Evolution of an Andean Margin: A Tectonic and Magmatic View from the Andes to the Neuque´n Basin (35°-39°S lat)
Neogene tectonic evolution of the Neuquén Andes western flank (37–39°S)
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Published:January 01, 2006
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CiteCitation
D. Melnick, M. Rosenau, A. Folguera, H. Echtler, 2006. "Neogene tectonic evolution of the Neuquén Andes western flank (37–39°S)", Evolution of an Andean Margin: A Tectonic and Magmatic View from the Andes to the Neuque´n Basin (35°-39°S lat), Suzanne Mahlburg Kay, Victor A. Ramos
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This paper integrates new field observations to summarize the evolution of the 37–39°S segment of the Andean margin during the Neogene period. The western Neuquén Andes represent a transitional segment between the high, broad Central Andes and the low, narrow Patagonian Andes. The Main Cordillera at this latitude was uplifted between 11 and 6 Ma. Since then, extension and transtension has dominated the area. South of 38°S, deformation concentrates along the Liquiñe-Ofqui fault zone, a crustal-scale dextral strike-slip system that accommodates part of the margin-parallel component of oblique subduction. The architecture of the volcanic arc is strongly controlled by this fault zone. We differentiate four main tectonic phases: (1) late Oligocene–middle Miocene extension and development of a segmented intra-arc continental rift basin and broad volcanic zone; (2) late Miocene shortening, resulting in uplift, exhumation, and inversion of the former basins and a volcanic gap in the Main Cordillera; (3) Pliocene–early Pleistocene extension of the orogenic structure, reestablishment of the volcanic arc, and transtension along the intra-arc zone; and (4) late Pleistocene–Holocene narrowing of the arc and localized extension-transtension along the axial intra-arc zone. In the Central Andes, shortening has been more or less continuous since the Miocene, whereas in the Neuquén Andes, shortening stopped at ca. 6 Ma, probably related to the increase of the slab angle triggering the extension of the former orogenic structure and the onset of arc-parallel strike-slip faulting. The episodic evolution and migration of volcanism are related to changes in dip of the subducting plate.
- Andes
- Argentina
- Cenozoic
- Central Andes
- crustal shortening
- dip
- extension tectonics
- faults
- geometry
- grabens
- horsts
- island arcs
- lateral faults
- Neogene
- neotectonics
- Neuquen Basin
- normal faults
- observations
- orogeny
- Patagonia
- Patagonian Andes
- plate tectonics
- right-lateral faults
- segmentation
- South America
- strike-slip faults
- subduction
- systems
- tectonics
- tectonostratigraphic units
- Tertiary
- transtension
- volcanism
- Liquine-Ofqui fault zone
- Bio Bio River
- Lago de la Laja Fault
- Bejar Fault
- Nuble National Park