Applied mineral exploration methods, hydrothermal fluids, baro-acoustic decrepitation, CO2 rich fluids
Viewpoints:

Thermodynamics shows Au is insoluble in CO2 fluids

Do IOCG deposits form from CO2 rich fluids?

Inclusion shapes can prove heterogeneous trapping

Disproportional FI trapping from heterogeneous fluids explains gas-dominant systems

A discussion of H2 analysis by mass spectrometry

A mechanism to form H2 in the MS ioniser during analyses

Why don't Exploration geologists understand fluid inclusions?

News:

New model 205 decreptiometer

Studies of 6 Pegmatite deposits

A study of the Gejiu tin mine, China

Data on MVT Pb-Zn deposits, Tunisia

Data from Hall and Mt Hope Mo, Nevada

A magnetite study - Bergslagen region, Sweden

Exploration using palaeo-hydrothermal fluids

Using opaque minerals to understand ore fluids

Decrepitation using Fe-oxide opaques

Understanding baro-acoustic decrepitation.

An introduction to fluid inclusions and mineral exploration applications.



 Interesting Conferences:


Futores II, June 4-7, Townsville, Australia

ECROFI 2017, June 23-29, Nancy, France

AOGS 14th, Aug 6-11, Singapore

SGA 2017, Aug. 20-23, Quebec city, Canada

SEG 2017, Sept. 17-20, Beijing, China

Exploration 17, Oct. 21-25, Toronto, Canada

AAG 2017 at RFG2018, June 16-21 2018, Vancouver, Canada


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 8 8988 1599       Fax +61 8 8988 1859
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
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 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
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

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

Decrepitation related references in date order

CASE STUDIES:

Archaean & Proterozoic hosted quartz vein deposits
Western Australia
Victory mine
Kalgoorlie
Mt Charlotte, Kalgoorlie

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

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


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
Western Australia
Greenbushes (pegmatite)
Kalgoorlie
Londonderry (pegmatite)
Mt Charlotte, Kalgoorlie
Victory mine
Southern Cross

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

Uzbekistan

Muruntau

India

Malanjkhand Cu

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

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
Contact Details

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