Applied mineral exploration methods, hydrothermal fluids, baro-acoustic decrepitation, CO2 rich fluids #
Newest Topics:

Exploration of the Mt. Boppy Au deposit, NSW

Forensic tests on soil samples

Gold at Okote, Ethiopia

Viewpoints:

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



News:

Kalgoorlie Au data

Sangan skarn Fe deposits, Iran

New models 205 & 216 decreptiometer

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.



 Interesting Conferences:

-----2021-----

ECROFI 2021, Reykjavik, Iceland

SGA, Rotorua NZ, RESCHEDULED to march 28-31 2022
-----2022-----
6th Archean, Perth, W.Aust. RESCHEDULED unknown date 2022


Comprehensive Geology Conference Calendar


Using fluid inclusion data in mineral exploration

Rapid data acquisition by the baro-acoustic decrepitation method

An overview of  information and results on using fluid inclusion information in exploration
Kingsley Burlinson
Burlinson Geochemical Services Pty. Ltd.
P.O. Box 37134,   Winnellie,  NT,  0821,     Australia
Ph. +61 411 443 097    (Within Australia  0411 443 097)
decrepitation  <at>  appliedminex.com

Skip down to:     CONTENTS       Case studies by deposit       Case studies by location  You can search this site here

OVERVIEW

Fluid inclusions are trapped remnants of the fluids which formed hydrothermal mineral deposits and provide a unique insight into the chemical and physical conditions  of ore forming fluids. Academic studies of ore deposit genesis have long relied on this vital fluid inclusion data to understand the genesis of ore deposits. But despite the obvious relevance of this information, the exploration community has largely failed to use this data in their routine exploration activities to target potentially economic hydrothermal systems.

Baro-acoustic decrepitation is a simplified method to obtain reproducible, non-subjective fluid inclusion data quickly and without the need for polished thin sections or microscopes. It can provide information about the source fluid environment and targeting vectors on project-scale numbers of samples, at modest price and with quick analytical turnaround. It does not provide fluid salinities or the pedantic levels of precision required in academia, but these aspects are not particularly useful in exploration and frequently just add confusion rather than resolution.

The most important use of baro-acoustic decrepitation is in determining approximate total gas contents of samples, as this data is frequently closely correlated with mineralisation potential. Examples in this documentation show this use as well as others including the  discrimination between samples which are visually identical and in discerning temperature zonation effects within a vein, mine or small exploration area. It can even be used on opaque minerals where microscopy is completely impossible, and many examples from iron oxide minerals are shown here.

The baro-acoustic decrepitation method was wrongly discredited by early work in the 1950's in Canada at a time when the presence of gas-rich fluids in hydrothermal systems was not understood and neither was the thermodynamic behavior of such fluids within inclusions. With the benefit of our currently much improved understanding of fluid systems it is now clear that baro-acoustic decrepitation does in fact provide a very useful and practical mineral exploration technique, particularly given the ability to digitally automate the instrumentation as has been done.

Baro-acoustic decrepitation is not intended to compete with the very high accuracy of slow and painstaking microscopic fluid inclusion research. However, as with soil geochemical surveys, where low cost and speed are more important than extreme accuracy, baro-acoustic decrepitation has a valuable role to play in many types of exploration programme. Although the method is usually applied to quartz samples, it has been used on various minerals including sulphides, haematite, magnetite, fluorite, carbonates and jasperoids.

An extensive database of some 5000 analyses from numerous ore deposits worldwide is the basis for the following information.

 

CONTENTS:

An introduction to fluid inclusions and their application in mineral exploration
Gold exploration using Baro-acoustic decrepitation
The decrepitation method - what is it and why use it?
Decrepitometry application to porphyry deposits (1981 report)
The fluid inclusion technique in exploration for Au mineralisation (Old report, 1982)

Sample collection techniques
Result interpretation
Decrepigram interpretation features
Using fluid inclusions in the opaque minerals haematite and magnetite
Fluid Inclusion Studies on Opaque Minerals
Customs information for sample entry to Australia
Selecting the best sample grainsize to use for decrepitation analyses
Forensic comparison or contrasting of soil samples
Using curve fitting to deconvolve the results to precisely identify multiple component sub-populations of inclusions
Using 3 software packages to de-convolve decrepigrams into component populations for quantitative interpretation
Using Baro-acoustic decrepitation data in exploration at the Drake mineral field, NSW and the application of curve fitting to the decrepitation data
Understanding baro-acoustic decrepitation
Why CO2-rich fluid inclusions decrepitate at low temperatures
Decrepitation behavior of all non-condensing gases are similar
Inclusion abundances and controls on decrepitation
Using baro-acoustic decrepitation to semi-quantitatively measure CO2 contents
Decrepitation ONLY detects fluid inclusions, it does not detect crystallographic changes.
Model 216 decrepitometer developed,2019.
Model 205 decrepitometer developed, march 2017.
The Model 105 decrepitometer - a brief description
Comparison of different decrepitation Instruments
Comparison of the Russian decrepitometer and the BGS model 105 decrepitometer.
Comparison of decrepitation with mass spectrometric gas determinations during heating

