This study aims at further understanding of the mechanisms how lattice-preferred orientations (LPO) develop during deformation in the main eclogite minerals. Microstructures and textures of deformed eclogites from the Les Essarts complex (Western France) were investigated using optical microscopy and electron backscatter diffraction (EBSD) in the scanning electron microscope. Microfabric analyses of eclogite-facies minerals are used to identify their deformation mechanisms, which define the rheology at high-pressure metamorphic conditions. Mechanisms of intracrystalline deformation by dislocation movement (dislocation creep) result usually in a non-linear flow law (typically power law), while diffusive processes (diffusion creep) correspond to linear flow laws. General microstructural observations may suggest intracrystalline deformation (dislocation creep) of omphacite. The omphacite LPO vary between S- and L-type and correlate with oblate or prolate grain shape fabrics, respectively. Until now, these LPO types have not been understood by plasticity models based on dislocation glide on the known slip systems in clinopyroxene. An alternative interpretation is given in terms of anisotropic growth and dissolution, with grain boundary diffusion as the rate controlling process. There are further indications suggesting diffusion creep with concomitant anisotropic growth and dissolution as a main deformation mechanism in omphacite. In omphacite around a hollow garnet, crystallographic and shape fabrics align with the c[001] axes parallel to the grain elongations defining the mineral lineation, which rotates locally with the inferred flow direction. In this part, the grain sizes of omphacite and rutile are larger than in the surrounding matrix. The geometry of both the shape and crystallographic fabrics is interpreted to represent the local stress regime (directions and ratios of the principal stresses). The LPO of rutile duplicate the LPO of omphacite and a similar distinction between S- and L-type was used. Rutile deformation mechanisms probably involve dislocation creep as well as diffusion creep. Quartz mainly occurs as an interstitial phase with weak LPO patterns interpreted as random. No representative obliquity of the LPO in omphacite nor rutile with respect to foliation and lineation was observed to be used as potential shear sense criteria. However, the rutile LPO was slightly rotated relative to the omphacite LPO consistently in most samples. The results suggest that diffusion processes are strongly involved in the deformation of eclogites. A linear flow law should be taken into account in tectonic models where eclogites are incorporated. 

Since the freeing of the market price of gold in 1971. exploration for epithermal gold deposits in the southwest Pacific region has been intense, and has been encouraged by some major successes. Sufficient discoveries have been made to summarise what has been found to date, and to assess what implications may be drawn for future exploration. Data are tabulated for 137 epithermal precious metal deposits and prospects in Australia (30), Fiji (2). Indonesia (43 ). New Zealand (22), Palau and Yap (2), Papua New Guinea (18), the Philippines (19), and Solomon Islands (1).

Comparison of the character of epithermal deposits in the southwest Pacific with those in other regions (e.g., the northeastern Pacific margin) suggests that they are in most respects similar with, however, three differences: (i) through much of the region (especially the Philippines and Indonesia) low-sulfidation style deposits commonly show characteristics suggestive of formation at deeper levels than is typical elsewhere; (ii) high-sulfidation deposits appear to be more common than along the northeast Pacific margin; (iii) many of the largest deposits show atypical features, particularly those suggestive of a transition to porphyry or mesothermal conditions, or indicating overprinting of an epithermal system on a porphyry environment. These differences can be partly understood in terms of the tectonic setting and evolution of the volcanic arcs of the southwest Pacific, and the consequent hydrological conditions that existed during mineralization.

The results of exploration in the southwest Pacific indicate that, while the principles of formation of epithermal deposits still apply, deposit models developed in other tectonic/volcanic settings should not be rigidly applied. Gold explorers should first consider the character of the geologic environment at the time of mineralization to try to predict the hydrological conditions during mineralization. Once the likely volcanic environment and paleorelief have been established, then the types, distribution, and zoning of hydrothermal alteration, coupled with observations of deposit form, vein textures and mineralogy, will allow a judgement to be made on the level of system that is now exposed, and on the probable controls that localized mineralization.

The very dynamic character of the tectonic and volcanic setting throughout much of the southwest Pacific has resulted in deposits that reflect changes in the environment of the deposit, in some cases even while deposition was occurring. This has produced some deposits with unusual characteristics which could not have been predicted before exploration.

Западное Забайкалье, в пределах которого расположена Бурятия,, ммеет весьма .сложную историю геологического развитая. Основные черты тектонической структуры Бурятии были заложены еще в докембрии и окончательно сформированы в нижнем палеозое. Современный облик страны возник в результате переработки древних структур молодыми тектоническими движениями, начавшимися во второй половине мезозоя и продолжающимися до наших дней. Убедительным примером этого служат периодически повторяющиеся землетрясения, сила которых достигает 8—9 и в ряде случаев 10 баллов. К таким относятся всем известные землетрясения  1742, 1814, 1862, 1850, 1950, 1957 и 1959 гг.

