Epithermal gold deposits in Chile are Cretaceous to Cenozoic in age. The ores and the volcanic rocks with which they are associated were generated at a noncollisional, ocean-continent convergent plate margin. They are related to long, slightly sinuous north-northeasttrending magmatic belts roughly parallel to the Pacific coast. Most of the deposits are associated with eroded volcanic centers and subvolcanic porphyries. North-south variations in the nature, extent, and timing of magmatism control the succession of mineralization events. In the Late Cretaceous, vein districts (e.g., E1 Bronce) and hydrothermal alteration zones were formed in central Chile.

Both the petroleum industry and academia continue to undergo a transition whereby active knowledge transfer by experienced earth scientists represented by faculty teachers and researchers, Chief geoscientists, etc. is rapidly changing to passive knowledge (or data transfer) through a variety of electronic media and systems. Over the recent past, the broad experience base in both industry and academia has been phased out through retirement, redundancy and focus on specific research areas. In the case of industry, a new generation of younger specialists, sometimes called Nintendo geoscientists, are trained to solve specific practical problems based on highly focussed data acquisition and interpretation using work stations. In academia, an increasingly holistic focus on earth systems science is eroding the broader geological base that has hitherto underpinned scholarly research. <...>

Stratigraphy lies at the heart of geology and we have set for ourselves the rather daunting task of describing, albeit in summary fonn, the regional stratigraphy of North America. Our purpose is to develop a stratigraphic framework against which to view the history of the continent and with which to test ideas about Earth mechanics. No such treatment can ever be complete, as ours is not, but we hope the attempt will provide the reader with at least a working summary of North American stratigraphy and geological history.

Granites from the Tunka pluton of the Sarkhoi complex, located in the eastern Tunka bald mountains (East Sayan), have been dated at the Middle Ordovician (462.6 ± 7.8 Ma) by LA ICP MS. The granites of the Sarkhoi complex within the studied area cut a foldthrust structure consisting of deformed fragments of the Vendian (Ediacaran)–Early Cambrian cover of the Tuva–Mongolian microcontinent (Upper Shumak metaterrigenous formation, Gorlyk carbonate formation). The red-colored conglomerates and sandstones of the Late Devonian–Early Carboniferous(?) Sagan-Sair Formation overlie the eroded surface of the Tunka pluton granites in the eastern Tunka bald mountains. The Sagan-Sair Formation, in turn, is overlain along a low-angle thrust by a group of tectonic sheets, which comprises the volcanic and carbonate sediments of the Tolta Formation, biotitic schists, and plagiogneisses with garnet amphibolite bodies. Two nappe generations have been revealed on the basis of the described geologic relationships, the Middle Ordovician age of the Tunka pluton granites, and numerous Late Paleozoic Ar–Ar dates of syntectonic minerals from the metamorphic rocks in the area. The first thrusting stage was pre-Middle Ordovician, and the second, Late Carboniferous–Permian. The Lower Paleozoic thrust structure resulted from the accretion of the Tuva–Mongolian microcontinent to the Siberian Platform. The Late Paleozoic nappes resulted from intracontinental orogeny and the reactivation of an Early Paleozoic accretionary belt under the effect of the Late Paleozoic collisional events