Sandstone Type Uranium Mineralisation in Gondwana Sediments of Central India: A case study from Satpura Basin By Amit Majumdar, Scientific Officer-H Atomic Minerals Directorate Department of Atomic Energy
INTRODUCTION Gondwana sediments are deposited worldwide in dominantly Rift-related basins during Permo–Triassic, Jurassic and Cretaceous Period. These fluvio-deltaic sediments are known for Sandstone type Uranium Mineralisation and important among them are Karoo Basin, S. Africa and Parana Basin S. America. In India, Gondwana sediments are widespread and found in intracratonic rift related basins represented by a mosaic of graben, half graben and tilted blocks complicated by intersection and termination of normal faults . Among Indian Gondwana Basins, ~14700 sq km large and spindle shaped Satpura – Gondwana Basin (200km x 60km) in Central India - Potential for Uranium Mineralisation.
GLOBAL DISTRIBUTION OF URANIUM MINERALISATION IN GONDWANA SEDIMENTS Congo Gaban Rukwa Satpura Sonvalley Tanzana Damodar valley Carnarvin Luano Godavari Paraniba Perth Canning Parana Mocambique Ngalia Limpopo Springbok Flats Peru Bolivia Main Karoo Victoria Botswana Central Patagonia Paganzo Copper Galilee Callingasta Trans Antarctic Sydney Uspallata Neuquen South PatagoniaLocation of uranium mineralization in Gondwana rocks of Gondwana land
GLOBAL CORRELATION OF GONDWANA FORMATIONS AND URANIUM DEPOSITSPeriod South Africa South Eastern Narmada America India Valley, IndiaJurassic Elliot Santamaria Jabalpur Fm. Molteno PanchetLower Triassic Formation Bagra Beaufort Estrata nova Raniganj Conglomerate Group Formation (Coal Denwa Fm. Measures)Permian Pachmarhi Ecca Series Fm. Irati Shales (CoalMeasu.) Barakar Bijori Fm Tarat Fm., Formation (Up. Permian) Dwyaka Shale Itarare Series (Coal Measures) Motur Fm.Carboniferous Dwyaka Tillite Guezauman Karharbari Barakar Fm. Fm (L. Permian) Tillite ~~~Unc~~~ Talchir Tillite Talchir Tillite Tupe Tillite ~~~Unc~~~~ ~~~Unc~~~ ~~~Unc~~~ ~~~~Unc~~~~Archaean Basement Basement Basement Basement Uranium Deposits Significant Anomalies
TYPES OF URANIUM MINERALIZATION IN GONDWANA BASINS Sand stone hosted Uranium Mineralisation e.g. Sierra Pintada, Argentina; Figueira, Brazil; Akouta, South Africa; Arlit, Niger etc. Coal hosted Uranium Mineralisation e.g. Springblock Basin, South Africa Pelite Hosted Uranium Mineralisation e.g. Gregorio Formation, Uruguay Vein type Uranium Mineralisation e.g. Rincon del Atuel, Argentina
DIAGONOSTIC CHARACTERISTICS OF SANDSTONE TYPE OF U DEPOSITS1. Provenance : Granitic rocks / volcanic ash (tuffaceous)2. Depositional Envn. : Fluvial / marginal marine3. Host rock : Silurian or younger in age.4. Host rock having porosity and permeability.5. Host rock having low angle basin ward dip6. Presence of carbonaceous / humic material.7. Low temperature ground water and meteoric water are the mineralising solution.8. Cover rocks.
METALLOGENETIC ASPECTSThe sedimentary uranium enrichment cycle consists of three stages A. Leaching of uranium from provenance/source. 1. SOURCE - Granite / Volcanic ash 2. WEATHERING B. Transportation of uranium to an accumulation site. 1. TRANSPORTATION IN SURFACE WATER - As dissolved uranyl dicarbonate complex - Attached to dissolved or colloidal organic acids (humates) - In original mineral as bed-load 2. IN GROUND WATER - In areas of tectonic activity, relief & dissection - Water expulsion from burial compaction C. Concentration of uranium. 1. DIFFERENT DEPOSITIONAL ENVIRONMENTS 2. PRECIPITATION
DEPOSITIONAL ENVIRONMENTMost sandstone hosted epigenetic mineralisation occurs primarily within facies ofterrestrial system i.e in spectrum of fluvial and alluvial fans; while secondary but important setting is marginal marine/Shore zone. SOURCE AREA FAN •Unconfined flow Fan Delta • gravity mass transport • confine flow Braid Delta LACUSTRINE Lacustrine Geochemical isolation Delta FLUVIAL EOLIAN •Water mass stratification •Channelized flow •Unconfined flow •Instability SHORE ZONE •Waves •Tides •Storm processes DELTA • SHELF Transitional confine •Unconfined flow To unconfined flow •Strom processes •waves SLOPE AND BASE -OF-SLOPE The eight terrigenous clastic depositional system and the Gavity mass transport sediment transport pathways ± boundary confined flow that commonly connect them.
