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Ventura 2004
Ventura, G. (2004). The strain path and kinematics of lava domes: An example from Lipari (Aeolian Islands, Southern Tyrrhenian Sea, Italy). Journal of Geophysical Research 109. doi: 10.1029/2003JB002740. issn: 0148-0227.

A circular dome from Lipari Island consists of latitic enclaves hosted in a rhyolitic magma. A strain analysis of the enclaves has been carried out and the pure shear (α) and simple shear (γ) deformation, the vorticity number Wk and flow kinematics are determined. The axial ratio Rf of the enclaves and the angle φ between the long axis of the enclaves and the transport direction are measured in 131 sites concentrated in the axial zone (z1), upper-distal zone (z2) and basal zone (z3) of the flow. The φ values depict a pattern suggesting endogenous growth. In z1, α/γ > 1. In z2, 1 0.8. Lateral stretching due to the upward motion of magma from the conduit prevails in z1. Here the increase of pure shear strain from the bottom to the top reflects strain accumulation due to endogenous growth. z2 and z3 suffer simple shear deformation. In z3, the sense of shear is consistent with the transport direction. An opposite sense of shear characterizes z2. This is due to velocity gradients located in the lower and upper portions of the flow. The kinematics is viscous spreading in z1 and viscous gliding (hyperbolic flow) in z2--z3. Possible rupturing of the exterior may be important in z1, where lateral stretching occurs, and in z3, where γ is at a maximum. The effusion rate is ~1.93 m3/s. Strain rates calculated using structural data span a range from 1.9 to 5.8.10-6 s-1.

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Abstract

Keywords
Structural Geology, Mesoscopic fabrics, Structural Geology, General or miscellaneous, Tectonophysics, Physics of magma and magma bodies, Volcanology, Lava rheology and morphology, lava domes, emplacement mechanism, strain analysis, enclaves, viscous flows, kinematics
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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