TMCC Community Education Classes—begin June 3

TMCC is offering some community classes with a focus on geology. You can check out the classes here:
https://truckee.augusoft.net/index.cfm?fuseaction=1010&
Click on “Recreation and Wellness—Outdoors”

TMCC Workforce Development and Community Education, 5270 Neil Road #216, Reno, (775) 829-9010

Gold Prospecting Series
Save 10 dollars when you register for gold panning and gold sluicing at the same time.

Mother Lode Gold Panning
Find out why gold panning is one of the fastest growing outdoor recreational activities in the country. Take in the beauty of a Sierra river while you practice your gold panning skills. Must provide own transportation. Save $10 when you register for gold panning and gold sluicing at the same time. $10 materials fee

Gold Sluicing
Prerequisite: Mother Lode Gold Panning. Build on the experience you have gained from the gold panning class. Try out sluicing and other prospecting techniques. Learn how to use the river’s flow to find more gold. Must provide own transportation. Save $10 when you register for gold panning and gold sluicing at the same time.

Geology Exploration: Sierra Nevada
Discover how our majestic mountains were formed during this lecture and field trip course. Discuss area glaciation, earthquake faults and more. Then tour with a geologist to visit fascinating features in Genoa, the Walker River and Hope Valley. Enjoy collecting cool rocks and discussing area history.

GSN Regular Membership Meeting—May 17

 

“The location is again at Great Basin’s Taps & Tanks, 1155 S. Rock Blvd. Reno, NV. Drinks @ 6:00 pm, APPETIZERS @ 6:30 pm, Talk @ 7:15 pm. Speaker, Mike Ressel, NBMG/UNR. Title: “Carlin-type Deposits As Part of the Great Basin’s Eocene Metallogeny“. DRINKS SPONSORED BY: FALCON DRILLING AND HARRIS EXPLORATION DRILLING! Appetizers only for $15—prepay online or pay at the door. GSN students are free. For more info contact Laura Ruud at gsn@gsnv.org or 775-323-3500. Details on page 3. To PREPAY for appetizers please click on this link: https://squareup.com/store/GSNV

No reservations required but avoid the line by pre-paying!”

Speaker: Mike Ressel, NBMG

Topic: Carlin-type Deposits As Part of the Great Basin’s Eocene Metallogeny

Mike Ressel, Curtis Johnson, Elizabeth Hollingsworth, Christopher Henry, and Philipp Ruprecht, Nevada Bureau of Mines and Geology and/or University of Nevada, Reno

Abstract: Late Eocene (~42-34 Ma) ore deposits have contributed a majority of the Great Basin’s precious- and base-metal production through 2015, including about 6.2 Kt Au (199 Moz), 27.6 Kt Ag (887 Moz) , 17.5 Mt Cu, and 0.5 Mt Mo. The production of these four metals alone from Eocene deposits would have a present-day value of over $400 billion (USD), ~64% of which is attributable to gold, 29% to copper. Eocene ore deposits are restricted to the northern half of the Great Basin, coincident with arc magmatism and the earliest stages of Cenozoic crustal extension. Curiously, metal production from Eocene deposits is strikingly polarized, with 79% of Au production derived from mines in north-central Nevada, and 98% of Cu and 86% of Ag derived from mines in north-central Utah. Most Nevada Au production is from three major Au belts that host giant sedimentary rock-hosted Carlin-type Au deposits: Carlin, Battle Mountain-Eureka, and Getchell. Three major Utah districts produced the bulk of Cu, Mo, Au, and Ag (Oquirrh, Park City, and Tintic), with the vast majority of Cu, Mo, and Au coming from the Bingham Canyon porphyry system. In addition, Eocene deposits in northern Nevada contain more than 1.68 Kt of Au (54 Moz) and 0.67 Mt Mo in reserves, and Bingham Canyon contains reserves of about 2.72 Mt of Cu and 0.15 Mt of Mo.