Explaining the formation of CO2-only fluid inclusions
Gold deposition from heterogeneous aqueous, CO2-rich fluids: resolving the enigmatic and misleading hypothesis of deposition from CO2 only fluids.
Gas dominated inclusion assemblages may be trapped from aqueous dominant heterogeneous fluids by disproportional trapping
The extreme differences between aqueous boiling heterogeneous fluids and immiscible gas aqueous heterogeneous fluids.
Spherical inclusion morphology of CO2 only inclusions indicates heterogeneous trapping from a liquid.
Fluid inclusions in quartz cannot prove that non-aqueous fluids CO2 formed the ore.
Why don't exploration geologists use or understand fluid inclusions? The case at the Cadia Au-Cu mine, NSW, Australia.
Hydrogen contents of fluid inclusion volatiles should not be analysed by mass spectrometer.
A model for the formation of H2 from water in the electron impact ioniser of the mass spectrometer
A discussion and reply on the error of using  mass spectrometry to analyse hydrogen in aqueous analytes.

Geochemical exploration using hydro-thermal fluids - a paper at the SGA conference, Uppsala Sweden, Aug. 2013
Fluid Inclusion Studies on Opaque Minerals - a paper presented at the ACROFI-4 conference, Brisbane QLD., August 2012
Gold exploration using Baro-acoustic decrepitation - a paper presented at the IMA, Budapest, 2010
Understanding baro-acoustic decrepitation - a paper presented at ACROFI-2, Kharagpur, 2008
Exploration for gold using fluid inclusions - a paper presented at the AAG conference, Oviedo, Spain, 2007.
An updated understanding of the baro-acoustic decrepitation method. (proposed for the ECROFI meeting, Bern, 2007)
Acoustic decrepitation as a rapid means of determining CO2 (and other gas) content of inclusion fluids and its use in exploration (Nanjing, 2006)
Fluid inclusions in mineral exploration - a paper presented at the AAG conference, Santiago, Chile, 2001.    Poster presentation
  • Exploration of the Mt. Boppy Au deposit region, Cobar, NSW, Australia:  by K.G. McQueen
  • Intrusion related gold at Okote, Southern Ethiopia:  by Solomon Geda
  • Exploring for Au using fluid inclusions in the Tanami region, NT, Australia:  by T. Mernagh
  • The use of fluid inclusion decrepitometry to distinguish mineralised and barren quartz veins in the Aberfoyle tin-tungsten mine area, Tasmania. (1983)   (abstract)      (full paper, pdf)

    An instrument for fluid inclusion decrepitometry and examples of its application. (1988)  (abstract)       (full paper, pdf)

    The recognition of variations in sample suites using fluid inclusion decrepitation - applications in mineral exploration (1988)   (abstract)    (full paper, pdf)

    Decrepitation studies in gold exploration. A case history from the Cotan prospect, N.T., Aust.  (1991)   (abstract)   (full paper, pdf)

    Comparison of decrepitation, microthermometric and compositional characteristics of fluid inclusions in barren and auriferous mesothermal quartz veins of the Cowra Creek gold district, New South Wales, Australia  By: J.A. Mavrogenes et. al., (1995)  (abstract)

    Acoustic Decrepitation as a means of rapidly determining CO2 (and other gas) contents in fluid inclusions and its use in exploration, with examples from gold mines in the Shandong and Hebei provinces, China  (2007)   (full paper, html)

    A discussion to point out errors in H2 analyses of fluid inclusion volatiles by mass spectrometry.  (2013)

    Fluid types and their genetic meaning for the BIF-hosted iron ores, Krivoy Rog, Ukraine.  By Marta SoĊ›nicka et.al.  (2015) Extract (PDF file, 3.5 Mbyte) here

    Mineral geochemistry of the Sangan skarn deposit, NE Iran: Implication for the evolution of hydrothermal fluid. By Fatemeh Sepidbar et.al. (2017) Extract (PDF file, 5.8 Mbyte)

    Decrepitation related references in date order

    CASE STUDIES:

    Archaean & Proterozoic hosted quartz vein deposits
    Western Australia
    Victory mine, Kalgoorlie
    Archaen gold - Kalgoorlie
    Mt Charlotte, Kalgoorlie
    Kalgoorlie
    Coolgardie
    Southern Cross

    Northern Territory, Australia
    Tanami and Arunta areas
    Arltunga area
    Tennant Creek

    Pine creek (COTAN project)
    Enterprise

    Cosmo Howley

    Ontario, Canada
    Dome mine
    Abitibi region, general

    Palaeozoic sedimentary hosted deposits
    Victoria, Australia
    New South Wales, Australia
    Meguma Terrane, Nova Scotia, Canada
    Nevada, USA
    Italy
    Brusson


