TY - JOUR

T1 - Oligocene Deformation of the Chuandian Terrane in the SE Margin of the Tibetan Plateau Related to the Extrusion of Indochina

AU - Li, S.

AU - Su, T.

AU - Spicer, R.A.

AU - Xu, C.

AU - Sherlock, S.

AU - Halton, A.

AU - Hoke, G.

AU - Tian, Y.

AU - Zhang, S.

AU - Zhou, Z.

AU - Deng, C.

AU - Zhu, R.

PY - 2020/7/1

Y1 - 2020/7/1

N2 - Mechanisms driving the tectonic evolution of the southeast (SE) margin of Tibet include the Paleogene extrusion of the coherent Indochina lithospheric block and the continuous deformation caused by lower crustal flow since the middle Miocene. The timing and style of regional deformations are keys to determining the role of each mechanism. Fault-bounded and fault-controlled Cenozoic basins within the SE margin of Tibet record regional deformation, surface uplift, and variations in paleoclimate but often are poorly dated. New magnetostratigraphy and 40Ar/39Ar dating of volcanic ashes constrain precisely the timing of sedimentation within the Lühe Basin to between ~35 and 26.5 Ma. The basin is located in the Chuandian terrane along the Chuxiong fault, which lies ~70 km north of, and parallel to, the Ailao Shan-Red River fault. The asymmetric syncline of the Lühe Basin suggests syncontractional sedimentation, and the basal age of the basin represents the initiation of the Chuxiong fault and crustal shortening at ~35 Ma. This is coincident with the onset of the Ailao Shan-Red River fault and supports a kinematic link between them. Our study suggests that, like the Ailao Shan-Red River fault, the Chuxiong fault is a Paleogene transpressional structure that developed during the extrusion and clockwise rotation of Indochina around the Eastern Himalayan Syntaxis, which caused the late Paleogene deformation and surface uplift of the Chuandian terrane and Indochina. Our revised chronostratigraphy of the Lühe Basin provides further evidence that many of the “Neogene” sedimentary basins in the SE margin of Tibet may be much older than previously thought.

AB - Mechanisms driving the tectonic evolution of the southeast (SE) margin of Tibet include the Paleogene extrusion of the coherent Indochina lithospheric block and the continuous deformation caused by lower crustal flow since the middle Miocene. The timing and style of regional deformations are keys to determining the role of each mechanism. Fault-bounded and fault-controlled Cenozoic basins within the SE margin of Tibet record regional deformation, surface uplift, and variations in paleoclimate but often are poorly dated. New magnetostratigraphy and 40Ar/39Ar dating of volcanic ashes constrain precisely the timing of sedimentation within the Lühe Basin to between ~35 and 26.5 Ma. The basin is located in the Chuandian terrane along the Chuxiong fault, which lies ~70 km north of, and parallel to, the Ailao Shan-Red River fault. The asymmetric syncline of the Lühe Basin suggests syncontractional sedimentation, and the basal age of the basin represents the initiation of the Chuxiong fault and crustal shortening at ~35 Ma. This is coincident with the onset of the Ailao Shan-Red River fault and supports a kinematic link between them. Our study suggests that, like the Ailao Shan-Red River fault, the Chuxiong fault is a Paleogene transpressional structure that developed during the extrusion and clockwise rotation of Indochina around the Eastern Himalayan Syntaxis, which caused the late Paleogene deformation and surface uplift of the Chuandian terrane and Indochina. Our revised chronostratigraphy of the Lühe Basin provides further evidence that many of the “Neogene” sedimentary basins in the SE margin of Tibet may be much older than previously thought.

KW - Ailao Shan-Red River fault

KW - crustal shortening

KW - extrusion and rotation

KW - magnetostratigraphy

KW - SE margin of the Tibetan Plateau

KW - surface uplift

KW - Extrusion

KW - Rivers

KW - Volcanoes

KW - Chronostratigraphy

KW - Clockwise rotation

KW - Continuous deformations

KW - Crustal shortening

KW - Lower crustal flows

KW - Magnetostratigraphy

KW - Regional deformations

KW - Tectonic evolution

KW - Deformation

KW - deformation

KW - Oligocene

KW - sedimentary basin

KW - tectonic evolution

KW - tectonic rotation

KW - terrane

KW - transpression

KW - uplift

KW - China

KW - Chuandian

KW - Indochina

KW - Qinghai-Xizang Plateau

KW - Xizang

U2 - 10.1029/2019TC005974

DO - 10.1029/2019TC005974

M3 - Journal article

VL - 39

JO - Tectonics

JF - Tectonics

SN - 0278-7407

IS - 7

M1 - e2019TC005974

ER -