eventually blocked by volcanic activity. The Ab-i-Khanduli dry valley still connects Dacht-i-Navar to the Arghandab river. Another possibility is that the valley originally drained eastward towards Qarabagh. Metamorphic rocks of Paleozoic age form the basement. Additional volcanic centres are found both west and east of Dacht-i-Navar. The volcanism appears to be associated with left-lateral strike-slip faulting in the area. Petrology The field has erupted andesite and dacite. The dacites are found in the lower parts and the andesites in the upper part of the volcanic deposits; some rhyodacites and rhyolites are found among the oldest rocks. The rocks have a porphyric nature and phenocrysts include amphibole, biotite, clinopyroxene, magnetite, olivine, orthopyroxene, plagioclase and quartz, with different rock types having different composition. Chemically, the rocks belong to the calc-alkaline series. Dacht-i-Navar is a source of obsidian, one of the few in Southwest Asia. Some Paleolithic archeological sites in the area have used this obsidian. This obsidian does not appear to have been transported to large distances from Dacht-i-Nawar. Eruptive history Potassium-argon dating has yielded ages of 2.7–2.8 million years ago for the dacites. Quaternary pebbles lie on top of the andesites. The Zarkadak volcano was active 1.68–1.59 million years ago. One eruption deposit of Mamikala has a volume of over . Volcanic activity involved the eruption of ignimbrites followed by the extrusion of lava domes. Volcanic activity at Dacht-i-Navar was accompanied by the activity of hot springs that deposited travertine. Dacht-i-Navar is considered to be the source of volcanic ash layers found in the Sivalik Hills that were erupted 2.31 ± 0.84 to 2.8 ± 0.56 million years ago. Such tephra deposits have been reported from Jammu in India and Chandigarh in India, sometimes about away from Dacht-i-Navar. The age of the last eruption is unknown. No emissions from this volcanic group have been detected over Pakistan, but hot springs are still active in the Dacht-i-Navar basin. See also List of volcanoes in Afghanistan Lists of volcanoes References Sources External links Satellite images Global Volcanism Program Volcanoes of Afghanistan Mountains of Afghanistan Pleistocene lava domes Volcanic groups