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.


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The remnants of the Southern Neotethys are represented by ophiolitic bodies and subduction/accretion complexes along the Southeast Anatolian-Zagros suture belt in the Eastern Mediterranean. Around Malatya and Elazig areas (SE Turkey), they are found within imbricated slices of a melange complex, known as the Yuksekova Complex. The studied basaltic rocks are common members of this melange complex, and show distinctive features of sources with tholeiitic to tholeiitic-transitional character. Petrography, whol...
Early-Middle Triassic echinoderm remains from the Istranca Massif, Turkey
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Middle Carnian Arc-Type Basalts from the Lycian Nappes, Southwestern Anatolia: Early Late Triassic Subduction in the Northern Branch of Neotethys
Sayıt, Kaan; Göncüoğlu, Mehmet Cemal (2015-11-01)
The Turunc Unit, which represents one of the tectonic slices within the Lycian Nappes in southwestern Anatolia, preserves the remnants derived from the northern branch of Neotethys. The unit includes basalts intercalated with pelagic limestones of middle Carnian age (early Late Triassic) based on the characteristic radiolarian assemblage of the Tetraporobrachia haeckeli Zone. The Turunc lavas reflect trace element signatures resembling those from subduction zones, displaying selective enrichment of Th and l...
Citation Formats
S. Gursu and M. C. Göncüoğlu, “Early Cambrian back-arc volcanism in the western Taurides, Turkey: implications for rifting along the northern Gondwanan margin,” GEOLOGICAL MAGAZINE, pp. 617–631, 2005, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32520.