Crustal Composition and Moho Variations of the Central and Eastern United States: Improving Resolution and Geologic Interpretation of EarthScope USArray Seismic Images Using Gravity

H. L. Zhang, D. Ravat, A. R. Lowry

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

EarthScope's USArray Transportable Array has shortcomings for the purpose of interpreting geologic features of wavelengths less than the Transportable Array station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce nonuniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously derived density variations of sedimentary basins, crustal Vp/Vs variation, Moho variation, and upper mantle density variation derived from body wave imaging informed by surface wave tomography to estimate Vp/Vs. Although average densities and density contrasts for these seismic variations can be derived, the gravity anomalies modeled from them do not explain the entire observed gravity anomaly field in the United States. We use the unmodeled gravity anomalies (residuals) to reconstruct local variations in densities of the crust associated with geologic sources. The approach uses velocity-density relationships and differs from density computations that assume isostatic compensation. These intracrustal densities identify geologic sources not sampled by and, in some cases, aliased by the USArray station spacing. We show an example of this improvement in the vicinity of the Bloomfield Pluton, north of the bootheel of Missouri, in the central United States.

Original languageEnglish
Article numbere2019JB018537
JournalJournal of Geophysical Research: Solid Earth
Volume125
Issue number3
DOIs
StatePublished - Mar 1 2020

Bibliographical note

Funding Information:
The crustal density data set generated for this research is publicly available at Zhang et al. ( ). Continental U.S. Bouguer gravity data used in the study were downloaded from the Pan‐American Center for Earth and Environmental Studies (PACES). The seismic refraction data set used in the study was provided by Dr. Walter Mooney, and the sedimentary thickness data set used for comparison purposes was provided by Dr. Mikhail Kaban. Dr. Ellett of Indiana Geological Survey provided the Illinois basin sedimentary thickness data, and Dr. Hickman of Kentucky Geological Survey provided the Rome Trough sedimentary thickness data. We also benefitted from the CRUST1.0 model of Laske et al. and the Bouguer gravity data from “Bureau Gravimétrique International (BGI, http://bgi.obs‐mip.fr ).” We thank William J. Hinze and one anonymous reviewer for their assistance in reviewing this manuscript. This work was motivated and supported by the U.S. National Science Foundation Awards 1246921 and 1246977 to D. R. and A. R. L. It was also financially supported in part by the National Nature Science Foundation of China (41604121), and the Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology (MGQNLM201708).

Funding Information:
The crustal density data set generated for this research is publicly available at Zhang et al. (). Continental U.S. Bouguer gravity data used in the study were downloaded from the Pan-American Center for Earth and Environmental Studies (PACES). The seismic refraction data set used in the study was provided by Dr. Walter Mooney, and the sedimentary thickness data set used for comparison purposes was provided by Dr. Mikhail Kaban. Dr. Ellett of Indiana Geological Survey provided the Illinois basin sedimentary thickness data, and Dr. Hickman of Kentucky Geological Survey provided the Rome Trough sedimentary thickness data. We also benefitted from the CRUST1.0 model of Laske et al. and the Bouguer gravity data from “Bureau Gravimétrique International (BGI, http://bgi.obs-mip.fr).” We thank William J. Hinze and one anonymous reviewer for their assistance in reviewing this manuscript. This work was motivated and supported by the U.S. National Science Foundation Awards 1246921 and 1246977 to D. R. and A. R. L. It was also financially supported in part by the National Nature Science Foundation of China (41604121), and the Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology (MGQNLM201708).

Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.

Keywords

  • EarthScope USArray
  • crustal composition
  • crustal density
  • gravity
  • velocity-density relationship

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)

Fingerprint

Dive into the research topics of 'Crustal Composition and Moho Variations of the Central and Eastern United States: Improving Resolution and Geologic Interpretation of EarthScope USArray Seismic Images Using Gravity'. Together they form a unique fingerprint.

Cite this