Migration and enrichment of elements in the nickel laterite weathering crust of the tropical region: A case study of the Pili Nickel deposit in the Surigao district, southern Philippines
Author:
Affiliation:

Clc Number:

Fund Project:

  • Article
  • |
  • Figures
  • |
  • Metrics
  • |
  • Reference
  • |
  • Related
  • |
  • Cited by
  • |
  • Materials
  • |
  • Comments
    Abstract:

    The Philippines and Indonesia in tropical Southeast Asia are the world’s major producers of laterite nickel deposits. Laterite nickel deposits are widely distributed in the Surigao district of the southern Philippines and are generally hydrous magnesium- silicate type. In this study, we discuss the zonation characteristics and element migration- enrichment of the laterite nickel weathering crust in the tropical region. Methods: We studied the detailed field geology of the Pili laterite nickel deposit in the Surigao district, Philippines, combining mineralogical compositions and geochemical characteristics of the laterite nickel weathering crust profile. Results: According to the mineral compositions, the weathering crust profile of Pili laterite nickel ore is divided into four layers from top to bottom: clay layer, laterite layer, saprolite layer, and bedrock. Saprolite is the main Ni ore- bearing layer of the deposit, which contains about 1 wt% nickel. Geochemical characteristics of the laterite profile show that the laterite is rich in Fe and Mn, and poor in Si and Mg. The upper clay layer is rich in Al, Si, Cr, and Ni, and poor in Fe and Mn compared with the laterite layer. Different from common laterite nickel deposits, the laterite of the Pili nickel deposit is quite Ni- poor. The element migration ratios in the profile show that the clay layer has experienced strong losses of Si, Mg, Fe, and Mn, and the red soil has experienced strong losses of Mg and Si and a moderate loss of Fe and Mn. The lower saprolite layer experienced the enrichment of Fe, Mn, Cr, and Ni.Conclusions: Based on the above findings, we propose three stages of processes to explain the element migration and enrichment of Pili laterite nickel deposits: the saprolite development stage, laterite development stage, and late dissolution and precipitation stage. There was no obvious element migration or loss during the initial development stage of saprolite. At the initial development stage of laterite, the loss of Mg, Si, and other elements occurred under the influence of surface fluids. After the initial formation of laterite, the upper part of laterite also experienced strong losses of Fe and Mn and formed the clay layer due to the continuous leaching of reducing surface fluids, which was probably affected by heavy rainfalls in the tropical region. In the middle laterite layer, there were strong Ni loss and moderate Fe and Mn losses. The intense element migration at this stage may be the specific characteristic of nickel laterite weathering crust in the tropical region. The fluid- leached nickel gradually migrates down from the laterite layer following the fluid and eventually accumulates in the saprolite in the form of nickel- bearing magnesium silicate. The findings of this study provide significant indications for the exploration of laterite nickel deposits in the district.

    Reference
    Related
    Cited by
Get Citation

GAO Ya, DENG Jianghong, YANG Xiaoyong, DUAN Liu’an, LUO Xiandong.2022. Migration and enrichment of elements in the nickel laterite weathering crust of the tropical region: A case study of the Pili Nickel deposit in the Surigao district, southern Philippines[J]. Geological Review,68(5):1839-1852.

Copy
Share
Article Metrics
  • Abstract:
  • PDF:
  • HTML:
  • Cited by:
History
  • Received:December 24,2021
  • Revised:May 01,2022
  • Adopted:
  • Online: September 19,2022
  • Published: September 15,2022