26 Jan 2023
 | 26 Jan 2023
Status: this preprint is open for discussion.

Thrusts control the thermal maturity of accreted sediments

Utsav Mannu, David Fernández-Blanco, Ayumu Miyakawa, Taras Gerya, and Masataka Kinoshita

Abstract. Thermal maturity assessments of hydrocarbon-generation potential and thermal history rarely consider how upper-plate structures developing during subduction influence the trajectories of accreted sediments. Our thermomechanical models of subduction support that thrusts evolving under variable sedimentation rates and décollement strengths fundamentally influence the trajectory, temperature, and thermal maturity of accreting sediments. This is notably true for the frontal thrust, which pervasively partitions sediments along a low and a high maturity path. Our findings imply that interpretations of the distribution of thermal maturity cannot be detached from accounts of the length and frequency of thrusts and their controlling factors. Taking these factors into consideration, our approach provides a robust uncertainty estimate in maximum exposure temperatures as a function of vitrinite reflectance and burial depth thereby reducing former inconsistencies between predicted and factual thermal maturity distributions in accretionary wedges.

Utsav Mannu et al.

Status: open (until 22 Apr 2023)

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  • RC1: 'Comment on egusphere-2023-30', Jonas B. Ruh, 10 Feb 2023 reply

Utsav Mannu et al.

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Utsav Mannu et al.


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Short summary
Accretion during subduction, in which one tectonic plate moves under another, forms a wedge where sediments can be transformed into hydrocarbons. We utilised realistic computer models to investigate this, in particular, how accretion affects mobility in the wedge and found that the evolution of the wedge, and the thrusts it develops fundamentally control the thermal maturity of sediments. This can help us better understand the history of subduction and the formation of hydrocarbons in wedges.