Statistics in the interpretation of geochemical data

Williams, X. K.

doi:10.1080/00288306.1967.10431092

Cited by 14 publications

(8 citation statements)

References 6 publications

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“…The lodes at the two localities are of comparable thickness, and some data (Modriniak & Marsden 1938;Williams 1964;Williams & Wood 1967), suggest that they may be of similar extent.…”

Section: Comparison Wim Moke Creek Mineralisationmentioning

confidence: 84%

“…In hydrochemical and so~ the main stream below the workings was "rich in copper", and that soil samples taken mainly from the positions of the earlier electrical survey lines showed copper anomalies. The geochemical and geophysical surveys Williams (1964; found that sediment rn;.. anomalies did not coincide, but were considered close enough to "suggest the presence of a zone of copper mineralisation" . Bishop (1964) added structural notes and a sketch map to his report on trials with a portable diamond drill at the locality.…”

Section: History and Previous Workmentioning

confidence: 98%

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Mineragraphy and origin of copper-bearing sulphides at Waitahuna River, eastern Otago

Lowery

1979

New Zealand Journal of Geology and Geophysics

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The mineralogy and textures of specimens from a sulphide occurrence in a green schist at Waitahuna River are described, and their origin is discussed. The ore minerals are chalcopyrite, pyrite, marcasite, pyrrootite, and minor sphalerite, and there is a small amount of supergene alteration. Marcasite, and the later of two main types of pyrite, are believed to have formed from pyrrhotite after the main stage of metamorphism, but are not supergene.The occurrence is thought to be a stratiform volcanic-sedimentary deposit, but the textures are mainly of metamorphic origin. Mineralogy, geological environment, and probably origin, are similar to those of the occurrence at Moke Creek, near Queenstown.

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“…The lodes at the two localities are of comparable thickness, and some data (Modriniak & Marsden 1938;Williams 1964;Williams & Wood 1967), suggest that they may be of similar extent.…”

Section: Comparison Wim Moke Creek Mineralisationmentioning

confidence: 84%

Section: History and Previous Workmentioning

confidence: 98%

Mineragraphy and origin of copper-bearing sulphides at Waitahuna River, eastern Otago

Lowery

1979

New Zealand Journal of Geology and Geophysics

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“…It exhibits a straight line in coincidence with a normal distribution, possibly suggesting a singular event (Sinclair, ; McLachlan & Basford, ). In addition, a bimodal or polymodal distribution of grade of ores generally should be identified in an episodic/multi‐stage mineralization (Tennant & White, ; Williams, ; Li et al ., ). Therefore, the skarn alterations and Fe mineralization might have occurred in a singular geological event, which should be the intrusion of Yanshanian Dayang–Juzhou granite.…”

Section: Discussionmentioning

confidence: 99%

Geological Features and Formation Processes of the Makeng Fe Deposit, China

Zhang

Cheng

2015

Resource Geology

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Recent studies have revealed that the Makeng Fe deposit is a skarn type deposit. However, the skarns in Makeng, occurring primarily between limestone and sandstone, are not typically associated with limestone and plutons. Different periods of intrusions, e.7. Hercynian mafic intrusions and Yanshanian (i.e. early Cretaceous) Dayang-Juzhou granitic intrusion, occurred in the Makeng deposit district. In this study, the formation processes of the skarns and Fe mineralization are constrained by detailed fieldwork, petrology, geochronology, and geochemistry. Skarns and Fe mineralization intersecting the Hercynian mafic intrusions are observed in consecutive specimens from the 106# tunnel. They suggest that the skarn formation and Fe mineralization occurred after the Hercynian mafic intrusions and are related to the later Yanshanian Dayang-Juzhou granitic intrusion. The geochronological characteristics of weakly skarn-altered diabases, the decreasing nature of Fe contents in altered diabase, and the major element compositions of pyroxenes and garnets also support that Hercynian mafic intrusions are strongly reformed by Yanshanian granitic magmas and the Fe migrated from mafic intrusion was responsible for formation of iron ore.

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“…When the cumulative frequency of the results is plotted on probability paper, the curve becomes a straight line when one distribution is present; a break or point of inflection in the curve indicates the presence of two distributions, one background and the other anomalous. The point of inflection gives a good estimate of the threshold concentration (Cassie, 1954;Williams, 1967a). This method gives a threshold concentration of 198 p.p.m., with 30'4 percent of the anomalous distribution below this value, and 2'5 percent of the background distribution above it.…”

Section: Mcconnochie's Soil Surveymentioning

confidence: 99%

Geochemical prospecting for copper, West Otago

Williams

Wood

1967

New Zealand Journal of Geology and Geophysics

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Results of geochemical prospecting surveys for copper in the Moke 'Creek area, the Shotover district, and the Skippers Creek area of west Otago are presented. Copper in soils was found to be contained almost entirely within the finest fractions, and to be associated mainly with clastic chlorite. Anomalies in soils indicate that the cupriferous sulphide laminae of the Moke Creek Copper Lode extend beneath the soil at least 500 ft southward from the most southerly prospect pits, but the lack of anomalies to the north indicates that the copper lode does not extend much beyond Moke Creek. The source rocks of a cupriferous boulder found in the Shotover River may be a greenschist band in Ironstone Creek, with which are associated soil and water anomalies. Additional anomalies were found during a reconnaissance hydrochemical survey of the upper Shotover drainage system. The absence of strong geochemical anomalies in the Skippers Creek area suggests that cupriferous schist at Skippers Point does not extend into that area.

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Statistics in the interpretation of geochemical data

Abstract: 771A statistical method of determining the threshold concentration in geochemical exploration is described. Examples are presented of its use in prospecting surveys at Parakao, Northland; Shotover River, Moke Creek, and Waitahuna, Otago; and the Longwood Range, Southland.

Cited by 14 publications

References 6 publications

Mineragraphy and origin of copper-bearing sulphides at Waitahuna River, eastern Otago

Mineragraphy and origin of copper-bearing sulphides at Waitahuna River, eastern Otago

Geological Features and Formation Processes of the Makeng Fe Deposit, China

Geochemical prospecting for copper, West Otago

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