Joint modeling receiver functions and autocorrelograms to estimate crustal structure in the presence of deep sediments.

P receiver functions use large, distant earthquakes to image local structure. They record the interactions of teleseismic P waves with impedance contrasts, such as the Moho and sediment-basement interface, which generate conversions of P type to S type energy. Typically, receiver functions are used to determine contrast depth and the ratio of P velocity to S velocity (Vp/Vs). We refine receiver function methodologies for application to sedimentary basins, which is useful because basin structure introduces complexity to the receiver functions. First, we consider vertical autocorrelograms along with P receiver functions. The same interfaces that generate Ps conversions also reflect P reverberations after direct P arrivals. This better constrains structure and enables P velocity (Vp) determination. Second, we use waveform matching to consider the full complexity recorded on the receiver functions and autocorrelograms. Waveform modeling takes significant computational power, so non-linear global optimization methods are used to efficiently navigate the parameter space. Our first study applies this method to the Permian Basin. We matched the expected basin structure with our modeling, with basin depths of up to 8 km and an average basin Vp of 4.6 km/s. We observed high Vp/Vs values, an indicator of mafic materials, in crystalline crust previously interpreted as mafic igneous intrusions based on gravity data. Our second study focuses on a profile across the south-central United States. This profile moves from the North American Craton in northern Arkansas to a passive margin at the Gulf Coast, crossing several accreted terranes and sedimentary basins. We observe the crust thinning from north to south from ~47 km to ~26 km, with the Ouachita Mountains marking boundary in average crystalline crustal Vp values, potentially indicating compositional differences. Our third study models crustal structure in the Bengal Basin. This >20 km deep sedimentary basin lies between the Indian shield and Indo-Burma Ranges. We observe the basin deepening from north to south, with two apparent low-velocity zones likely linked to fluids trapped in deep sediments. The crystalline crust thickness ranges from 14-25 km and has an average Vp of 6.9 km/s, which we interpret as extended crust.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Doctoral

Grantor

Baylor University.

Year dc:date.issued

2024

Author dc:creator

• Sadler, Benjamin O., 1995-

Advisor dc:contributor.advisor

• Pulliam, Jay.

• Seismology.
• Receiver functions.
• Autocorrelograms.
• Sedimentary basins.
• Crustal modeling.

Statement dc:rights

• Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2104/13190

OAI identifier oai:identifier

oai:baylor-ir.tdl.org:2104/13190