Fission-track constraints on the thermal and tectonic evolution of the Apuseni Mountains (Romania)

摘要: New zircon and apatite fission-track (FT) data, including thermal modelling, are combined with an extensive literature survey reconnaissance-type structural fieldwork in the Eastern Apuseni Mountains. This leads to a better understanding of complex history key area at boundary between two megatectonic units Balkan peninsula, namely Tisza Dacia Mega-Units. Following Late Jurassic obduction Transylvanian ophiolites onto part Mega-Unit, that is, Biharia nappe system, both were buried minimum 8 km during late Early Cretaceous times when these underthrust below Mega-Unit consisting present-day Codru Bihor systems. formed upper plate (‘Austrian’) east-facing orogeny. Turonian Campanian FT cooling ages (95–71 Ma) from systems Baia de Aries nappes (at present structurally lowest Mega-Unit) record exhumation immediately followed second Cretaceous-age (i.e. Turonian) orogenic event. Thrusting this overprinting event was NW-facing led overall geometry stack Zircon ages, modelling show relatively rapid post-tectonic induced by third shortening pulse latest (‘Laramian’ phase), slower across 120°–60 °C temperature interval earliest Paleogene (75–60 Ma). Cenozoic-age slow (60–40 probably related erosional denudation postdating ‘Laramian’ large-scale updoming.