Applied mineral exploration methods, hydrothermal fluids, baro-acoustic decrepitation, CO2 rich fluids
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New model 216 decreptiometer

Exploration of the Mt. Boppy Au deposit, NSW

Forensic tests on soil samples


Do IOCG deposits form from CO2 fluids?

How CO2 inclusions form from aqueous fluids (UPDATED)

Understanding heterogeneous fluids : why gold is not transported in CO2-only fluids

Gold-quartz deposits form from aqueous - CO2 fluids: NOT from CO2-only fluids

Discussions why H2 analysis by mass spectrometry is wrong


Gold at Okote, Ethiopia

Kalgoorlie Au data

Sangan skarn Fe deposits, Iran

Studies of 6 Pegmatite deposits

A study of the Gejiu tin mine, China

Exploration using palaeo-hydrothermal fluids

Using opaque minerals to understand ore fluids

Understanding baro-acoustic decrepitation.

An introduction to fluid inclusions and mineral exploration applications.

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     July 2-6

AOGS Singapore
    30 Jul - 4 Aug 2023

SGA Zurich Aug 2023

Comprehensive Geology Conference Calendar

Woods Point - Curve fitting details for selected samples

The data de-convolution was performed using 2 different software packages. The details of the fitting procedure are discussed here.

Analytical run h2284 of sample number 505a is from the Campbell's reef location.
In this plot, the yellow "Gaussian_6" plot is the mathematical sum of the components and overlies the red "nonlinear fit" curve. This is merely a confirmation that the deconvolution is correct. The 4 component populations provide a good match to the original "rawdata_6" graph, but note that the peaks are visibly skewed rather than being symmetrical gaussian distributions. This fit was done using the Scidavis software package.

fit 2284

Analytical run h2288 of sample number 508 is from the 7 sublevel of the Morning Star mine.
In this fit, performed using the fityk software package, 5 populations were required to provide a good fit to the raw data shown by the unconnected filled circles. Note that 4 of the peaks are close to symmetrical, while the low temperature peak at 240 C is moderately skewed.

fit 2288The details of the fitting procedure are discussed here.

Analytical run h2303 of sample number 511 is from the Morning Star adit.
In this fit, 5 component populations provide a good fit to the raw data curve.

fit 2303

Analytical run h2306 of sample number 519 is from Dicken's reef.
In this fit 7 separate population components are required to provide a good fit to the raw data. Note that all of the components are close to symmetrical gaussian distributions.

fit 2306

Analytical run h2319 of sample number 529 is from the 6 level of the Morning Star mine.
in this fit 8 component populations are required to fit the raw data. Note the interesting additional low temperature peak at 190 C in addition to the commonly observed population at 240 C. This indicates a complex multiple stage deposition from fluids with significantly different CO2 contents over time. This sample is thought to contain 200 ppm of Au, one of the highest in the survey and perhaps this additional CO2 peak is an especially favorable indicator for Au mineralisation potential. (Sample descriptions are here)

fit 2319

This plot shows the results of the peak fitting for all the samples in this study. The mode temperature of each fitted population component is shown by the black plus sign, with the radius of the blue circle around each of these points being proportional to the height of the fitted population peak. The most interesting feature is the presence of large low temperature CO2 peaks in almost all of the samples.

Note that the cleaning quartz has a distinctly different low temperature peak.
Note also that sample h2319 (plotted at number 40) is the only sample with an additional low temperature peak at 190 C.

woods point all data plot


The de-convolution of the decrepigrams provides a quantitative means to compare and contrast the samples. It is best used within a spatial suite of samples to define areas of similar mineralisation potential or to discriminate between anomalous and background samples. The complexity of the fits with many population components highlights the known fact that hydrothermal systems are indeed complex with multiple fluid events and they should not be thought of as simple homogeneous events as they too often are merely because the quartz all looks the same.

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