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Byline: Staff Writers Matsuyama, Japan (SPX) Dec 11, 2019, 2019 Hydrogen is the most abundant element in the universe and it plays important roles in the structure, dynamics, and evolution [...]

Byline: Staff Writers Potsdam, Germany (SPX) Jun 15, 2018, 2018 In the seabed, there are numerous microorganisms that play an important role in the global carbon cycle. Up to now, [...]

Byline: Staff Writers Fort Collins CO (SPX) Jan 19, 2018, 2018 Everything on the surface of the Earth rests on massive tectonic plates that resemble a jelly sandwich, with two [...]

Byline: Staff Writers Mainz, Germany (SPX) Dec 18, 2015, 2015 One of the big mysteries in the history of the Earth is the emergence of plate tectonics. When exactly did [...]

The Paleoproterozoic post-kinematic Ubendian mafic rocks from northeastern Katanga (Democratic Republic of Congo) are olivine-and-quartz tholeiites which in many respects resemble Phanerozoic continental tholeiites. The analogies are suggested by the petrographic features and the major element diagrams classically used to infer magmatic affinity. The clinopyroxene compositions straddle the boundary between clinopyroxenes from orogenic and extensional tectonic settings. In addition, the whole-rock compositions are mostly Ti- and P-poor as in low Ti–P continental flood basalts and in subduction-related mafic magmas. The same conclusion is sustained by the trace-element compositions (e.g., occurrence of mafic magmas with high Th/Ta and La/Ta values; low Sr/Ce ratios, etc). These geochemical features indicate involvement of a subduction component at the source of these extensional igneous rocks. Convective mixing of asthenospheric mantle with the overlying lithospheric mantle enriched during the Ubendian subduction or mixing of melts from both mantle components can account for the composition of the post-orogenic Ubendian mafic rocks. [ABSTRACT FROM AUTHOR]