Zoning in eclogite garnets from Nordfjord,West Norway     

I. Bryhni  W. L. Griffin 《Contributions to Mineralogy and Petrology》1971,32(2):112-125

Some of the garnets in eclogites within the quartzo-feldspathic gneisses of Nordfjord, West Norway, are zoned with higher calcium, iron and manganese in the cores and more magnesium at the rims. The zoning is discussed in terms of the apparent distribution coefficients of Fe²⁺/Mg between garnet and clinopyroxene (which will be aberrantly high for the garnet cores) and in terms of the metamorphic evolution of the eclogites.Publication nr. 32 in The Norwegian geotraverse project.  相似文献   

Stockwork tectonics in the Appalachian Piedmont of South Carolina and Georgia     

Dr. V. S. Griffin Jr 《International Journal of Earth Sciences》1971,60(3):868-886

The northeast trending belts in the crystalline Appalachian Piedmont of South Carolina are discussed and related to a detailed study in northwestern South Carolina and to a reconnaissance study of the Piedmont along the South Carolina - Georgia border.A regional tectonic stockwork model based on these studies is proposed for the Appalachian Piedmont. The inner portion of the Piedmont, characterized by recumbent isoclinal folds and nappes, containing migmatitic sillimanite mica schist and gneiss, amphibolite and granite gneiss comprises the infrastructure. Lower grade, tightly folded, non-migmatitic and partially cataclastized zones flanking both sides of this innermost Piedmont belt are considered the detachment zone. The suprastructure is believed to be preserved within the Piedmont near the Atlantic Coastal Plain offlap as two belts. One consists of a moderately deformed, low grade metamorphosed slaty assemblage of volcanics and elastics; the other belt is similar, but extensively intruded by plutons and consequently raised in metamorphic grade.

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Zusammenfassung Diese Studie diskutiert die nordöstlich verlaufenden Faltengürtel der kristallinen appalachischen Vorgebirge Südkarolinas und bezieht sich auf eine detaillierte Studie Nordwest-Südkarolinas sowie auf eine Untersuchungsstudie der Vorgebirge entlang der Grenze Südkarolinas und Georgias.Aufgrund dieser Studien ist ein regionales tektonisches Stockwerkmodell für die appalachischen Vorgebirge vorgeschlagen worden. Der Kern des Vorgebirges stellt den Unterbau dar und ist durch liegende isokline Falten und Decken gekennzeichnet, die migmatischen Sillimanit-Glimmerschiefer und Gneise sowie Amphibolit und Granitgneis enthalten. Kleingefaltete, unmigmatische und teilweise kataklastische Zonen von niedriger Temperatur begrenzen beide Seiten dieser Kernzone und werden für Abscherungszonen gehalten. Es wird angenommen, da\ der Oberbau innerhalb der Vorgebirge in der NÄhe der atlantischen Küstenauflage als zwei Faltengürtel erhalten ist. Der eine besteht aus einer mÄ\ig durchbewegten, niedrig metamorphisierten Schieferansammlung von Vulkaniten und detritischen Ablagerungen; der andere Gürtel hat eine Ähnliche Zusammensetzung, besitzt aber ausgedehnte Plutone und folglich eine intensivere Metamorphose.

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Résumé Les zones de plissement courant vers le nord-est qui se trouvent dans le Piedmont cristallin des Appalaches de la Caroline du Sud sont le sujet d'une discussion que l'on rapproche d'une étude détaillée de la région nord-ouest de la Caroline du Sud et d'une étude de reconnaissance du Piedmont le long de la frontière entre la Géorgie et la Caroline du Sud.Un modèle tectonique des strates de la région, basé sur ces études, est proposé pour le Piedmont appalachien. La partie intérieure du Piedmont (l'infrastructure) se caractérise par des plis couchés isoclinaux et par des nappes, et elle contient du schiste, du gneiss de sillimanite migmatitiques, et du gneiss amphibolitique et granitique. Certaines zones non-migmatitiques, partiellement cataclastiques, étroitement pliées et d'un degré inférieur se trouvant de chaque cÔté de cette région centrale du Piedmont sont considérées comme la zone de détachement. Dans le Piedmont près de la plaine sédimentaire littorale de l'Atlantique d'origine marine, la superstructure, semble-t-il, reste intacte, formant deux bandes: l'une comprenant un mélange un peu déformé de matière volcanique et clastique, métamorphosé, d'apparence ardoiseuse, et de qualité inférieure; l'autre semblable, mais contenant de grandes quantités de matière plutonique d'injection ayant élevé sa qualité métamorphique.

