Use of Moran’s I and robust statistics to separate geochemical anomalies in Jiurui area (Southeast China)

Year 2018, Volume: 156 Issue: 156, 179 - 192, 27.06.2018

Thanh Nguyen Tien

https://doi.org/10.19111/bulletinofmre.351376

Cited By: 2

Abstract

Separation of geochemical anomalies from background plays an important
role in the study of exploration geochemistry. The limitations of commonly used
methods are not taken into account spatial correlation, variability and the
unsatisfactory of the statistical assumption of the normality of geochemical
data. For solving these limitations, an indirect method for the separation of
geochemical anomalies is proposed based on anomaly separation of local Moran’s
Ii values using robust statistics in this study. The experiment was carried out
using 1481 samples collected from Jiurui copper prospect (southeast China). The
steps for the anomaly separation are (i) spatial association and variability
were fi rst analyzied by means of Moran scatterplots at six spatial scales (2,
4, 6, 8, 10 and 12 km) using both raw data and Box-Cox transformed data; (ii)
local Moran’s Ii was used to measure spatial autocorrelationat these six local
scales; (iii) anomalous separation was fi nally performed using the MEDIAN ±
1.5*IQR (IQR: interquartile range) rule on local Moran’s Ii values. The results
show that geochemical anomalies are mostly concentrated around known
ore-deposits, according the objective reality and a strong correlation with
known ore-deposits in Jiurui copper prospect.

Keywords

Anomaly distribution, Terrestrial Moran Statistic, Robust Statistics, Jiurui Copper Field.

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