Showing papers in "Journal of Geochemical Exploration in 1989"

TL;DR: In this paper, the authors show that overbank sediment produces broad geochemical patterns with high contrasts reflecting the bedrock geochemistry, and a large Mo-deposit missed by a traditional stream survey is readily detected in the over-bank sediment.

TL;DR: In this paper, the authors propose a method to identify statistical outliers, which are candidates for interpretation as true geochemical anomalies, and isolate a multi-element subset that is representative of the geochemical background.

TL;DR: In this article, the authors compare the relative merits and required assumptions of various threshold selection techniques, or evaluate their efficiencies and sensitivities under various data-distribution forms, under various case histories.

TL;DR: In this paper, the shape and chemical composition of Au nuggets sampled at various depths in a lateritic profile in the proximity of a site where Au mineralization has occurred was studied.

TL;DR: In this paper, the dispersion of Au and associated trace elements was studied in detail from the fresh ore in deep drill hole samples to soils in surface materials in the Betare Oya region, in east Cameroun, gold mineralization was indicated by contents of As, Bi, Ag, Mo, W, Pb, and Au.

TL;DR: The Chinese national geochemical mapping project (RGNR) as mentioned in this paper was initiated in 1978 and has been successfully used to discover hundreds of new mineral deposits and occurrences by follow-up of the geochemical anomalies delineated by the project.

TL;DR: In this article, large sediment samples collected from a 5 km reach of a mature highland stream were used to investigate the effects of bar morphology and channel slope on the downstream dispersion of Au.

TL;DR: In this article, the authors used termitaria sampling in the search for gold in this arid environment, where the soil cover is less than 2 m thick and detailed (100 m × 50 m) soil sampling for gold is effective in delineating target areas.

TL;DR: A consistent pattern has been observed in the results obtained for Au in three soil and two porphyry copper ore samples serving as control reference standards in geochemical analyses as discussed by the authors, and it is concluded that methods based upon AR dissolution can lead to low results, the magnitude being dependent upon the sample matrix and the mineralogical association of the Au present.

TL;DR: In this article, a conceptual model is outlined for the genesis of at least some quartz-carbonate gold deposits, showing that gold was carried upwards in the narrowing shear, to be focused and precipitated at or above the brittle-ductile transition.

TL;DR: The chalcophile trends revealed by regional multi-element laterite geochemistry are typically 15-30 km wide and 50-100 km long, some extending to 150 km as mentioned in this paper.

TL;DR: Lecomte et al. as discussed by the authors studied gold dispersion in a tropical rainforest weathering profile at Dondo Mobi, Gabon, and found that the dispersion pattern is somewhat anisotropic, a strong enlargement being observed in the upper (Hl) and intermediate nodular (H2) horizons alike.

TL;DR: In this paper, all platinum-group metals (PGM) in ashed plant tissues, from an area of platinum mineralization in Saskatchewan, have been measured by neutron activation analysis of a NiS fire assay bead.

TL;DR: The Bamble Belt of south Norway is a major transcurrent shear zone, 30 km wide, comprised of lower Proterozoic supracrustal rocks and tholeiitic intrusions as discussed by the authors.

TL;DR: In this article, generalized exploration models were established for deeply weathered terrains, based on the degree of preservation of pre-existing profiles formed under predominantly humid, tropical climates, and the modification due to later climatic and tectonic events.

TL;DR: In this article, a biogeochemical study was conducted in the semiarid environment of the Zenda property, which is located approximately 50 km east of Bakersfield, California in addition to semiaridity, the test also was able to measure the influence of high relief on the effectiveness of plants as sample media for Au.

TL;DR: In this paper, the progress of epimerisation of 20R 5α(H), 14α (H),17α( H) 24-ethylcholestane to the corresponding 20S diastereomer with increasing maturity of the sediments was investigated.

TL;DR: The O'Toole nickel sulphide mine is located in the Southern Plateau morphological and structural province of Minas Gerais, Brazil and has a humid tropical climate characterized by a mean temperature of 19°C and rainfall of 1600 mm as mentioned in this paper.

TL;DR: The Geochemical Atlas of Finland as mentioned in this paper is designed to give comprehensive background information on the distribution of elements in rocks, soils, and the surficial environment, which is used in the Geochemical Mapping of till.

TL;DR: In this article, geochemical and mineralogical investigations have been carried out on laterite profiles developed in the Lake Sonfon Au district of northern Sierra Leone, and the significance of these observations is discussed in relation to the origin of the lateritic Au and the role of the associated trace elements as indicators of the mineralization.

TL;DR: A comparison of gold distribution in several sieved fractions with various pedologic horizons shows that the distribution of gold changes abruptly from the coarser sizes near the source to the finest sizes 150 m downstream as discussed by the authors.

TL;DR: In this paper, a database of analyses of C 1 and C 7 hydrocarbons from an oil and gas producing region in Mexico has been assembled from gas samples collected at depths of 3, 15 and 30 meters from surficial holes drilled in traverses over producing and barren structures.

TL;DR: An orientation survey was conducted over the Quartz Mountain, Oregon, hot-spring type disseminated gold deposit to address three questions critical to successful exploration of the area: What is the relationship between bedrock geology and the trace-element content of trees and soils; do these relationships change seasonally; are these relationships similar in the two tree species which discontinuously blanket the area? Twig, needle and wood samples were collected four times during the year from both ponderosa pine ( Pinus ponderosa ) and white fir ( Abies concolor ). Soils were collected once as mentioned in this paper.

TL;DR: In this article, multivariate geostatistics conceptualize this observation by defining various spatial categories on the basis of a variogram model, which represent a classification of regional, local and pointwise spatial scales.

TL;DR: In this article, the authors describe a number of filtering techniques motivated by the development of exploratory data analysis (EDA) and robust statistical procedures These are the median filter (MF) and the adaptive trimmed mean filter (ATM) for the smoothing of regional geochemical data to reduce spurious variations; two new filters, the fence filter and the notch filter (NF), have been developed to define geochemical anomalies.

TL;DR: In this paper, the distribution of gold in overburden in a 2400-km 2 area of southwestern Gaspesie, Quebec, Canada is examined to ascertain parameters which govern the distribution.

TL;DR: In this paper, the authors discuss the monitoring and prediction of seismic activities by measuring the Hg content of water and reach the preliminary conclusions that changes in the water demonstrate the most sensitive reaction to seismic activities known at the present time and can be used for monitoring and predicting such activities.

TL;DR: The Koyukukuk-chandalar mining district of the Brooks Range mineral belt in northcentral Alaska contains numerous placer gold deposits but few known lode gold sources as discussed by the authors.

TL;DR: The Unst ophiolite consists of four major units, a basal harzburgite overlain by dunite, clinopyroxene-rich cumulates and gabbro as discussed by the authors.