Proposed Genetic Model For The Precipitaton Of Uranium In ...

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WSTAGE OF MULTCPHA- 3REFORMLlTlOH OF* -LAHIUM ORE BODIESDOsraGe OF FORMATION ANTICU%OF TECTONIC FRAMEWORK OF THE STUDYSYHCLiNEZlNDA PIRANTICLINEYAF,",","STAGE OF THE SOAN 7FORMATION DEPOSlTlONI)cMAIN-;--PALE0 INDUS. DRAINAGESTAGE OF THE DEVEL-OPMENT OF THEFOREDEEP BASIN l ANDNOFT 'HESTAGE OF THE BEGINNINGOF THE COWTlHENTALFOREDEEP DEPRESS-SlOM BASIN.STAGE OF THEPRE-SIWLLLIK FORM-ATION DEVELOPMENTIt4 MARINEEMVlRONMf NT.PETRITAL SEDIMENT FEEDING-UPLIFmG-1 EXPANSION-*?7EOCENE.OLICC)CENELATE-CRETACE WS TOPALEOCENEFERRUGIHOUS CRUST OFWWHERINGFLUVIAL-CONGLOMERATEUNCONFORMITYINFERRED FAULTLIMESTONE & SANDSTOHESUB MOUSSE PRE.MESOZOICEASEMENTURANIUM ORE BODYFig. 3. A complete conceptual diagram illustrating tectonic development of' the sulairnanUranium Mineral Belt during the Hima-Layan Orogeny (dimensinns not to scale)(modified after Wang et al,, 1996).
GENESIS OF SUBSURFACE URANIUMACCUMULATION IN THE AREAThe uranium accumulation is ribbon-shaped,tabular hanging structure that follows thestrike direction. The width of surfaceradioactivity of uraniferrous horizon is 30 m,but the subsurface width of uraniumaccumulation is up to 82 m i.e., the spread ofuranium in the subsurface is more than thecorresponding surface radiometry. Theaverage thickness of the ore lenses is 5 meter.This uranium is remobilized 1 reworked,which is accumulated at the expense ofleaching and remobilization of pre-existingsurface anomalies at redox boundary thatexists at a depth of 45-50 m, 20 m below thepresent day water table (Fig. 4).A comparison of the character of thecharacter of oxidation zone, transitional zone andreducing zone is given in Table 2 and 3, Thesubsurface uranim accumulation with weakradioactivity predicts the following workinghypothesis. The sediments hosting the ore bodywere deposited in a fluviatile environment withsufficient supplies of airborne volcanic matter &uranium from the primary rocks.The uranium in this area is derived fromsyndeposited volcanic ejecta in the form ofvolcanic ash fdls and tuffs. The volcanics aremore prone to enter into oxidized humidenvironment to liberate uranium. The liberationof uranium took place during diagensis whenthese sediments were partially altered. Thismobilized uranium got fixed with the carbon richpaleo-channel type sediments to form the initialore body, which is still visible on the surface withgrey clay balls, carbonaceous trash pockets andhaernatitized organic matter. As a result oforogenic movement, the sediments underwentintense folding due to which tectonic uplift of thearea took place. The uranium got liberatedthrough dissolution by ground water and wasmobilized to the paleo water table. Duringperiodic uplift the water table of the arearepeatedly got lowered. The precipitated uraniumhad continuously been oxidized upon uplift andthe redox boundary had gradually been shifteddownward to the next stage contemporaneous tothe phases of uplift. Gamma logs of the ore bodyrepresent three levels of uranium accumulation,which either show age difference or repeatedmobilization-precipitation scenario. These threegeneration peaks indicate reprecipitationremobilizationphenomenon (Fig. 5).Fig. 4. Conceptual diagram depicting the mode of leaching of uranium from the surface outcrop and corresponding accumulation in the sub surface below ground water table.95
Page 1: Geol. Bull. Univ. Peshawar, Vol. 37
Page 4 and 5: TABLE 1.ROCK SAMPLE ANALYSES COLLEC
Page 8 and 9: TABLE 2.ROCK SAMPLES ANALYSES OF TH
Page 10 and 11: TABLE 4.HYDROCHEMICAL CHARACTER OF

Proposed Genetic Model For The Precipitaton Of Uranium In ...

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