A series of experiments was conducted in which boron minerals were precipitated by water evaporation from solutions containing boron and potassium, sodium or lithium at 25°C, and boron isotope fractionation accompanying such mineral precipitation was investigated. In the boron-potassium ion system, K₂[B₄O₅(OH)₄]·2H₂O, santite (K[B₅O₆(OH)₄]·2H₂O), KBO₂·1.33H₂O, KBO₂·1.25H₂O and sassolite (B(OH)₃) were found deposited as boron minerals. Borax (Na₂[B₄O₅(OH)₄·8H₂O) was found deposited in the boron-sodium ion system, and Li₂B₂O₄·16H₂O, Li₂B₄O₇·5H₂O, Li₂B₁₀O₁₆·10H₂O, LiB₂O₃(OH)·H₂O and sassolite in the boron-lithium ion system. The boron isotopic analysis was conducted for santite, K₂[B₄O₅(OH)₄]·2H₂O, borax and Li₂B₂O₄·16H₂O. The separation factor, S, defined as the ¹¹B/¹⁰B isotopic ratio of the precipitate divided by that of the solution, ranged from 0.991 to 1.012. Computer simulations for modeling boron mineral formations, in which polyborates were decomposed into three coordinated BO₃ unit and four coordinated BO₄ unit for the purpose of calculation of their boron isotopic reduced partition function ratios, were attempted to estimate the equilibrium constant, K_B, of the boron isotope exchange between the boric acid molecule (B(OH)₃) and the monoborate anion (B(OH)₄^-). As a result, the K_B value of 1.015 to 1.029 was obtained. The simulations indicated that the K_B value might be dependent on the kind of boron minerals, which qualitatively agreed with molecular orbital calculations independently carried out.

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Geological fractures commonly contain the minerals calcite and zeolite, which have crystallized in the fracture after its formation. The minimum age of formation of the fracture can be estimated from the age of the fracture-filling minerals. We tried to determine the age of fracturing by applying the Rb-Sr mineral isochron method to the fracture-filling paragenetic calcite and zeolite samples from fractures in the Kurihashi granodiorite and a skarn in the Kamaishi mine in northeastern Japan. The age of crystallization of fracture-filling minerals was estimated to be in the range 74 to 58 Ma in the Kurihashi granodiorite. The main causes of fracturing were considered to be igneous activities and the cooling of magma. We could not determine ages for some of the fractures we investigated, probably because of the subsequent low-temperature alteration after fracturing, or because of host wall rock contamination of the fracture-filling mineral samples. The ages determined for fractures in the skarn pre-dated the skarnization process. It is possible that these fractures formed before the skarnization. However, selective leaching of rubidium during skarnization reduces the Rb/Sr ratio. Therefore, skarnization can have the effect of producing erroneously old Rb-Sr ages. From the initial ⁸⁷Sr/⁸⁶Sr ratios, we determined changes in the strontium isotopic ratio in the local groundwater from the Late Cretaceous through the Paleocene, noting a significant increase at 62 Ma.

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Chotanagpur Gneissic Complex basement rocks of the Eastern Indian shield has been dissected by numerous mafic dykes, now occurring as amphibolitic dykes and gneissic amphibolites. These dykes are subalkaline, ranging in composition from basalt through basaltic-andesite to andesite. These rocks have enriched incompatible trace element patterns. These are particularly enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE) with depleted high field strength elements (HFSE; Nb, P, Ti) characterisitcs (i). Negative Sr anomaly is conspicuous. Nb/La and Nb/Ce ratios of the dykes are lower compared to the primitive mantle but these values are closer to average crustal values. Incompatible trace element data suggest enriched source characteristics and influence of crustal contamination in their genesis. Trace element ratios such as Gd/Yb of these dykes indicate at least two different sources. They probably represent Precambrian continental rifting in this region.

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The pyrite framboid diameter and the extractable organic matter from the Middle Famennian rhythmic succession of limestones, nodular limestones and marly shales with pyritized fauna (KPG horizon) from the Holy Cross Mountains (Poland) were analyzed in order to constrain the water column structure during their deposition. In all samples investigated, small framboids (<5 μm) that may have formed in the water column occur but the majority of the framboids have larger diameters, characteristic for their formation within the sediments, below an oxic or dysoxic water column. This suggests that during deposition of the KPG horizon, the depositional environment was highly dysoxic, but not anoxic. Low concentration of the aryl isoprenoids and isorenieratane, and very high values of the AIR parameter point to the episodic photic zone euxinia and later post-depositional, partial degradation of the OM in suboxic conditions. Intermittent, but certainly short-lasting, anoxic conditions on the sea-floor, may also be supported by the lamination of the rock matrix and increased mortality of the juvenile ammonoids. The results of this study indicate that anoxic conditions prevailed in the shallow depths below the water-sediment interface, where pyritization following by dissolution of aragonitic shells of fauna occurred.

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Investigation of molecular and carbon isotopic composition variability of hydrocarbon gases (methane, ethane and propane) has been performed on gases from coal and rock samples from Kozlu district of the Zonguldak Basin in order to ascertain the origin of gases and to explain possible reasons of variations in molecular and isotopic composition. For this purpose, the molecular and isotopic composition of eight headspace and associated gases from coals and adjacent organic rich sediments of two different stratigraphic levels of Kozlu formation in the Zonguldak basin have been determined. Total organic carbon (TOC) measurements and Rock-Eval pyrolysis were performed in order to determine bulk organic geochemical characteristics of the respective intervals. Coal and associated rock samples contain predominantly vitrinite rich type III organic matter with hydrogen indices (HI) up to 162 mgHC/gTOC. The stable carbon isotope ratios (δ¹³C) of the kerogen vary from -25.52‰ to -28.05‰. All the headspace gaseous hydrocarbons are dominated by methane (>94%). δ¹³C range for methane, ethane and propane of the headspace samples are defined as; δ¹³C₁: -48.4‰ to -36.3‰, δ¹³C₂: -26.7‰ to -17.5‰ and δ¹³C₃: -31.8‰ to -22.3‰, respectively. Methane isotopic composition and molecular ratios of the gases show that the origin of gases is mainly thermogenic. But admixture of some biogenic gas is also possible. The amount of the biogenic admixture is controlled mainly by cleat/fracture intensity of the coal or rock. The biogenic admixture of methane increases with increasing intensity of the rock fractures. In other words, methane isotope composition becomes much lighter with increasing proximity to a fault of to a crushed zone. Isotopic composition of methane and geological history of the basin led to the conclusion, that biogenic component is related with secondary bacterial gas generation. Ethane is unexpectedly heavier than the propane in all of the analyzed samples. It becomes heavier in samples particularly from the Mileopera seam, which is intensively cleated. The gases with a negative stable carbon isotope sequence of δ¹³C₂>δ¹³C₃ may possibly imply a microbial alteration. Respective isotope values of headspace and associated gases can also be influenced additionally by desorption process, which is caused by uplift of the basin during the last 42 million years.

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