PETROTECTONICS, PETROLOGY AND GENESIS OF URANIUM MINERALISATION OF THE SIWALIK GROUP OF THATTI NASRATI AND SHAVAH-SHANAWAH AREA

Azizullah, Azizullah (1997) PETROTECTONICS, PETROLOGY AND GENESIS OF URANIUM MINERALISATION OF THE SIWALIK GROUP OF THATTI NASRATI AND SHAVAH-SHANAWAH AREA. Doctoral thesis, University Of Punjab Lahore.

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Abstract

The Himalayan Malayan molasses sediments of the Siwalik Group, which range in age from Pliocene to Pleistocene is the Thatti-Nasrati and Shanawah-Godi Khel of Trans Indus areas were studied in order to understand their nature, origin chemical and petrotectonic investigations helped to understand the genesis of uranium mineralization in the Dhok Patthan Formation of the study area. The Siwalik Group is comprised of four formations i.e. Chinji, Nagri, Dhok Pathan and Soan. The Rawalpindi Group is absent in this area. The Chinji age. This formation consists of maroon and reddish brown colored shale and subordinate sandstone horizons. The thickness of the Chinji Formation varies from 1160 m to 1400 m. The nagri formation is marked by a thick sequence of massive sandstone with a lot of palaeochannels. Shales are present as rare thin patches. The thickness of the Nagri Formation varies from 1050m to 2075m. The Dhok Pathan Formation exhibits excellent development of cyclic deposition of shale and sandstone. the thickness of this formation varies from 950m to 1200m. The soan formation consists of conglomerates sandstone, siltstone and shale horizons. The thickness of this formation varies from 300 to more than 500m. A number of uranium bearing mineralized horizons are present in the upper part of the Dhok Pathan Formation. These horizons have secondary uranium mineral carnotite in the study area. Uranium mineralization is widely distributed throughout the Siwaliks. A few uranium deposits of small size source nor indeed the control of mineralization were properly understood. The size, of the discovered deposits are very small as compared to the regional surface showings. The study of lateral and vertical accretion deposits, presence of scouring, channel abandonment behaviour, facies association and channel fill of the Siwalik Group sow that it was deposited by a braided river system. The Siwalik Group of the Shinghar-Surghar ranges were deposited from 12.M.a to 0.5M.a as compared to the siwaliks of the potwar plateau, where these sedimentation rates of the siwalik group were generally higher in the trans-indus ranges than that of the potwar plateau area. The entire molasse sequence covering the time span of 12M.a to 0.5 M.a is conformable. There was no tectonic activity other than subsidence of the basin till folding began about 0.5 Ma, which stopped the siwalik sedimentation in the study area. These molassic sediments were deposited by high velocity streams are indicated by the presence of pebbles, cobbles and boulders. Poor sorting and angularity of fragments as well as their compositional immaturity suggests that the sediments are texturally as well as compositionally immature. Within uranium bearing horizons the sandstone is subarkose to lithic arenite. The mineralized palaeochannels contain bentonitized volcanic clasts, which still retain 11 ppm uranium such volcanic clasts provided the indigenous and subtropical climatic conditions as it contains plant fragments and vanadium rich minerals. In some areas the formation contains considerable amount of humic acid and pyrite, formed during diagenesis. These served as important reductants for uranium deposition. Studies based on nature, origin and conditions of deposition coupled with petrographic, chemical and petrotectonic investigations strongly suggest a potential for sandstone type uranium deposit in the Dhok pattan formation of the thatti nasrati and shanawah godi kehl area. This potential deposit may be similar in characters to those of baghalchur. Nanagar nai and qabul khel areas. As a large number of surface samples of the study area have more than 0.05% chemical U3O8, further integration of data and exploration work particularly core drilling may prove the existence of a uranium deposit.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: petrotectonics, petrology, uranium mineralisation, siwalik group, thatti nasrati, shavah-shanawah, pliocene, pleistocene, chinji, nagri, dhok pathan, soan
Subjects: Q Science > QE Geology
Depositing User: Muhammad Khan Khan
Date Deposited: 25 Oct 2016 07:58
Last Modified: 25 Oct 2016 07:58
URI: http://eprints.hec.gov.pk/id/eprint/2681

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