Crustal motion in the Southern Andes (26°–36°S): Do the Andes behave like a microplate?

Brooks, Benjamin A.; Bevis, Michael; Smalley, Robert; Kendrick, Eric; Manceda, René; Laurı́a, Eduardo; Maturana, Rodrigo; Araújo, Maria Rizoneide Negreiros de

doi:10.1029/2003gc000505

Cited by 142 publications

(190 citation statements)

References 43 publications

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“…The measurements of the fold and thrust belt shortening in different sections across the Andes between 288 and 328S in the last 20 Ma show that shortening rates vary from 7.3 to 7.7 mm/year along the La Ramada northern section to 5.5-5.7 mm/year in the Aconcagua southern section (Ramos et al 2004). These values are of the same order than the GPS displacements of $4.5 mm/year measured across the orogenic front by Brooks et al (2003). If we assume some elastic recovery of these displacements, there is a good correlation between absolute motion relative to the Pacific hotspot frame and GPS data.…”

Section: Chile-type Subductionsupporting

confidence: 57%

The tectonic regime along the Andes: Present‐day and Mesozoic regimes

Ramos¹

2009

Geological Journal

217

139

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The analyses of the main parameters controlling the present Chile-type and Marianas-type tectonic settings developed along the eastern Pacific region show four different tectonic regimes: (1) a nearly neutral regime in the Oregon subduction zone; (2) major extensional regimes as the Nicaragua subduction zone developed in continental crust; (3) a Marianas setting in the Sandwich subduction zone with ocean floored back-arc basin with a unique west-dipping subduction zone and (4) the classic and dominant Chile-type under compression. The magmatic, structural and sedimentary behaviours of these four settings are discussed to understand the past tectonic regimes in the Mesozoic Andes based on their present geological and tectonic characteristics. The evaluation of the different parameters that governed the past and present tectonic regimes indicates that absolute motion of the upper plate relative to the hotspot frame and the consequent trench roll-back velocity are the first order parameters that control the deformation. Locally, the influences of the trench fill, linked to the dominant climate in the forearc, and the age of the subducted oceanic crust, have secondary roles. Ridge collisions of seismic and seismic oceanic ridges as well as fracture zone collisions have also a local outcome, and may produce an increase in coupling that reinforces compressional deformation. Local strain variations in the past and present Andes are not related with changes in the relative convergence rate, which is less important than the absolute motion relative to the Pacific hotspot frame, or changes in the thermal state of the upper plate. Changes in the slab dip, mainly those linked to steepening subduction zones, produce significant variations in the thermal state, that are important to generate extreme deformation in the foreland.

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Section: Chile-type Subductionsupporting

confidence: 57%

The tectonic regime along the Andes: Present‐day and Mesozoic regimes

Ramos¹

2009

Geological Journal

217

139

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“…The recent phase of contraction and shortening that initiated the uplift of the Andes was accompanied by extensive arc activity starting in the Eocene in the Central Andes; in the Northern Patagonian Andes these processes began in the early Miocene (Allmendinger et al, 1990;Jordan, 1993;Kley and Monaldi, 1998;. Total shortening decreases southward from ~ 300 km in the Central Andes to only ~ 15 km in the Northern Patagonian Andes (Isacks, 1988;Allmendinger et al, 1990;Diraison et al, 1998;Kley et al, 1999;GregoryWodzicki, 2000;Vietor and Echtler, 2006) (Figure 1 shortening rates in the Central Andes (Dewey and Lamb, 1992;Klotz et al, 2001;Brooks et al, 2003). Based on shortening rates and tectonic activity, the Central to Southern Andes can be subdivided into four tectonic provinces (Figure 1).…”

Section: Geologic Settingmentioning

confidence: 99%

The topographic imprint of a transient climate episode: the western Andean flank between 15·5° and 41·5°S

Rehak

Bookhagen

Strecker

et al. 2010

Earth Surf Processes Landf

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Mountain-range topography is determined by the complex interplay between tectonics and climate. However, often it is not clear to what extent climate forces topographic evolution and how past climatic episodes are reflected in relief. The Andes are a tectonically active mountain belt encompassing various climatic zones with pronounced differences in rainfall and glacier extent under similar plate-boundary conditions. In the Central to South-Western Andes climatic zones range from hyperarid desert with mean annual rainfall of 5 mm/a (22.5°S) to year-round humidity with 2500 mm/a (40°S). The Andes thus provide a unique setting for investigating the relationship between climate and topography. We present the analysis of 120 catchments along the western Andean watersheds between 15.5° and 41.5°S, which is based on SRTMV3-90m data and the new medium-resolution rainfall (TRMM) dataset. For each basin, we extracted geometry, relief, and climate parameters to test whether Andean topography shows a climatic imprint and to analyze how climate influences relief. Our data document that elevation and relief decrease with increasing rainfall and descending snowline elevation. Furthermore, we show that local relief reaches high values of 750 m in a zone between 28° to 35°S. During Pleistocene glacial stages this region was affected by the northward shifting southern hemisphere Westerlies, which provided moisture for valley-glacier formation and extended glacial coverage as well as glacial erosion. In contrast, the southern regions between 35° to 40°S receive higher rainfall and have a lower local relief of 200 m, probably related to an increased drainage density. We distinguish two different, climatically-controlled mechanisms shaping topography: (1) fluvial erosion by prolonged channel-hillslope coupling, which smoothes relief, and (2) erosion by valley glaciers that generates relief. Finally, our results suggests that the catchment-scale relief of the Andes between 28° to 35°S is characterized by a pronounced transient component reflecting past climatic conditions.

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“…Geophys. decades (e.g., NORABUENA et al 1998;KENDRICK et al 1999). Several early interpretations modeled GPS observations with a uniformly totally locked shallow plate boundary and a significantly deforming backarc region (e.g., KENDRICK et al 2001;KHAZARADZE and KLOTZ 2003;BROOKS 2003). VIGNY et al (2009) conclude that only 40-45 % of the total convergence rate between the Nazca and South American plates is causing accumulation of elastic deformation in the upper plate.…”

Section: Introductionmentioning

confidence: 99%