X-ray diffraction studies of shocked lunar analogs

The X-ray diffraction experiments on shocked rock and mineral analogs of particular significance to lunar geology are described. Materials naturally shocked by meteorite impact, nuclear-shocked, or artificially shocked in a flat plate accelerator were utilized. Four areas were outlined for investigation: powder diffractometer studies of shocked single crystal silicate minerals (quartz, orthoclase, oligoclase, pyroxene), powder diffractometer studies of shocked polycrystalline monomineralic samples (dunite), Debye-Scherrer studies of single grains of shocked granodiorite, and powder diffractometer studies of shocked whole rock samples. Quantitative interpretation of peak shock pressures experienced by materials found in lunar or terrestrial impact structures is presented

The application of high temperature radiative thermal conductivity of minerals and rocks to a model of lunar volcanism

Lunar volcanism model based on high temperature radiative thermal conductivity of minerals and rock

Trend-Surface Analysis of the Trunk Lake Granitic Pluton, Maine

A trend-surface modal analysis of the Tunk Lake granitic pluton was performed using a program for the IBM 30/40 computer (Appendix 1) by Heiner and Geller (MIRL Report No. 9) and data from Karner (1968). The quartz, total mafics, oligoclase, perthite, and albite in perthite percentages were analyzed. All the trends show a southwest-northeast alignment, with the perthite, albite-in-perthite, and total mafic values increasing towards the margin of the pluton and quartz and oligoclase values decreasing outward to the margin. There is an area in the northwest part of the pluton which is an area of high values for total mafics, perthite, and albite-in-perthite, and an area of low values for quartz and oligoclase. For the sixth-degree surfaces, the total mafics accounted for 49 percent of the total variation, quartz for 40 percent, oligoclase for 71 percent, perthite for 67 percent, and albite-in-perthite for 75 percent. The difference in the percentages points to two different types of trend. The quartz and total mafics trends are not as distinct as the oligoclase, perthite, and albite in perthite trends. This is a reflection of different processes involved in the formation of the pluton resulting in different trends. Water vapor pressure and cooling temperature govern the trends of oligoclase, perthite, and ablite-in-perthite and magma differentiation and movement govern the trends of quartz and total mafics

Routine characterization and interpretation of complex alkali feldspar intergrowths

Almost all alkali feldspar crystals contain a rich inventory of exsolution, twin, and domain microtextures that form subsequent to crystal growth and provide a record of the thermal history of the crystal and often of its involvement in replacement reactions, sometimes multiple. Microtextures strongly influence the subsequent behavior of feldspars at low temperatures during diagenesis and weathering. They are central to the retention or exchange of trace elements and of radiogenic and stable isotopes. This review is aimed at petrologists and geochemists who wish to use alkali feldspar microtextures to solve geological problems or who need to understand how microtextures influence a particular process. We suggest a systematic approach that employs methods available in most well founded laboratories. The crystallographic relationships of complex feldspar intergrowths were established by the 1970s, mainly using single-crystal X-ray diffraction, but such methods give limited information on the spatial relationships of the different elements of the microtexture, or of the mode and chronology of their formation, which require the use of microscopy. We suggest a combination of techniques with a range of spatial resolution and strongly recommend the use of orientated sections. Sections cut parallel to the perfect (001) and (010) cleavages are the easiest to locate and most informative. Techniques described are light microscopy; scanning electron microscopy using both backscattered and secondary electrons, including the use of surfaces etched in the laboratory; electron-probe microanalysis and analysis by energy-dispersive spectrometry in a scanning electron microscope; transmission electron microscopy. We discuss the use of cathodoluminescence as an auxiliary technique, but do not recommend electron-backscattered diffraction for feldspar work. We review recent publications that provide examples of the need for great care and attention to pre-existing work in microtextural studies, and suggest several topics for future work

Geochemistry and Protolith Determination of the Hypersthene-Quartz-Oligoclase Gneiss from the Hudson Highlands, New York

The hypersthene-quartz-oligoclase gneiss of the Hudson Highlands, NY mapped by Dodd (1965) has been of unknown origin due to complex field relations resulting from metamorphism and deformation during the Ottawan Orogeny, and a lack of geochemical data. The rock types in the Hudson Highlands and New Jersey Highlands are grouped into four general categories: metasedimentary gneisses, metaigneous gneisses, quartzofeldspathic gneisses, and syn-tectonic intrusive granitoid rocks (Dodd, 1965). Major element geochemistry and mineralogy of the Losee Metamorphic Suite of the physically contiguous New Jersey Highlands is similar to that of the hypersthene-quartzoligoclase gneiss of the Hudson Highlands. Based on the high A120 3, CaO, Na20/K20 ratios, and mineralogical similarities between these units suggests an igneous protolith is likely the source of the hypersthene-quartz-oligoclase gneiss rather than a sedimentary protolith. Geochemical diagrams reveal that the hypersthene-quartz-oligoclase gneiss is of calc-alkaline affinity, ranges in composition from basalt to dacite, and is indicative of a convergent margin tectonic setting. Trace element data plotted on multi-element diagrams and Rare Earth Element (REE) plots are indicative of a continental arc subduction zone setting for the hypersthene-quartz-oligoclase gneiss. Variable heavy rare earth element (HREE) enrichment and depletion in the samples indicates that crystal fractionation from a single parent magma was unlikely. Rather, the REE patterns suggest that the magmas that formed the hypersthene-quartz-oligoclase gneiss were generated from different source rocks (e.g. upper mantle and lower mafic continental crust) and at varied depths in a continental arc setting (Winter, 2010)

