Mantle transition zone structure beneath the Central Asian Orogenic Belt
Mantle transition zone structure beneath the Central Asian Orogenic Belt
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中亚造山带下地幔过渡带结构
DOI：
10.1007/s11430-018-9429-3
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发表时间：
2019-09
期刊：
影响因子：
--
通讯作者：
Qingju Wu
中科院分区：
文献类型：
--
作者：
Jing He;Qingju Wu
中亚造山带新生代火山作用的深部演化机制一直是地球动力学界争论的热点。其中，上地幔不连续面的高分辨率结构，尤其是410 km（D410）和660 km（D660）处的不连续面，是研究岩浆通道及其演化的重要依据。在这项工作中，我们采用了共转换点叠加技术与双折射径向P波接收函数检查D410和D660的不连续面。初步结果表明，不同速度模型得到的地幔过渡带的主要特征基本一致。在汉诺坝火山下方，D410明显升高，D660略低，表明D410处沉积的岩石圈可能发生了拆沉作用。这一过程可能导致软流圈物质上涌，填充岩石圈脱层后留下的空间，从而引发火山爆发。在Dariganga火山以西的D410和D660深度处都观察到强烈的凹陷，D660的凹陷更明显。它导致明显增厚的MTZ，表明在D660处存在冷物质。这种冷物质被推测为来自俯冲的太平洋板块的停滞板，或者是来自碰撞和CAOB形成的分离岛弧系统的遗迹。在亨泰山脉和中部戈壁火山下面发现了稍薄的MTZ。显然，这个较薄的MTZ是不足以支持高的热异常的存在，这可能会排除大规模的热物质从本地MTZ甚至下地幔上涌的可能性。
Over the past decades, there have been hot debates in the geodynamic community regarding to the deep evolution mechanisms of Cenozoic volcanism in the Central Asian Orogenic Belt (CAOB). Of all the constraints available, high resolution structure of upper mantle discontinuities, especially the discontinuities at depths of 410 km (D410) and 660 km (D660), is of the most important, which may provide reliable clues on the magma channel as well as its evolution. In this work, we adopt the common conversion point stacking technique with teleseismic radial P-wave receiver functions to examine the D410 and D660 discontinuities. The primary results exhibit that the major characteristics of the mantle transition zone (MTZ) obtained by different velocity models are largely consistent. Obviously elevated D410 and slightly depressed D660 are observed beneath the Hannuoba Volcano, suggesting possible delamination of the local lithosphere deposited at the D410. This process may induce upwelling of the asthenospheric materials filling the space left by the delaminated lithosphere, and subsequently trigger volcanic eruptions. Strong depressions are observed at both D410 and D660 depths beneath west of the Dariganga Volcano, and the depression of D660 is more pronounced. It leads to the apparently thickened MTZ, indicating the presence of cold material at the D660. This cold material is speculated as a stagnant slab from the subducted Pacific Plate or the remains of a detached island arc system from the collision and formation of the CAOB. Slightly thinner MTZ is found beneath the Hentey Mountains and the Middle Gobi Volcano. Apparently, this thinner MTZ is not significant enough to support the existence of high thermal anomalies, which may rule out the possibility of large-scale hot material upwelling from either the local MTZ or even the lower mantle.
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影响因子：
0.9
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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