Strain Partitioning around Faults in the Lake District of the Southern Andes
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Date
2024-05
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The Ohio State University
Abstract
This study addresses the variation of principal strains throughout the Southern Andean Volcanic Zone (SVZ). The SVZ has two prominent fault structures known as the Liquiñe-Ofqui Fault System (LOFS) and Andean Transverse Faults (ATF). The LOFS is a major transverse fault structure that strikes parallel to the margin and the ATF are crustal scale faults that strike NW and NE. Both fault structures are seismically active, underly many of the volcanic edifices in the SVZ, and partition strain from the obliquely convergent margin. To understand the strain partitioning throughout the region, kinematic information like slip direction and slip sense of brittle fractures were collected at various localities. The analyses of the fractures were run as fault-slip data inversions at the local and regional scale. The regional scale strain analysis displayed kinematically heterogeneous faulting with the predominate dextral strike-slip NE-striking faults of the LOFS. The local scale strain analysis displayed either homogeneous or heterogeneous results based on the individual locality. I discuss the calculated principal strain directions for each locality in the context of the local fault structure. Principal strain orientations vary considerably from locality to locality and deviate from the regional strain tensor. This can be interpreted in terms of strong strain partitioning throughout the SVZ due to mechanical interactions between the LOFS and ATF.
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Keywords
Strain partitioning, Transpression, Liquiñe-Ofqui Fault System, Andean Transverse Faults