Perhaps more than any other deposit type in the Great Basin, Carlin-type gold deposits are enigmatic. After more than five decades of mining more than 150 Moz of gold from Carlin-type deposits in north-central Nevada, we continue to debate what one is, resorting to terms such as Carlin-like to qualify our uncertainty. As a result, the rest of the exploration world is even more baffled by them. Uncertainty has hindered exploration beyond the Great Basin because of lack of a well-constrained exploration model that incorporates not only elements of existing descriptive models but also the syn-mineral regional geologic framework of type deposits in Nevada.

We assess findings contributing toward a global Carlin-type deposit exploration model. Key regional components of the model based on Great Basin geology are: 1) age and age progression of Carlin-type gold mineralization, 2) spatial and temporal association of Carlin-type deposits with other gold-rich deposits, and 3) the regional geologic setting of gold deposition including crustal architecture and syn-mineral tectonism and magmatism. The progressive change in Eocene ore deposits from Au- to Cu-dominant across the central to eastern parts of the northern Great Basin is extraordinary and has major exploration implications. This change in metals parallels changes in the geochemical and isotopic character of magmatism across the Eocene arc, although rocks are grossly similar in terms of their mineralogy and bulk composition. We preliminarily interpret west to east variations in Eocene igneous chemistry and styles of metallization as interrelated, with contrasting chemistries reflecting major differences in architecture and composition of the crust through which magmas traveled.

Thus, the range of Eocene sedimentary rock-hosted, disseminated gold deposits (SHDGs), including Carlin-type deposits, in northern Nevada defines a distinct intrusion-related gold metallogeny that contrasts with the “classic” deposits formed in many other continental arc settings, including the eastern Great Basin in Utah, which are typified by porphyry Cu and Cu-Mo, polymetallic skarns and replacements, and high- and intermediate-sulfidation epithermal Au-Ag deposits. The reduced mineralogy and geochemistry of ores and Au-dominant or Au-only character of SHDGs in northern Nevada infer overall reduced ore fluids that fundamentally differ from highly oxidized fluids indicated for porphyry-related systems. We suggest that emplacement of the Eocene arc far inboard of the plate margin and into kilometers-thick carbonaceous slope and basinal rocks of the Neoproterozoic through Paleozoic passive margin progressively modified and chemically reduced mid-crustal magmas from mafic to silicic compositions through assimilation of reduced crust.

Carlin Anniversary—May 4, 1965, First Gold Bar Poured at the Carlin Mill from the Carlin Mine

“The discovery of the Carlin deposit is one of the most significant events in worldwide mining and in the history of Nevada.

Named for a town on the banks of the Humboldt River, the Carlin deposit was overlooked by the ’49ers who rushed by, along the Emigrant Trail, on their way to the gold fields in California. Because of the extremely fine grain size of its gold particles, Carlin was missed by the ’49ers and by the prospectors that combed the hills of the western United States in the late 1800s. A few gold deposits of what would later be known as the Carlin type were found in the late 1800s and early 1900s, but their significance was not recognized until the Carlin discovery in 1961 and the opening of the Carlin mine in 1965.

Closely following Carlin were discoveries of other deposits along the Carlin trend, a 50-mile long, 5-mile wide belt that now includes more than 20 major deposits. The Carlin trend has developed into one of the premier gold fields of the world. Known resources are immense, tens of billions of dollars worth of gold, and growing, as new discoveries continue to be made. The deposits of the Carlin trend and other Carlin-type deposits have catapulted Nevada into the lead among gold producing states and have made the United States a major gold-producing country and net exporter of gold.

Discoveries of Carlin-type deposits have helped to diversify the Nevada economy. Gold mining directly provides thousands of jobs for Nevadans, indirectly provides thousands more, helps build and maintain infrastructure in rural parts of the state, and broadens the tax base for education and other government programs. Highly skilled miners, including heavy equipment operators and mechanics, engineers, and individuals well versed in computer operations, earn the highest average wages of any industry within the state.

Deposits on the Carlin trend have set new standards for gold mining throughout the world. Large-scale mining, heap leaching, and automation at various levels in the mining, milling, and assaying processes have cut overall costs and allowed lower and lower grades of ore to be mined.

