Late Cretaceous volcanic arc magmatism in southeast Anatolian Orogenic Belt: Constraints from whole-rock, mineral chemistry, Sr-Nd isotopes and U-Pb zircon ages of the Baskil Intrusive Complex (Malatya, Turkey)

NURLU N., KÖKSAL S., Kohut M.

GEOLOGICAL JOURNAL, cilt.57, sa.8, ss.3048-3073, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 57 Sayı: 8
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1002/gj.4460
  • Dergi Adı: GEOLOGICAL JOURNAL
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aquatic Science & Fisheries Abstracts (ASFA), Geobase, INSPEC
  • Sayfa Sayıları: ss.3048-3073
  • Anahtar Kelimeler: Baskil intrusive complex, southeast Anatolia, Sr-Nd isotopes, Turkey, U-Pb gechronology, volcanic arc, TRACE-ELEMENT, GEOCHRONOGICAL EVIDENCE, TECTONIC IMPLICATIONS, OPHIOLITIC ROCKS, EASTERN TAURIDES, CALC-ALKALINE, GEOCHEMISTRY, EVOLUTION, ELAZIG, AREA
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

The voluminous intrusive and extrusive magmatism was formed in the Elazig-Malatya region of the Southeast Anatolian Orogenic Belt (SAOB) as a consequence of the continental collision and/or convergent orogeny. The SAOB holds a great number of stratigraphic, metamorphic and tectonomagmatic units in the Elazig-Malatya region that are crucial for recognition of the geodynamic setting of southeast Anatolia during the Upper Cretaceous. The Baskil Intrusive Complex (BIC) is composed of mainly tonalitic/granodioritic and dioritic/gabbroic plutonic rocks, while its sub-volcanic phase is represented by granophyre, aplite and microgabbro, which were intruded into the Upper Cretaceous supra-subduction zone (SSZ)-type Ispendere ophiolites (SE Turkey). New U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon data provided crystallization ages ranging from 84.3 to 81.5 Ma for the BIC. Mafic and felsic rocks of the BIC have a low- to medium-K calc-alkaline, I-type, metaluminous character, whereas extremely evolved felsic rocks of this complex show a peraluminous composition. The aluminium-in-hornblende barometery (similar to 196 to 299 MPa) of magnesio-hornblendes in the Baskil intrusive rocks indicates their emplacement in the shallow- to moderate crustal plutonic levels at a minimum of 7.3 km to a maximum of 11.1 km depth. The Baskil intrusive rocks present depletion in Ti, Nb, Ta, light REE with respect to primitive mantle, and relative enrichment in large-ion lithophile element (Rb, Ba, Pb, Sr, Th), thus infer a pronounced subduction signature. Both mafic and felsic intrusives show low initial Sr-87/Sr-86 ratios (0.70357-0.70561) together with a high initial Nd-143/Nd-144 ratios (0.51279-0.51289), and high epsilon Nd((T) )values (5.0-7.0) and relatively young Nd crustal residence model ages (T-DM - 0.31-0.48 Ga). Based on our field, mineralogical and geochemical findings, we suggest that the BIC was originated from an amphibolitic source that interacted with subducted crust within SSZ and was changed by fluids during the early stages of the short-lived volcanic arc magmatism that evolved at the fringe of the Tauride Platform.