TABULAR SANDSTONE TYPE URANIUM DEPOSITProvenance : Granite / Basement gneises When U+6 in ground water comes in contact with carb.Host : Sst. with reducing environment matter in sediments, it is reduced to U +4 and getsTransporting agent : Ground water precipitated to form uranium deposit Cretaceous fluvial Uranium deposit Tertiary sediments sediments U+6 U+4 U+6 Carb. matter U+4 U+6 U+6 U+6 readily form soluble salts, gets dissolved and moves downdip along with ground water U+4 O U+6 oxidation U+4 U+6 U+4 U+4 Granite gneiss with uranium Granite with labile uranium
FAVOURABILITY FACTORS FOR FORMATION OF SEDIMENTARY TYPE URANIUM DEPOSITS, INDIA Favourability Criteria Gondwana Siwalik Mahadek (Meghalaya)Palaeogeography: Stable platform P P Por foreland interior basin; shelfmarginProvenance: Crystalline of silicic P P Pmagmatic or tuffaceous (granites) (Central Himalayan (Precambrian gneises &sediments Crystallines) Neoproterozoic Granite)Palaeoclimate: Humid followed by P P Parid-semiaridSedimentation: Fluvial / lacustrine P P P/ marginal marineStratigraphic traps:Alteration of P P Pcoarse and fine grained (Intermittent clay (Upp. & middle Siwalik (Palaeo-topography)continental fluvial sediments/ horizon) boundary)permeability barrier/topographicdepressionChemical traps: Arkosic P P Psediments with carbonaceousmatter/pyrite.Protective cover P P (only in few cases) PAge: Mostly Carboniferous to Upper carboniferous to Middle Miocene- Upper CretaceousTertiary Lower Cretaceous PlioceneP- Present
68° 00’ 76° 00’ 84° 00’ 92° 00’ Distribution of Indian Gondwana Sediments ● Srinagar32° ● Chamba 32°00’ 0 200 400 km 00’ ● Shimla Delhi ■ ● Lochi Total Area of Indian Gondwanas Gosainthan ●● Mt. Everest ● Sikkim Mesozoic-Tertiary ▲ Sediment-Filled Gondwana rocks Cambey Graben Damadar-Koel In frontal zone of Individual Basins Area Gondwana 24°32° S. Rewa Basin E. Himalaya 00’ (Sq km)00’ Bhuj Late Gondwana ● Continental Basin ▲ Sediments ▲ Mahanadi Calcutta Pranhita-Godavari = 29,000 ▲● ■ Satpura ▲ Satpura Basin = 14,700 Gondwana Basin Golsi-Malda Basin ▲ Rajmahal Bengal & Bihar = 13,000 Wardha ● Basin ● Athgarh Gondwana Basin Upper Mahanadi = 8,771 Trough ■ Mumbai Godawari Eastern Son Valley = 5,002 ▲ Basin ●16° ■ 16°00’ Hyderabad ● Godawari-Krishna 00’ Trough GONDWANA IN LESSER Palar HIMALAYA & TETHYAN DOMAIN Trough ■ Chennai EASTERN COASTAL TROUGH PENINSULAR GONDWANA BASIN Cauvery Trough ▲ URANIUM ANOMALIES ● THORIUM ANOMALIES8° 8°00’ 00’ 76° 00’ 84° 00’ 92° 00’
SOME SALIANT POINTS The Satpura Basin, located in the central part of Indian subcontinent, is the westernmost exposed Gondwana basin. This basin is limited to the north by Son-Narmada geo fractures, while the southern limit is marked by the faulted contact with Betul–Chhindwara plateau. It is an intra cratonic basin occurring at the junction of two tectonic trends namely sub latitudinal ENE-WSW Satpura trend and NW-SE Godavari grain. Structurally, basin can be divided into Denwa sub-basin in the north and Pench Kanhan sub basin in the south. Malni–Tamia high separates these two basins. The Betul–Chhindwara Crystallines form basement for Gondwanas and represent a conspicuous lithotectonic unit of the Central Indian Tectonic Zone (CITZ). These are traversed by several ENE –WSW trending ductile shear zones.
