Geochemical criteria for identifying diamond-bearing areas
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-01-01 |
| Journal | E3S Web of Conferences |
| Authors | Lev Krinochkin, V.A. Kilipko, A. G. Trofimov, Olga Krinochkina, Dinya Mamina |
| Analysis | Full AI Review Included |
Geochemical Criteria for Identifying Diamond-Bearing Areas
Section titled âGeochemical Criteria for Identifying Diamond-Bearing AreasâExecutive Summary
Section titled âExecutive SummaryâThis research establishes and validates geochemical criteria for identifying and grading diamondiferous targets using medium-scale lithochemical survey data from the Myunyusyakhsk area (Anabar Craton).
- Core Achievement: Developed two multiplicative geochemical indices, Kkim and Kdiam, capable of pinpointing potentially diamond-bearing areas (kimberlite halos) that are significantly larger than the source pipes.
- Data Source: Reinterpretation of 1:200,000 scale lithochemical surveys (2020-2022), utilizing ICP-MS analysis of stream sediments and soils.
- Key Indicators: Diamondiferous kimberlites are strongly correlated with high clarke-normalized concentrations of Cr, Ni, Mg, and Co.
- Prospectivity Grading: The Kdiam coefficient differentiates diamondiferous kimberlites from barren alpicrites by contrasting the Cr-Ni-Co suite against the V-Cs-Rb suite.
- Target Identification: 51 anomalous geochemical fields were identified and grouped into 11 clusters. The study successfully pinpointed 11 potentially diamondiferous targets, including one area (Anomaly No. 7) estimated to have the highest prospectivity in the region.
- Exploration Impact: The criteria allow for effective, low-cost targeting of small kimberlite bodies using widely spaced (1-1.5 km) sampling data, expanding the known boundaries of diamondiferous districts.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Geochemical Survey Scale | 1:200,000 | N/A | Scale of lithochemical sampling |
| Sampling Interval Range | 1 to 1.5 | km | Distance between sampling points |
| Analytical Method | ICP-MS | N/A | Used for analysis of 60 chemical elements |
| Kimberlite Occurrence Index (Kkim) Formula | KcCr x KcNi x KcCo | N/A | Multiplicative index for identifying kimberlite halos |
| Diamond Prospectivity Coefficient (Kdiam) Formula | (KcCr x KcNi x KcCo) / (KcV x KcCs x KcRb) | N/A | Index for grading potential diamond content |
| Kkim Threshold (Assessment) | > 2.0 | N/A | Minimum value for an anomaly to be considered an assessment object |
| Kkim Value (Highest Anomaly, No. 1) | 90.1 | N/A | Highest recorded Kkim value in the study area |
| Kimberlite Indicator Elements | Cr, Ni, Mg, Co | N/A | Elements showing highest clarke-normalized values in diamondiferous kimberlites |
| Alpicrite Indicator Elements | V, Cs, Rb | N/A | Elements used in the Kdiam denominator; show inverse correlation with Cr, Ni, Co |
| Malokuonamsk Pipe Dimensions | 255 by 320 | m | Dimensions of the reference diamond pipe (Pipe 5) |
Key Methodologies
Section titled âKey MethodologiesâThe assessment of diamond potential relied on a systematic, multi-step geochemical approach:
- Lithochemical Sampling: Medium-scale (1:200,000) sampling of stream sediments and soils was conducted across the Myunyusyakhsk area, with sample analysis performed by ICP-MS for 60 elements.
- Indicator Element Selection: Clarke-normalized concentrations of elements in known alkaline ultrabasites were analyzed. Diamondiferous kimberlites were characterized by high Cr, Ni, Mg, and Co, while barren alpicrites showed high V, Nb, Ce, Ta, etc.
- Kkim Calculation (Kimberlite Occurrence): The concentration coefficient (Kc) for Cr, Ni, and Co was calculated (element content / background content). These coefficients were multiplied to define the Kkim index (Kkim = KcCr x KcNi x KcCo), used to map geochemical halos.
- Anomalous Field Delineation: 51 anomalous geochemical fields were contoured using Kkim isolines (Kkim > 2.0). These fields were then grouped into 11 geochemical clusters based on spatial and geological context.
- Kdiam Calculation (Diamond Prospectivity): To grade the anomalies, the diamond prospectivity coefficient was introduced. This index uses the ratio of kimberlite indicators (Cr, Ni, Co) to alpicrite indicators (V, Cs, Rb), reflecting the inverse geochemical trend: Kdiam = (KcCr x KcNi x KcCo) / (KcV x KcCs x KcRb).
- Target Differentiation: Anomalous fields were plotted on a Kkim vs. Kdiam scatter diagram. This diagram allowed for differentiation into high, moderate, and unclear prospectivity areas, resulting in the identification of 11 high-potential targets.
Commercial Applications
Section titled âCommercial ApplicationsâThe developed geochemical criteria provide a cost-effective and efficient tool primarily for the mineral exploration sector.
- Diamond Exploration:
- Greenfield Targeting: Rapidly assessing large, previously unexplored territories (like the SE Anabar) to identify high-priority drilling targets.
- Cost Reduction: Utilizing existing medium-scale survey data (1:200,000) to locate small, elusive kimberlite pipes, avoiding expensive, high-density sampling in non-prospective areas.
- District Expansion: Geochemically defining and expanding the boundaries of known diamondiferous districts (Birigindinsk I, Kuronakhsk II) and identifying new potential districts (Talakhtakhsk III).
- Mining Resource Management:
- Resource Grading: Providing a quantitative, geochemically derived estimate (Kdiam) of the potential economic significance of newly discovered anomalies.
- Rare Metal Exploration:
- Differentiation Tool: The methodology inherently distinguishes diamond-bearing kimberlites (Cr, Ni rich) from rare metal-bearing carbonatites/alpicrites (Nb, Ta, REE rich), allowing exploration efforts to be precisely focused on either diamond or rare metal resources.
View Original Abstract
The paper demonstrates that diamondiferous objects may be pinpointed even by the middle-scale geochemical surveys. Relevant criteria were developed to identify and classify such objects by their prospectivity. The study materials are the results of geochemical surveys carried out in the Myunusyak area, Sakha-Yakutia, RF, in 2020-2022. The geochemical study was carried out by lithochemical sampling. Sampling was carried out on a scale of 1:200,000, i.e., the sampling interval varied between 1 and 1.5 km. The samples were analyzed by ICP-MS. The results of the study show the possibility of identifying potentially diamondiferous areas by geochemical methods identifying geochemical halos of kimberlite fields. The prerequisite for this was the idea of diamondiferous objects as areas of spatially close kimberlite bodies and associated host rock alterations. The products of their destruction form secondary halos and trains of indicator elements of kimberlite magmatism, which dimensions can significantly exceed the those of the pipes and are detectable by the medium-scale geochemical surveys. Using the criteria developed, produced an assessment of the diamond potential of the Myunyusyak area, Anabar Craton. A number of promising areas were identified by the authors, including one of especially high prospectivity.