Andean uplift and erosion surfaces near Uncia, Bolivia

Walker, Eugene H.

doi:10.2475/ajs.247.9.646

Cited by 14 publications

(6 citation statements)

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“…Numerous investigations, including both local studies (McLaughlin, 1924;Walker, 1949;Mortimer and Saric, 1975;McKee and Noble, 1982;Megard, 1984;Tosdal et al, 1984;Swanson et al, 1987;Soler and Bonhomme, 1988;Lavenu et al, 1989;Ellison, 1990;Noble et al, 1990;Wasteneys, 1990;Cheilletz et al, 1992;Soler and Jiménez, 1993) and regional syn theses (Mégard, 1987;Sébrier et al, 1988;Sébrier and Soler, 1991), have identified several widespread orogenic episodes in the Cenozoic stratigraphic record of the Central Andes. In this context, it should be noted that whereas the Cordillera Occidental, and particularly its arid or hyperarid Pacific slopes, is dominated by extensive but abruptly generated erosion sur faces, the Tertiary geomorphologic features of the Cordillera Oriental are more complex.…”

Section: Interrelationships Of Magmatismmentioning

confidence: 96%

An Integrated Tectono-Magmatic Model for the Evolution of the Southern Peruvian Andes (13-20°S) since 55 Ma

Sandeman

Clark

Farrar

1995

International Geology Review

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The definition and characterization of the Oligocene-Miocene Crucero Supergroup of the southern Peru Inner Arc domain provide a previously unavailable lithostratigraphic framework for the clarification of the geodynamic context of magmatism across the southern Peruvian transect. We integrate new lithostratigraphic, petrologic, and 40 Ar/ 39 Ar geochronologic data for these volcanic and hypabyssal rocks with published information to establish a geotectonic model for the transect since 55 Ma.The early Eocene to Early Miocene tectono-magmatic history of the region was controlled by the evolution of a flat-subduction regime, which was initiated at ~52 Ma with the onset of rapid convergence, terminating the magmatic and hydrothermal activity of the Toquepala superunit of the Coastal Batholith. Collision of the flat slab with the leading edge of the Brazilian Shield lithospheric mantle at 39-40 Ma resulted in catastrophic failure of the overriding plate and crustal-scale, NE-directed ramping, generating the "Incaic" Zongo-San Gaban tectonothermal zone in the proto-Cordillera Oriental. Failure of the flat slab (~37 Ma), its progressive foundering into the asthenosphere (from ~37 to 20 Ma), and the upwelling of asthenosphere in its wake are inferred to have generated an eastward-migrating thermal anomaly that severely weakened the lower crust. This resulted in the resumption of Main Arc magmatism in the protoCordillera Occidental (~32 Ma) in an axial regime of transtension, followed at 29 Ma by quasiinstantaneous broadening of the arc to a width of ~200 km. Further continentward arc expansion into the Inner Arc at ~25 Ma, generating the mixed crust-and mantle-derived suites of the Picotani Group, resulted in a 360-km-wide swath of magmatism. Termination of magmatism in the Inner Arc at ~22 Ma reflected the waning stages of anomalous mantle flow associated with foundering of the slab, and was accompanied by substantial uplift and crustal thickening.The subsequent evolution of the transect was initiated and prompted by the broad zone of thermally weakened lower crust. Ductile shortening of the lower crust from ~22 to 17 Ma generated widespread crustal thickening and uplift across the orogen, and was accompanied by the antithetic oceanward subduction of Brazilian Shield lithosphere beneath the Inner Arc and the initiation of thrusting and folding along the Sub-Andean zone. Delamination and, probably, detachment of the Brazilian Shield from its lithospheric mantle root, as well as partial melting of this root, yielded enriched mafic melts that ascended into the orogenic crust and contributed both thermally and through the release of volatiles to the generation of the Quenamari Group.We emphasize the spatial association of the Crucero Supergroup and comparable suites of the Bolivian Cordillera Oriental with the Bolivian Orocline, and delimit a ~250-km amagmatic longitudinal zone separating the sites of anatexis in southern Peru and northern Bolivia. This is inferred to represent the zone of maximum orthogonal convergence thro...

