Сравнение результатов моделирования перспективности и данных прошлых геологоразведочных работ: на примере порфировых Cu–Au минеральных систем в дуге Маккуори, складчатый пояс Лахлан, Новый Южный Уэльс

Mineral exploration is undertaken in stages, with each stage designed to get to the next decision point of whether or not to keep exploring a particular area based on the results at hand. As a general rule, each consecutive exploration stage is more expensive due to the progressively more drill- and study-intensive nature of the work required, in particular after discovery of a potentially economic mineral deposit.

Proterozoic hydrothermal iron oxide deposits occur within two metallogenic belts in the northeastern U.S.: the Adirondack region, and the Mid-Atlantic (Reading Prong) belt. A 175 km wide belt of Palaeozoic cover separates these two regions, although some iron deposits occur in Proterozoic rocks near the unconformity, suggesting a possible continuation beneath the cover. Although potentially part of the same continuous metallogenic province sharing similar mineralogy, host rock composition and hydrothermal alteration, deposits in the two regions differ in degree of deformation. Differences in the degree of metamorphic deformation fuel the debate of the relative timing of mineralisation, igneous activity, and metamorphism. Generally less deformed textures in the Adirondack deposits led workers in the New York deposits to conclude iron ores in the Adirondacks are associated with anorogenic granites that postdate peak metamorphism. Folded iron ores in granitic gneiss of the Mid-Atlantic belt suggest some deposits in eastern Pennsylvania, northern New Jersey, and southern New York predate peak metamorphism. REE-enriched deposits in both belts are characterised by abundant apatite, tourmaline, and manganese concentrations, as well as the presence of hematite-chlorite alteration in addition to magnetite. Unlike deposits hosted exclusively within granite gneisses, deposits within supracrustal rocks commonly contain significant sulphides and so are potential hosts for copper mineralisation.

For any oilfield analysis, it is necessary to understand how to calculate areas, volumes and capacities. Fortunately, areas and capacities of tubing and casing are in most field handbooks and in the engineering tables of this book. Most readers of this document will remember how to calculate areas and volumes from grade school, so only a brief review is presented here. The engineering tables at the back of this book provide all the necessary data to determine well capacities quite easily. The first few sample problems are solved manually to show how the tables were generated. Thereafter, the tables will be used as much as possible to simplify the problem solving. Understanding how the data was generated will make the calculations more meaningful and the tables easier to use. In any case, a clear understanding of the basic principles is necessary before proceeding as subsequent concepts will build on prior ones <...>

The distribution of rare earth elements was analyzed in the Early Cambrian diamondiferous calcsilicate rocks and gneisses, calciphyres, and marbles of the Kumdy-Kol deposit. These data were compared with the lithogeochemical characteristics of the sedimentary assemblages of weakly metamorphosed Late Precambrian graphite-bearing sedimentary rocks of the Kokchetav metamorphic belt. The obtained results allowed us to suppose that the protoliths of the Kumdy-Kol rocks were compositionally similar to the Late Precambrian graphite-bearing terrigenous–carbonate and sand–shale sequences of the continental shelf of the Kokchetav microcontinent, some of which were transformed in a subduction zone into diamondiferous rocks.