TY  - JOUR
A1  - León, Santiago
A1  - Cardona, Agustín
A1  - Mejia Velez, Dany
A1  - Botello, G. E.
A1  - Villa, Víctor
A1  - Collo, Gilda
A1  - Valencia, Victor A.
A1  - Zapata, Sebastian Henao
A1  - Avellaneda-Jimenez, D. S.
T1  - Source area evolution and thermal record of an Early Cretaceous back-arc basin along the northwesternmost Colombian Andes
JF  - Journal of South American earth sciences
N2  - Identifying the provenance signature and geodynamic setting on which sedimentary basins at convergent margins grow is challenging since they result from coupled erosional and tectonic processes, which shape the evolution of source areas and the stress regime. The Early Cretaceous evolution of the northern Andes of Colombia is characterized by extensional tectonics and the subsequent formation of a marginal basin. The Abejorral Formation and coeval volcano-sedimentary rocks are exposed along the western flank and axis of the Central Cordillera. They comprise an Early Cretaceous transgressive sequence initially accumulated in fluvial deltaic environments, which switched towards a deep-marine setting, and are interpreted as the infilling record of a marginal back-arc basin. Available provenance data suggest that Permian-Triassic metamorphic and less abundant Jurassic magmatic rocks forming the basement of the Central Cordillera sourced the Abejorral Formation. New detailed volcanic and metamorphic lithics analyses, conventional and varietal study of heavy minerals, detrital rutile mineral chemistry, allowed us to document changes in the source areas defined by the progressive appearance of both higher-grade and more distal low-grade metamorphic sources, which switched from pelitic to dominantly mafic in composition. Crystallochemical indexes of clay minerals of fine-grained rocks of the Abejorral Formation suggest that samples located close to the Romeral Fault System show characteristics of low-medium P-T low-grade metamorphism, whereas rocks located farther to the northeast preserve primary diagenetic features, which suggest a high heat-flow accumulation setting. We interpret that the Abejorral Formation records the progressive unroofing of the Central Cordillera basement that was being rapidly exhumed, as well as the incorporation of distal subduction-related metamorphic complexes to the west in response either to the widening of extensional front or the reactivation of fault structures on the oceanward margin of the basin. Although the deformational record of the Abejorral Formation would have resulted from over-imposed episodes, our new geochronological constraints suggest that this sedimentary sequence must have been deformed before the Paleocene due to the presence of arc-related intrusive non-deformed magmatic rocks with a crystallization age of ca. 60 Ma.
KW  - Back-arc basin
KW  - Northern Andes
KW  - Early cretaceous
KW  - Provenance
KW  - Clay mineralogy
KW  - Rutile mineral chemistry
Y1  - 2019
U6  - https://doi.org/10.1016/j.jsames.2019.102229
SN  - 0895-9811
VL  - 94
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Leon, Santiago
A1  - Cardona, Agustin
A1  - Parra, Mauricio
A1  - Sobel, Edward
A1  - Jaramillo, Juan S.
A1  - Glodny, Johannes
A1  - Valencia, Victor A.
A1  - Chew, David
A1  - Montes, Camilo
A1  - Posada, Gustavo
A1  - Monsalve, Gaspar
A1  - Pardo-Trujillo, Andres
T1  - Transition from collisional to subduction-related regimes
BT  - an example from neogene Panama-Nazca-South america interactions
JF  - Tectonics
N2  - A geological transect across the suture separating northwestern South America from the Panama Arc helps document the provenance and thermal history of both crustal domains and the suture zone. During middle Miocene, strata were being accumulated over the suture zone between the Panama Arc and the continental margin. Integrated provenance analyses of those middle Miocene strata show the presence of mixed sources that includes material derived from the two major crustal domains: the old northwestern South American orogens and the younger Panama Arc. Coeval moderately rapid exhumation of Upper Cretaceous to Paleogene sediments forming the reference continental margin is suggested from our inverse thermal modeling. Strata within the suture zone are intruded by similar to 12 Ma magmatic arc-related plutons, marking the transition from a collisional orogen to a subduction-related one. Renewed late Miocene to Pliocene acceleration of the exhumation rates is the consequence of a second tectonic pulse, which is likely to be triggered by the onset of a flat-slab subduction of the Nazca plate underneath the northernmost Andes of Colombia, suggesting that late Miocene to Pliocene orogeny in the Northern Andes is controlled by at least two different tectonic mechanisms.
Y1  - 2017
U6  - https://doi.org/10.1002/2017TC004785
SN  - 0278-7407
SN  - 1944-9194
VL  - 37
IS  - 1
SP  - 119
EP  - 139
PB  - American Geophysical Union
CY  - Washington
ER  -