Toronto Geological Discussion Group






 

Events



Upcoming events

    • 26 Sep 2017
    • 4:00 PM - 6:00 PM
    • 20 Toronto Street
    • 42

    MVT Deposit Genesis at the Start of the 21st Century


    “I didn’t know until recently that stratigraphy is dead. Many schools don’t teach it any more. To me that’s writing the story without knowing the alphabet." - John McPhee, 1986: Rising from the Plains


    Theorising about the origin of Mississippi Valley Type Lead Zinc Deposits came to an abrupt climax in the middle 1980s and interest declined soon after. Quantitatively, there were fewer students and supervisors, and less stratigraphy. Many, if not all of us, switched to gold exploration or retired from the field.


    I have had nearly 40 years to think, but not much research was available for input. The field appears to be fallow from disuse. Considering the states of art in 1980 and 2017; there may be a place for cryogenics after all. Last year the price of zinc and lead, principal metals of MVTs rose to a dollar a pound and more, riding the particularly strong US dollar. As many large zinc producers closed, zinc and lead greenfield deposits have had their Easter and are rising from the dead.


    MVTs are a subset of base metal deposits competing with volcanogenic (VMS) and SEDEX deposits, but are lower in iron content. All smelters will find MVT concentrates desirable.

    The typical Frankenstein genetic model (constructed from many parts) has structural control, reefs or not, facies fronts, basinal brines or not, fluid mixing or not, complex breccia, disconformities and karst, dolostone or limestone; remind yourself of the fable of the blind men examining an elephant. In Jainism, it is explained that truth can be stated in seven different ways.


    There is something old (Sloss sequence stratigraphy) and something new (cathode-luminescence) that narrows my personal 2017 model from the 1980 genetic model. Sloss sequence stratigraphy coincides with continent-wide erosion surfaces (disconformities) which have controlled regolith porosity and permeability and provides a locus not only for MVT deposits but probably for sediment hosted gold deposits.


    Cathodoluminescence in carbonate rocks is activated by manganese and inhibited by the presence of iron. In many MVT cases C-L distinguishes mineralisation paragenesis because the precipitation of iron sulphide as pyrite allows visualisation of carbonate gangue history. At Robb Lake in the Muskwa range of the Canadian Rockies C-L shows that the brecciation of epigenetic dolostone collapse features was dynamic and is penecontemporaneous with mineralisation and the replacement of evaporite minerals; selenite gypsum for certain and very possible wholesale replacement/removal of a thicker nodular anhydrite unit.


    There is a lot of catching up to do.


    Dr. Francis Tucker Manns is a geologist/stratigrapher and the sole practitioner of Artesian Geological Research in Toronto, Canada. He has had a long year career in geology of base metals and gold in Canada, US and Borneo. Fran has worked as a consultant at Derry, Michener and Booth in Toronto, as an exploration geologist at whatever he was told to look for, and as a mining analyst. He recommended Eldorado Gold Corp. when it had one mine in Mexico, and recommended Virginia Gold because of the people, but thought Bre-X was too lean and too deep. He became a geologist at the Toronto Stock Exchange during the launch of NI 43-101 and retired to MVT land after 14 years in 2014.


    Education:

    PhD - University of Toronto Dissertation (1982) on the stratigraphic aspects of the Robb Lake lead/zinc deposit, NE British Columbia. In 1972, he was part of a team exploring for lead/zinc on Cornwallis Island near Polaris. He contracted each summer at Robb Lake and throughout the main range of the Rockies from the Peace River north with Texasgulf, Brinex, and later into Alaska for Northgate Exploration Ltd. While in grad school he managed drill programs in the Rockies and Newfoundland.


    He participated in a large working group specialised in Mississippi Valley type lead and zinc deposits at UofT. He visited and sampled operating mines in Missouri, Tennessee, New York, Newfoundland, Pennsylvania, Nova Scotia and Ireland.


    BA, MA – Temple University, Philadelphia, Pennsylvania Specialised in stratigraphy and paleoenvironments of limestone and dolostone of the central Appalachians and western New York.


    Publications:

    On resource estimation and quantification of the nugget effect.


    • 10 Oct 2017
    • 4:00 PM - 6:00 PM
    • 20 Toronto Street
    Discovery of the Kencana Au-Ag ore deposit, Indonesia


    Discovery of the Gosowong, Toguraci and Kencana ore deposits on Halmahera Island in Indonesia owes much to serendipity, good science and necessity. The deposits are examples of high grade, low-sulphidation epithermal Au-Ag mineralisation and were discovered between 1992 and 2003.


    Gosowong and Toguraci were identified with surface sampling even though outcrop was mostly absent and were mined by open pit. The much larger and deeper Kencana deposit had no identifiable surface expression and is being mined underground. The Gosowong, Toguraci and Kencana deposits contained in situ mineral resources which totalled >6.0 M oz Au, with an average grade of >20 g/t Au.


