Thermomechanical Implications of Sediment Transport for the Architecture and Evolution of Continental Rifts and Margins

Abstract

Erosion and deposition redistribute mass as a continental rift evolves, which modifies crustal loads and influences subsequent deformation. Surface processes therefore impact both the architecture and the evolution of passive margins. Here we use coupled numerical models to explore the interactions between the surface, crust, and lithosphere. This interaction is primarily sensitive to the efficiency of the surface processes in transporting mass from source to sink. If transport is efficient, there are two possible outcomes: (1) Faulting within the zone of extension is longer lived and has larger offsets. This implies a reduction of the number of faults and the width of the proximal domain.(2) Efficient transport of sediment leads to significant deposition and hence thermal blanketing. This will induce a switch from brittle to ductile deformation of the upper crust in the distal domains. The feedbacks between these two outcomes depend on the extension history, the underlying lithospheric rheology, and the influence of submarine deposition on sediment transport. High erosion/sedimentation during early faulting leads to abrupt crustal necking, while intermediate syntectonic sedimentation rates over distal deep submarine hotter crust leads to unstructured wide distal domains. In models where rheological conditions favor the formation of asymmetric conjugate margins, only subaerial transport of sediments into the distal domains can increase conjugate symmetry by plastic localization. These models suggest that passive margin architecture can be strongly shaped by the solid Earth structure, sea level, and climatic conditions during breakup. Correspondence to: M. Andrés-Martínez, andresma@uni-bremen.de Citation: Andrés-Martínez, M., Pérez-Gussinyé, M., Armitage, J. J., & Morgan, J. P. (2019). Thermomechanical implications of sediment transport for the architecture and evolution of continental rifts and margins, Tectonics, 38, 641-665.

Morphotectonic Evolution of Passive Margins Undergoing Active Surface Processes: Large‐Scale Experiments Using Numerical Models

“…Our models show symmetric margins similarly to Theunissen and Huismans () but in contrast to models from Brune et al () and Andrés‐Martínez et al (). Huismans and Beaumont () showed that the large‐scale asymmetry observed in numerical models is likely the result of feedback between the dominant rheology (in a layered lithosphere context) and the parameterization of the strain softening.…”

Origin of Serpentinization Patterns Beneath the S‐Reflector Detachment Fault in the Galicia Margin, Offshore Spain

“…A linear relationship has been established between P wave velocities and volume percent serpentine in peridotites (Carlson & Miller, ; Christensen, ; O'Hanley, ). In particular, the correlation at 200 MPa and 200 °C of Christensen () closely approximates the conditions expected along the Galicia crust‐mantle boundary during rifting (Andrés‐Martínez et al, ). This correlation was utilized to convert the mantle velocities (supporting information Text S2) presented in Schuba et al () into a map of mantle serpentinization beneath the S‐reflector detachment fault (Figure ).…”

Assessing the impact of sedimentation on fault spacing at the Andaman Sea spreading center

“…Erosion and sedimentation have been shown to enhance the lifespan of individual normal faults in numerical simulations (Olive et al, 2014;Andrés-Martínez et al, 2019; Theunissen and Huismans, 2019). Olive et al (2014) attributed this effect to surficial mass redistribution alleviating the energy cost of topography buildup.…”

“…Tectonic models commonly predict that erosion and sedimentation enhance strain localization onto a few major faults at subaerial plate boundaries such as orogens (e.g., Masek and Duncan, 1998;Willett, 1999) and continental rifts (Olive et al, 2014;Andrés-Martínez et al, 2019;Theunissen and Huismans, 2019). By contrast, the influence of seafloor-shaping processes on the tectonic makeup of submarine boundaries has received far less attention, possibly because erosion is commonly considered highly inefficient in the deep ocean.…”