Crustal structure of Mesozoic rifting in the northeastern Gulf of Mexico from integration of seismic and potential fields data

Abstract

We have investigated the crustal structure of a 400 km wide zone of thinned continental crust in the northeastern Gulf of Mexico (GOM) using gravity and magnetic modeling along two deeply penetrated seismic transects. Using this approach, we identify two zones of prominent, southward-dipping reflectors associated with 7–10 km thick, dense, and highly magnetic material. Previous workers have interpreted the zones as either coarse clastic redbeds of Mesozoic age that are tilted within half-grabens or seaward-dipping reflectors of magmatic origin. Both seismic reflection lines reveal a 10 km thick and 67 km wide northern zone of high density near the Florida coastline beneath the Apalachicola rift (AR). The southern zone of high density occurs 70 km to the south in the deepwater central GOM along the northern flank of the marginal rift, a 48 km wide, southeast-trending structure of inferred Late Jurassic age that is filled by 3 km of low-density and low-magnetic susceptibility sediments including complexly deformed salt deposits. We propose that these two subparallel rifts and their associated magmatic belts formed in the following sequence: (1) AR formed during Triassic-early Jurassic (210–163 Ma) phase 1 of diffuse continental stretching and was partially infilled on its northern edge by southward-dipping volcanic flows; and (2) the similarly southward-dipping southern magmatic zone formed adjacent to the marginal rift during the early phase 2 of late Jurassic (161–153 Ma) rifting of the GOM continental extension; this southern area of SDR formation immediately preceded the formation of the adjacent oceanic crust that separated the rift-related evaporates into the northern and southern GOM. Our integrated approach combining 2D seismic, gravity, and magnetic data sets results in a more confident delineation of these deep crustal features than from seismic data alone.

New insights into the crustal architecture and tectonic evolution of the Eastern Gulf of Mexico

“…The pre‐rift sequence is identified only in the shelf domain at the northern part of the Florida margin. We distinguish this sequence by high amplitude reflections with consistent original thickness, which are tilted and truncated (Figure 4; see also Pindell et al, 2011; Liu et al, 2019; Izquierdo‐Llavall et al, 2022). This sequence has previously been interpreted as a syn‐rift volcaniclastic sequence (Liu et al, 2019; Menzies et al, 2002), but could also be Appalachian deformed section (Eddy et al, 2014).…”

“…The GUMBO Lines in the Florida margin reveal different crustal types within the transitional domain with interpreted SDRs in Line 3 (Eddy et al, 2014) and attenuated continental crust in Line 4 (Christeson et al, 2014). The crustal and magmatic variability from the northern to southern province of Florida has also been supported by seismic reflection data (Curry et al, 2018;Eddy et al, 2014;Izquierdo-Llavall et al, 2022;Liu et al, 2019;Pindell et al, 2011). In addition, aeromagnetic data analysis suggests the presence of hyperextended continental crust and exhumed mantle along the Florida margin (Curry et al, 2018;Minguez et al, 2020;Pindell et al, 2016).…”

“…The presence of subaerial SDRs within the EGOM has been debated. Seismic reflection and refraction data, potential field data and seismic velocity analysis have been previously used to investigate the presence of SDRs or interbedded igneous and sedimentary sequences at the northern part of the Florida margin and the Yucatan conjugate margin (Christeson et al, 2014;Curry et al, 2018;Filina & Hartford, 2021;Imbert, 2005;Imbert & Philippe, 2005;Izquierdo-Llavall et al, 2022;Liu et al, 2019;Pindell et al, 2011Pindell et al, , 2014Rowan, 2014Rowan, , 2018Steier & Mann, 2019).…”

“…Houston Magnetic Anomaly (HMA), Florida Magnetic Anomaly (FMA) and the Campeche Magnetic Anomaly (CMA; Figure 2b) are major magnetic anomalies that formed in relation to the emplacement of volcanic flows (i.e. seaward dipping reflections—SDRs) in the EGOM (Eddy et al, 2014; Filina & Beutel, 2022; Hall, 1990; Imbert & Philippe, 2005; Kneller & Johnson, 2011; Liu et al, 2019; Mickus et al, 2009; Pindell et al, 2011; Rowan, 2014; Steier & Mann, 2019). Salt deposition also occurred at the end of this phase of continental rifting.…”

Salt morphologies and crustal segmentation relationship: New insights from the Western Mediterranean Sea

“…For the Gulf of Mexico, we compiled salt morphologies from several published seismic profiles (Fig. 11) (Wu et al, 1990;Radovich et al, 2007;Pilcher et al, 2011;Rodriguez, 2011;Fort and Brun, 2012;Hudec and Jackson, 2013a;Ismael, 2014;Pindell et al, 2014;Rowan, 2014;Weimer et al, 2017;Curry et al, 2018;Liu et al, 2019) and from already published salt-distribution maps (Seni, 1992;Diegel et al, 1995;Peel et al, 1995) Concerning the Morocco and Nova Scotia conjugated margins (Fig. 12), the salt structures interpretation originate from works by Hinz et al, (1982); Keen and Potter, (1995);Sahabi, (2004) ;Shimeld, (2004); Neumaier et al, (2016); Tari et al, (2000Tari et al, ( , 2003Tari et al, ( , 2013…”