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Trace elements in garnets and chromites: Diamond formation in the Siberian lithosphere   总被引：1，自引：0，他引：1  

W.L. Griffin  N.V. Sobolev  C.G. Ryan  N.P. Pokhilenko  T.T. Win  E.S. Yefimova 《Lithos》1993,29(3-4):235-256

Proton-microprobe analyses of trace elements in garnet and chromite inclusions in diamonds (DI) from the Mir, Udachnaya, Aikhal and Sytykanskaya kimberlites in Yakutia, CIS, provide new insights into the processes that form diamond. Equivalent data on garnet and chromite concentrates from these pipes yield information on the thermal state and chemical stratification of the Siberian lithosphere. Peridotite-suite diamonds from Yakutia have formed over a temperature interval of ca. 600°C, as measured by Ni and Zn thermometry on garnet and chromite inclusions in diamonds. Individual diamonds contain inclusions recording temperature intervals of >400°C; ranges of >100°C are common. Diamond formation followed a severe depletion event(s), and a separate enrichment in Sr. Comparison of temperatures on DI garnet and spinel with temperatures derived from diamondiferous harzburgites, exposed inclusions in boart and concentrate minerals suggests that the diamond-containing part of the lithosphere has cooled significantly since the Siberian diamonds crystallized. The peridotite-suite diamonds probably formed mainly in response to one or more relatively short-lived thermal events, related to magmatic intrusion. The northern part of the Daldyn-Alakit district may have had a typical cratonic geotherm at the time of diamond formation, and during kimberlite intrusion. The southern part of the district, and the Malo-Botuobiya kimberlite field, probably had a relatively low geotherm (ca. 35 mW/m²). The vertical distribution of garnet and chromite types indicates that the mantle above 120 km depth is dominated by lherzolites, whereas the deeper parts of the lithosphere are a mixture of lherzolites and more depleted harzburgites and dunites.  相似文献   

Calculation of equilibration conditions for garnet granulite and garnet websterite nodules in African kimberlite pipes     

Dr. D. A. Carswell  Dr. W. L. Griffin 《Mineralogy and Petrology》1981,28(3):229-244

Summary Pressure/temperature estimates based on different combinations of calibrated mineralogical thermometers and barometers and alternative assumptions concerning the Fe²⁺/(Fe²⁺+Fe³⁺) ratios in the mineral phases are compared for a suite of fourteen nodules. PreferredP/T values have been obtained by simultaneous solution of eq. (12) ofWood (1974) for garnet-orthopyroxene equilibria and theEllis andGreen (1979) equation defining theP,T,X dependence of the Fe²⁺–Mg²⁺ partition coefficient for coexisting garnet and clinopyroxene. However, to obtain realistic results it is first necessary to calculate the Fe³⁺ contents in the minerals—conveniently done on a charge balance basis. The favoured meanP/T estimates of 654±36°C and 10.8±3.1 kbs are compatible with a lower crustal origin for this nodule suite.

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Berechnung von Gleichgewichts-Bedingungen von Granat-Granulit und Granat-Websterit-Xenolithen in afrikanischen Kimberliten

Zusammenfassung Druck-Temperatur-Berechnungen auf Grund verschiedener Kombinationen von kalibrierten mineralogischen Thermometern und Barometern sowie alternativer Modelle der Fe²⁺/(Fe²⁺+Fe³⁺)-Verhältnisse in den Mineralen einer Gruppe von 14 Einschlüssen werden verglichen. BevorzugteP/T-Werte ergaben sich durch simultane Lösung der Gl. (12) für Granat-Orthopyroxen-Gleichgewichte vonWood (1974) und der Gleichung vonEllis undGreen (1979), die dieP-T-X-Abhängigkeit des Fe²⁺–Mg²⁺-Verteilungskoeffizienten für koexistierende Granat und Clinopyroxen definiert. Um realistische Ergebnisse zu erhalten, ist es jedoch zuerst notwendig, die Fe³⁺-Gehalte der Minerale zu berechnen, vorzugsweise auf der Grundlage des Ladungsausgleichs. Die bevorzugten Durchschnittswerte von 654°±36°C und 10.8–3.1 kb sind in guter Übereinstimmung mit einer Herkunft aus der unteren Kruste.

