation with synmagmatic crustal thickening.