Diachroneity in the closure of the eastern Tethys Seaway: evidence from the cessation of marine sedimentation in northern Pakistan

Naseem

Acta Geologica Sinica (Eng)

et al. 2022

The present study deals with the depositional facies, diagenetic processes and sequence stratigraphy of the shallow marine carbonates of the Samana Suk Formation, Kohat Basin, in order to elucidate its reservoir quality. The Samana Suk Formation consists of thin to thick-bedded, oolitic, bioclastic, dolomitic and fractured limestone. Based on the integration of outcrop, petrographic and biofacies analyses, the unit is thought to have been deposited on a gentle homoclinal ramp in peritidal, lagoonal and carbonate shoal settings. Frequent variations in microfacies based sea-level curve have revealed seven Transgressive Systems Tracts (TSTs) and six Regressive Systems Tracts (RSTs). The unit has undergone various stages of diagenetic processes, including mechanical and chemical compaction, cementation, micritization, dissolution and dolomitization. The petrographic analyses show the evolution of porosity in various depositional and diagenetic phases. The fenestral porosity was mainly developed in peritidal carbonates during deposition, while the burial dissolution and diagenetic dolomitization have greatly enhanced the reservoir potential of the rock unit, as is further confirmed by the plug porosity and permeability analyses. The porosities and permeabilities were higher in shoal facies deposited in TSTs, as compared to lagoonal and peritidal facies, except for the dolomite in mudstone, deposited during RSTs. Hence good, moderate and poor reservoir potential is suggested for shoal, lagoonal and peritidal facies, respectively.

Section: Depositional and Diagenetic Controls On The Reservoir Qualitymentioning

confidence: 54%

Facies Analysis, Sequence Stratigraphy and Diagenetic Studies of the Jurassic Carbonates of the Kohat Basin, Northwest Pakistan: Reservoir Implications

Naseem

Acta Geologica Sinica (Eng)

et al. 2022

“…The Triassic is overlain by Pliocene strata, which indicates a large timespan unconformity in the area (Alam and Khan, 2019). Furthermore, in the adjacent regions of the Indus Basin, Mesozoic and Cenozoic successions are well developed with a clear demarcation of the diachronous closure of Eastern Tethys in the basin (Wadood et al, 2021a). The detailed stratigraphic framework of the Middle Permian Amb Fm.…”

Section: Geological Settingmentioning

confidence: 96%

Middle Permian Mixed Siliciclastic‐Carbonate System on the Northwestern Margin of the Indian Plate, Pakistan: Implications for Paleoclimate and Carbonate Platform Evolution

Wadood

Acta Geologica Sinica (Eng)

Hong

2022

“…The exhumation of Precambrian to Quaternary strata along the Salt Range is attributed to the Himalayan Orogeny (Kadri, 1995). The orogeny has resulted due to the closure of the Tethys as a result of convergence between India and Eurasia (Wadood et al, 2021). The intra‐oceanic subduction in the western Himalaya has resulted in two suture zones, namely, Main Karakoram Thrust (MKT) and Main Mantle Thrust (MMT; Rehman, Seno, Yamamoto, & Khan, 2011).…”

Section: Geological Settingmentioning

confidence: 99%

Dating and tectonostratigraphy of the Early Jurassic rift delta at the northwestern margin of the Indian Plate, Pakistan

et al. 2022

Self Cite

The study aims to establish the palynostratigraphy, tectonostratigraphy, and palaeoclimate of early Jurassic deltaic strata of the Datta Formation deposited on the northwestern margin of the Indian Plate, Eastern Tethys. Two palynomorph Oppel Biozones namely Quadraeculinaanellae formis-Chasmatosporites cf. elegans and Callialasporites turbatus were erected which suggest an Hettangian-Bajocian age for the Datta Formation. The palynofacies integrated with established lithofacies data indicate the dominance of delta plain settings in the western Salt Range and Trans-Indus Ranges. Such clastic dominated facies truncated along palaeohighs and marine settings in its surroundings, offer good chances of stratigraphic traps within the unit.The literature review suggests that the deposition of deltaic sediments occurred in rift settings, which dominated Gondwana during the Early Jurassic. Such synchronous rift settings with associated continental and deltaic sediments are recorded in almost all continents of Gondwana affinity, thus the Datta Formation is part of a regional delta system. The dominance of Araucariaceae in association with Cycadaceae, as well as the evergreen trees of Cyatheaceae and Matoniaceae within the Datta Formation, indicates warm humid conditions during the deposition of the studied unit.