Integrating Seismic Data With Regional Geology and Aeromagnetic Data to Deduce Basin Evolution: Gulf of Mexico Case Example

Abstract

Abstract

We integrate onshore and offshore seismic reflection and refraction data, Atlantic relative motions, pre-Mesozoic terrane restorations (Chortis, Andes), Gulf of Mexico (GoM) aeromagnetic map interpretation, paleomagnetic data, and onshore field studies in Mexico into a working model for the GoM's Mesozoic evolution. The aeromagnetic map shows the central GoM rotational seafloor spreading fabric and approximate limit of ocean crust (LOC), corroborated and refined by new seismic data. Spreading occurred about two distinct stage poles of rotation. The paleo-ridge system seen in satellite gravity pertains only to the later pole. Geometrical aspects of the magnetic pattern and western GoM transform are related to spreading history. Ocean closure provides an Early Oxfordian post-rift reconstruction that realigns LOCs; abuts Louann and Campeche autochthonous salts and post-rift, planar sub-salt unconformities; places Chiapas Massif along Tamaulipas Arch, south of the Burgos marginal offset; and provides a template for assessing syn-rift history and salt deposition mechanisms. Continent-ocean transitions (COTs) adjacent to the LOCs denote magma poor breakup. Local magmatism occurs in the NW Florida, NW Yucatán, and NE Yucatán margins, interpreted as synrift rather than breakup magmatism. Marginal offset segments of the western Campeche COT show 2.5 km relief from base salt to top ocean crust, indicating that the syn-rift/sag section kept the GoM filled near sea level prior to salt deposition. Planar base salt unconformities tilt basinward from updip salt onlap limits to the COTs, where they are deeper than the adjacent oceanic crust. The COTs form a trough between continental and ocean crust, and are filled with slumped salt and early overlying sediment that are in turn onlapped by earliest oceanic abyssal plain strata. The slumped section over salt likely comprises initially shallow marine facies (<300m, Oxford) that deepen upward rapidly into Kimmeridgian-Tithonian source rock. The early slumping, the tilting of the planar base salt unconformity into the COTs (outer marginal troughs), and the rapid upward deepening above foundered section record the outer marginal collapse. Base salt unconformities are faulted in the COTs only; the faults appear to enter the syn-rift/sag sections above exhumed mantle and not continental crust, and thus probably do not affect margin subsidence suggesting that outer marginal collapse is a critical aspect of basin analysis.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016