Post-Triassic evolution of Central Pontides: evidence from Amasya region, northern Anatolia


ROJAY F. B.

Geologica Romana, vol.31, pp.329-350, 1995 (Peer-Reviewed Journal) identifier

  • Publication Type: Article / Article
  • Volume: 31
  • Publication Date: 1995
  • Journal Name: Geologica Romana
  • Journal Indexes: Scopus
  • Page Numbers: pp.329-350

Abstract

The Central Pontides is an orogenic belt evolved since Triassic by the progressive closure of Paleo- and Neo-Tethys oceans, which is bounded by the IzmirAnkara-Erzincan Suture (Northern Neotethyan Suture) from the south. The post-Triassic Neo-Tethyan evolution in Amasya region started with Liassic transgression on the rifted pre-Liassic basement rocks. Later, the initial rifting failed and the platform was uplifted. The uplifted platform turned into an open-marine depositional realm as recorded by the deposition of Callovian Ammonitoco Rosso facies. The open-marine to deep sea depositional period was followed by a regressive platform carbonate deposition during Callovian-Valanginian. After a short period of nondeposition, the ongoing 'rifting' continued with the deposition of Aptian-Cenomanian deep-sea pelagics and turbidites. The passive margin was already destructed and turned into an active continental margin as a result of northward subduction of northern branch of the Neo-Tethyan oceanic crust during post-Cenomanian - pre-Campanian interval. Thermal doming beneath the future magmatic arc to the north and tectonic transportion of mobile accretionary prism towards south, resulted in the development of constructive forearc basins during mid Campanian-Maastrichtian. Ongoing emergence in the Amasya region and the cumulative amalgamation of the accretionary prism were followed by a newly arising extensional regime during Lutetian. The retrochariage of accreted melange onto Lutetian peripheral passive rift basin units from south to north, was followed by the dacitic intrusions which were probably the result of thickening of continental crust in the region. The entire region emerged under the control of a N-S directed compressional contractional regime until the initiation of compressional-extensional tectonic regime (North Anatolian Fault System).