    Gosowong was discovered serendipitously while exploring for epithermal Au and porphyry Au-Cu mineralisation in Miocene-age andesitic volcanic rocks. Discovery is generally attributed to sampling a very short stream which closely parallels the strike of the Gosowong vein. Discovery of the Toguraci cluster of ore shoots, in several adjacent epithermal veins during a necessity-driven search for additional ore to sustain the Gosowong mining operation, followed from re-sampling a narrow quartz vein.


    The Kencana deposit is about three times the size of the combined Gosowong and Toguraci deposits and was discovered by applying good science, but was assisted by serendipity.


    Speaker: Dan Wood, AO


    Dan Wood retired as an exploration geologist in 2008 after 24 years with BHP and 18 years with Newcrest Mining where he was Executive General Manager Exploration. Newcrest was judged by Metals Economics Group of Canada to have been the World’s most successful gold explorer, 1992-2005.


    He has received several international exploration awards and is the 2017 Thayer Lindsley Visiting Lecturer for the Society of Economic Geologists. In 2015, he was appointed an Officer of the Order of Australia (AO) by the Australian Government for his service to the mining industry.


    • 07 Nov 2017
    • 4:00 PM - 6:00 PM
    • 20 Toronto Street
    • 80


Past events

12 Sep 2017 Geology of the Barkerville Deposit
23 May 2017 Geogames for Grown-Ups Challenge
09 May 2017 Castelo de Sonhos: De-risking a gold paleo-placer using tools and methods from the petroleum industry
25 Apr 2017 Mini-Symposium - Turning the Switch On: The Geology of Li-Ion Battery Materials and how to Evaluate Risk in Today's Markets
04 Apr 2017 Richmont's Island Gold Mine: Exploration continues to rejuvenate the potential of the Goudreau-Lochalsh District of the Wawa Gold Camp
21 Feb 2017 The Marathon Gold Valentine Lake Property in Central Newfoundland, an emerging Gold Camp
31 Jan 2017 Geology, Chemostratigraphy, and Alteration Geochemistry of the Rosemont Cu-Mo-Ag Skarn Deposit, Southern Arizona
17 Jan 2017 Evaluating the interplay of magmatism, tectonics, and basin redox in the genesis of the Wolverine volcanogenic massive sulfide (VMS) deposit, Yukon, Canada
13 Dec 2016 Gahcho Kué Diamond Mine: The Long Road from Discovery to Production
24 Nov 2016 Mini-Symposium - Innovation and Change in Mineral Exploration
01 Nov 2016 Qiqavik: A New District Scale Au-Cu Camp in Nunavik, Quebec?
18 Oct 2016 Spectral, multispectral, hyperspectral: What works, what could work, and what will not work
27 Sep 2016 Ontario Geological Survey Geoscience Programs Update
13 Sep 2016 Structural Controls on Magmatic Ni-Cu-PGM Sulfide at Wallbridge Mining’s Parkin Offset Dyke Deposit in Sudbury, Ontario
17 May 2016 Transition Metals PGM-Ni-Cu Discoveries: Sunday Lake and Aer-Kidd, a Separation of 700 Kilometers and 700 Million Years
04 May 2016 Integrating multiple lines of evidence to define the exploration target range for the Castelo de Sonhos Paleo-placer gold Project, Brazil
19 Apr 2016 Mini-Symposium - The Big Bang: Understanding the Magmatic Controls of Mineral Deposits
05 Apr 2016 Alturas – A Recent High Sulphidation Gold Discovery on the El Indio Belt, Chile
18 Feb 2016 Geology and Mineralization of the New Afton alkalic porphyry Cu-Au deposit
10 Feb 2016 Murray Brook Polymetallic VHMS Deposit, Bathurst, New Brunswick
26 Jan 2016 From Sadiola to the recently discovered Boto Gold Deposit, 25 years of gold mining and exploration discovery in West Africa
15 Dec 2015 Mining Project Development Experience – Where Do Things Go Wrong and Why
18 Nov 2015 Mini-Symposium – Abitibi Gold: The next 135 million ounces
02 Nov 2015 TerraX Minerals Inc.
20 Oct 2015 Recent Advances in Ocean Mining
29 Sep 2015 55 Zone - A new high grade gold mine on the Yaramoko Property, Burkina Faso
14 Sep 2015 The Arrow Uranium Zone, a Rapidly Emerging Discovery - NexGen Energy Ltd.
05 May 2015 Brucejack Project,B.C.
18 Apr 2015 Mini-Symposium – Working Smart: Using the downturn in the economy as an opportunity
31 Mar 2015 The (geochemical) Hitchhikers’ Guide to Magmatic Ni-Cu Prospectivity in a Greenstone Belt
03 Feb 2015 Amaruq: The early days of a significant gold discovery
