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- Title
High‐Resolution Ps Receiver Function Imaging of the Crust and Mantle Lithosphere Beneath Southern New England and Tectonic Implications.
- Authors
Luo, Yantao; Long, Maureen D.; Karabinos, Paul; Kuiper, Yvette D.; Rondenay, Stéphane; Aragon, John C.; Sawade, Lucas; Makus, Peter
- Abstract
Southern New England exhibits diverse geologic features resulting from past tectonic events. These include Proterozoic and early Paleozoic Laurentian units in the west, several Gondwana‐derived terranes that accreted during the Paleozoic in the east, and the Mesozoic Hartford Basin in the central part of the region. The Seismic Experiment for Imaging Structure beneath Connecticut (SEISConn) project involved the deployment of a dense array of 15 broadband seismometers across northern Connecticut to investigate the architecture of lithospheric structures beneath this region and interpret how they were created and modified by past tectonic events in the context of surface geology. We carried out P‐to‐S receiver function analysis on SEISConn data, including both single‐station analysis and common conversion point (CCP) stacking. Our images show that the westernmost part of Connecticut has a much deeper Moho than central and eastern Connecticut. The lateral transition is a well‐defined, ∼15 km step‐like offset of the Moho over a ∼20 km horizontal distance. The Moho step appears near the surface boundary between the Laurentian margin and the Gondwana‐derived Moretown terrane. Possible models for its formation include Ordovician underthrusting of Laurentia and/or modification by younger tectonic events. Other prominent features include a strong positive velocity gradient (PVG) beneath the Hartford basin corresponding to the bottom of the sedimentary units, several west‐dipping PVGs in the crust and mantle lithosphere that may correspond to relict slabs or shear zones from past subduction episodes, and a negative velocity gradient (NVG) that may correspond to the base of the lithosphere. Plain Language Summary: The eastern margin of North America has a complicated tectonic history. It has been shaped by past episodes of landmasses coming together to form a supercontinent, with later breakup of the supercontinent to form a new ocean basin. This supercontinent cycle involves fundamental plate tectonic processes including subduction, the accretion of geologic microcontinents, the formation of mountain ranges, and rifting during the breakup of continents. These processes have led to the complex geology of southern New England that is visible at the surface, and they have also likely modified the deep structures of the crust and upper mantle. In this study, we analyzed data from seismometers deployed across northern Connecticut to investigate underground interfaces separating layers with different properties. We measured seismic waves from distant earthquakes and looked for evidence of specific wave behavior at these interfaces. We found that the interface separating the crust and the mantle, known as the Moho, is not continuous beneath this region. The Moho is much deeper in the west of our study area than in the east, and the transition from thick to thin crust corresponds to a key geologic boundary. We also identified several other interfaces, providing information on past tectonic events. Key Points: We conducted Ps receiver function analysis on a dense seismic array across northern Connecticut to investigate lithospheric structuresWe observe a step‐like change in Moho depth near the boundary between Laurentia and the Gondwana‐derived Moretown terraneSeveral seismic discontinuities within the lithosphere have implications for the complicated tectonic history of southern New England
- Subjects
NEW England; PLATE tectonics; SEISMIC arrays; P-waves (Seismology); SHEAR waves; EARTH'S mantle; LITHOSPHERE; LAURENTIA (Continent)
- Publication
Journal of Geophysical Research. Solid Earth, 2021, Vol 126, Issue 7, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2021JB022170