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In a recent review article, Groves et al. (1998) suggested that lode-gold deposits worldwide, which have been variously termed mesothermal, turbidite-hosted, slate-belt hosted, greenstone-hosted, Mother lode-type or gold-only deposits, are a coherent group of gold deposits with a common origin.
Secondary alteration of rocks and their contained minerals is common in nature. Alteration reflects the interaction of fluid, typically dominated by water, with rock at temperatures that range from warm (< 100°C) to hot (>500°C). For geologists who wish to study the primary mineralogy and chemistry of rocks, alteration is a nuisance to be avoided. Alteration mineralogy, however, documents the post-formation history of the rock, information that has practical implications. In particular, alteration is ubiquitous in and around hydrothermal mineral deposits. The distribution and mineralogy of this alteration relates to the hydrothermal environment, and hence, the type of mineral deposit. More importantly for mineral exploration, hydrothermal alteration around mineral deposits commonly forms halos that provide a target which is much larger than the deposit itself. The mineralogy and in some environments the chemical composition of the alteration provide an indication of the proximity of mineralization, or in the ideal case, a vector towards mineralization. Interpretation of alteration is, therefore, a routine part of exploration for hydrothermal mineral deposits. Similarly, as a product of geothermal activity, the mineralogy of hydrothermal alteration provides information on reservoir and fluid characteristics, and the evolution of the geothermal system. These data are used in conjunction with other information to evaluate potential geothermal resources.
Our knowledge of metamorphic and deformational rock fabrics has been acquired largely by studying the products of deformation in ancient fold belts. As such, our understanding of how rock fabrics form has been built up from inferences about, rather than direct observations of, processes that might have operated, and many of those inferences have proved incorrect.
Orogens in space and time are the potential sources of information in understanding the mechanism of episodic global material circulation on a whole-mantle-scale. They represent the hallmarks of the interaction among lithospheric plates. The word “orogen” is derived from Greece (oros for “mountain,” genesis for origin). The term “orogen” or “orogenic belt” has been traditionally described as a mountain belt composed of different types of rocks or rock strata forming a complex of variable size, typically tens to hundreds of kilometres wide and several thousand kilometre long, later fragmented during younger geological time due to various processes (e.g., Miashiro, 1961). In modern terminology, an orogen can be defined as a major linear deformed zone, sandwiched between cratons with prolonged deformational history, repeatedly reactivated and associated with different events of magmatic pulses and metamorphic episodes in space and time (Dewey and Bird, 1970). An orogen or orogenic belt develops when a continental plate crumples and is pushed upwards to form one or multiple mountain ranges. This involves a series of geological processes called “orogenesis.” <...>
Atlas of igneous rocks and their textures A companion volume to the Atlas of Rock-forming Minerals in Thin Section, this full-colour handbook is designed to be used as a laboratory manual both by elementary students of earth sciences undertaking a study of igneous rocks in thin section under the microscope, and by more advanced students and teachers as a reference work. The book is divided into two parts — Part One is devoted to photographs of many of the common textures found in igneous rocks with brief descriptions accompanying each photograph. Part Two illustrates the appearance of examples of some sixty of the commonest (and a few not so common) igneous rock types; each photograph is accompanied by a brief description of the field of view shown. Nearly 300 full-colour photographs are included, and in many cases the same view is shown both in plane-polarized light and under crossed polars. A brief account of how thin sections can be prepared is included as an appendix. It is believed that the amateur geologist using these instructions will be able to make his own thin sections and, with the aid of a relatively simple microscope, enjoy the study of rocks in thin section.
The study of rocks in thin section using a petrographic microscope is an essential part of any undergraduate course in geology. This is the fourth volume in a series of photographic atlases of minerals and rocks in thin section. As in previous volumes the main purpose of the book is to provide the student with a handbook for use in practical classes to enable him or her to become familiar with the more common mineral associations and textures to be found in metamorphic rocks. In addition, some more unusual rocks which have given rise to particular significant ideas about metamorphism are also illustrated; the aim of this atlas is however to complement, not replace, a theoretical course in metamorphism.
Migmatites are spectacular, complex-looking rocks that can inspire, fascinate, or confuse geologists. All migmatites viewed in an outcrop represent the sum of a series of processes that acted in parallel, or sequentially, and the influence of various local factors (see the photographs in section A). In order to begin to understand the complexity and seemingly endless variety in migmatites, and to provide the reader context for the subject of this book, some of the key factors and processes that make individual migmatites the way they are should be outlined at the outset <...>
Mineral resources are of great strategic significance since they matter in every aspect of social and economic development. However, existing mineral resources are unlikely to support sustainable economic development given the planning and construction of urbanization in China.
Almost forty years have elapsed since Leonard Wills published his 'Palaeogeographical Atlas of the British Isles'; those forty years have seen a revolution in the earth sciences which has overturned many earlier ideas in geology. Palaeogeography has been affected just as much as other parts of the subject by this change. The advent of the plate tectonic theory has transformed our ideas of the Lower Palaeozoic palaeogeographical evolution of the British area and has rendered totally obsolete many aspects of Wills' maps. The application of plate tectonics has caused us to produce totally new palaeogeographical models for the late Precambrian and early Palaeozoic, and has emphasised that definitive palaeogeographies for this time interval cannot yet be compiled. Wills was at pains to point out that his Atlas was an 'Aunt Sally' at which to 'hurl one's own and other field observations'--our atlas too must be viewed in that light. <...>
The purpose of this book is to illustrate the appearance of many of the common rockforming minerals in thin section under the microscope. It is not our intention that it should be used as a substitute lor a mineralogy text book but rather as a laboratory handbook for use in practical classes together with one ot the standard textbooks on mineralogy <...>
