Doğu Akdeniz Bölgesinde yer alan neojen basenlerinin (İskenderun,Miss-Andırın) tektono- stratigrafi birimleri ve bunların tektonik gelişimi

TEZ2629Tez (Doktora) -- Çukurova Üniversitesi, Adana, 1997.Kaynakça (s. 181-186) var.xiii, 186 s. ; hrt. ; 30 cm.

Güney Türkiye' de Yumurtalık fayı (Adana) boyunca gözlenen alkali bazaltların iz element ve Sr-Nd izotop jeokimyası

Güney Türkiye'de, genç volkanikler Geç, Pliyosen'den beri litosferin gerilmesi sonucu Afrika-Anadolu plakalarını sınırlayan KD-GB gidişli sol yönlü Yumurtalık doğrultu atımlı fayı boyunca gelişen açılma zonlarında yüzeye ulaşmışlardır. Bu volkanik kayaçlar alkali olivinli bazaltlar ile temsil edilirler. Bu volkaniklerin nadir toprak element içerikleri yüksek -derecede ayrımlaşma [(La/Yb)N=22-6] göstermektedir, ilksel mantoya göre normalize edilen uyumsuz iz element içerikleri okyanus adası bazaltlara yakın benzerlik göstermektedirler. Bazı uyumsuz iz element oranları da (Ce/Y=1.4-3.8, Zr/Nb=3.9-6.5, La/Ba=0.05-0.1, La/Nb=0.6-0.8, Zr/Ba=0.4-0.8) okyanus adası bazaltlarla uyumluluk göstermektedir. $^{87}Sr/^{86}Sr$ oranları düşük {0.703080-0.703918 arasında) olup, buna karşın $^{143}Nd/^{144}Nd$ oranları yüksektir (0.512600-0.512985) ve okyanus adası bazalt özelliğine sahiptir. Bu volkanik kayaçlardan elde edilen jeokimyasal veriler, güney Türkiye'de gözlenen kıta içi volkaniklerin Geç Pliyosen'den beri Anadolu-Afrika plakaları arasındaki sınırı teşkil eden sol yönlü doğrultu atılımlı fayların neden olduğu kıtasal kabuktaki kırıklar boyunca astenosferik mantodan türediklerine işaret etmektedir.Young volcanics erupted since late Pliocene as a result of lithospheric extension within the transtensional zones along the NE-SW trending letf-lateral Yumurtalik fault zone that mark the boundary between the African and the Anatolian plates in southern Turkey. These volcanics are characterized by alkali olivine basalts. The REE patterns exhibit a strong fractionation characterized by (La/Yb)N ratio between 22 and 6. Primitive mantle normalized incompatible trace element patterns exhibit close similarity to OIB. Ratios of some selected incompatible trace elements (i.e., Ce/Y=1.4-3.8, Zr/Nb=3.9-6.5, La/Ba=0.05-0.1, La/Nb=0.6-0.8, Zr/Ba=0.4-0.8) are also well comparable to those of ocean island basalts. The $^{87}Sr/^{86}Sr$ ratios show low values (between 0.703081 to 0.703920), whereas the $^{143}Nd/^{144}Nd$ ratios show high values (ranging from 0.512601 to 0.512986), suggesting an OIB signature. All the evidence suggest that the intracontinental volcanics in this region were derived from an asthenospheric mantle following the fractures of the continental lithosphere that resulted from the left lateral strike-slip fault system bounding the African-Anatolian plates since Late Pliocene in southern Turkey

Intracontinental Plio-Quaternary volcanism along the African-Anatolian plate boundary, southern Turkey

Plio-Quaternary volcanics crop out along the African-Anatolian plate boundary in southern Turkey. NE-SW trending sinistral strike-slip fault systems controlling this volcanism have resulted from the of continuous compressional tectonic regime at the K. Maras triple junction (southern Turkey), where the collision of the African-Arabian and Anatolian plates occurs. As a result, intracontinental basaltic volcanic have erupted within the transtensional zones oriented along the strike of the main fault. Massive basaltic lava flows displaying columnar jointing are often intercalated with agglomerates and tuffs. Volcanic rocks are represented by olivine alkali basalts (Na₂O+K₂O=4-7 %). These basaltic rocks exhibit high TiO₂ (2-3%) and low SiO₂ (43-48%) values. The clinopyroxene compositions (high TiO₂, CaO and Al₂O₃) also confirm their alkaline affinity. Tectonomagmatic discrimination diagrams based on major and trace element geochemistry suggest that these volcanic rocks belong to the within-plate basalt environment. REE geochemistry shows LREE enrichment indicating typical intracontinental alkaline basaltic volcanism

Neoproterozoic continental arc volcanism at the northern edge of the Arabian Plate, SE Turkey

New geochemical, Sr/Nd isotope and zircon U–Pb LA-ICP-MS data from the Derik Volcanics in the Southeast Anatolian Autochthone Belt of Turkey are consistent with an Andean-type Cadomian arc that developed along the northern edge of the Arabian Plate during the Late Neoproterozoic. The Derik Volcanics represent a volcanic complex including andesites, rhyolites and basalts, with volcanoclastic and fluvial sediments. They are unconformably overlain by playa sediments with Early Cambrian ichno-fossils, followed by Middle Cambrian-Silurian shallow marine deposits.Geochemically, the Derik Volcanics (DV) display transitional-calcalkaline affinities. On Th/Nb–Ti/Zr diagram, DV display negative trends from rhyolites to late to early-stage andesites and mafic dykes, respectively. The REE patterns are highly to moderately fractionated, with [(La/Yb)N=5.20–6.77 in late-stage andesites, 4.38–10.51 in rhyolites, 2.58–4.65 in the early-stage andesites, and 2.51–4.21 in mafic dykes]. Normalized trace element and REE diagrams display Th, La, Ce, Sm enrichment and depletion of Nb, Ti and Eu as is typical for Andean-type active continental margin igneous rocks. The enrichment of LILE and LREE, combined with depletion of HREE also suggests that the Derik Volcanic rocks were formed in relation with a subduction zone. Negative Eu anomalies (Eu/Eu)N, range from 0.50 to 1.81, indicates fractional crystallization of feldspar. The DV have positive ɛNd (+0.15 to +4.20) and mean model ages of 1.28Ga for the early-stage andesites, 1.34Ga for rhyolites, 1.35 for late-stage andesites, and 1.36Ga for mafic dykes. The positive ɛNd(T)data show that DV are product of mantle-derived magmas. Lower143Nd/144Nd isotope ratios than the depleted MORB mantle (DMM) source indicate that the DV may have been contaminated by crustal material during magma genesis. Geochemical modeling shows that all four volcanic rock types may have been formed by different percentages of batch melting of DMM and subducting slab sources.Zircon LA-ICP-MS data give crystallization ages of 581.4±3.5Ma (n=7) and 559.2±3.2Ma (n=3) for the early and late-stage andesitic rocks, as well as ages of 569.6±1.6Ma (n=17), 571.6±1.9Ma (n=18), 575.4±4.3Ma (n=6) for the rhyolites.The geological and geochemical features together with the new age data suggest that the Derik Volcanics formed along a continental arc in the course of the southward subduction of Prototethys oceanic lithosphere along the northern margin of the Arabian Plate, which is attributed to a late-stage phase of the Cadomian Orogeny of the Pan-African cycle