Monazite as an indicator of formation conditions of quartz veins at the Zhelannoe deposit,the Subpolar Urals

At the Zhelannoe quartz deposit, the content of monazite attains 0.5 wt % in unaltered sericitolite and 18 wt % in hydrothermally altered sericitolite. Two monazite generations, including four varieties, characterize the sequence of formation and alteration of sericitolite bodies at the Zhelannoe deposit. Monazite of the first generation occurs in unaltered sericitolite as prismatic and tabular crystals characterized by (Nd,Ce) > La and enrichment in HREEs and ThO₂ (5–16 wt %). Its formation is accompanied crystallization of milk white quartz. Monazite of the second generation occurs in altered sericitolite as the product of recrystallization of the first-generation monazite. The large drusy crystals of second-generation monazite were formed similarly with Alpine-type veins. Monazite of the second generation is characterized by Ce > (La,Nd), low contents of HREEs and ThO₂ (0.5–7 wt %) and high contents of CaO and SO₃ (up to 3–5 wt %). Monazite of the second generation appeared as a result of local superimposed processes and is a characteristic feature of the Zhelannoe deposit.     

Lignin as an indicator of the sedimentation conditions on the Arctic shelf

It is shown for the first time that the proportion of lignin in shelf deposits may range from 1/3 to the total concentration of organic carbon. The distribution of wood residues and lignin in the studied sedimentary formation is very uneven, which reflects the dynamic flux environment of sedimentation and OM supply. The calculated molecular indexes showed that most of the OM in deposits underwent insignificant diagenetic alterations.     

Aluminum-fluorine sphene (Titanite) as an indicator of fluorine fluid

Doklady Earth Sciences -     

Geochemistry of paleozoic terrigenous sediments from the Oldoi terrane, eastern Central Asian orogenic belt, as an indicator of geodynamic conditions during deposition

The analysis of the major and trace element geochemistry of Paleozoic terrigenous sediments from the Oldoi terrane, eastern Central Asian orogenic belt, supports a predominantly felsic source consisting of granites and recycled sediments. The geological data suggest that detrital material could be derived from Early Paleozoic granitoids, which were identified within tectonic blocks in the Silurian and Devonian terrigenous successions. The analysis of conventional discrimination diagrams indicates that the initial stage was marked by deposition along a passive continental margin, which continued in island-arc or active continental margin environments. This interpretation is consistent with geological evidence, such as the presence of volcanic interlayers and lenses in the Middle-Late Devonian successions and granitoids with ages of 386 +/- 10 and 371+/- 5.5 Ma. The timing of changes in geodynamic settings constrained by tectonic reconstructions corresponds to the age of the inception of the Norovlya continental-margin magmatic arc.     

Coupled Sr-O isotope variations as an indicator of source heterogeneity for the Northern peninsular ranges batholith

Primary ¹⁸O values for tonalitic rocks from the San Jacinto Intrusive Complex range from +9.0 to +10.6; initial⁸⁷Sr/⁸⁶Sr for the same samples varies from 0.7058 to 0.7076. Rocks with low ¹⁸O tend to have higher initial⁸⁷Sr/⁸⁶Sr. The majority of samples have a limited range of ¹⁸O values (+10.0–+10.4) that is anticorrelated with colour index; this variation is compatible with crystallization of rocks with varying mineral abundances from an homogeneous (for oxygen) reservoir. More mafic rocks show a large range of ¹⁸O values, reflecting original variations in source material compositions. The combined Sr-O isotope data demonstrate that three or more distinct components were involved in the genesis of these rocks; these three components are also seen in batholithic rocks from the Mojave Block and Sierra Nevada to the north. These data are interpreted as indicating a 0–35% (oxygen atom basis) contribution to the San Jacinto rocks from an old continental lithosphere source.Division Contribution No. 4064     

Normative quartz as an indicator of the mass transfer intensity during the postmagmatic alteration of the Botuobinskaya pipe kimberlites (Yakutia)

The intensity of postmagmatic processes in the Botuobinskaya pipe kimberlites was estimated from the calculated content of normative secondary quartz (Q). Several simple algorithms are proposed to calculate the Q content from chemical analyses of kimberlites. Ten groups of altered kimberlites have been recognized from the Q contents. The contents of MgO, some trace elements, and LREE in the groups, the contents of Cr and Ca of crimson garnets, the diamond contents of kimberlites, and the average weight of diamonds decrease as the Q content increases. It is shown that the negative SiO₂–MgO correlation is the most effective indicator of the postmagmatic alteration of kimberlites. As the degree of their secondary alteration increases, the kimberlites transform into an assemblage of quartz and clay minerals enriched in some trace elements and almost completely lacking REE and diamonds.     

Liptinite as an indicator of environmental changes during formation of coal seam No. 207 (Upper Silesia, Poland)

The coal seam No. 207 was a subject of palynological and petrographic studies. According to the results of the vitrinite random reflectance measurements supplemented by moisture and calorific value determinations, the rank of this coal is matching the boundary between sub-bituminous and bituminous coals. The aim was to reconstruct the environmental conditions during the biochemical stage of seam formation, as well as the facies development throughout the seam profile. The maceral (incident and fluorescence mode) and microlithotype compositions (incident light) supplemented by palynological analyses, show that there were two main facies developments. In the authors opinion, they correspond with a phase of ombrogenous, raised bog marked by the presence of crassidurite with Densosporites variabilis and a wet-forest swamp phase represented by vitrite and clarite with more diverse spore assemblage including densospores. Other minor but distinctive sediments, a cannel layer and a reeds facies, both occurring in the lower part of the seam. Above the tonstein horizon, a dry forest type of sedimentation is recognized.     

