The effect of obliquity on temperature in subduction zones: insights from 3-D numerical modeling
The effect of obliquity on temperature in subduction zones: insights from 3-D numerical modeling
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俯冲带倾角对温度的影响：来自 3D 数值模型的见解
DOI：
10.5194/se-9-759-2018
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发表时间：
2018
期刊：
影响因子：
3.4
通讯作者：
D. V. van Hinsbergen
中科院分区：
文献类型：
--
作者：
A. Plunder;C. Thieulot;D. V. van Hinsbergen
抽象的。俯冲带的地温被认为是俯冲速率和俯冲岩石圈年龄的函数。沿着一个单一的俯冲带，由于海沟和板块会聚矢量之间的角度变化，俯冲速率可能会发生很大变化，即，由于海沟的弯曲，俯冲的弯曲度。我们目前观察到这样的曲率，例如，马里亚纳群岛智利和阿留申群岛的战壕最近，强烈的沿走向变化俯冲结晶度被认为是造成土耳其西部和中部白垩纪地质记录之间的主要温度差异的原因。我们在这里测试是否在俯冲带的一阶温度变化可能是由于在沟槽的几何形状变化，使用简单的热运动有限元3-D数值模型。我们通过一个简单的数学函数来描述海沟的几何形状，并通过求解质量和动量守恒方程来计算地幔楔中的地幔流。然后我们求解能量守恒方程，直到达到稳态。我们分析的结果（i）在地幔楔流，重点是沟平行分量和（ii）在温度沿着板界面的地图和深度-温度路径的接口。在我们的实验中，海沟曲率对地温的影响是很大的。一个小的结晶度产生一个小的但不可忽略的沟平行地幔流，导致30 °C的差异沿走向的模型。平流热导致这样的温度变化（与速度的沟平行分量的大小有关）。随着温度的增加，平行于沟槽的速度分量随之增加，温度变化沿走向达到200 °C。最后，我们讨论了我们的模拟无处不在的倾斜系统，在地球上观察到的影响和我们的建模方法的局限性。与曲率相关的板块下沉速率的横向变化将进一步增强这种温度对比。我们的结论是，土耳其中部和西部之间的同步变质温度的差异可能是由于重建的主要变化俯冲结晶。
Abstract. The geotherm in subduction zones is thought to vary as a function of the subduction rate and the age of the subducting lithosphere. Along a single subduction zone the rate of subduction may strongly vary due to changes in the angle between the trench and the plate convergence vector, i.e., the subduction obliquity, due to trench curvature. We currently observe such curvature in, e.g., the Marianas, Chile and Aleutian trenches. Recently, strong along-strike variations in subduction obliquity were proposed to have caused a major temperature contrast between Cretaceous geological records of western and central Turkey. We test here whether first-order temperature variation in a subduction zone may be caused by variation in the trench geometry using simple thermo-kinematic finite-element 3-D numerical models. We prescribe the trench geometry by means of a simple mathematical function and compute the mantle flow in the mantle wedge by solving the equation of mass and momentum conservation. We then solve the energy conservation equation until steady state is reached. We analyze the results (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of temperature along the plate interface by means of maps and the depth–temperature path at the interface. In our experiments, the effect of the trench curvature on the geotherm is substantial. A small obliquity yields a small but not negligible trench-parallel mantle flow, leading to differences of 30 °C along-strike of the model. Advected heat causes such temperature variations (linked to the magnitude of the trench-parallel component of velocity). With increasing obliquity, the trench-parallel component of the velocity consequently increases and the temperature variation reaches 200 °C along-strike. Finally, we discuss the implication of our simulations for the ubiquitous oblique systems that are observed on Earth and the limitations of our modeling approach. Lateral variations in plate sinking rate associated with curvature will further enhance this temperature contrast. We conclude that the synchronous metamorphic temperature contrast between central and western Turkey may well have resulted from reconstructed major variations in subduction obliquity.
影响因子：
3.9
作者：
A. Garcia‐Casco;C. Lázaro;Y. Rojas‐Agramonte;A. Kröner;R. Torres-Roldán;Kenya Núñez;F. Neubauer;G. Millán;I. Blanco-Quintero
通讯作者：
A. Garcia‐Casco;C. Lázaro;Y. Rojas‐Agramonte;A. Kröner;R. Torres-Roldán;Kenya Núñez;F. Neubauer;G. Millán;I. Blanco-Quintero