Earthquakes to mountains: Fault behavior of the San Andreas fault and active tectonics of the Chinese Tian Shan.

摘要

This dissertation examines how tectonic processes are accommodated in Earth's crust, starting with a detailed study of the individual effects of earthquakes and progressing to the structure, rates, and kinematics of actively growing mountains.; Although research since the famous 1906 earthquake has advanced understanding of the behavior of the San Andreas fault, the frequency and recurrence patterns of earthquakes are poorly known due to the brevity of the historic record. To lengthen the record, I present paleoseismic evidence for 14 earthquakes that occurred between ∼3300 and 1500 BC on the southern San Andreas fault near Wrightwood, California. A detailed discussion of the quality of earthquake indicators is a significant contribution of this work. Different chemical, physical, and biological fractions of peat dated by carbon-14 analysis result in broad layer ages, which are used to calculate the earthquake ages. The broad distributions are refined with Bayesian statistics to systematically reduce uncertainty in the layer ages, earthquake ages, and recurrence intervals. The average recurrence interval is 130 +/- 20 years; the shortest and longest intervals are 60 and 190 years, respectively.; The southernmost expression of the collision between the Tarim basin and the Chinese Tian Shan consists of sub-parallel folds that expose late Cenozoic basin strata. From seven structural transects through four anticlines, I interpret that the folds accommodate ∼1 to 7 km of shortening by detachment folding. Initiation of folding is indicated by a regional transition from conformable basin strata to growth strata deposited on the flanks of growing anticlines. A paleomagnetic study constrains the age of the strata, from which I calculate an average of ∼5 mm/yr of shortening occurred since ∼1.2 Ma. To explore the kinematics of fold growth, I model deformation of fluvial terrace flights undergoing different mechanisms of detachment fold growth, such as limb rotation and hinge migration. The models predict that limb rotation progressively rotates the terraces whereas hinge migration creates self-similar geometries. A synoptic evolution, combining the model predictions, terrace deformation, and regional structural studies suggests that limb rotation accommodated most of the shortening.; This dissertation includes both my previously published and my co-authored materials.