Supplemental Material: Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Geochronology, geochemistry, and paleomagnetic datasets. <br>

Supplemental Material: Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Geochronology, geochemistry, and paleomagnetic datasets. <br>

Petrogenesis and tectonic settings of Proterozoic mafic magmatism from the Northern Indian Shield and the Himalaya: possible role for interaction of mantle plume with the sub-continental lithospheric mantle (SCLM)

Northern Indian shield and the western Himalaya have an impressive record of mafic magmatism. The Aravalli Craton preserved 2.3 Ga komatiitic (picritic) and 2.1 Ga to 1.8 Ga tholeiities. Gwalior and Betul belts preserved 2.1 Ga and 1.5 Ga to 1.2 Ga tholeiites, respectively. Western Himalaya has preserved 2.1 Ga to 1.8 Ga tholeiites in Garhwal and Himachal regions. Studied rocks depict enriched REE, LILE and depleted HFSE. Whereas, komatiites/picrites represent higher degrees of partial melting (∼35-40%) at higher temperatures (∼1500° C), tholeiites represent lower degrees of partial melting (∼10%) at lower temperatures (∼1200° C). Our results indicate interaction of mantle plume with variably enriched SCLM sources, causing generation of these varied magmatic suites of rocks. Whereas, the higher temperature komatiitic/picritic melts from the Aravalli region appear to have been generated closer to the plume head, the lower temperature tholeiitic melts from the shield region and western Himalaya were generated towards the plume margins. Different terrains of the study have undergone plume tectonics causing development of the rift valleys, majority of these developed into aulacogens, except for the Aravalli basin, which developed into deeper marine facies.

Discussion on “From Pan-African transpression to Cadomian transtension at the West African margin: New U-Pb zircon ages from the Eastern Saghro Inlier (Anti-Atlas, Morocco)” by Errami et al. 2020 (GSL-SP 503, 209-233)

Recent U-Pb igneous ages obtained in the SW Domain of the Anti-Atlas are not consistent with the model proposed in the recently published paper by Errami et al. (2020). The formations of the Taghdoute and Lkest groups in the SW Domain, also known as the “limestones and quartzites” series, were previously considered to have a Cryogenian age due to similarities with the series of limestone and quartzite of the Tachddamt Bleida Formation in the Bou-Azzer Inlier located in the NE Domain of the Anti-Atlas. However, recent U-Pb ages on zircon and baddeleyite of 1.71-1.65 Ga obtained on intrusive sills and dykes in the Taghdoute and Lkest groups, constrain this sedimentary series of the SW Domain to be approximately 1 Ga older than previously thought. Absence of Paleoproterozoic series in the NE Domain combined with the available age constraints suggests that it has a Pan-African age. However, recent 1.71-1.65 Ga ages of mafic magmatism in the SW Domain conflict with the previously inferred Tonian to Cryogenian age for the mixed carbonate-siliciclastic series of the Taghdoute and Lkest groups and raises uncertainty about the age of tectonic events previously attributed to the Pan-African Orogeny in this part of the Anti-Atlas. Furthermore, the age difference between the NE and SW domains of the Anti-Atlas suggests their independent geodynamic evolution before the Ediacaran Period.