IMAGING CRUSTAL STRUCTURE BENEATH TEXAS FROM RECEIVER FUNCTIONS

The shallow crust in Texas has been intensively investigated through seismic exploration for hydrocarbon resources. However, the deep crustal structure of Texas is not well understood. This thesis aims to illuminate crustal structure beneath Texas using P receiver functions at 66 stations of the Transportable Array. Individual receiver functions were calculated and stacked by station using both common conversion point (CCP) and H-κ stacking methods to image the Moho depth variation. Results from the two methods show similarities in the central and southern part of the Ouachita belt. The Moho depth along the Ouachita belt is generally among 35-40 km, and the deepest Moho appears in the Llano uplift area with a thickness approaching 45 km, while it is thinning towards the southern end of the Ouachita belt to about 35 km. In addition, the Vp/Vs ratios calculated using the H-κ method are high (above 1.9) for a couple of stations near the southeastern side of the Ouachita belt, which may correspond to the volcanic material beneath the southern margin of Laurentia and thus imply the ancient rifting activity. However, the Moho structure beneath the Gulf coast plain was not well resolved due to interference between the primary Moho conversion and the multiples from the base of the sedimentary layer. Nevertheless, a Ps phase with delay time varying from 0.5 to 4 s was identified at several stations near the coastline, which appears to be the Ps conversion from the interface between sediments and crystalline basement.