В настоящее время в пределах Бурятии выделены архей, протерозой, кембрий, юра, мел, неоген   и четвертичные отложения,

The role played by plume-generated crustal magmatic complexes in the segmentation of volcanic margins is highlighted by a preliminary study of magma flow directions in shallow intrusives from the East Greenland volcanic margin. We investigate the magmatic texture using anisotropy of magnetic susceptibility for eight dykes of tholeitic affinity belonging to a dyke swarm associated with the Tertiary opening of the North Atlantic Ocean. The thickness of the sampled dykes ranges from 3 to 37 m. The dykes are of doleritic texture and contain up to 12% of opaque minerals and 35% of plagioclase laths. Dykes showing a magnetic foliation plane within the dyke plane, i.e. a magnetic fabric usually attributed to magmatic processes, represent 40% of the samples from the studied swarm. These dykes have a low degree of anisotropy and their ellipsoid of magnetic susceptibility is strongly oblate. Inverse magnetic fabrics, where the maximum principal susceptibility axis lies near the pole to the dyke account for 60% of the data. We interpret these inverse fabrics either as alteration minerals with highly prolate ellipsoids of magnetic susceptibility or primary titanomagnetites with oblate ellipsoid of low anisotropy. The flow direction is inferred for normal fabric dykes using the mirror imbrication of magnetic lineation. Analysis of thin sections shows a good agreement between magnetic fabric directions and phenocryst preferred orientations. The inferred flow directions are predominantly horizontal, throwing a new light on volcanic margin development. 

В сборнике представлены данные последних лет по исследованию складчатых структур раннедокембрийских регионов. Конкретным материалам по Балтийскому и Украинскому щитам и Восточной Сибири предпослана теоретическая и методическая часть, в которой рассматриваются общие особенности и генезис раннедокембрийской складчатости, структурная корреляция эндогенных процессов, значение различных механизмов деформаций и типовых структур в раннедокембрийских складкообразующих процессах.

Сборник предназначен для специалистов в области тектоники и структурного анализа кристаллических комплексов.

Книга представляет собой увлекательный рассказ о современных проблемах науки о Земле, о новых геофизических методах, позволяющих проникнуть далеко в глубь дна океана и изучить его строение. Автор книги был научным руководителем кругосветной экспедиции на английском гидрографическом судне «Челленджер», и в книге широко использованы материалы этой экспедиции. Живо и интересно в книге рассказано о коралловых атоллах, о строении и рельефе дна океана, о гипотезе расширения Земли и других интереснейших вопросах современной геофизики.

Книга Гэскелла написана в популярной форме, живым и образным языком. Она будет интересна и полезна широкому кругу читателей, интересующихся географией, геологией или геофизикой.

Samples of synthetic, ultrafine-grained quartzite were prepared by hot-pressing aggregates of crushed, clear Brazilian quartz of mean grain size 0.4 mm at 300 MPa and 1373 and 1473 K. The samples displayed rapid grain-growth to ca. 12–20 mm with ,2% porosity at 1473 K, facilitated by the 0.6 wt% of water adsorbed onto the grain boundaries during sample preparation. This water could be driven off by preheating, thereby preventing grain-growth. Sufficient water was incorporated during growth into the coarsened samples to render them weak and ductile. These were deformed experimentally in the b-quartz field using an argon gas medium apparatus at 300 MPa confining pressure at temperatures mainly between T ¼ 1273 and 1473 K. Ductile flow was described by the flow law

with stress, s, in MPa, and grain size, d, in microns and strain rate e_ in s21. R is the gas constant and f(H2O) is water fugacity. Based on observation of grain flattening, optical strain features, shapes and densities of dislocation arrays, and flow law parameters, samples deformed dominantly by dislocation creep, with some contribution from grain-boundary sliding. Bearing in mind possible changes in the flow law parameters over the extrapolation interval and possible effects of the a–b phase transition, extrapolation to natural strain rates and temperatures predicts plastic flow at higher flow stresses at the same water fugacity at greenschist facies temperatures than previously published flow laws.

Предлагаемая читателю книга посвящена весьма актуальной проблеме современной геологии — флюидному режиму в земной коре. Огромная роль флюидов в образовании и преобразовании слагающих земную кору магматических и метаморфических горных пород, их химизма и структуры, в формировании большинства месторождений полезных ископаемых очевидна, и авторы попытались показать это в своей интересной и оригинальной работе. Авторы поставили перед собой сложную задачу — учесть совместное воздействие многих факторов на формирование природных объектов. Используя в своих геологических исследованиях достижения точных наук, они в то же время не увлекаются формальным математическим описанием геологических явлений, чем часто страдают работы подобного рода.

В 1978 г. при бурении скважины для целей водоснабжения в пос. Выяж Плесецкого р-на Архангельской обл. непосредственно под четвертичными отложениями в интервале глубин 43–70 м была вскрыта стекловатая лава андезит-базальтового состава, содержащая выделения самородного железа. Она залегает на терригенно-карбонатной толще ассельско-сакмарского (?) ярусов нижней перми и перекрывается четвертичными глинами и валунными суглинками. K-Ar возраст эффузивной породы составляет 27 ± 1,6 млн. лет, что соответствует позднему олигоцену и хорошо согласуется с положением лавового покрова в геологическом разрезе. Эта находка открывает район с неизвестной ранее магматической деятельностью и устанавливает новый кайнозойский этап магматизма на Русской платформе.

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.