矿床开发经济意义概略研究——以北祁连山雪泉铜(锌)矿为例

通过对国内外铜矿资源状况及市场供需的分析,认为雪泉铜(锌)矿床勘查研究工作的开展,将对北祁连乃至中国与塞浦路斯型富铜块状硫化物矿床的寻找和研究具有重要意义。全球已发现200多条蛇绿岩带,但其中仅50多条发现了塞浦路斯型铜矿床。因此,雪泉铜(锌)矿床的勘查研究具有重要的实际和学术意义。     

Variability of natural effluents as an indicator of groundwater retention in the Carpathian foothills (southern Poland)

 Research into the patterns of natural underground water effluents has been conducted in a small catchment basin (Wierzbanówka) that is representative of the Carpathian foothills. The aim of this study was to understand the long-term dynamics of the effluents and their responses to natural and artificial factors in order to estimate groundwater resources. High variability of the effluent patterns in the Carpathian foothills is a result of precipitation fluctuations, low ground retention capacity, a low rate of absorption in the flysch rock formation areas, and of the Quaternary covers. In addition, the dominance of agricultural land use, low forest coverage, and poor hydrological management are the main causes of this variability. Any local increase in underground water resources would only be possible if forests were planted on some of the agricultural land and changes were made to water management. Received: 16 August 1999 · Accepted: 12 January 2000     

从典型矿(床)点分析全椒大庙山式金矿 控矿条件及找矿方向

从典型矿床点分析大庙山含金角砾岩工业矿体的控矿条件及找矿方向。     

Calcite veins as an indicator of fracture dilatancy and connectivity during strike-slip faulting in Toarcian shale (Tournemire tunnel,Southern France)

The reactivation of faults induced by natural/human induced fluid pressure increases is a major concern to explain subsurface fluid migration and to estimate the risk of losing the integrity of reservoir/seal systems. This study focusses on paleo-fluid migration in a strike slip fault with >100 m long, affecting a Toarcian shale (Causses Basin, France). A high calcite concentration is observed in a 5 cm thick zone at the boundary between the fault core and damage zone. Cumulated displacements in this zone are of millimeter-to-centimeter-scale offsets and different dilatant deformation textures are observed. The zone is affected by thin slip planes containing gouge. Cathodo-luminescence observations indicate that two phases of vein formation occurred. The first phase coincides with the fluid migration along this centimeter thick dilatant zone. The second one is associated to re-shear along the millimeter thick slip planes that results in more localized mineralization, but also in a better hydrologic connection through the shale formation. These results show that in shales fluids may migrate off a slipping surface in centimeter scale dilatant volumes, at first controlled by the intact shale anisotropy related to bedding and then favored by brecciating, structures re-orientation and strengthening processes induced by calcite sealing effects.     

利国矿区铜（金）成矿条件的研究

利国矿区是江苏省重要铁矿基地之一,矿区位于秦岭一昆仑纬向构造带东延的南侧与新华夏构造体系第三隆起带的交接复合部位。铁矿床主要产于燕山期闪长玢岩杂岩体与下奥陶统碳酸盐地层的接触带及其附近灰岩中,矿体呈似层状一透镜状等,产状与围岩一致,具层控矿床的特征。笔者主要从成矿地质特征着手,分析总结了该区铜、金矿化特征及主要成矿规律,指出了利国矿区铜（金）矿的找矿方向和有望靶区。     

The electrum of the Agatovskoe deposit (Northeast Russia) and its formation conditions

This paper discusses the largest electrum units precipitated in calcite of the final (“nonproductive”) stage of ore formation. Notably, during examination of the chemical composition of these gold grains, sphalerite and other minerals belonging to the early (“productive”) association have been found. The results of thermo- and cryometric investigations of fluid inclusions in calcite of the Agatovskoe deposit have indicated that in the composition of two-phase fluid solutions of admixtures, NaCl, KCl, and MgCl dominated. This is evidenced by chloride eutectics of the admixture solutions in the temperature interval from −35 to −39°C. The complete homogenization of the fluid admixtures takes place in a narrow temperature interval (from 206 to 213°C) and concentration of salts is 3.7–6.0 mass % in NaCl equivalent. The density of the fluid changes starting from 0.88–0.89 g/cm³. The derived homogenization temperatures correspond to the temperatures of gold deposition, since the pressure during formation of gold veins in the deposit was small.     

Morpho-tectonic evolution of the Crimean mountains (Ukraine) as constrained by apatite fission track data

Apatite fission track thermochronology (AFT) is used to investigate the low-temperature thermal evolution of the Crimean Mountains and provide new insights into the geodynamic and geomorphic evolution of the westernmost tip of the Caucasus–Crimean fold-and-thrust belt. The vast majority of the samples taken from Jurassic sedimentary and magmatic rocks revealed AFT ages in the range of 51–32 Ma. These ages, together with modelled cooling paths, show that the mountain range experienced a thermal overprint after the Late Cimmerian orogeny. We interpret the overprint in terms of the burial of Cimmerian structures by a thick pile (>4 km) of platform sediments during Early Cretaceous–Late Eocene times. This scenario implies that highly elevated palaeosurfaces of Early Cretaceous age survived in large part because of the protection provided by thick accumulations of platform deposits. Since final uplift in the middle Pliocene, the palaeosurfaces have been significantly degraded and dissected by fluvial incision and large-scale landslides.