INTEGRATION OF DUAL BORDER EFFECTS IN RESOURCE ESTIMATION: A COKRIGING PRACTICE ON A COPPER PORPHYRY DEPOSIT
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Date
2021-06-22
Authors
Madani, Nasser
Maleki, Mohammad
Sepidbar, Fatemeh
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI AG
Abstract
Hierarchical or cascade resource estimation is a very common practice when building a
geological block model in metalliferous deposits. One option for this is to model the geological
domains by indicator kriging and then to estimate (by kriging) the grade of interest within the
built geodomains. There are three problems regarding this. The first is that sometimes the molded
geological domains are spotty and fragmented and, thus, far from the geological interpretation. The
second is that the resulting estimated grades highly suffer from a smoothing effect. The third is
related to the border effect of the continuous variable across the boundary of geological domains.
The latter means that the final block model of the grade shows a very abrupt transition when crossing
the border of two adjacent geological domains. This characteristic of the border effect may not be
always true, and it is plausible that some of the variables show smooth or soft boundaries. The
case is even more complicated when there is a mixture of hard and soft boundaries. A solution is
provided in this paper to employ a cokriging paradigm for jointly modeling grade and geological
domains. The results of modeling the copper in an Iranian copper porphyry deposit through the
proposed approach illustrates that the method is not only capable of handling the mixture of hard
and soft boundaries, but it also produces models that are less influenced by the smoothing effect.
These results are compared to an independent kriging, where each variable is modeled separately,
irrespective of the influence of geological domains
Description
Keywords
Border effect, Cokriging, Copper porphyry deposit, Indicator kriging, Smoothing effect, Type of access: Open Access
Citation
Madani, N., Maleki, M., & Sepidbar, F. (2021). Integration of Dual Border Effects in Resource Estimation: A Cokriging Practice on a Copper Porphyry Deposit. Minerals, 11(7), 660. https://doi.org/10.3390/min11070660