Influence of Pre-rift Orogenic Activity on the Syn-rift and Post-rift Development of Eastern North America: Insight into the Early Development of the Gulf of Mexico

Abstract

Eastern North America (ENAM) is a natural laboratory for studying the development of passive margins. It hosts one of the world’s largest rift systems (the eastern North American rift system), one of the world’s oldest intact passive margins, and one of the world’s largest igneous provinces (the Central Atlantic Magmatic Province, CAMP). Additionally, it shares much of its early tectonic history with its southern continuation, the passive margin of the Gulf of Mexico, both having undergone intense Paleozoic orogenic activity followed by Mesozoic rifting and breakup. To better understand the early development of both margins, we have analyzed and synthesized geologic and geophysical data from the onshore Newark rift basin and adjacent onshore and offshore basins of the Mid-Atlantic region, USA. Our work indicates that rifting had three distinct phases: (1) An initial, prolonged main rifting phase (Late Triassic, ~230 to 201.5 Ma) with relatively slow rates of extension and subsidence. The rift basins in the study area widened significantly through time with widths locally exceeding 100 km, and the basins likely became interconnected. (2) A short-lived late rifting phase (latest Triassic to earliest Jurassic, 201.5 to ~ 198 Ma) with more rapid rates of extension and subsidence. During this phase, magmatic activity affected the basins with CAMP-related dikes, sills, and sheets intruding the basin fill and the surrounding basement rocks. CAMP-related basalt flows episodically filled the basins. The border-fault systems remained active and, for the first time, major intrabasin faults developed, linking with the border-fault systems. (3) A final rifting phase (early Early Jurassic) with declining rates of extension and subsidence. The border-fault system and intrabasin faults remained active, but little deposition occurred in their hanging walls, signaling a transition from regional subsidence and deposition to regional uplift and erosion.

AAPG Datapages/Search and Discovery Article #90369 © 2020 AAPG Hedberg Conference, Geology and Hydrocarbon Potential of the Circum-Gulf of Mexico Pre-salt Section, Mexico City, Mexico, February 4-6, 2020