The Coloured Mélange Complex is part of the North Makran domain (SE Iran) and consists of an assemblage of\ud
metric- to decametric-thick slices mainly represented by volcanic rocks, locally stratigraphically associated\ud
with radiolarian cherts. In this paper, we present new geochemical data on volcanic rocks and biochronological\ud
data on the associated cherts. Our data indicate the occurrence of awide range of volcanic rocks-types,which are:\ud
1) normal-typemid-ocean ridge basalts (N-MORB); 2) oceanic plateau basalts (OPB); 3) alkaline basalts; 4) calcalkaline\ud
basalts, basaltic andesites, and andesites; 5) volcanic arc tholeiitic basalts and andesites, and high pressure\ud
- low temperature metabasalts formed in deep levels of an accretionary wedge. The volcanic arc tholeiites\ud
range fromEarly (lateHauterivian - early Aptian) to Late (latest Cenomanian - lower late Campanian) Cretaceous,\ud
whereas the calc-alkaline rocks and OPBs are Late Cretaceous in age (early Coniacian - Santonian and early\ud
Turonian - early Campanian, respectively). Alkaline basalts, OPBs, and N-MORBs represent remnants of the\ud
Mesozoic Neo-Tethys oceanic branch located between the Arabian plate and the Lut block. In this paper we\ud
document that this oceanic sector was characterized by the development of an oceanic plateau in the Late\ud
Cretaceous. In contrast, calc-alkaline and volcanic arc tholeiitic rocks represent remnants of a continental volcanic\ud
arc and forearc, respectively, developed onto the southernmost realm of the Lut block. The petrogenesis and age\ud
of volcanic rocks allow us to propose a newtectono-magmaticmodel for the evolution of the convergent margin\ud
developed in the northern sector of the Neo-Tethys from Early to Late Cretaceous. This model is basically\ud
constrained by the collision of the oceanic plateau with the continental arc, which led to the jump of the subduction\ud
toward the south, as well as to the formation of the imbricate pile of different units today observed in the North\ud
Makran area
In the northwestern part of Northern Apennines, between Curone and Staffora Valleys, the tectonic superposition between the External Ligurian Units (i.e. the ophiolitic-bearing chaotic complex of the Groppallo Unit and the non-ophiolitic Cassio Unit), the Middle Eocene-Miocene wedge-top basin Epiligurian Units succession, and the Late Messinian-Pliocene Po Plain succession, records the multistage tectono-stratigraphic evolution from subduction to continental collision. Our geological map, at the 1:20,000 scale, allows us to define 6 main tectonic stages on the basis of (i) the crosscutting relationships between main faults and local to regional stratigraphic unconformities and (ii) the differentiation among different types of chaotic rock unit (olistostromes and broken formations) deposited since Late Cretaceous to late Messinian. This approach provides a new understanding on the tectono-stratigraphic evolution of this sector, and its meaning in the evolution of the northwestern part of Northern Apennines.
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