Early Cambrian back-arc volcanism in the western Taurides, Turkey: implications for rifting along the northern Gondwanan margin

The Lower Cambrian (Tommotian) Gogebakan Formation in western Central Anatolia is made up of slightly metamorphosed continental to shallow marine elastic rocks with pillowed and massive spilitic lavas and dolerite dykes. Spilitic lavas, commonly amygdaloidal, are albite-and pyroxene-phyric with the metamorphic mineral paragenesis albite + calcite + sericite +/- epidote +/- tremolite +/- chlorite. Dolerite dykes mainly include plagioclase and pyroxene as primary minerals and tremolite epidote chlorite as low-grade secondary minerals. Geochemical data show that the spilitic lavas and dolerite dykes are sub-alkaline, of oceanic tholeiitic basalt character and display a tholeiitic fractional trend, characterized by an increase in FeO/MgO and Zr and TiO2 in variation diagrams. They are characterized by relatively high Zr/Y (2-4.5), relatively high Th/Yb (0.15-1.0) and La/Nb (0.5-2.5). Both show marked negative Nb and Ti anomalies relative to Th and La (Ce), implying a subduction-related chemistry. Chondrite-normalized REE patterns display slight enrichment of light REE (spilitic lavas (La/Yb)(N) = 0.79-1.56; dolerite dykes (La/Yb)(N) = 0.89-3.50) fairly comparable with MORB. The geochemical similarity of the spilitic lavas and dolerite dykes suggests a co-genetic origin. La/Nb ratios of both types are slightly higher than average MORB values and were possibly formed in the early stages of back-arc basin development. Petrogenetic modelling suggests the mafic rocks of the formation were formed by 9% batch melting of spinel 1herzolite in shallower depths (c. 60 km). Taken together the data suggest that the Early Cambrian mafic rocks of the Taurus units were developed in a back-are basin along the northern edge of Gondwana above the southward-subducting oceanic lithosphere and may represent initial rifting that resulted in separation of the peri-Gondwanan terranes

Geology and geochemistry of the pre-Early Cambrian rocks in the Sandikli area: Implications for the Pan-African evolution of NW Gondwanaland

The pre-Early Cambrian Sandikli Basement Complex in western Central Anatolia comprises a low-grade metasedimentary succession (Guvercinoluk Formation) and meta-rhyolites intruded by meta-quartz porphyry rocks (Kestel Cayi Porphyroid Suite). The Guvercinoluk Formation consists of alternation of meta-siltstones and meta-sandstones with olistostromal conglomerates, rare black chert and cherty meta-dolomite lenses. The Kestel Cayi Porphyroid Suite is a deformed, highly sheared dome-shaped rhyolitic body with quartz porphyry rocks. Quartz porphyry dykes intrude both the volcanic carapace and the meta-sedimentary rocks of the Guvercinoluk Formation. Both the meta-quartz porphyry rocks and meta-rhyolites are typically mylonitic with relict igneous textures. Geochemical data indicate that the felsic rocks of the Kestel Cayi Porphyroid Suite are subalkaline and display characteristic features of post-collisional, I-type granitoids. The basement complex is unconformably overlain by variegated conglomerates, mudstones and arkosic sandstones with andesitic lavas, followed by siliciclastic rocks and carbonates that yielded Early Middle Cambrian fossils

Erratum: Art in science: Orthopaedics through philatelic material (Clinical Orthopaedics and Related Research (2013) 471 (3755-3759) DOI: 10.1007/s11999-013-3280-4)

[No abstract available