The Carlin trend contains the largest concentration of Carlin-type gold deposits in the world. Two major controversies about these giant gold deposits have been their age, which is now firmly established as Eocene, and the source of heat, fluids, and metals, which remains debated. We present data that demonstrate an intense period of Eocene magmatism coincided in time and space with deposit formation and was arguably the primary heat source. Geologic studies over the last 40 years have emphasized the stratigraphy and structure of Paleozoic sedimentary rocks, which are the major ore hosts. However, four igneous episodes affected the Carlin trend, in the Jurassic, Cretaceous, Eocene, and Miocene. A Jurassic diorite-granodiorite laccolith and related dikes were emplaced at about 158 Ma in the northern Carlin trend. A Cretaceous granite intruded the northcentral part of the trend at 112 Ma. Abundant Eocene dikes intruded along most of the trend and were accompanied by lavas in a large volcanic field along the southwest edge of the trend between ~40 and 36 Ma. Miocene rhyolite lavas erupted just west of and across the southern part of the trend at ~15 Ma.

Igneous rocks, apart from those few which are wholly or partly glassy, are composed of minerals and a knowledge of these minerals therefore is one logical starting point for study. Indeed the microscopic determination in thin sections of the content, abundance, and textural relations of component minerals remains, as it was for classical petrographers, the most widely used tool in the investigation of igneous rocks

Decades of field and microscope studies and more recent quantitative geochemical analyses have resulted in a vast, and sometimes overwhelming, array of nomenclature and terminology associated with igneous rocks. Under the auspices of the International Union of Geological Sciences (IUGS), a group of petrologists from around the world has laboured for more than 30 years to collate these terms, gain international agreement on their usage, and reassess

the methods by which we categorize and name igneous rocks.

В тезисах Докладов Второго семинара по геодинамике Кавказа изложены представления различных геологических школ и направлений Советского Союза об основных закономерностях становления земной коры и верхней мантии Кавказа, а также соседних стран.