Abstract
AbstractWe have analyzed and synthesized geologic and geophysical data from the onshore Newark rift basin and adjacent onshore and offshore basins to better understand the Mesozoic development of the eastern North American rift system and passive margin. Our work indicates that rifting had three phases: (1) an initial, prolonged phase of extension and subsidence; (2) a short-lived phase with higher rates of extension and subsidence, intrabasin faulting, and intense magmatism; and (3) a final phase with limited subsidence and deposition. Additionally, our work shows that anomalous uplift and erosion, associated with crustal-scale arching/warping subparallel to the prerift and syn-rift crustal fabric not the continent-ocean boundary, affected a region landward of the basement hinge zone. Uplift and erosion began during the final rifting phase and continued into early drifting with erosion locally exceeding 6 km. Subsequent subsidence was minimal. We propose that denudation unloading related to relic, prerift orogenic crustal thickness and elevated topography triggered the anomalous uplift and erosion. After the Paleozoic orogenies, postorogenic denudation unloading (cyclic erosion and isostatic rebound/uplift) significantly thinned the thickened crust and reduced topographic elevation. During rifting, extension stretched and tectonically thinned the crust, promoting widespread subsidence and deposition that dampened the postorogenic cycle of erosion and isostatic rebound/uplift. During the rift-drift transition, with extension focused near the breakup site, denudation unloading resumed landward of the basement hinge zone, producing significant erosion and uplift (related to isostatic rebound), crustal thinning, and topographic decay that left behind only eroded remnants of the once massive rift basins.
Highlights
The classic model of passive-margin development (e.g., [1]) has two distinct stages
Researchers have proposed a variety of mechanisms to explain the development of a breakup/postrift unconformity, including contributions from depth-dependent stretching with excess thinning of the lithospheric mantle near the site of breakup (e.g., [5]), lateral conductive heat transfer from the site of breakup (e.g., [6]), a dynamic response to secondary small-scale convection triggered by rifting and breakup (e.g., [7, 8]), deep lithospheric necking during rifting and breakup (e.g., [9]), magmatic underplating during rifting and breakup (e.g., [10, 11]), flexural uplift caused by mechanical unloading during rifting and breakup [12], peripheral bulging that accompanied offshore postrift subsidence and deposition [13], phase transitions associated with density reductions within the lithospheric mantle during rifting and breakup
To further understand the characteristics and causes of uplift on the eastern North America (ENAM) margin, as well as other passive margins, we have analyzed and synthesized geologic and geophysical data from the onshore Newark rift basin, the adjacent onshore and offshore rift basins, and the northern end of the postrift Baltimore Canyon trough (Figures 1–5) As discussed below, our work shows that a distinctive style of uplift and erosion affected the study area landward of the basement hinge zone
Summary
The classic model of passive-margin development (e.g., [1]) has two distinct stages. During the initial rifting stage, regional extension thins the continental lithosphere, producing subsiding rift basins. Depth-dependent stretching or delamination and/or dripping would produce a more transient phase of uplift and erosion surrounding the site of breakup followed by significant subsidence, whereas deep lithospheric necking, flexural uplift caused by mechanical unloading, or peripheral bulging would produce a prolonged phase of erosion near the basement hinge zone flanking the site of breakup. The uplift and erosion were associated with broad, crustal-scale arching/warping, extending well landward of the basement hinge zone and subparallel to the prerift and syn-rift crustal fabric, not the continent-ocean boundary. We propose that denudation unloading associated with relic crustal thickening and elevated topography created during prerift Paleozoic orogenic activity contributed to the late syn-rift and early postrift uplift and erosion observed landward of the basement hinge zone
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
