Preface to SEG Compilation on Carlin-type Gold Deposits

John Muntean

Nevada Bureau of Mines and Geology

University of Nevada Reno

Since the discovery of the original Carlin gold deposit in 1961, approximately 200 million ounces of gold in Carlin-type deposits have been mined or identified in northern Nevada, making the United States one of the world’s largest gold producers for the past several decades. Despite their importance, Carlin-type deposits remain enigmatic.   Controversy over their origin mainly stems from the very fine grained character of the ore and gold. Carlin-type gold deposits are largely hydrothermal replacement bodies with visually subtle alteration dominated by decarbonatization and silicification of carbonate-bearing host rocks. Gold occurs in solid solution or as submicron particles in very fine grained disseminated arsenian pyrite or marcasite. To date, over 90% of the gold mined from what most geologists would call Carlin-type deposits has come from northern Nevada, and debate exists whether similar-looking deposits elsewhere share a comparable origin or whether the deposits in Nevada represent a unique occurrence.