Application of geostatistics to complete uranium resources estimation of Rabau Hulu Sector, Kalan, West Kalimantan

Roni Ciputra,Dhatu Kamajati,Heri Syaeful,Suharji Suharji,E Haryono,F Lavigne,A Cardenas Tristan,R Fitria Putri,R Che Omar,D Rahmawati Hizbaron,B White

doi:10.1051/e3sconf/202020006001

Abstract

Kalan is one of the focus areas for uranium exploration in West Borneo that conducted by BATAN. Situated in the central part of Kalan, previous works in Rabau Hulu Sector consisted of surface geology and radiometric anomaly mapping, trenching, drilling, logging, and conventional uranium resource estimation. Nevertheless, the complete resource estimation of the previous work was still using 2D modeling, and the latest one using 3D modeling is a method-application case study in one orebody. To increase the confidence level and completing the uranium resource estimation of all orebodies in this sector, a geostatistical estimation with 3D orebody modeling using SURPAC mine planning software was conducted in this paper. Gamma-ray log data from 32 drill holes were collected and then interpreted to obtain uranium grade-thickness data. Based on the correlation of grade-thickness data according to surface orebody orientation, the orebody 3D modeling was done. It resulted in 26 orebodies with one control system of lithology as the mineralization only taken place in the quartzite unit. This 3D model then used as a constraint for block model with 4x4x2 m block size and 0.25x0.25x0.125 m minimum block size. Block model calculation was performed using ordinary kriging which generated the kriging efficiency attribute for the determination of the resource category. Within 25 meters searching radius, the calculation resulted in 408, 480 tons of ore, while total uranium resource was 268 tons of uranium with 677 ppm average grade. There were 214 tons of uranium (79%) categorized as measured while the other 54 tons of uranium (21%) categorized as indicated.

Highlights

It dated back to 1969 when Indonesia, through BATAN, conducted the uranium exploration in the country’s territory
After the period of collaboration between BATAN and France’s CEA in 1977, the exploration program focused on Kalan Area of Ella Hilir Region, West Borneo which had the most significant uranium mineralization indication
Situated in the northern margin of the Schwaner Mountains as portrayed by Figure 1, Kalan geologically consists of Pinoh Metamorphic Group (PMG) rocks that were intruded by later granitic rocks of Sepauk Tonalite and Sukadana Granite in some parts

Summary

Introduction

It dated back to 1969 when Indonesia, through BATAN, conducted the uranium exploration in the country’s territory. The Protolith of the Pinoh Metamorphic was the volcanogenic sediments that suggested to be formed during subduction at the PaleoPacific margin after the collision of South West Borneo to Sundaland in Early Cretaceous (130 Ma) [1] These rocks going through thermal metamorphism due to volcanic arc-related emplacement of I-type granitoid rocks from c. The latest work on the uranium resource of Rabau Hulu Sector was a case study of the application of geostatistic for resource category in one orebody (Orebody 15) with 3D modeling and Ordinary Kriging interpolation method on SURPAC mine planning software[8]. The objective of this paper is to estimate the uranium resource of all orebodies in Rabau Hulu Sector with the Ordinary Kriging method using SURPAC mine planning software. The result is expected to contribute to the inventory of uranium resources of Indonesia as a material for the stake holder’s decision making

Regional Geology of Kalan

Methods

Findings

And Discussion