Stratigraphy and geochemical features of the early miocene bimodal (ultrapotassic and calc-alkaline) volcanic activity within the NE-trending Selendi Basin, western Anatolia, Turkey

ERSOY E. Y., Helvaci C.

TURKISH JOURNAL OF EARTH SCIENCES, cilt.16, sa.2, ss.117-139, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 16 Sayı: 2
  • Basım Tarihi: 2007
  • Dergi Adı: TURKISH JOURNAL OF EARTH SCIENCES
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, TR DİZİN (ULAKBİM)
  • Sayfa Sayıları: ss.117-139
  • Anahtar Kelimeler: western Anatolia, lamproite, ultrapotassic volcanism, bimodal volcanism, continental extension, METAMORPHIC CORE COMPLEX, SOUTHERN MENDERES MASSIF, FIELD EVIDENCE, GEDIZ GRABEN, CHEMICAL CLASSIFICATION, EXTENSIONAL TECTONICS, CRUSTAL EXTENSION, 2-STAGE EXTENSION, ALASEHIR GRABEN, GORDES BASINS
  • Dokuz Eylül Üniversitesi Adresli: Evet

Özet

Western Anatolia has experienced thickening and orogenic collapse subsequent to the Eocene continent-arc collision. The early stage of the post-collisional volcanism in the region was thought to have produced widespread lavas and pyroclastic deposits of calc-alkaline basaltic andesite to rhyolite composition. However, in the Selendi Basin, one of the NE-trending basins in western Anatolia, there are two distinct volcanic unit compositions associated with the Lower Miocene sedimentary rocks: ( 1) a calc-alkaline, high-potassic felsic unit; and ( 2) alkaline, ultrapotassic lamproitic units, i.e. both are bimodal in character. The calc-alkaline felsic volcanic rocks ( Egreltidag volcanic unit) are composed of wide-spread pyroclastic rocks and lava flows, whilst the ultrapotassic-lamproitic mafic rocks ( Kuzayir lamproite) consist of small-volume syn-sedimentary lava flows. The geochemical characteristics of the Kuzayir lamproite are similar to those of the 'Mediterranean lamproites' that were widely produced in post-orogenic tectonic settings. A temporal and spatial association between these volcanic units clearly describes a post orogenic bimodal volcanic activity. The data also imply that the continental extensional tectonic regime in western Anatolia began, at least, in the Early Miocene, and produced not only calc-alkaline felsic activity but also mantle-derived alkaline, ultrapotassic volcanic rocks.