GEOLOGY AND PALAEOCURRENT MAP OF SATPURA GONDWANA BASIN NORTH 0 15 km KHARATORIA MATKULI NANNER JHIRPA BANDHI PACHMARHI RAMPUR POLAPATHAR TAMIYA GHORADONGRIINDEX PARASIADECCAN TRAPSJABALPUR FORMATION UPPERDENWA FORMATION GONDWANAPACHMARHI FORMATION RADIOACTIVITY OCCURRENCE MAJOR FAULTBIJORI FORMATIONMOTUR FORMATION LOWER MINOR FAULTBARAKAR FORMATION GONDWANA PALAEOCURRENT DIRECTIONTALCHIR FORMATIONBASEMENT (Geology after Peter et. al., 2001)
GENERALISED STRATIGRAPHIC SUCCESSION Thickness Age Formation Litho-unit (m) Trap BasaltEocene to Lameta (Infratrappean) Calcareous Sandstone, -- Mudstone & ConglomerateUp. Cretaceous ~~~~~~~~~~ Unconformity ~~~~~~~~~~Early to Middle Calcareous Sandstone and G Jabalpur ~250Cretaceous LimestoneLate Jurassic to Early O U N Coarse grained sandstone andCretaceous P Bagra 250 - 500 D conglomerates P W E Sandstone – MudstoneEarly to Middle Triassic A Denwa 300-600 R alternations N Coarse grained and pebblyEarly Triassic A Pachmarhi 500 - 800 sandstones ~~~~~~~~~~ Disconformity ~~~~~~~~~~ S U Sandstones and CarbonaceousLate Permian Bijori 450- 2000 P ShaleMiddle Permian E L Motur 400-750 Sandstone and Red Clay R O G W Sandstones, CarbonaceousEarly Permian R Barakar 120-500 E shale and Coal beds O R U Polymictic boulderLate Carboniferous to P Talchir 120 - 700 conglomerate, sandstones andEarly Permian olive green shale ~~~~~~~~~~ Unconformity ~~~~~~~~~~Precambrian Betul–Chhindwara Crystalline Complex (Basement)
Basement Characteristics Presence of granite gneiss, intrusive granites Presence of recycled metasediments, tuffs Average Radioelement content Metasediments : U3O8 3.2, ThO2 17 ppm (n=30) Granite : U3O8 7.9, ThO2 50 ppm (n=47) Uranium Anomalies within Basement Associated with ENE-WSW trending fractures containing Cherty cataclasites Radioactive phases: Collophane, allanite, zircon. Host Rock Characteristics: Rich in P2O5 and CaO with positive correlation with U content. U3O8 values upto 0.31% without ThO2 (n=98)
Variation in Paleocurrent direction in Motur Formation
DEPOSITIONAL ENVIRONMENT (MOTURS) Claystone Sandstone PASS 90 Semi- humid 80 Semi- arid H U M I D 70 AridSiO2 % A R I D 60 (After Suttner et al. 1986) 50 0 5 10 15 20 25 30 Al2O3+K2O+Na2O (%) Semi-arid to Semi-humid depositional palaeo-climate indicates low to moderate order of Chemical Maturity
PROVENANCE STUDY (MOTURS) 8 PASS Claystone Sandstone 6 Quartzose sedimentary Discriminant Function 2 ( f2) 4 provenance 2 Mafic 0 Igneous provenance Felsic -2 Igneous provenance -4 Intermediate Igneous provenance -6 (After Roser and Krosch 1988) -8 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 Discriminant Function 1 (f1)Discriminant function coefficients using TiO2, Al2O3, FeO(t), MgO, Na2O andK2O i. e., F1 and F2 scores exhibit predominance of felsic igneous provenance,along with little contribution from Quartzose Sedimentary and intermediateigneous Provenance is supported by the presence of Granites, Metasediments inBetul Complex. This is further substantiated by Al2O3/TiO2 ratio (8.49 to 70.11).
