Moho, seismogenesis, and rheology of the lithosphere
Moho, seismogenesis, and rheology of the lithosphere
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DOI：
10.1016/j.tecto.2012.12.019
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发表时间：
2012-12
期刊：
影响因子：
2.9
通讯作者：
Wang-Ping Chen;Chunquan Yu;T. Tseng;Zhaohui Yang;Chi‐yuen Wang;J. Ning;T. Leonard
中科院分区：
文献类型：
--
作者：
Wang-Ping Chen;Chunquan Yu;T. Tseng;Zhaohui Yang;Chi‐yuen Wang;J. Ning;T. Leonard
莫霍面并不总是一个清晰的界面，但地震相SspPmp产生了可靠的，物理平均的地壳厚度估计（虚拟深地震测深，VDSS）。In S.西藏的莫霍面深达75 km，地震深度呈双峰分布，一个峰值在地壳上部，另一个峰值在莫霍面以下，这引起了人们对岩性对比如何影响地震活动性和流变学的极大兴趣。一般来说，地震活动受到不同温度（Tc）的限制：地壳为350 ± 50 °C，地幔为700 ± 100 °C（地震测温法）。实验室实验表明，不同的Tcreflect的开始，大量的晶体可塑性的主要地壳和地幔矿物，分别。高于这些Tc，摩擦不稳定性结束，由于速度减弱的滑移。因此，地震到地震的转变与地壳和上地幔的脆韧性转变密切相关，预计大陆岩石圈的强度将达到峰值（“果冻三明治”）。塑性指数取决于温度（随时间变化），因此地热和地壳厚度之间的相互作用可能导致上地壳的地震活动集中-这是非常温暖的岩石圈中温度低于350 °C的唯一部分（“Crème Brélée”）。相反，如果整个地壳低于350 °C（最上层地幔也低于700 °C），那么地震可能发生在很大的深度范围内，包括整个地壳和最上层地幔（“焦糖板”）。
The Moho is not always a sharp interface; but seismic phaseSsPmpyields robust, physically averaged estimates of crustal thickness (virtual deep seismic sounding, VDSS). In S. Tibet where the Moho is as deep as 75 km, bimodal distribution of earthquake depths, with one peak in the upper crust and the other below the Moho, generated much interest in how lithological contrast affects seismicity and rheology. Generally seismicity is limited by distinct temperatures (Tc): 350 ± 50 °C in the crust and 700 ± 100 °C in the mantle (Earthquake Thermometry). Laboratory experiments show that distinctTcreflect the onset of substantial crystal plasticity in major crustal and mantle minerals, respectively. Above theseTc, frictional instability ends due to velocity weakening of slip. So the seismic to aseismic transition is closely linked with brittle-ductile transitions in the crust and in the uppermost mantle, where the strength of the continental lithosphere is expected to peak (“Jelly Sandwich”). Plasticity depends exponentially on temperature (which evolves over time), so interplay between the geotherm and crustal thickness could result in concentrated seismicity in the upper crust — the only portion of a very warm lithosphere where temperature is below ~ 350 °C (“Crème Brûlée”). Conversely, where the entire crust is below ~ 350 °C (and the uppermost mantle is also below ~ 700 °C), then earthquakes could occur over a wide range of depths, including the entire crust and the uppermost mantle (“Caramel Slab”).