From arc evolution to arc-continent collision: Late Cretaceous-middle Eocene geology of the Eastern Pontides, northeastern Turkey


Kandemir O., Akbayram K., Cobankaya M., Kanar F., PehRyan S., Tok T., ...More

GEOLOGICAL SOCIETY OF AMERICA BULLETIN, vol.131, pp.1889-1906, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 131
  • Publication Date: 2019
  • Doi Number: 10.1130/b31913.1
  • Title of Journal : GEOLOGICAL SOCIETY OF AMERICA BULLETIN
  • Page Numbers: pp.1889-1906

Abstract

The Eastern Pontide Arc, a major fossil submarine arc of the world, was formed by northward subduction of the northern Neo-Tethys lithosphere under the Eurasian margin. The arc's volcano-sedimentary sequence and its cover contain abundant fossils. Our new systematical paleontological and structural data suggest the Late Cretaceous arc volcanism was initiated at early-middle Turonian and continued uninterruptedly until the end of the early Maastrichtian, in the northern part of the Eastern Pontides. We measured similar to 5500-m-thick arc deposits, suggesting a deposition rate of similar to 220 m Ma(-1) in similar to 25 m.y. We have also defined four different chemical volcanic episodes: (1) an early-middle Turonian- Santonian mafic-intermediate episode, (2) a Santonian acidic episode; when the main volcanic centers were formed as huge acidic domes-calderas comprising the volcanogenic massive sulfide ores, (3) a late Santonian-late Campanian mafic-intermediate episode, and (4) a late Campanian-early Maastrichtian acidic episode. The volcaniclastic rocks were deposited in a deepwater extensional basin until the late Campanian. Between late Campanian and early Maastrichtian, intra-arc extension resulted in opening of back-arc in the north, while the southern part of the arc remained active and uplifted. The back-arc basin was most probably connected to the Eastern Black Sea Basin. In the back-arc basin, early Maastrichtian volcano-sedimentary arc sequence was transitionally overlain by pelagic sediments until late Danian suggesting continuous deep-marine conditions. However, the subsidence of the uplifted-arc-region did not occur until late Maastrichtian. We have documented a Selandian-early Thanetian (57-60 Ma) regional hiatus defining the closure age of the Izmir-Ankara-Erzincan Ocean along the Eastern Pontides. Between late Thanetian and late Lutetian synorogenic turbidites and postcollisional volcanics were deposited. The Eastern Pontide fold-andthrust belt started to form at early Eocene (ca. 55 Ma) and thrusting continued in the post-Lutetian times.