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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The strain path and emplacement mechanism of lava flows: an example from Salina (southern Tyrrhenian Sea, Italy)
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The strain path and emplacement mechanism of lava flows: an example from Salina (southern Tyrrhenian Sea, Italy)

机译：熔岩流的应变路径和位移机制：以萨利纳河为例（意大利第勒尼安海）

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摘要

A lava flow from Salina (southern Tyrrhenian Sea) consists of subcircular to ellipsoidal basaltic enclaves dispersed in a dacitic host. A 2D strain and kinematic analysis of the enclaves has been performed in order to determine (a) the relative contribution of the coaxial (α) and non-coaxial (γ) components to the bulk flow deformation, (b) the flow vorticity Wk, (c) the strain path and (d) the mechanism of flow emplacement. The axial ratio R_f and the angle φ_f between the long axis of the enclaves and the transport direction have been measured in 196 sites located at different distances from the vent. In the near vent zone α > γ whereas further from the vent γ > α. α values were always larger than 1, ranging from 1.6 in the near vent zone to 1 at the front. γvalues were between 0.2 (at the back) and 2.6 (at the front). Wk was between 0.13 and 1 and increased from the back to the front. The enclaves result from the injection of basalt into dacite. Most of the deformation was acquired during the lava flow emplacement and not during the rise in the conduit (plug flow). The strain path depicted by the enclaves is consistent with that resulting from experimental analogue models and reveals that the lava suffers lateral extension near the vent. Further from the vent, the lava deforms according to an ideal non-coaxial model. The lava emplacement is mainly controlled by the gravity. Evidence of deformation induced by the magma pressure is lacking. Near the vent, the lava behaves as a hyperbolic flow whereas at the front it behaves as a simple shear flow. The mechanism of flow emplacement is consistent with a mixed 'viscous gliding-spreading' transport model at the back and with a 'viscous gliding' model at the front.
机译：来自萨利纳（第勒尼安海南部）的熔岩流由散布在大洋洲宿主中的亚圆形到椭圆形的玄武岩群组成。为了确定（a）同轴（α）和非同轴（γ）分量对整体流动变形的相对贡献，（b）流动涡度Wk，已经对飞地进行了2D应变和运动学分析。 （c）应变路径和（d）流动引入的机理。已经在距通风口不同距离的196个位置测量了轴向比R_f和飞地的长轴之间的夹角φ_f和输送方向。在排气孔附近区域，α>γ，而在排气孔附近，γ>α。 α值始终大于1，范围从排气孔附近的1.6到前面的1。 γ值介于0.2（在后面）和2.6（在前面）之间。 Wk在0.13和1之间，并且从后到前增加。这些飞地是由玄武岩注入da榴石形成的。大部分变形是在熔岩流注入期间获得的，而不是在管道上升（塞流）期间获得的。飞地所描绘的应变路径与实验模拟模型得出的应变路径一致，表明熔岩在通风口附近遭受横向扩展。熔岩远离喷口，会根据理想的非同轴模型变形。熔岩的位置主要由重力控制。缺乏由岩浆压力引起的变形的证据。在喷口附近，熔岩表现为双曲线流动，而在前部表现为简单的剪切流动。流动安置的机制与后面的混合“粘稠滑移扩散”运输模型以及前面的“粘稠滑移”运输模型一致。

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