Cenozoic burial and exhumation history of the eastern Los Angeles Basin, California, from low-temperature thermochronology

The eastern Los Angeles basin, California, is bound to the northeast by the San Jose Hills and the Puente Hills, and to the south by the San Joaquin Hills. These positive inversion structures formed in response to middle to late Miocene (∼ 8 Ma) contractual deformation. Low-temperature thermochronology was used to reconstruct the thermal history of the eastern Los Angeles basin and to assess magnitudes and timing of burial and exhumation of these structures. Throughout the eastern Los Angeles basin, exhumation of these anticlines was limited to 1--3 km. The greatest amount of exhumation is documented in the Puente Hills where greater than 2 km of sediments was removed from the hanging wall of the Whittier Fault in the last 8 Ma. Average exhumation rates for the Puente Hills range between 0.6 and 1.1 mm/yr. In the San Jose Hills, exhumation along the Buzzard Peak Anticline is limited to 2 km or less. In the San Joaquin Hills no more than 2 km of exhumation is documented in the last 8 Ma due to contractional deformation with exhumation rates between 0.12 to 0.26 mm/yr. Overall, the cooling events documented by low-temperature thermochronology in these anticlines are related to the transpressional phase of the evolving Los Angeles basin.