BH No:PM-22 BH No:PM-28 BH No: PM-29 INDEX Altered brown sandstone Violet clay stone Grey clayey sandstone 0.029%eU3O8 Light grey bleached X2.30m sandstone Sandstone with black carb.(?) shale & pyrite Grey sandstone with shale fragments 0.041%eU3O8 X2.70m 0.011%eU3O8 X0.40m 0.045%eU3O8 X3.00m
Lithology Colour GrainsizeDepth S F M C G 0m Lithology Index Overburden Depth vs. Ra eU3O8 & ThO2 Sandstone for core sample Claystone/mudstone 20m Colour Index Values in ppm Brownish Yellow 0 100 200 300 Buff 175 40m Brown/Chocolate brown Ra eU3O8 Dark Grey Grey 176 ThO2 Light Grey/Dirty white 60m 177 Grainsize Index S Silt/Clay Porosity 15% F Fine 178 by volume M Medium 80m C Coarse 179 G Very Coarse/Grit 100m 180 Depth (m) 181 120m 182 Porosity 11% by LITHOLOG OF BOREHOLE PM-69 183 volume 140m Polapathar-Mansingpur Area, Betul Dist., M.P. 184 160m Porosity 185 13% volume 186 180m U-Mineralisation (1.90m x 0.014%) 187 200m 188
SOURCE OF URANIUM FOR SATPURA GONDWANA SEDIMENTS Satpura Gondwana Basin is surrounded by Granites and Metasediments of Betul – Chhindwara Crystalline Complex and acted as provenance for the supply of detritus material to the basin. Fertile basement - Metasediments of Betul crystalline complex contains an average content of 3.2 ppm U3O8 and 17 ppm ThO2 17 ppm and granite and gneisses contain 7.9 ppm U3O8 and 50ppm ThO2. Uraninite, Brannerite, Davidite, Monazite, Zircon, Apatite, Sphene, Pyrochlore and Betafite are present in the basement. Presence of Acid Volcanics in the Provenance and Volcaniclastic Material in Gondwana Sediments are also one of the important source of Uranium in the system. Sediment of Lower Gondwana contains higher intrinsic uranium content
CONTROLS OF URANIUM MINERALISATION Eh-pH condition of the depositional environment. Change in the Palaeocurrent direction. Alternate sequence of sandstone and claystone/shale with shallow dip of Formation. Porosity and permeability of host rock. Presence of basic dykes/sills leading to compaction of sediments and expulsion of connate water rich in dissolved uranium, as well as act as barrier for the flow of uraniferous groundwater. Presence of pyrite and carbonaceous matter as reductant in the system.
FAVOURABILITY FACTORS FOR URANIUM MINERALISATION IN MOTUR FORMATION OF SATPURA GONDWANA BASIN Highly Fertile Palaeoproterozoic Basement–cum-Provenance with Labile Uranium Presence of Acid Effusives in the Provenance Thick pile of Gondwana Sediments with alternating sequence of arenaceous and argillaceous beds in Rift related Basin Porous and Permeable Feldspathic to Sub-feldspathic Arenites with volcaniclastic material as well as presence of Oxidised and Reduced Arenites Pre- and Post-depositional reactivations and tectonic deformations providing channel ways for hydrothermal solution movements Enhanced Thermal Gradient by Profuse Mafic/Basic intrusives Presence of suitable reductants such as Carbonaceous Matter, Pyrite and Iron in sediments etc. to Fix & Precipitate U Availability of suitable environment and locales such as Redox interfaces in Unconformity Planes and Fracture Zones for Fixation of Uranium INDICATES HIGH POTENTIAL OF SATPURA GONDWANA BASIN FOR SANDSTONE-HOSTED D URANIUM MINERALISATION
CONCLUSIONSGEOLOGY OF THE SATPURA GONDWANA BASIN Satpura Gondwana basin (14700 sq km) is located in the environs of Son – Narmada Rift Zone, which is an important Structural Domain in Central India and known for Base Metal, Precious Metal, Radioelement and REE mineralisation associated with various lithounits located in its vicinity. Exposes a thick pile of Gondwana Sediments in this Rift related Basin over Palaeoproterozoic Basement Rocks. Gondwana sediments exhibit large facies variation right from Glacial Tillites (Talchir) to alternate sequences of Arenaceous and Argillaceous rocks signifying the change in depositional and tectonic environment. Satpura Gondwana Basin has various signatures of Pre- and Post- depositional Tectonic activity and Reactivation viz. Faults/ Fractures, profuse emplacement of Basic Intrusives and Effusives etc. Out of all the Formation of Lower and Upper Gondwana; Motur Formation of Lower Gondwana seems to be the most promising horizon.