Supercontinental inheritance and its influence on supercontinental breakup: The Central Atlantic Magmatic Province and the breakup of Pangea

Abstract

The Central Atlantic Magmatic Province (CAMP) is the large igneous province (LIP) that coincides with the breakup of the supercontinent Pangea. Major and trace element data, Sr-Nd-Pb radiogenic isotopes, and high-precision olivine chemistry were collected on primitive CAMP dikes from Virginia (VA). These new samples were used in conjunction with a global CAMP data set to elucidate different mechanisms for supercontinent breakup and LIP formation. On the Eastern North American Margin, CAMP flows are found primarily in rift basins that can be divided into northern or southern groups based on differences in tectonic evolution, rifting history, and supercontinental inheritance. Geochemical signatures of CAMP suggest an upper mantle source modified by subduction processes. We propose that the greater number of accretionary events, or metasomatism by sediment melts as opposed to fluids on the northern versus the southern Laurentian margin during the formation of Pangea led to different subduction-related signatures in the mantle source of the northern versus southern CAMP lavas. CAMP samples have elevated Ni and low Ca in olivine phenocrysts indicating a significant pyroxenite component in the source, interpreted here as a result of subduction metasomatism. Different collisional styles during the Alleghanian orogeny in the North and South may have led to the diachroneity of the rifting of Pangea. Furthermore, due to a low angle of subduction, the Rheic Plate may have underplated the lithosphere then delaminated, triggering both the breakup of Pangea and the formation of CAMP.

Synthesizing Seemingly Contradictory Seismic and Magnetotelluric Observations in the Southeastern United States to Image Physical Properties of the Lithosphere

“…During this time, at 200 Ma, the Central Atlantic Magmatic Province (CAMP; Figure 2) erupted across the Atlantic rift zone; voluminous lava flows and dike swarms that comprise this large igneous province are found along the passive margins of all Atlantic-bounded continents (e.g., McHone, 2000). Geochemical evidence from the SEUS indicates, at least in this region, that CAMP erupted in association with orogenic collapse and slab foundering and that constituent magmas were formed from a subductionmodified mantle (Whalen et al, 2015). Following the formation of CAMP and the waning of rift-flank tectonism in the Jurassic, the SEUS became a passive margin.…”

3-D Potential Field Inversion of Camp Clubhouse Crossroads Mafic Intrusive Pluton, Coastal Plain, South Carolina

“…1) just before Pangea broke up. CAMP spans four continents and covers an estimated area of 7-10 ×10⁶ km² (Marzoli et al, 1999;McHone, 2000 (Whalen et al, 2015). CAMP Rocks are found in buried rift basins, including the South Georgia Rift (SGR)…”

“…Early Mesozoic rift-basin formation along the eastern margin of North America typically involved igneous activity emplaced as diabase dikes, sills, and basalt flows in sedimentary groups (Olsen, 1997). Rifting and the depositional history of Mesozoic rift basins after Olsen (1997) in Whalen et al (2015) proposes that synrift CAMP flows are absent from the southern rift basins, but age constraints for basin fill rely on biostratigraphy, paleomagnetic data, and Milankovitch cyclicity and are poorly constrained (Olsen, 1997). It has long been assumed that the largest of the CAMP flows was preserved in the South Georgia Rift as the prominent "J" reflector at the base of the Atlantic coastal plain (Figure 1.3).…”

New 40Ar–39Ar dating of Lower Cretaceous basalts at the southern front of the Central High Atlas, Morocco: insights on late Mesozoic tectonics, sedimentation and magmatism

“…Atlantic Ocean basin (e.g., Marzoli et al 1999Marzoli et al , 2004Hames et al 2000;McHone 2003;Knight et al 2004;Verati et al 2007;Frizon de Lamotte et al 2008;Callegaro et al 2014;Whalen et al 2015).…”