![]() ![]() The first three episodes marks the end of Rodinia amalgamation metamorphic cycle. These ages coincide with several magmatic-metamorphic events at Cape Meredith Complex, Dronning Maud Land, Natal Belt, among others. It was followed by a t3 event ofcrustal delamination at 1006 ± 13 Ma. A continent-continent collision caused the t2 event at 1032 ± 12 Ma. Arc-Continent metamorphism, t1,is interpreted as coincidingthe minimum sin-tectonic granitoid age of ≥ 1068 ± 28 Ma. MEBC protolith rocks mostly consisted of arkosean psammites. Neoproterozoic low-temperature resetting in Biotite K-Ar system (t4). metamorphic climax reaching granulitic facies (t3). long-lasting high-temperature, high-pressure metamorphic condition (t2). rapid burial in a high pressure, low temperature (t1). Four episodes of recrystallization and/or progressive deformation were identified, mainly related with two metamorphic cycles. Thereby defining their tectonic, recrystallization/deformation time path and comparing with the main units from Natal-Maud orogeny. ![]() This works aims to study, define, and interpret the former, Maurice Ewing Bank Complex (MEBC), using petrology and geochemistry. ![]() That is the case, for example, of two yet unknown remnants of continental crust - Maurice Ewing Bank, and Agulhas Plateau and their relation with the Stenian-Tonian Natal-Maud orogeny. The evolution of Rodinia still have several geological questions that remain incognito. The correlation of the geotectonic environment and coeval magmatic-metamorphic events indicates that the MEBC comprises the roots of an orogenic hinterland of the Natal-Maurice-Maud belt during Rodinia-forming orogenies caused by the interaction of Kaapvaal and Patagonia cratons. Late retrograde metamorphic events, demonstrated by Rb-Sr and K-Ar isotopes, were generated by far-field thermal anomalies of Neoproterozoic-Palaeozoic tectonic events such as the Pan-African orogeny and Gondwanides. Episode four (R4) was marked by a regional anatectic process linked to crustal delamination at 1006 ± 13 Ma. The third episode (R3) involved granulite-facies metamorphism (P = 0.7-0.9 GPa, T = 830-930☌) during tectonic exhumation that led to generation of syn-to late metagranitoids at 1032 ± 12 Ma. The R2 episode (P = 1.05 GPa, T = 800☌) coincided with an older syn-deformational metagranitoid age of 1068 ± 28 Ma. The first two episodes (R1-R2) occurred under conditions of progressive amphibolite-and granulite-facies metamorphism related to an orogenic hinterland. The MEBC is a polyphase metamorphic terrane with four progressive tectono-metamorphic events in subduction-related rocks. Petrological and geochemical studies were conducted to unravel the metamorphic history of the Maurice Ewing Bank Complex (MEBC). The Mesoproterozoic crust of remnant terranes such as Maurice Ewing Bank can provide crucial clues about Rodinia supercontinent. The open error boxes are discordant analyses which were not included in the age calculation. (d) Strongly zoned igneous zircons of G3 granite give the emplacement age of 1003&16 Ma. The age of magmatic overgrowth is 1067&9 Ma (closed error boxes). The probability histograms represent the two ages derived from mixture modelling following the method of Sambridge & Compston (1994). (c) Analyses of the cores and overgrowths of G2 granite sample CM51 yield ages which correspond to the ages of inheritance (or protolith) and magmatism. (b) Zircons from G1 granite (CM93) are very complex but analyses from the main morphotypes cluster around what is interpreted as the emplacement age at c. Two rim analyses with low Th/U ratios are significantly younger (closed error boxes) and are interpreted as later metamorphic overgrowth at c. One strongly discordant analysis (open error box) was not included in the age calculation. ![]() (a) The majority of zircon analyses from the metavolcanic rock sample CM94 give one age population of 1118&8 Ma (shaded error boxes), which is interpreted as the crystallization age of the felsic volcanic rock. U-Pb concordia diagrams of the four analysed samples. ![]()
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