Shock compression of feldspars

Hugoniot data for oligoclase and microcline to 670 and 580 kb and release adiabat data for oligoclase were obtained by means of the inclined mirror and immersed-foil-reflected-light techniques, respectively. Oligoclase and microcline have Hugoniot elastic limits in the range of 40–55 and 80–85 kb. These limits increase slightly with increasing driving shock pressure. Above the elastic limit, extending to ∼300 and ∼400 kb, transition regions of anomalously high compression are observed for microcline and oligoclase. These data and the data of McQueen, Marsh, and Fritz for albitite and anorthosite indicate that at successively higher shock pressures within this region, the feldspars gradually transform to a high-pressure, high-density polymorph. This polymorph probably corresponds to the rutile-like hollandite structure obtained in high-pressure quenching experiments by Kume, Matsumoto, and Koizumi (in KAlGe_3O_8) and by Ringwood, Reid, and Wadsley (in KAlSo_3O_8, microcline). In the hollandite structure germanium or silicon is in octahedral coordination with oxygen. The zero-pressure density and the Birch-Murnaghan equation of state parameters for the adiabat and isotherm are calculated for the high-pressure polymorphs of oligoclase, microcline, anorthosite, and albitite. The release adiabat centered at 180 kb indicates that at this shock pressure some (∼15%) of the hollandite phase forms but apparently reverts to a lower-density phase on pressure release. Release adiabat curves centered at 272 and 417 kb and calculated postshock temperatures indicate that material of feldspar composition recovered from meteorite and laboratory impacts is converted to the hollandite structure upon shock compression; upon pressure release this material probably reverts to the low-density maskelynite form

Characterization of the feldspars in felsic gneiss from Mt. Riiser Larsen in Napier Complex, East Antarctica

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議室前フロ

Maine Granite Quarries and Prospects

Maine Granite Quarries and Prospects : Minerals Resources Index No.2 John R. Rand, State Geologist - Maine Geological Survey Department of Economic Development, Augusta, Maine : May 1, 1958. Contents: Introduction / Acknowledgements / Explanatory Considerations / Selected Bibliography / Granite Quarries and Prospects -- Alphabetical Index / Granite Quarries and Prospects -- Country-Township Index / Buildings and Structures Built of Maine Granites / Granite Quarries and Prospects-Map Index (missing).https://digitalcommons.usm.maine.edu/me_collection/1034/thumbnail.jp

Textures of the ternary feldspar in garnet-bearing felsic gneiss from the Mt. Riiser-Larsen in the Archean Napier Complex, East Antarctica and the synthetic experiment of the ternary feldspar

第30回極域地学シンポジウム「極域から探る固体地球ダイナミクス」ポスター発

Geology of igneous extrusive and intrusive rocks in the Sundance area, Crook County, Wyoming

Two major igneous rock types occur in the Sundance, Wyoming area including foyaite of the Bear Lodge Mountain sill and quartz latite of Sundance Mountain and Sugarloaf Mountain. The igneous bodies were mapped on a scale of 1:5000 in an effort to determine petrogenetic relationships between the two rock types. Sundance Mountain and Sugarloaf Mountain are extrusive in origin. Quartz latite occurs as subparallel units of breccia, tuff, and massive flows without any clear cross-cutting relationships. Fragmental types (breccia and cuff) constitute 41 to 76 percent of the rocks, suggesting that Sundance Mountain is a mixed cone. The quartz latite has a pre dominantly cryptocrystalline groundmass consisting of alkali feldspar and quartz. Oligoclase occurs as microlites and as zoned phenocrysts. The phenocrysts have distinct, oscillatory zones with narrow ranges in composition, suggesting that the crystals were subject to sudden changes in pressure. Sugarloaf Mountain is interpreted to be a satellite volcano of Sundance Mountain. Rocks from both igneous bodies have similar texturest structures, and compositions. The Bear Lodge Mountain sill was passively emplaced along the con tact between the Pennsylvanian Minnelusa Formation and the Mississippian Pahasapa Formation. Foyaite dikes in the area have similar textures and compositions, and were probably emplaced during the same intrusive event, Primary analcime is the only feldspathoid present in the foyaite. The quartz latite is interpreted as being the youngest of the two rock types, A maximum age for the quartz latite is Paleocene, based on the presumed age of plagiofoyaite(?) clasts found in Sugarloaf Mountain breccla, If the rocks are extrusive in origin the establishment of the present erosional character of the Black Hills region gives a younger age of post-early Oligocene