Metal Associations of Volcaniclastic Strata

Course Details

Volcaniclastics host a wide range of metals in both sub-aerial and sub-aqueous settings. The list of deposit types includes Volcanogenic Massive Sulfides, Lithium Clays, Epithermal, and Orogenic Gold (metamorphosed to Greenschist facies). Mapping of these units in the sub-surface requires a through understanding of volcanic and depositional processes. Not only is it important to understand porosity-permeability controls within pyroclastic units – as in the case of the El-Indio High Sulfidation Epithermal Deposits in Chile, but also unconformities that may form high permeability streaks such as the ore zone in the Lepanto Copper-Gold deposit, Philippines.

A series of world-class outcrops have been picked from the Central San Juan Caldera Complex in Colorado, USA. Participants will be able to see:

1. Block and Ash Flow facies
2. Pyroclastic Fall, Flow and Surge facies
3. Hyaloclastites
4. Lithium-bearing clays
5. Coherent and auto-brecciated lava flow facies
6. Alteration zones in a High-Sulfidation Epithermal Deposit 
7. Ag-bearing Intermediate-Sulfidation Epithermal Veins

Unlike your typical SEG field trip, this is not a “show-and-tell” excursion. Participants will be collecting data by measuring sections and will be participating in a series of exercises.

By the end of the trip you should be able to:

1. Identify common volcanic, pyroclastic and epiclastic facies
2. Predict alteration zones in high and intermediate sulfidation epithermal systems
3. Map volcanic units in the sub-surface
4. Describe and interpret volcaniclastic facies in core
5. Understand controlling parameters on Li grade in clay deposits

This field trip focuses on the controlling parameters on the distribution and stratigraphy of volcaniclastic host rocks, if you are wanting a field trip on magmatic hydrothermal systems please click here.

If you are working in SE Asia we would recommend attending a version of this course taught in Indonesia where we lead you to Ijen Crater Lake and the exposed porphyries of Pulau Merah.


Who Should Attend

• Geologists • Geochemists
• Mining Engineers • Resource Modelers • Geotechs

This course is meant for all who are required to describe volcanics and volcaniclastic strata in core and create maps and cross-sections 

Need more information?

    Course Outline

    Day 1

    HSE briefing, orientation to the field area and lectures on pyroclastic fall versus pyroclastic flow and surge deposits

    In the field we will look at the Fish Canyon “Tuff” – a series of world-class outcrops associated with the La Garita eruption. Participants will learn how to describe and interpret common pyroclastic lithofacies, interpret textures and map their distribution.

    We will be spending the night in South Fork.

    Day 2

    The Creede Mining District has produced 60 million Troy Ounces of Silver along with Zinc, Lead and minor Gold. The amethyst-rich vein textures are exemplified as textbook examples of intermediate sulfidation epithermal deposits. 

    After a classroom lecture on epithermal deposits and the volcaniclastic host rocks in the area we will be visiting outcrops around Creede to look at lacustrine moat deposits and a mine tour where participants can see vein textures purchase samples of amethyst veins if so inclined!


    Day 3

    Summitville Mine is where the classic models of alteration zones associated with high-sulfidation epithermal deposits were developed. We will be checking-out of our hotel in South Fork in the morning visit outcrops and will spend the night in Saguache.

    Day 4

    We will spend the day in the North Pass and Cochetopa Calderas and will focus on sub-aerial pyroclastic surge deposits, coherent vs auto-brecciated facies in lava flows, columnar jointing in dacitic lava flows, and pyroclastic fall deposits with incinerated tree trunks.

    The highlight of the day will be examining lacustrine clays that are have values of Lithium as high as 860 ppm. We will be discussing volcanic and depositional processes that control Lithium grade in clay deposits.

    Day 5

    We will be checking out of our hotel in Buena Vista and head for the United States Geological Survey Core Repository to learn how to describe and interpret volcaniclastics associated with underwater explosive eruptions. You will not only get to see hyaloclastites but the full spectrum of turbidites, debrites and hyperpycnites associated with sub-aqueous volcanic activity.

    The field trip ends at 1 pm and their airport is only 30 minutes away, so we recommend booking an evening return flight.

    This course will be offered between September 23-27, 2024 and costs $3500/person. This all inclusive rate includes five nights hotel stay, all meals, snacks and drinks in the field, fuel, permits, transportation during the field trip, tuition and field guide.

    Our location

    Our headquarters are twenty minutes away from downtown Denver and half an hour from the largest core facility in the United States. Or field office in Ouray allows us quick access to world-class outcrops in Utah and New Mexico.