The evolution of the Mesozoic lithosphere of northwestern Neotethys: a petrogenetic and geodynamic perspective

Abstract

A complex and chaotic assemblage of the north Croatian inselbergs, considered a geological conundrum, is marked by omnipresent ophiolite mélange. This is a vestige of the unbroken formation of the lithosphere in the northwestern segment of Neotethys during the Mesozoic, spanning from the late Anisian to the late Tithonian. In this contribution, we present detailed mineralogical, petrological, geochemical and isotopic data on the mélange collected from 1991 to 2023. These data include the entire normal ophiolite sequence, from mantle tectonites and cumulate ultramafic rocks through cumulate and isotropic gabbro and sheeted dyke complex to massive and pillow lavas with interbedded radiolarian cherts. We found that the continuous development of oceanic lithosphere during the Mesozoic is recorded by seven geochemical groups of ophiolitic rocks, each representing a distinct basalt–gabbro suite. Based on their geochemical and isotopic characteristics, a sequence of petrogenetic processes and tectonomagmatic events has been reconstructed. Proposed geodynamic models that shed light on the Mesozoic evolution of the northwestern segment of Neotethys are consistent with the current geodynamic understanding of the broader Mediterranean region. The similarities in the tectonomagmatic and geodynamic history of NW Neotethyan ophiolites and ophiolites from the Dinaridic–Albanide–Hellenide belts suggest that they evolved together, probably within a single branch of the Neotethys Ocean during Triassic to Jurassic time. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists