Description:    In order to elucidate the genesis of green and orange glasses in Apollo 15 and Apollo 17 samples of lunar rocks, two alternative hypotheses are analyzed, according to which the glasses are produced either (1) by a comet or meteorite impact (impact model) or (2) by volcanic activity (volcanic model). The green and orange glasses are clearly genetically and petrochemically autonomous, i.e., the composition of the glasses themselves differs from those of the major types of the primary rocks. The mechanisms responsible for the origin of the glasses are analyzed along with mathematical models of their genesis. The theoretically calculated size distribution of glass particles is in good agreement with those measured in Apollo 15 and Apollo 17 samples. Simulation results and the analysis of the composition and structure of the green and orange glasses lead to the conclusion that the impact hypothesis of their genesis is the most realistic. Content Type Journal Article Pages 408-414 DOI 10.1134/S0869591112050037 Authors Yu. P. Dikov, Institute of the Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry (IGEM), Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017 Russia V. I. Mal’kovsky, Institute of the Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry (IGEM), Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017 Russia A. A. Pek, Institute of the Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry (IGEM), Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    The mineralogy and petrology of pumice exposed in two small outcrops at the top of two hills in western Spain suggest that these rocks are of impact genesis. Ringwoodite, which was identified in the rocks, can crystallize from melt under pressures of 10–11 GPa in static regime or at the relief of pressure of a shock wave under pressures of 15–17 GPa and more. The other minerals crystallizing from the melt at a pressure decrease are ferrous hortonolite (unit cell parameters of ringwoodite and hortonolite are reported), minerals belonging to the spinel group and having variable Fe mole fractions, clinopyroxene, orthopyroxene, anorthite, and corundum. Hollow, skeleton, dendritic, and whisker crystals of these minerals suggest that they crystallized at the cooling and strong undercooling of the melt. The crystallization temperature of the hercynite is 1780°C. The temperature of the melt that produced the pumice is estimated at 1900–2700°C. Our find of ringwoodite is the first discovery of this mineral in natural impact rocks. Content Type Journal Article Pages 415-426 DOI 10.1134/S0869591112050049 Authors L. I. Glazovskaya, Geological Faculty, Moscow State University, Leninskie gory, Moscow, 119991 Russia V. I. Feldman, Geological Faculty, Moscow State University, Leninskie gory, Moscow, 119991 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    In order to describe sulfide-silicate liquid immiscibility, coefficients and constants in sulfide thermobarometer equation X S = EXP( A / T − β P / T − B − CT − − Σ J i X i ) were determined by multidi-mensional statistic analysis of a data set of more than 200 quench experiments on the solubility of sulfide sulfur in dry basaltic melts. Experiments characterize the sulfide-silicate equilibrium in a wide range of compositions, temperatures (1115-1800°C), pressures (1 atm-90 kbar) and oxygen fugacities ( from −3.7 to −12.2). The average difference between experimental and calculated values of sulfur contents in sulfide-saturated basaltic melts is close to zero (0.0006 mol %), which indicates the absence of a systematic shift. The values of 5% confidence interval are described by equation ±(0.415 C S 2 − 0.211 C S + 0.038) ( C S in mol %) and fall within the range from ±0.012 to ±0.076 mol %. Proposed thermobarometer is presently a single thermobarometer that provides accuracy better than ±10 rel % of sulfur content, not logarithmic contents, within concentration range of 0.1-0.7 mol %. Verification of the thermobarometer on the basis of layered intrusion data showed that the proposed thermobarometer predicts the position of cumulus sulfide in the vertical sections of the Tsipringa and Kivakka intrusions with an accuracy of ±70 meters. At the same time, the reliable local prediction of layering-associated low-sulfide mineralization is impossible in the framework of model with ideal convective magma mixing in a chamber. Content Type Journal Article Pages 450-466 DOI 10.1134/S0869591112050050 Authors E. V. Koptev-Dvornikov, Geological Faculty, Moscow State University, Moscow, 119991 Russia N. S. Aryaeva, Geological Faculty, Moscow State University, Moscow, 119991 Russia D. A. Bychkov, Geological Faculty, Moscow State University, Moscow, 119991 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    The Volch’etundrovsky Massif occupies the middle part of the autonomous anorthosite complex of the Main Range, has a sheet morphology and marks the tectonic suture between the Kola block and the Belomorian mobile belt. The massif is characterized by homogenous structure and consists of the volumetrically dominant Main Zone including leucogabbro, leucogabbronorites, and anorthosites, and Marginal Zone made up of leuconorites and gabbronorites with subordinate plagioclasites and orthopyroxenites. Chemically, the rocks of the Volch’etundrovsky Massif are ascribed to the normal (tholeiitic and calc-alkaline) petrochemical series with typomorphic high Al 2 O 3 contents (11.71–29.32 wt %). With Al 2 O 3 increase in the leuconorite-anorthosite series, the SiO 2 and TiO 2 contents show weak variations, CaO and alkalis insignificantly increase, whereas the MgO and FeO contents sharply decrease. The rocks of the Volch’etundrovsky Massif reveal significant REE fractionation and increase in total REE content in the leuconorite-anorthosite series, most approximating the Paleoproterozoic (Sumian) anorthosites of the Kola region. The anorthosites and leucogabbro are characterized by flat HREE, while the leuconorites is strongly depleted in HREE due to garnet fractionation. All rocks of the massif have significant positive Eu anomalies caused by the plagioclase accumulation. Zircons are characterized by LREE depletion and enrichment in HREE. This defines the steep positive slope of the plots complicated by the negative Eu and positive Ce (in zircons from leucogabbro) anomalies, which is typical of the REE distribution patterns in the unaltered zircons from igneous rocks. In zircons from anorthosites, the Ce anomaly is weak to absent. The trace-element distribution in the rocks of the Volch’etundrovsky Massif show positive Ba, Ta, Pb, Sr, Sc, and V anomalies, being controlled by the mineral specifics of the massif and the presence of definite accessory minerals. New U-Pb zircon data on the rocks of the Volch’etundrovsky Massif indicate that the leuconorites from the Marginal Zone were formed 2473 ± 7 Ma and 2463 ± 2.4 Ma ago, and the leucogabbro from the Main Zone, 2467 ± 8 Ma. These rocks have negative ɛ Nd (T) from -1.54 up to -3.10, which indicates their derivation from enriched mantle reservoir variably contaminated by crustal material. The anorthosites of the Main Zone define an U-Pb age of 2407 ± 3 Ma and ɛ Nd (T) = −3.78, which presumably reflect the timing of hydrothermal-metasomatic alterations in the upper part of the magmatic chamber accompanied by significant crustal contamination. Content Type Journal Article Pages 467-490 DOI 10.1134/S0869591112050025 Authors V. V. Chashchin, Yukspor Joint-Stock Mining Company, Komsomol’skaya ul. 23, Monchegorsk, Murmansk oblast, 184111 Russia T. B. Bayanova, Geological Institute, Kola Science Centre, Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk oblast, 184209 Russia I. R. Yelizarova, Institute of Rare-Element Chemistry and Technology and Mineral Resources, Kola Science Centre, Russian Academy of Sciences, Akademgorodok 26a, Apatity, Murmansk oblast, 184209 Russia P. A. Serov, Geological Institute, Kola Science Centre, Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk oblast, 184209 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    Analysis of currently available data (877 individual high-precision zircon analyses) on the composition of zircons from eclogite complexes worldwide reveals general relations in the zircon composition: an anomalous decrease in the Th concentration (no higher than 3 ppm on average) and the Th/U ratio (0.33 on average), a significant decrease in the concentrations of all REE (to 22 ppm) and particularly LREE (〈2 ppm), and relatively low concentrations of Y (34 ppm), U (100 ppm), and P (41 ppm) at an elevated Hf concentration (11 400 ppm on average). The REE patterns of eclogitic zircons are noted for pronounced flat HREE patterns, poorly pronounced (if any) negative Eu anomalies, strongly reduced positive Ce anomalies (Ce/Ce* = 11 on average), and U-shaped configurations of LREE patterns up to the development of negative Nd anomalies. The relations detected in the distribution of trace elements and REE in eclogitic zircons are of universal nature and occur irrespective of the rock type (metabasites, metaultrabasites, or gneisses) and the metamorphic pressure (eclogites of high and ultrahigh pressure). The application of the aforementioned criteria makes it possible to reliable distinguish eclogitic zircons from those of magmatic or metamorphic genesis (not related to high-pressure metamorphism). Eclogites in the Belomorian Mobile Belt (in the Salma and Gridino areas) were determined to contain zircons in metagabbro eclogites; the cores of these zircons have an age of 2.8–2.9 Ga and