Abstract
AbstractWe modeled crustal and lithospheric thickness variation as well as the variations in temperature, composition, S wave seismic velocity, and density of the lithosphere beneath the Saharan Metacraton (SMC) applying an interdisciplinary 3‐D modeling. Regardless of the limited data set, we aimed at consistent imaging of the SMC lithospheric structure by combining independent data sets to better understand the evolution of the metacraton. We considered that the SMC was once an intact Archean‐Paleoproterozoic craton but was metacratonized during the Neoproterozoic due to partial loss of its subcontinental lithospheric mantle (SCLM) during collisional processes along its margin. This has permitted the preservation of three cratonic remnants (Murzuq, Al‐Kufrah, and Chad) within the metacraton. These cratonic remnants are overlain by Paleozoic‐Mesozoic sedimentary basins (Murzuq, Al‐Kufrah, and Chad), which are separated by topographic swells associated with the Hoggar Swell, Tibesti Massif, and Darfur Dome Cenozoic volcanism. The three cratonic remnants are underlain by a relatively thicker lithosphere compared to the surrounding SMC, with the thickest located beneath Al‐Kufrah reaching 200 km. Also, the SCLM beneath Al‐Kufrah cratonic remnant is significantly colder and denser. Modeling of the lithosphere beneath the Chad and Murzuq Basins yielded a complex density and temperature distribution pattern, with lower values than beneath the Tibesti Massif. Further, our modeling indicated a uniform and moderately depleted mantle composition beneath the SMC. The presence of a relatively thinner lithosphere beneath the noncratonic regions of the SMC is attributed with several tectonic events, including partial SCLM delamination during the Neoproterozoic, Mesozoic‐Cenozoic rifting, and Cenozoic volcanism.
Highlights
Cratons are parts of Earth's continental lithosphere that have not been affected by major tectonic or magmatic events for a long time, possibly since the time of their formation (Black & Liégeois, 1993; Griffin et al, 2009)
We modeled crustal and lithospheric thickness variation as well as the variations in temperature, composition, S wave seismic velocity, and density of the lithosphere beneath the Saharan Metacraton (SMC) applying an interdisciplinary 3‐D modeling
We considered that the SMC was once an intact Archean‐Paleoproterozoic craton but was metacratonized during the Neoproterozoic due to partial loss of its subcontinental lithospheric mantle (SCLM) during collisional processes along its margin
Summary
Cratons are parts of Earth's continental lithosphere that have not been affected by major tectonic or magmatic events for a long time, possibly since the time of their formation (Black & Liégeois, 1993; Griffin et al, 2009). There are several examples of regions that may have experienced decratonization including the North China craton (e.g., Kusky et al, 2007a, 2007b, 2014; Santosh, 2010; Zhai & Santosh, 2011; Zhang et al, 2011, 2014; Zhao & Zhai, 2013), the Wyoming craton (Dave & Li, 2016; Föster et al, 2006; Kusky et al, 2014), the Southwest Kaapvaal craton (Eriksson et al, 2009; Kobussen et al, 2008), and the West Amazon craton (Kusky et al, 2014) This process has been proposed for the Saharan Metacraton (SMC) (Abdelsalam et al, 2002). Liégeois et al (2013) suggested that the metacratonization processes could occur either at the craton's boundaries or within the craton's interior during lithospheric plate collisions or development of lithospheric‐scale shear zones
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