首页|The transition from backarc extension to Andean growth:Insights from geochronologic,sedimentologic,and structural studies of Mesozoic and Cenozoic sedimentary and volcanic rocks in south-central Chile(36°S)

The transition from backarc extension to Andean growth:Insights from geochronologic,sedimentologic,and structural studies of Mesozoic and Cenozoic sedimentary and volcanic rocks in south-central Chile(36°S)

扫码查看
原文链接
  • NETL
  • NSTL
  • 万方数据
Many studies propose a significant shift in the tectonic and paleogeographic evolution of the Andes in south-central Chile and Argentina during the Late Cretaceous.It has been proposed that the preceding Jurassic-Early Cretaceous extensional regime that resulted in a low-relief volcanic arc and the backarc Neuquén basin came to an end,giving way to shortening and Andean growth from the Late Cretaceous onward.Nevertheless,there are disagreements regarding the timing and nature of this transition to Andean orogenesis.To address these issues,we conducted geochronologic(U-Pb and 40Ar/39Ar),sedi-mentologic,and structural studies on Mesozoic-Cenozoic sedimentary and volcanic rocks in the Río Maule area(Principal Cordillera,Chile,36°S).From our findings and prior analyses,we propose the fol-lowing tectono-stratigraphic evolution of the region.(1)Marine deposition of the Tithonian-Hauterivian Banos del Flaco Formation took place in an extensional backarc basin.(2)After a～40 Myr hiatus,fluvial deposits of the Colimapu Formation and volcanic rocks of the Plan de los Yeuques Formation accumulated during the Cenomanian-Danian.Whereas the Colimapu Formation displays evi-dence of syndepositional shortening,the Plan de los Yeuques Formation exhibits synextensional growth strata.Contrary to other studies,our results suggest that the Chilean part of the Principal Cordillera was largely a zone of active deposition rather than an elevated fold-thrust belt during the Late Cretaceous.We propose that sedimentation occurred within a series of relatively stable intermontane subbasins gener-ated by shortening,followed by extension.(3)After a～20 Myr hiatus,middle Eocene to early Miocene(Lutetian-Aquitanian)accumulation of a thick succession of andesitic lavas and minor clastic sediments of the Abanico Formation occurred in an intraarc extensional basin.(4)Finally,major shorten-ing and uplift of previously deposited Mesozoic-Cenozoic rocks took place throughout the Neogene.This phase constituted the primary contractional deformation in the Andes of south-central Chile and Argentina.In terms of the transition to early Andean deformation,we propose that structural deforma-tion did not generate a major,regional-scale fold-thrust belt during the late Albian-Santonian.Modest extension,tectonic quiescence,or low-magnitude shortening seem to have dominated during the early to middle Cenozoic.

AndesSouth-central ChileBackarc basinForeland basinFold-thrust belt

Alfonso Encinas、Nicolás Henríquez、Daniel Castro、Darío Orts、Diego Kietzmann、Franco Iovino、Paulo Vásquez、Andrés Folguera、Victor Valencia、Facundo Fuentes

展开 >

Departamento de Ciencias de la Tierra,Facultad de Ciencias Químicas,Universidad de Concepción,Víctor Lamas 1290,Concepción 4030000,Chile

Universidad Nacional de Río Negro.Instituto de Investigación en Paleobiología y Geología.General Roca,Río Negro,Argentina

Instituto de Investigación en Paleobiología y Geología(IIPG).CONICET.Av.J.A.Roca 1242,8332 General Roca,Río Negro,Argentina

Universidad de Buenos Aires,Facultad de Ciencias Exactas y Naturales,Departamento de Ciencias Geológicas,Ciudad Universitaria,Pabellón Ⅱ,Intendente Güiraldes 2160,C1428EHA Ciudad Autónoma de Buenos Aires,Argentina

CONICET-Universidad de Buenos Aires,Instituto de Geociencias Básicas,Ambientales y Aplicadas de Buenos Aires(IGeBA),Ciudad Universitaria,Pabellón Ⅱ,Intendente Güiraldes 2160,C1428EHA Ciudad Autónoma de Buenos Aires,Argentina

Instituto de Estudios Andinos"Don Pablo Groeber"(IDEAN),CONICET-Universidad de Buenos Aires,Buenos Aires,Argentina

Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires,Buenos Aires,Argentina

Washington State University,School of the Environment,Pullman,USA

Yacimientos Petrolíferos Fiscales(YPF)S.A.,Buenos Aires,Argentina

展开 >

ANID,Fondecyt Regular projectsANID,Fondecyt Regular projectsANID,National Doctoral Scholarship

11511461200428

2024

10.1016/j.gsf.2024.101824

地学前缘(英文版)
中国地质大学（北京） 北京大学

地学前缘(英文版)

CSTPCD
影响因子：0.576
ISSN：1674-9871
年,卷(期)：2024.15(5)