TY - JOUR
T1 - Andean topographic growth and basement uplift in southern Colombia
T2 - Implications for the evolution of the Magdalena, Orinoco, and Amazon river systems
AU - Anderson, Veronica J.
AU - Horton, Brian K.
AU - Saylor, Joel E.
AU - Mora, Andrés
AU - Tesón, Eliseo
AU - Breecker, Daniel O.
AU - Ketcham, Richard A.
N1 - Publisher Copyright:
© 2016 Geological Society of America.
PY - 2016
Y1 - 2016
N2 - Surface uplift of the Garzón Massif in the northern Andes formed a critical orographic barrier (2500-3000 m elevation) that generated a deep rain shadow and strongly influenced the evolution of the largest river systems draining northern South America. This basement massif and its corresponding foreland basement high define the headwaters and drainage divides of the Amazon, Orinoco, and Magdalena Rivers. Despite its pivotal role, the exhumation history of the Garzón Massif and its relationships to the structural evolution of the broader Eastern Cordillera fold-thrust belt remain unclear. The northern Andes underwent major Cenozoic shortening, with considerable thin-skinned and thick-skinned deformation and topographic development in the Eastern Cordillera focused during late Miocene time. On the basis of widespread coarse-grained nonmarine sedimentation, previous studies have inferred that uplift of the Garzón Massif began during the late Miocene, coincident with rapid elevation gain elsewhere in the Eastern Cordillera. We take an integrated, multiproxy approach to better reconstruct Andean topographic growth and distinguish between exhumation and surface uplift of the Garzón Massif. We present new U-Pb detrital zircon provenance data, sandstone petrographic data, and paleoprecipitation data from upper Miocene clastic fill of the Neiva Basin within the adjacent Upper Magdalena Valley of the modern hinterland. In addition, six new apatite fission track (AFT) ages from the central segment of the northeast-trending Garzón Massif (Jurassic granite and Proterozoic gneiss and schist) directly constrain its Neogene exhumation history. The results indicate that early exhumation may have initiated by ca. 12.5 Ma, but a substantial orographic barrier was not fully established until ca. 6-3 Ma, when > 1 km/m.y. of material was exhumed. Thermal history modeling of the AFT data suggests diminished exhumation thereafter (3-0 Ma), during latest Cenozoic oblique Nazca-South America convergence. This exhumation history is consistent with paleontological data suggesting late Miocene divergence of the three river systems, with associated transcontinental drainage of the Amazon River.
AB - Surface uplift of the Garzón Massif in the northern Andes formed a critical orographic barrier (2500-3000 m elevation) that generated a deep rain shadow and strongly influenced the evolution of the largest river systems draining northern South America. This basement massif and its corresponding foreland basement high define the headwaters and drainage divides of the Amazon, Orinoco, and Magdalena Rivers. Despite its pivotal role, the exhumation history of the Garzón Massif and its relationships to the structural evolution of the broader Eastern Cordillera fold-thrust belt remain unclear. The northern Andes underwent major Cenozoic shortening, with considerable thin-skinned and thick-skinned deformation and topographic development in the Eastern Cordillera focused during late Miocene time. On the basis of widespread coarse-grained nonmarine sedimentation, previous studies have inferred that uplift of the Garzón Massif began during the late Miocene, coincident with rapid elevation gain elsewhere in the Eastern Cordillera. We take an integrated, multiproxy approach to better reconstruct Andean topographic growth and distinguish between exhumation and surface uplift of the Garzón Massif. We present new U-Pb detrital zircon provenance data, sandstone petrographic data, and paleoprecipitation data from upper Miocene clastic fill of the Neiva Basin within the adjacent Upper Magdalena Valley of the modern hinterland. In addition, six new apatite fission track (AFT) ages from the central segment of the northeast-trending Garzón Massif (Jurassic granite and Proterozoic gneiss and schist) directly constrain its Neogene exhumation history. The results indicate that early exhumation may have initiated by ca. 12.5 Ma, but a substantial orographic barrier was not fully established until ca. 6-3 Ma, when > 1 km/m.y. of material was exhumed. Thermal history modeling of the AFT data suggests diminished exhumation thereafter (3-0 Ma), during latest Cenozoic oblique Nazca-South America convergence. This exhumation history is consistent with paleontological data suggesting late Miocene divergence of the three river systems, with associated transcontinental drainage of the Amazon River.
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U2 - 10.1130/GES01294.1
DO - 10.1130/GES01294.1
M3 - Article
AN - SCOPUS:84982677494
SN - 1553-040X
VL - 12
SP - 1235
EP - 1256
JO - Geosphere
JF - Geosphere
IS - 4
ER -