This report, written and reviewed by some of the individuals involved, provides a first-hand account of the Carlin discovery, a milestone in the history of Nevada and in the history of mining.” (“Foreward” by Jonathan G. Price, from NBMG Special Publication 13 by J. Alan Coope)

Read the entire history here:
Carlin Trend Exploration History: Discovery of the Carlin Deposit
http://pubs.nbmg.unr.edu/Carlin-trend-exploration-histor-p/sp013.htm

More publications on the Carlin trend:
http://pubs.nbmg.unr.edu/SearchResults.asp?Search=Carlin

Exploration Resourcescheck out resources on the NBMG Open Data page:
https://data-nbmg.opendata.arcgis.com/pages/exploration-resources

The Nevada Mineral Industry 2017

Authors: John L. Muntean, David A. Davis and Bridget Ayling
Year: 2018
Series: Mineral Industry MI-2017
Format: 212 pages, includes color, plastic comb-bound report

View/download:
http://pubs.nbmg.unr.edu/The-NV-mineral-industry-2017-p/mi2017.htm

Starting in 1979, NBMG has issued annual reports that describe the mineral (precious and base metals and industrial minerals including aggregate), oil and gas, and geothermal activities and accomplishments.

This report describes those accomplishments in Nevada for 2017, which includes production, reserve, and resource statistics; exploration and development—including drilling for petroleum and geothermal resources, discoveries of orebodies, new mines opened, and expansion and other activities of existing mines; and a directory of mines and mills.

Preparation for this publication was supported by the Nevada Division of Minerals.

Nevada Active Mines and Energy Producers

e60

Authors: John L. Muntean and David A. Davis
Year: 2017
Series: Educational Series 60
Version: supersedes Educational Series 49 and 54
Format: 11 x 17 inches, color
Scale: 1 inch = 4 miles
View/download here: http://pubs.nbmg.unr.edu/NV-active-mines-and-energy-2016-p/e060.htm

Site locations and information on this map were obtained from a variety of published and non-published sources with the last updates made in January 2017. All sites shown on this map have had some form of production activity during 2016.

This map was prepared in cooperation with the Nevada Division of Minerals.

Lecture by Rick Martin, Thursday August 25, TONIGHT! Gold Dredges: The Land Leviathans

What: Gold Dredges: The Land Leviathans, by Rick Martin (Frances Humphrey Lecture Series)
When: Thursday August 25, 2016 (6:30 – 8:00 p.m., doors open at 6:00 p.m.)
Where: Nevada State Museum, 600 N. Carson St., Carson City, NV
Web: http://museums.nevadaculture.org/

“An in-depth presentation of the origin, operations and economics of giant land based gold dredges from the turn of the 20th century to their decline mid-century, and limited operations in the 1980-1990s. Photographs, early films, and personal experiences will offer unique insight into these massive mechanical marvels and the men who built and operated them. Rick Martin is the Senior Health and Safety consultant at the Tesla Gigafactory construction site, and his 40 + year career includes Law Enforcement, Fire Service, Emergency Medical Services, and Mining Safety Management. He is working on three books for publication, on the history of the Carson River mills, on early logging and deforestation of the Sierras, and on the history of giant gold dredges of the 19th century.”

Admission: $8.00 for adults; free for museum members and ages 17 and under.

For more information, please contact: Bob Nylen: Rnylen@nevadaculture.org or 775-687-4810, ext. 245.

The Nevada Mineral Industry 2014—just released!

mi2014_cover

Title: The Nevada Mineral Industry 2014
Authors: John L. Muntean, David A. Davis, and Lisa Shevenell
Year: 2016
Series: Mineral Industry MI-2014
Format: 171 pages, includes color

Starting in 1979, NBMG has issued annual reports that describe mineral and geothermal activities and accomplishments in Nevada, and include statistics of known gold and silver deposits.

This report describes mineral, oil and gas, and geothermal activities and accomplishments in Nevada in 2014: production statistics, exploration and development including drilling for petroleum and geothermal resources, discoveries of orebodies, new mines opened, and expansion and other activities of existing mines. Statistics of known gold and silver deposits, and directories of mines and mills are included.

Free download:
http://pubs.nbmg.unr.edu/The-NV-mineral-industry-2014-p/mi2014.htm

Click here for previous editions.