Role of partial melting in the evolution of the Sulu (eastern China) ultrahigh-pressure terrane
Role of partial melting in the evolution of the Sulu (eastern China) ultrahigh-pressure terrane
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DOI：
10.1130/g20991.1
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发表时间：
2005-02
期刊：
影响因子：
5.8
通讯作者：
S. Wallis;M. Tsuboi;Kazuhiro Suzuki;M. Fanning;Laili Jiang;Tsuyoshi Tanaka
中科院分区：
文献类型：
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作者：
S. Wallis;M. Tsuboi;Kazuhiro Suzuki;M. Fanning;Laili Jiang;Tsuyoshi Tanaka
中国东部苏鲁超高压变质地体北部广泛分布着强变形富钾长石岩脉。这些岩脉的结晶年龄与超高压变质峰的年龄重叠，说明在变质过程中存在熔融作用。岩脉的Sr同位素比值与它们的成因是苏鲁长英质片麻岩的部分熔体相适应。部分熔融可能是解决苏鲁和其他超高压地体的一些不寻常特征的关键，例如几乎完全缺乏超高压条件的矿物学证据，以及在超高压条件下，锆石在主要的长英质片麻岩中生长有限。此外，由于部分熔融会导致超高压片麻岩强度的急剧降低，因此最可能的挖掘机制是低粘度的、部分熔融的含有夹带榴辉岩块的物质的底辟上升，而不是通常认为的薄片。
Strongly deformed potassium feldspar–rich dikes are widely distributed in the northern part of the Sulu ultrahigh-pressure (UHP) metamorphic terrane, eastern China. The fact that the crystallization ages of these dikes overlap with the age of peak UHP metamorphic conditions implies the presence of melt during metamorphism. Sr isotopic ratios of the dikes are compatible with their origin as partial melts of the dominant felsic Sulu gneiss. Partial melting may be the key to solving several unusual features of the Sulu and other UHP terranes, such as the almost complete lack of mineralogical evidence for UHP conditions and the limited growth of zircon during UHP conditions in the dominant felsic gneiss. In addition, because partial melting will cause a drastic reduction in the strength of the UHP gneisses, the most likely exhumation mechanism is diapiric rise of a low-viscosity, partially molten mass containing entrained blocks of eclogite, and not a thin sheet as usually proposed.