20 Jan 2015 The Renard Diamond Project: 13 Years From Discovery, Now Under Construction
09 Dec 2014 Facts and Fallacies: a personal commentary on the last 45 years of uranium exploration and development in the Athabasca Basin of northern Saskatchewan.
09 Dec 2014 Exploration for Deep VMS Ore Bodies: The Hudbay Lalor Case Study
19 Nov 2014 Mini-Symposium – Canada's Mineral Landscape: Aboriginal Rights and Related Issues
21 Oct 2014 The Geologic Framework and Potential for Deep Seated Deposits at the Superior Project, Ontario
07 Oct 2014 Hardrock Gold Project, Geraldton, Ontario: Structural and stratigraphic settings of the deposits
23 Sep 2014 Timing and Controls on Gold Mineralization in the Abitibi Greenstone Belt
15 Sep 2014 Deep Mineral Exploration - The Next Economic Geology Frontier
09 Sep 2014 The discovery of the Goldrush deposit, Cortez Camp, Nevada
13 May 2014 Alexkor and the Richtersveld Land Claim – A retrospective diamond mineral property valuation case study
29 Apr 2014 Advancing Canada's newest gold district: The Borden gold project
09 Apr 2014 Mini-Symposium – Mexico Exploration: Finding the Treasure of the Sierra Madre and more
18 Feb 2014 Geometallurgical Modelling of the Dumont Deposit
04 Feb 2014 The Pistol Bay Gold Project, Nunavut, Canada A new district of Archean gold deposits in a variety of rocks - not just iron formation!
21 Jan 2014 Deep Mining Exploration reveals Ancient Waters of the Precambrian Shield
10 Dec 2013 OSC Staff Notice 43-705: a fair reflection of the mining industry’s recent performance?
21 Nov 2013 Mini-Symposium – Applied Earth Modelling: Better Targeting Using 3D Exploration
05 Nov 2013 The Curraghinalt Orogenic Gold Deposit, Northern Ireland. A Pot of High Grade Gold at the End of the Rainbow
22 Oct 2013 A multidisciplinary approach to the Attawapiskat kimberlite field: accelerating the discovery to production pipeline
01 Oct 2013 Discovery of the Mesel, Batu Hijau, and Elang Deposits, Indonesia: Successful Greenfields Exploration
17 Sep 2013 Exploring and Developing the Hope Bay Project: Approaches Both Old and New
28 May 2013 Do Recent Changes to Ontario’s Mining Act Make the Province a Less Competitive Jurisdiction to Explore?
14 May 2013 Sabodala Gold Mine, Senegal
30 Apr 2013 Key Elements for Mineral Exploration Success: An Example from Neves-Corvo, Portugal
16 Apr 2013 The Rovina Valley Au-Cu Project, Golden Quadrilateral, Romania: New Discoveries in an Old Mining District
02 Apr 2013 Economic geology of black shale – hosted vanadium mineralization in Xiushui County, Jiangxi Province, southeastern China
26 Mar 2013 Mini-Symposium – Laterites or Laterwrongs: Making the Pieces Fit
19 Feb 2013 Anna Fonseca – Infrared Spectroscopy Applied to Alteration Mapping
05 Feb 2013 Joe Hinzer – Challenging Mineral Property Evaluations
22 Jan 2013 Jean-Francois Ravenelle – Geology of the Eleonore Gold Deposit
04 Dec 2012 Jeremy Niemi – The Romero gold discovery, Dominican Republic
08 Nov 2012 Mini-Symposium: The future of mining and exploration in Canada
23 Oct 2012 John Ryder – Paleoplacers – Are Archean/Proterozoic diamondiferous placers/paleoplacers potentially new sources of diamond supply to meet the looming diamond shortage?
09 Oct 2012 Warren Bates – Geology, alteration and Geophysics an the Manfo Gold Project, Sefwi Belt, Ghana
25 Sep 2012 Brent Cook – Exploration vs. Finance and the Low Odds of Success
11 Sep 2012 Hernan Ugalde – Geological Modeling of Geophysical Data: Beyond the 3D inversion black box, v2.0
18 Apr 2012 Hamid Mumin – Iron Oxide Copper-Gold Deposits in Genetic Context
03 Apr 2012 Sally Pehrsson – A new evolution and architecture for the Trans Hudson orogeny and its use in targeting for world class VMS, Nickel and Gold deposits
20 Mar 2012 Jim Mungall – Formation of iron oxide and phosphate tephra of the El Laco volcano, Chile from an Fe-P-O-S magma.
21 Feb 2012 Sergio Cattalani – Discovery and Development of the Canadian Malartic Bulk-Tonnage Gold Deposit, Southern Abitibi, Quebec, Canada.
07 Feb 2012 Workshop and Mini-Symposium on the Complexities of Grade Estimation
24 Jan 2012 Xiaodong Zhou – The Use and Limitations of Aster Satellite Imagery for Exploration



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