    Epithermal Deposits
    El Penon, Chile
    Favona vein, Waihi, NZ
    Banksa Stiavnica district, Slovakia
    Cukuralan, Turkey
     
    Granite hosted & porphyry deposits
    Hebei province, China
    Shandong province, China
    Kisladag, Turkey


      Orogenic / Structual gold-quartz systems
    Motherlode, California, USA
    Muruntau, Uzbekistan
    Okote,  Ethiopia

    Iron oxide - Copper - Gold deposits
    Overview of FeOx-Cu-Au systems
    Great Bear magmatic zone, NWT, Canada
    Tennant Creek, NT, Australia
    Magnetite and haematite decrepitation data
    Mengku, northern Xinjiang, China
    Magnetite at Krivoy Rog, Ukraine
    Magnetite from the Bergslagen region, southern Sweden
    Comparing and contrasting skarn and BIF magnetites


    Hall porphyry Mo, Nevada
    Mt Hope porphyry Mo, Nevada

    Mt Bischoff, Tasmania, Australia
    East Kemptville (Mt. Pleasant), Nova Scotia, Canada

    Erzgebirge tin greisens, Germany - Czech Republic

    Gejiu, Yunnan, China
    Escondida, Chile
    Chuquicamata, Chile

    Malanjkhand, India
    Chessy, France
    Carbonatite
    Kapuskasing, Ontario, Canada
    Silica
    Black Bull, Nova Scotia, Canada
    Lead-Zinc
    Mississippi valley type, Tunisia
    Iron
    El Laco, Chile
    Krivoy Rog, Ukraine
    Sangan Fe skarn,  Iran
    Mengku, northern Xinjiang, China
    Magnetite from the Bergslagen region, southern Sweden
    Kola Peninsula, Russia

    Baryte
    Calcite
    Carbonate
    Nova Scotia
    Kunming, China

    Chert
    Fluorite

    Galena

    Garnet (China)

    Magnetite & Haematite

    Magnetite & Pyrite

    Magnetite at Krivoy Rog, Ukraine

    Magnetite in skarns and BIFs

    Pyrite

    Sphalerite
    Tourmaline (China)

     

    Australia

    Northern Territory
    Bynoe harbour (pegmatite)
    Enterprise, Pine Creek
    Pine creek (COTAN project)
    Cosmo Howley
    Tennant Creek
    Tanami and Arunta
    Arltunga area
    Victoria
    Ballarat
    Ballarat University grounds
    Fosterville
    Bendigo, Wattle Gully, Maldon
    Woods point - the Morning Star mine
    New South Wales, Australia
    Cowra Creek goldfield
    Mt. Boppy gold mine, Cobar area
    Western Australia
    Greenbushes (pegmatite)
    Archaen deposits - Kalgoorlie
    Londonderry (pegmatite)
    Mt Charlotte, Kalgoorlie
    Victory mine, Kalgoorlie
    Kalgoorlie area mines
    Coolgardie area mines
    Southern Cross area mines

    New Zealand

    North Island
    Waihi,  Favona vein

    North America

    Canada
    Ontario
    Abitibi area
    Grenville (pegmatite)
    Dome mine, Timmins
    Kapuskasing carbonatite

    Manitoba
            Tanco (pegmatite)
    Northwest Territories
            Great Bear magmatic zone
    Nova Scotia
            Black Bull Silica

            Dufferin
            Mt. Pleasant Sn
            The Ovens
            Regional

    USA
    California
    Motherlode
    Nevada
    Getchell mine
    Twin Creeks mine
    Regional Jasperoids
    Manhattan, Paradise Peak, Goldstrike
    Hall porphyry Mo
    Mt Hope porphyry Mo

    Asia

    China
    Dongping, Hougou, Huangtuliang - Hebei
    Jiaojia, Canshang, Sanshandao - Shandong
    Mengku Feoxide - Xinjiang
    Gejui and Kunming - Yunnan

    Uzbekistan

    Muruntau

    India

    Malanjkhand Cu

    Middle east

                        Sangan Fe skarn,  Iran

    South America

    Chile
    El Laco (iron)
    El Penon
    Escondida
    Chuquicamata

    Europe  (including Turkey)

    France
    Chessy, Cu-Zn.
    Massif Central (pegmatites)
    Italy
    Brusson Au

    Germany - Czech Republic
    Erzgebirge tin greisens, Germany - Czech Republic

    Slovakia
            The Banksa Stiavnica eptihermal gold veins

    Romania

    Sweden
            Bergslagen region, magnetite study

    Turkey
           
    Cukuralan, Turkey
            Kisladag, Turkey

     Ukraine
            Krivoy Rog, magnetite in BIF

    Africa

     Tunisia - Bou Jaber, Bou Grine
    Okote, Ethiopia

    Russia

    Kola Peninsula, Iron

    • Global comparisons

    Comparing and contrasting magnetite skarns
    A comparison of 6 pegmatite provinces - Sn, W & Ta deposits


    K. Burlinson 2009, 2011, 2012, 2019
    Contact Details

      The Instrument & Author