Abstract Plio-Pleistocene sediments in coastal escarpments of Makran in SE Iran shows different patterns of diagenetic features in diverse depositional facies and therefore implies a facies-controlled diagenetic evolution mainly related to different porosity patterns. Although geochemical characteristics of various cements in this sediment are masked by pervasive meteoric diagenesis, remnants of primary geochemical characteristics (Mg, Mn, Fe and Sr concentrations, and δ 18 O and δ 13 C values), cathodoluminescence of these cements and paragenetic sequences of diagenetic features help us to unravel the diagenetic history and to reconstruct the history of exposures. The correlation of diagenetic features between rock units in each sedimentary column, inferred by using two distinct dolomite cementation phases, suggests pulsatory changes in the fluid chemistry related to eight episodes of seaward and landward migration of fluids as a result of relative sea-level fluctuation during eight episodes of uplift and relaxation and/or eustactic sea-level fluctuation. Moreover, lateral correlation of paragenetic sequences (eastward increase in the number of phases of cementation and dissolution) implies that pulsation in fluid migration has developed toward the eastern part of each fault-limited block as uplift and erosion rate increased. In the last stage, a net seaward migration of fluids seems to have occurred as relative sea level fell (as a result of regional uplift and/or eustacy). In the last two stages of uplift, reverse fault activities enhanced methane seepage, as indicated by the geochemistry of dolomite cements (δ 13 C−16.15‰ to 20.16‰).

Abstract We use Pn -tomography to map lithospheric mantle velocity and anisotropy at the Arabia–Eurasia plate boundary, namely Makran and Zagros. We use catalogue events recorded by Oman, UAE, Saudi Arabia and Iran networks, the International Seismological Centre and the National Earthquake Information Center. Events of 1.8–16 degree distances were used for this Pn -tomography. In this study we show that the northeastern Arabia plate is characterized by cold and stable lithospheric mantle. Contrastingly, Eurasia is underlain by hot unstable lithospheric mantle. The Arabia–Eurasia lithospheric suture follows the Zagros collision surface suture within c. 70 km lateral proximity. At the southernmost Zagros collision, the Arabia lithosphere is inferred to extend further NE beneath Lut Block. This may be indicative of extended subduction of Arabia beneath Eurasia in southernmost Zagros. We find that eastern Makran shows typical subduction characteristics, with inferred oceanic lithosphere underlying the eastern Oman Sea and hot unstable lithospheric mantle below overriding Helmand Block. Contrastingly, the western Makran subduction zone including Arabia and Eurasia continental sides is underlain by a low- Pn -velocity anomaly, indicative of hot unstable lithospheric mantle. Surface evidence show that western, southern and eastern boundaries of western Makran low- Pn -velocity anomaly may represent a Late Neogene reactivated Precambrian terrane boundary in north Oman.

Abstract In the northern Arabian Sea the Arabian, Eurasian and Indian Plates are in tectonic interaction with one another. We present interpretations of multichannel seismic profiles across the Makran sub-duction zone (which is part of the Eurasian-Arabian Plate boundary) and the transtensional Murray Ridge and Dalrymple Trough (which are part of the Arabian-Indian Plate boundary). We distinguish four megasequences in the sedimentary succession, which we correlate over the entire study area. Regional unconformities separate the megasequences and enable us to establish a common history of the region before Late Miocene time (c. 20 Ma). The Early Pliocene (c. 4.5 Ma) reopening of the Gulf of Aden caused a reorganization of the plates and subsequent tilting of the oceanic crust of the Arabian Plate toward the Makran subduction zone. This event is documented by the regional M-unconformity. Since that time, sedimentation on the Oman Abyssal Plain has been permanently separated from the Indus Fan by the Murray Ridge, on the northern end of which there has been no significant sedimentation.

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 Gondwana-derived 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.