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Section: Interrelationships Of Magmatismmentioning

confidence: 96%

An Integrated Tectono-Magmatic Model for the Evolution of the Southern Peruvian Andes (13-20°S) since 55 Ma

Sandeman

Clark

Farrar

1995

International Geology Review

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“…† P-province: C-Cordillera, undifferentiated; E-Eastern Cordillera; W-Western Cordillera. §Ref = References: 1- Kennan et al (1995), ; 2- Sillitoe and McKee (1996);3-Masek et al (1994);4-Curry et al (1995);5-McLaughlin (1924), Walker (1949), Petersen (1958), Sébrier et al (1988); age from Gubbels et al (1993) and Kennan et al (1997). close to sea level and remained near sea level until 18 Ma, when the surface in this region was buried by ignimbrite sheets. However, we do not know the original slope of the surface.…”

Section: Estimates Based On Landscape Development Historymentioning

confidence: 99%

Uplift history of the Central and Northern Andes: A review

Gregory‐Wodzicki¹

2000

Geological Society of America Bulletin

979

405

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The elevation of the Andean Cordillera is a crucial boundary condition for both climatic and tectonic studies. The Andes affect climate because they form the only barrier to atmospheric circulation in the Southern Hemisphere, and they intrigue geologists because they have the highest plateau on Earth formed at a noncollisional plate margin, the Altiplano-Puna. Yet, until recently, few quantitative studies of their uplift history existed. This study presents both (1) a review of the quantitative paleoelevation estimates that have been made for the Central and Colombian Andes and (2) an examination of the source and magnitude of error for each estimate. In the Central Andes, paleobotanical evidence suggests that the Altiplano-Puna had attained no more than a third of its modern elevation of 3700 m by 20 Ma and no more than half its modern elevation by 10.7 Ma. These data imply surface uplift on the order of 2300-3400 m since the late Miocene at uplift rates of 0.2-0.3 mm/yr. Paleobotanical and geomorphological data suggest a similar uplift history for the Eastern Cordillera-namely no more than half the modern elevation present by 10 Ma. No evidence exists for an exponential increase in uplift rate, as has been interpreted from fissiontrack data. These uplift rates mostly reflect mean surface uplift rather than rock uplift-that is, uplift of material points-because little dissection of the western Eastern Cordillera has occurred south of lat 19°S and of the Altiplano-Puna. Thus, the Central Andean Plateau appears to be young. In the Colombian Andes, paleobotanical data imply rapid uplift of the Eastern Cordillera between 2 and 5 Ma at rates on the order of 0.6-3 mm/yr. However, some of this uplift is likely rock uplift due to erosion-driven isostatic rebound rather than mean surface uplift.

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“…This later surface is pre-Pliocene because it is covered by ignimbrites of the San Bartolo Fm (Formacidn Liparitica) which have been dated as spanning the whole of Pliocene time (Rutland, Guest & Grasty 1965). The pre-San Pedro surface is probably equivalent to the Bolivian Puna surface while the post-San Pedro surface is probably equivalent to the Bolivian Valle surface of Walker (1949)• Near Uncia (67°:18.5 °) in Bolivia, the main Puna surface occurs at 4400 m and the Valle surface at 4100 m (Walker 1949). The Puna surface itself is not a summit surface, being largely undissected and surmounted by central volcanoes of late Cenozoic age.…”

Section: Surface Shape Of T H E Segment In E L E V a T I O Nmentioning

confidence: 98%

Andes: Antofagasta Segment (20°–25°S.)

Rutland

1974

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Andean uplift and erosion surfaces near Uncia, Bolivia

Cited by 14 publications

References 0 publications

An Integrated Tectono-Magmatic Model for the Evolution of the Southern Peruvian Andes (13-20°S) since 55 Ma

An Integrated Tectono-Magmatic Model for the Evolution of the Southern Peruvian Andes (13-20°S) since 55 Ma

Uplift history of the Central and Northern Andes: A review

Andes: Antofagasta Segment (20°–25°S.)

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