The structure and tectonics of the Guyana Basin

Abstract

The Guyana Basin formed during the Jurassic opening of the North Atlantic. The basin margins vary in tectonic origin and include the passive extensional volcanic margin of the Demerara Plateau in Suriname, an oblique extensional margin inboard at the Guyana-Suriname border, a transform margin parallel to the shelf in NW Guyana, and an ocean-ocean margin to the northeast which morphed from transform to oblique extension. Plate reconstructions suggest rifting and early seafloor spreading began with NNW/SSE extension (∼190-160Ma) but relative plate motion later changed to NW/SE. The fraction of magmatic basin floor decreases westwards and the transition from continental to oceanic crust narrows from 200km in Suriname to less than 50km in Guyana. The geometry and position of the onshore Takutu Graben suggest it formed a failed arm of a Jurassic triple junction that likely captured the Berbice river during post-rift subsidence and funneled sediment into the Guyana Basin. Berriasian to Aptian shortening caused crustal scale folds and thrusts in the NE margin of the basin along with minor inversions of basin margin and basin segmenting faults. Stratigraphically trapped Liza trend hydrocarbon discoveries are located outboard of inverted basement faults, suggesting a link between transform margin structure and their formation.

Inverted Magma-rich Versus Magma-poor Rifted Margins: Implications for Early Orogenic Systems

“…Note that shortening in the Demerara Plateau took place simultaneously with the onset of the Caribbean mature subduction in the north. The orientation of the DMT (Figure 2) is the same as the regional Jurassic transform that occurred due to the NNW-SSE kinematic event (Trude et al, 2023). Based on this, we propose that the DMT resulted from a reactivated Jurassic transform structure, leading to a forced incipient and failed mature subduction.…”

“…Crustal-scale shortening offshore the Demerara Plateau has been reported by Museur et al (2021); Loparev et al (2021);Trude et al (2023), among others. This event occurred in late Lower Cretaceous, and it was suggested to result from the anticlockwise rotation of Africa with respect to South America (Trude et al, 2023). This compressional event is recorded and shown in Figure 2b and 2c where well-preserved and mildly shortening features are observed, involving former distal magmarich rifted domains (including SDRs and the Jurassic OCT, see details in Gómez-Romeu et al, 2022).…”

“…The Demerara Plateau is characterized by a western Jurassic magma-rich rifted segment, formed during the opening of the Central Atlantic Ocean, and a northern transform margin juxtaposing Jurassic Central Atlantic with Cretaceous Equatorial Atlantic oceanic crusts (Figure 1) (Gouyet et al, 1994;Greenroyd et al, 2007;Basile et al, 2013;Nemčok et al, 2016;Mercier de Lépinay et al, 2016;Loncke et al, 2022;Loparev et al, 2021). Crustal-scale shortening offshore the Demerara Plateau has been reported by Museur et al (2021); Loparev et al (2021);Trude et al (2023), among others. This event occurred in late Lower Cretaceous, and it was suggested to result from the anticlockwise rotation of Africa with respect to South America (Trude et al, 2023).…”

“…Shortening in the Demerara Plateau (DMT) occurred due to a change of plate kinematics, characterized by the anticlockwise rotation of Africa in respect to South America (Trude et al, 2023). Note that shortening in the Demerara Plateau took place simultaneously with the onset of the Caribbean mature subduction in the north.…”

Seismic Identification and Hydrocarbon Accumulation Characteristics of Submarine Fan in offshore Suriname

“…The exploration Wells in the shallow sea area have good oil and gas shows, which has a certain exploration potential. The Demerara plateau is caused by the African Plate counterclockwise rotation and rifting away from South America, dividing the basin into the Central Atlantic passive margin to the west and the Equatorial Atlantic Transform margin to the east [6][7][8][9][10][11][12][13][14] . the African Plate counterclockwise rotation to South America is recorded by smaller compressional structures, resulting in up to 50 km of NE-SW shortening and 6 km of erosion.…”