are of magmatic genesis, whereas their outer metamorphic zones have an age of 1.9 Ga and a trace-element composition typical of eclogitic zircons. Hence, the Belomorian Mobile Belt was affected only by single (Svecofennian, at ∼1.9 Ga) episode of eclogite metamorphism of Archean rocks. Content Type Journal Article Pages 427-449 DOI 10.1134/S0869591112050062 Authors S. G. Skublov, Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034 Russia A. V. Berezin, Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034 Russia N. G. Berezhnaya, Karpinskii All-Russia Research Institute of Geology (VSEGEI), Srednii pr. 74, St. Petersburg, 199026 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    Impact cratering is usually associated with the partial or complete vaporization of the high-temperature impact melts. According to its chemical characteristics, the vaporization of major oxides, silicate minerals, and rock melts can be classified into the following four types: (1) congruent vaporization without decomposition of the compound in the vapor phase, (2) congruent vaporization with the decomposition of the compound in the vapor phase, (3) incongruent vaporization, and (4) cluster vaporization. The latter type of vaporization pertains to the transfer of material into vapor phase in the form of complicated atomicmolecular groups (clusters) of certain stoichiometry. Cluster vaporization takes place at superhigh temperatures typical of impact processes. The clusters can comprise compounds of different individual volatility, and this often results in the enrichment of the vapor phase in elements traditionally thought to be refractory. Examples of cluster vaporization are offered by lately obtained experimental results on laser-pulse vaporization of larnite, merwinite, and wollastonite. Condensed vapor generated at the vaporization of orthosilicates (larnite and merwinite) was proved to be dominated by chain bonds of Si-O tetrahedrons and to contain molecular groups of wollastonite and pseudowollastonite stoichiometry. Content Type Journal Article Pages 399-407 DOI 10.1134/S0869591112040054 Authors M. V. Gerasimov, Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117810 Russia Yu. P. Dikov, Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117810 Russia O. I. Yakovlev, Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117810 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 5

Description:    This paper reports results of experimental study of the influence of shock waves on the structure, ion valence, and phase composition of oxides, including the minerals tenorite (CuO) and hausmannite (Mn 3 O 4 ) and perovskite-structured manganite LaMnO 3 . Shock-wave loading (SWL) was modeled by explosion experiments in spherical and cylindrical (in the case of tenorite) configurations. The results of strong quasi-static shear deformations of oxides under pressure are also given for comparison. The main focus was the investigation of shock wave-induced changes in oxides at the level of chemical bonds, disturbances of ionic composition and stoichiometry, relation of these processes to the formation of micro(nano)structures in the minerals, and stages and microscopic mechanisms of the development of new dense phases. It was shown that SWL-affected oxides can be successfully investigated by various methods of X-ray spectroscopy (photoelectron, absorption, and emission) and nuclear techniques (Rutherford back scattering, nuclear reaction analysis, and positron annihilation spectroscopy). Crystal structure and phase composition were explored by X-ray and neutron diffraction methods. Microscopic structures were investigated by optical, scanning electron, and scanning tunneling microscopy. It was shown that the effects of SWL are initially manifested in oxides as a stoichiometry violation, an increase in the number of low-valence cations, and formation of a micro(nano)structure. Plastic deformations developed during SWL are especially important for these processes. The decomposition of oxides during the solid-phase stage of shock metamorphism under the influence of high pressures, temperatures, and severe plastic deformations produces oxides with a low degree of oxidation and free oxygen, which can migrate over considerable distances to form new compounds. The ultradeep penetration of particles of the surrounding matrix into the target mineral during SWL can also serve as a mechanism of shock metamorphism at the solid-phase stage of transformation. Content Type Journal Article Pages 317-330 DOI 10.1134/S0869591112040042 Authors B. A. Gizhevskii, Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, ul. S. Kovalevskoi 18, Yekaterinburg, 620990 Russia V. R. Galakhov, Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, ul. S. Kovalevskoi 18, Yekaterinburg, 620990 Russia E. A. Kozlov, Russian Federal Nuclear Center, Zababakhin All-Russia Research Institute of Technical Physics, Snezhinsk, Chelyabinsk oblast, 456770 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 4

