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Three important lithologies occur in two drill wells from the Pan-African basement underlying the Mesozoic Sab’atayn Basin, in a previously undocumented area of the Pan-African, 83 and 90 km NE of known exposures in Yemen. Cores from well 1 include amphibolite, with basaltic to andesitic compositions, affected by crustal contamination during emplacement into a thickened crust. Deeper in the well, an unfoliated dark red monzogranite has a U–Pb zircon age of 628.8 ± 3.1 Ma and a Rb–Sr biotite cooling age of 591.6 ± 5.8 Ma (∼300 °C). Regional constraints suggest emplacement in a transitional tectonic setting with compressional terrane amalgamation followed by extensional collapse. Sm–Nd isotope analysis yields a T DM model age of 1.24 Ga with negative ε Nd values, suggesting the monzogranite is part of the Al Bayda island arc terrane. Cores from well 2 contains a weakly deformed, massive (unbedded) medium grey meta-arkose exhibiting essentially no geochemical signature of weathering and with an almost pure dacitic composition. This rock may have been directly derived from an (extrusive) granitoid that was emplaced prior to, or during terrane amalgamation. A (U–Th–Sm)/He zircon age of 156 ± 14 Ma constrains the time of basement cooling to ∼180 °C, synchronous with basin formation. These lithologies provide new insights in the development of the Pan-African basement of Yemen, extending our knowledge of the nearby surface geology to the subsurface. [ABSTRACT FROM AUTHOR]

This paper presents a new geological map of Kea, in the western Cyclades of Greece. The map shows the three-part tectonostratigraphy typical of many Cycladic islands: (i) Footwall of blue-grey calcitic marble mylonites and likely volcanoclastic-derived schists of the Cycladic Blueschist Unit, almost completely retrogressed to greenschist facies; (ii) Detachment zone of phyllonites, schistderived protocataclasites and foliated cataclasites, white calcitic marble ultramylonites and dolostone (ultra)-cataclasites; (iii) Hanging wall of dolostones, with a variable protocataclastic deformation, and occasional foliated calcitic marbles. In the footwall, relict blueschist facies assemblages are rare, being best preserved in gneisses and Fe-Mn-rich rocks (both uncommon lithologies). The bluegrey calcitic marble mylonites, which are generally thicker than elsewhere in the Western Cyclades are more common on the eastern side of the island. This may reflect a lateral ramp geometry between the footwall and overlying detachment-zone. Structural data indicate a consistent top-to-SW to S directed deformation, confirming that the detachment on Kea is part of the West Cycladic Detachment System. Few significant steep faults were observed on the island, although the linear coastlines and valleys suggest that many minor faults or fracture zones may be present. [ABSTRACT FROM AUTHOR]