Structural setting and evolution of the Afghan orogenic segment – a review

Abstract

The actual state of knowledge concerning the tectonic evolution of the Afghan orogenic segment is summarized in the context of the neighbouring regions. The segment can be divided into: (1) the Late Palaeozoic North Afghan Variscan domain, which forms the southern margin of the Turan Plate; (2) the Early Cimmerian (Late Triassic-Early Jurassic) Palaeotethys suture zone of Middle Afghanistan, with the associated magmatic arc and back-arc rift extending from the Parapamisos and western Hindu Kush to the northern Pamir Mountains; (3) the Late Cimmerian (Late Jurassic-Early Cretaceous) domain of the Central Afghan Block mosaic with Gondwanaderived terranes; and (4) the Cenozoic-age Himalayan domain, which fringes the Cimmerian domain along the transpressive boundary of the Indian Plate in the east and the accretionary complex of the Makran subduction zone in the south. This current review of the scattered literature of a country where geological fieldwork effectively ceased 35 years ago is intended to bridge the gap between the better-known regions to the west in eastern Iran, and to the east in the Pamir-Punjab syntaxis.

Facies analyses and depositional setting of the Lower Cretaceous Shurijeh–Shatlyk formations in the Kopeh Dagh–Amu Darya Basin (Iran and Turkmenistan)

“…Our studies and previous studies of palaeocurrent analyses by Jamali () and Mortazavi () indicate that in Early Cretaceous times, rivers flowed from the south and south‐east towards the north and north‐west in the study area. In addition, some data such as depth‐structure, isopach maps, and cross‐sections (Brunet et al, ), increases the proportion of quartz with respect to other detrital grains the east to the west in the Kopeh Dagh Foredeep (Ulmishek, ), uplift in the northern Afghanistan and Uchadzhi area (Klett et al, ; Siehl, ), and northward decreases of grain size in the north Afghanistan (Brookfield & Hashmat, ) support our interpretation that the main fluvial direction in the Amu Darya Basin was from the east–south‐east towards the west–north‐west during Early Cretaceous time. On the other hand, thinning of the shallow marine carbonate deposits of the Mozduran, as well as siliciclastics of the Shurijeh Formation to the east in the easternmost parts of the Kopeh Dagh Foldbelt, indicates that the Aghdarband erosional window was a palaeo‐high during the Late Jurassic–Early Cretaceous.…”

“…During the Late Cimmerian Orogeny (Late Jurassic–Early Cretaceous), most parts of the KDADB were exposed to erosion (Brunet et al, ; Klett et al, ; Siehl, ; Ulmishek, ). Our studies and previous studies of palaeocurrent analyses by Jamali () and Mortazavi () indicate that in Early Cretaceous times, rivers flowed from the south and south‐east towards the north and north‐west in the study area.…”

Geological evolution of Central Asian Basins and the western Tien Shan Range

“…Siehl (2015) points out that this zone has remained active up to the present day as a result of the northward drift of India to the east and Arabia to the west (Stöcklin 1977;Ş engör 1984;Boulin 1991). He reviews the geology of the Afghan portion of the Afghan -Tajik Basin, and examines the period following the Variscan orogenic events at the end of the Palaeozoic Era.…”

“…The regional evolution of the Tien Shan region is therefore characterized by two major orogenic phases: the Early Mesozoic Eo-Cimmerian Orogeny and the Cenozoic collision of India and Eurasia (e.g. Dumitru et al 2001;Jolivet et al 2010;Jolivet 2015;Siehl 2015). These two major events are separated by a transitional period characterized by a series of less-well-understood events (in terms of their far-field effects) extending from the Jurassic through the Cretaceous.…”

“…Lhasa Block) to Eurasia, is unclear; published reconstructions and timings for the various events often vary. In summary, the various accretionary events from Late Palaeozoic times onwards varied both in terms of their timing as well as their location, resulting in variations both in deformation as well as the related post-collisional magmatism towards the east (Klett et al 2006;Zanchi et al 2009Zanchi et al , 2012Siehl 2015).…”