Some thermal and tectonic models for crustal melting in continental collision zones
Some thermal and tectonic models for crustal melting in continental collision zones
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DOI：
10.1144/gsl.sp.1986.019.01.05
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
P. England;A. Thompson
中科院分区：
文献类型：
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作者：
P. England;A. Thompson
摘要计算的地热和压力-温度-时间（PTt）路径，随后在大陆增厚的情节解释相对于地壳熔体的体积，可能会形成在造山过程中的热量传递的情况下，地幔衍生的熔体。特别注意的是构造的历史，可能具有更广泛的造山带，如代表目前最明显的西藏。这包括一个地壳增厚的时期，然后是一个地壳因伸展应变而不是侵蚀而变薄的间隔。产生的地壳熔融物的量很大程度上取决于下地壳中所含的水（游离水和水合矿物）的量。然而，如果地壳的平均大陆表面热通量（60-70 mW m−2）增加到原来的2倍，我们可以预期造山带每平方公里会有几（1-5）立方千米的地壳熔融。对于较低的地表热通量，沉积源的部分熔融将主要产生S型花岗岩，并且在地热稍高的情况下，地壳厚度加倍可导致斜长角闪岩的部分熔融，从而产生I型花岗岩活动和钙碱性火山作用。
Summary Calculated geotherms and the pressure-temperature-time (PTt) paths followed by rocks during continental thickening episodes are interpreted with respect to the volumes of crustal melt that may be formed during orogenesis in the absence of heat transfer by mantle-derived melts. Particular attention is paid to a tectonic history that may characterize wider orogenic belts, such as are represented most obviously at present by Tibet. This comprises a period of crustal thickening, followed by an interval during which the crust is thinned by extensional strain, rather than by erosion. The amount of crustal melt produced depends strongly on the amount of water (free, and in hydrated minerals) contained in the lower crust. However, we may expect several (1–5) km3 of crustal melt per km2 of orogen if a crust of around average continental surface heat flux (60–70 mW m−2) is thickened by a factor of two. For the lower surface heat flux, partial melting of a sedimentary source would produce predominantly S-type granites and, with slightly higher geotherms, doubling of crustal thickness can lead to partial melting of amphibolites to give I-type granitic activity and calc-alkaline volcanism.