Title
Cenozoic forearc basin sediments in Southern Peru (15-18°S): Stratigraphic and heavy mineral constraints for Eocene to Miocene evolution of the Central Andes
Date Issued
15 May 2011
Access level
metadata only access
Resource Type
journal article
Author(s)
Decou A.
von Eynatten H.
Mamani M.
Wörner G.
Université de Toulouse
Abstract
A large sedimentary forearc basin developed in Cenozoic times between the present-day Coastal Cordillera and the Western Cordillera of the Central Andes, called Moquegua basin in southern Peru. The basin is filled by Moquegua Group deposits (~. 50 to 4. Ma) comprising mostly siliciclastic mudstones, sandstones and conglomerates as well as volcanic intercalations. Several facies changes both, along orogenic strike and through time, are described and have led to subdivision into four sedimentary units (Moquegua A, B, C and D). In this paper we present a refined stratigraphic scheme of the Moquegua Group combined with the first provenance analysis of the Moquegua basin based on (i) semi-quantitative analysis of heavy mineral abundance, (ii) electron microprobe (EMP) and laser ablation (LA) ICP-MS analyses of single detrital amphibole and Fe-Ti oxide grains, and (iii) comparative analysis of the different potential source rocks to clearly identify the most likely sources. Results allow us to reconstruct sediment provenance and to relate changes of the erosion-sedimentation system in the Moquegua basin to the evolution of the Andean orogen. At ~. 50 to ~. 40. Ma the Moquegua basin was close to sea level and fed by low energy rivers transporting mainly metamorphic basement and Jurassic-Cretaceous sedimentary detritus from local and distal sources. The latter might be as far as the present Eastern Cordillera. From ~. 35. Ma on the distal sediment sources were cut off by the uplift of the Altiplano and Eastern Cordillera leading to higher energy fluvial systems and increasing importance of local sources, especially the relevant volcanic arcs. From 25. Ma on volcanic arc rocks became the predominant sources for Moquegua Group sediments. The 10. Ma time lag observed between the onset of uplift-induced facies and provenance changes (at ~. 35. Ma) and the onset of intense magmatic activity (at ~. 25. Ma) suggests that magmatic addition was not the main driver for crustal thickening and uplift in the Central Andes during latest Eocene to Oligocene time. © 2011 Elsevier B.V.
Start page
55
End page
72
Volume
237
Issue
February 1
Language
English
OCDE Knowledge area
Geología
Scopus EID
2-s2.0-79953163760
Source
Sedimentary Geology
ISSN of the container
00370738
Sponsor(s)
We thank Andreas Kronz, Klaus Simon and Ulla Grunewald for providing analytical support respectively using the EMS, LA-ICPMS and heavy mineral separation laboratories in Göttingen. We also thank István Dunkl for his technical support, fruitful discussions and insights. Thorough reviews by Heinrich Bahlburg and an anonymous reviewer are gratefully acknowledged, as well as careful editorial handing by Gert-Jan Weltje. The German Science Foundation (DFG) funded this project through grant EY 23/14 to HvE and Wo 362/39 to GW.
Sources of information: Directorio de Producción Científica Scopus