Description:    Peculiar deformations were observed in potassium feldspar grains from the glass-poor suevites of the Zeleni Gay astrobleme on the Ukrainian shield. In cross-polarized light, they resemble kink bands in mica. We investigated the composition of the potassium feldspar and the optical orientation of the deformation features, which appeared to be in a twin relation to the crystal matrix. Twin laws and other characteristics of the deformations were determined. The origin of such textures was attributed to a combination of relatively low-pressure shock loading (possibly, under the conditions of impactor ricochet) of a block of target granites with a subparallel orientation of tabular microcline grains. Content Type Journal Article Pages 331-335 DOI 10.1134/S0869591112040091 Authors A. A. Valter, Institute of Applied Physics, National Academy of Sciences of Ukraine, Petropavlovskaya ul. 58, Sumy, 40030 Ukraine Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 4

Description:    The paper presents a concise review of results obtained by studying shock metamorphism of polymineralic rocks with the application of spherical hermetically sealed recovery devices. Such experiments are proved to be able to reproduce principally important features of transformations detected in rocks from natural meteoritic craters (astroblemes). The experimental samples show subspherical concentric zones with different rock transformations, which are generally analogous to zones in natural astroblemes (listed in order from the centers of the spherical samples to their margins): fracturing, diaplectic transformations, selective and then complete melting, and finally, evaporation. However, the laboratory scale of the experiments and the absence of younger overprinted processes, which can obliterate impact transformations of rocks in nature, enable the researcher to reveal distinctive compositional, textural, and phase features of transformations induced in the rocks at increasing isentropic shock wave-induced loading. Data on the mobility of major elements in the course of impact metamorphism show that the type and certain features of the crystal structures of minerals are of paramount importance for the amorphization of the minerals or their shock wave-induced thermal decomposition. The crystal chemical control of mineral transformations was proved to be exerted at a number of levels. High-pressure phases identified in experiments with shock wave loading were determined to crystallize from melt or via a phase transition associated with the migration of elements. Content Type Journal Article Pages 301-316 DOI 10.1134/S0869591112040066 Authors E. A. Kozlov, Russian Federal Nuclear Center-Zababakhin Research Institute of Technical Physics, ul. Vasil’eva 13, P.O. Box 245, Snezhinsk, Chelyabinsk oblast, 456770 Russia L. V. Sazonova, Geological Faculty, Moscow State University, Leninskie gory, Moscow, 119899 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 4

Description:    The possibility of shock wave-induced interaction between meteoritic iron was estimated based on the results of experiments on the shock wave loading of mixtures of kamacite from the Sikhote Alin iron meteorite with quartz, albite, oligoclase, enstatite, olivine, and serpentine. The experimental samples were then examined with the application of optical microscopy, microprobe analysis, and Mössbauer spectroscopy. As a result of shock wave load, the metal was proved to become enriched in Si, while the quartz, albite, and oligoclase melted glasses acquired bivalent Fe ions. The products of our experiments with quartz and feldspar mixtures with kamacite were determined to contain paramagnetic metallic iron, and the surroundings of iron atoms in the silicate constituent of the olivine and enstatite mixtures with kamacite become locally more heterogeneous. Our results indicate that shock waves induce redox reactions between Fe and silicates according to the scheme 2Fe +2 + Si +4 = 2Fe +2 + Si 0 , where Fe 0 and Si 0 are iron and silicon in metal and Fe +2 and Si +4 are iron and silicon in the sillimanite matrix. Content Type Journal Article Pages 347-355 DOI 10.1134/S0869591112040029 Authors D. D. Badjukov, Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, ul. Kosygina 19, Moscow, 119991 Russia V. S. Rusakov, Physical Faculty, Moscow State University, Moscow, 119899 Russia Yu. G. Kupin, Physical Faculty, Moscow State University, Moscow, 119899 Russia Journal Petrology Online ISSN 1556-2085 Print ISSN 0869-5911 Journal Volume Volume 20 Journal Issue Volume 20, Number 4