Age Determinations from Andean Peru: A Reconnaissance Survey

Stewart, John W.; Evernden, Jack F.; Snelling, N. J.

doi:10.1130/0016-7606(1974)85<1107:adfapa>2.0.co;2

Cited by 86 publications

(36 citation statements)

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“…Mineral K-Ar ages give a progressively younger ages from southwest to northeast in general (Stewart et al, 1974). The Cordillera Blanca Batholith rocks have very young apparent ages of 12-3 Ma (Stewart et al, 1974).…”

Section: Geological Outlinementioning

confidence: 97%

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Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic‐Cenozoic Batholiths in Peru

Ishihara

Hashimoto²,

Machida³

2000

Resource Geology

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: Plutonic rocks of the Coastal Batholith of Peru were evaluated in terms of the granitoid‐series classification using the bulk ferric/ferrous ratio from the literature and new measurements of magnetic susceptibility. The batholith is largely composed of magnetite‐series plutonic rocks; the magnetite series make up 85% by number of chemical analyses (n=130) and 80% by measurement of magnetic susceptibility (n=210). The ilmenite‐series rocks are mostly found in the felsic facies of the batholith. Asymmetrical distribution of magnetic susceptibility is not clear as in the Japanese Islands and Peninsular Range Batholith, but the magnetic susceptibility may decreases continentward (i. e., Peninsular Range type). The Cordillera Blanca Batholith and stocks are also composed of mainly magnetite series plutonic rocks, but ilmenite‐series rocks may be more predominant than in the Coastal Batholith, which is also indicated by the presence of Sn and W mineralizations.

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Section: Geological Outlinementioning

confidence: 97%

“…The Cordillera Blanca Batholith rocks have very young apparent ages of 12-3 Ma (Stewart et al, 1974). Sr and Nd isotopic ratios are 87/86 Sr 0 = 0.70437 ~ 0.704926, εNd = +0.16 ~ -0.21 for quartz diorite and tonalite, and 87/86 Sr 0 = 0.705248 ~ 0.705710 and εNd = -0.53 ~-2.45 for leucogranodiorite .…”

Section: Geological Outlinementioning

confidence: 99%

Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic‐Cenozoic Batholiths in Peru

Ishihara

Hashimoto²,

Machida³

2000

Resource Geology

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“…4B). In this area 363 the batholith is young ~4.5 Ma (Stewart et al, 1974;Giovanni, 2007); this NE-SW extension 364 exists at least since the Cordillera Blanca batholith emplacement and is consistent with the 365 initiation of the Callejón de Huaylas subsidence at ~5.4 Ma associated to the CBNF activity 366 (Bonnot, 1984;Giovanni, 2007). 367…”

Section: Phases 357mentioning

confidence: 99%

Stress field evolution above the Peruvian flat-slab (Cordillera Blanca, northern Peru)

Margirier

Audin

Robert

et al. 2017

Journal of South American Earth Sciences

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8In subduction settings, the tectonic regime of the overriding plate is closely related to the 9 geometry of the subducting plate. Flat-slab segments are supposed to increase coupling at the 10 plate interface in the Andes, resulting in an increase and eastward migration of the shortening 11 in the overriding plate. Above the Peruvian flat-slab, a 200 km-long normal fault trend 12 parallel to the range and delimits the western flank of the Cordillera Blanca. In a context of 13 flat subduction, expected to produce shortening, the presence of the Cordillera Blanca normal 14 fault (CBNF) is surprising. We performed a systematic inversion of striated fault planes in the 15 Cordillera Blanca region to better characterize the stress field above the Peruvian flat-slab. It 16 evidences the succession of different tectonic regimes. NE-SW extension is predominant in 17 most of the sites indicating a regional extension. We suggest that the Peruvian flat-slab trigger 18 extension in the Western Cordillera while the shortening migrated eastward. Finally, we 19propose that flat-slab segments do not increase the coupling at the trench neither the 20 shortening in the overriding plate but only favor shortening migration backward. However, 21 the stress field of the overriding plate arises from the evolution of plate interface properties 22 through time due to bathymetric anomaly migration. 23 24 Key-works 25Inversion of striated fault planes; crustal stress field; mountain building; Peruvian flat-slab; 26 Cordillera Blanca 27 28

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“…Although they determined the ages of only seven samples by themselves, they also identified a relatively intense volcanic activity in the southern Peru area about 12Ma ago together with that of about 40-5OMa ago on the basis of compiled data of the radiometric ages. STEWART et al (1974) reported more than 60 K-Ar ages on the Andean rocks from Peru, which ranged from 27 to 679Ma, but those rocks were mostly plutonic and metamorphic rocks. On the other hand, BAKER (1977) pointed out a possible migration of volcanic activities in the central Andes from west to east.…”

Section: Introductionmentioning

confidence: 99%

K-Ar age determinations of late Tertiary and Quaternary Andean volcanic rocks, southern Peru.

Kaneoka

Guevara

1984

Geochem. J.

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Age Determinations from Andean Peru: A Reconnaissance Survey

Cited by 86 publications

References 0 publications

Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic‐Cenozoic Batholiths in Peru

Magnetite/Ilmenite–series Classification and Magnetic Susceptibility of the Mesozoic‐Cenozoic Batholiths in Peru

Stress field evolution above the Peruvian flat-slab (Cordillera Blanca, northern Peru)

K-Ar age determinations of late Tertiary and Quaternary Andean volcanic rocks, southern Peru.

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