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Migration of Landfill Leachate Through Glacial Tills     

Keros Cartwright  Robert A. Griffin  Robert H. Gilkeson 《Ground water》1977,15(4):294-305

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Whitlockite and apatite from lunar rock 14310 and fromÖdegården,Norway     

W.L. Griffin 《Earth and Planetary Science Letters》1972

Microprobe analyses show that whitlockite from lunar rocks is enriched in REE relative to the associated apatite, whereas a terrestrial whitlockite is severely depleted in REE relative to the associated apatite. After considering other possibilities, we suggest that the lunar whitlockite originally crystallized as the high-T polymorph, which is capable of taking up excess CaO (and REE?). Inversion to the low-T form has been inhibited by the non-stoichiometry, so that the present “whitlockite” phase is poorly crystalline. Similar relations may exist in terrestrial basalts of low water content, but would be easily overlooked in petrographic studies.  相似文献   

Metamorphic feldspathization of metavolcanics and granitoids,Avnik area,Turkey     

C. Helvaci  W. L. Griffin 《Contributions to Mineralogy and Petrology》1983,83(3-4):309-319

In the Avnik area of the Bingöl massif the Lower Unit consists of basic to felsic metavolcanics (ca. 450 Ma), intruded by granitoids (ca. 350 Ma). These are unconformably overlain by an Upper Unit of micaschists and Permian marbles; both units have been deformed and metamorphosed in Alpine time. The metavolcanics and granitoids are extensively feldspathized and silicified. The granitoids, and basic-intermediate volcanics, are albitized, while felsic volcanics are K-feldspathized. Metasomatism has severely modified K/Rb and Rb/Sr ratios, but not REE patterns, and is inferred to have occurred at relatively low T. Nametasomatism of the Upper Unit micaschists has produced albite porphyroblasts. Metasomatism postdates formation of the Upper Unit sediments, and is probably related to reaction with sea water that infiltrated the basement of volcanics and granitoids during deposition of these sediments. Rb-Sr whole-rock dating of extensively feldspathized intermediate-felsic metavolcanics gives an age of ca. 90 Ma, which suggests that the most extensive reaction coincided with expulsion of the trapped sea water during the early stages of the Alpine orogeny. The distribution of albitization vs. K-felds-pathization suggests that the type of metasomatism was controlled on a local scale by permeability and grain size, rather than by T variations.  相似文献   

The orbit, mass, and albedo of transneptunian binary (66652) 1999 RZ₂₅₃     

Keith S. Noll  Denise C. Stephens  Ian Griffin 《Icarus》2004,172(2):402-407

We have observed (66652) 1999 RZ₂₅₃ with the Hubble Space Telescope at seven separate epochs and have fit an orbit to the observed relative positions of this binary. Two orbital solutions have been identified that differ primarily in the inclination of the orbit plane. The best fit corresponds to an orbital period, days, semimajor axis a=4660±170 km and orbital eccentricity e=0.460±0.013 corresponding to a system mass m=3.7±0.4×¹⁰¹⁸ kg. For a density of the albedo at 477 nm is p₄₇₇=0.12±0.01, significantly higher than has been commonly assumed for objects in the Kuiper belt. Multicolor, multiepoch photometry shows this pair to have colors typical for the Kuiper belt with a spectral gradient of 0.35 per 100 nm in the range between 475 and 775 nm. Photometric variations at the four epochs we observed were as large as 12±3% but the sampling is insufficient to confirm the existence of a lightcurve.  相似文献   

Combined U-Pb dating and Sm-Nd studies on lower crustal and mantle xenoliths from the Delegate basaltic pipes, southeastern Australia     

Y. D. Chen  Suzanne Y. O'Reilly  W. L. Griffin  T. E. Krogh 《Contributions to Mineralogy and Petrology》1998,130(2):154-161

Mafic rocks dominate the lower crustal and upper mantle xenolith suites within the Jurassic Delegate basaltic diatremes in the Paleozoic Lachlan Fold Belt, SE Australia. Two upper mantle mafic xenoliths from the Delegate pipes, a garnet pyroxenite and a garnet granulite (equilibrated at 1060 and 1140 °C, and 40–50 km), yield garnet-clinopyroxene Sm-Nd ages of 160 ± 4 Ma and 153 ± 10 Ma, respectively. Both ages are indistinguishable from the time of eruption of the diatremes, and are interpreted as showing continuous isotopic equilibrium within the mantle of Sm and Nd between garnet + clinopyroxene at temperatures ≥ 1050 °C. A lower crustal, 2-pyroxene granulite xenolith (equilibrated at 810–850 °C and ca. 25 km) yields a clinopyroxene + plagioclase + whole rock Sm-Nd isochron ages of 283 ± 26 Ma. This age probably reflects partial resetting of the isotopic systems of much older granulite during slow cooling, or after a heating event in the lower crust associated with the Jurassic magmatic activity represented by the basaltic host rock. Metamorphic zircons from the 2-pyroxene granulite xenolith were dated by the U-Pb method at 398±2 and 391 ± 2 Ma. These ages are considered to date granulite facies metamorphic events in the lower crust of the region. The age gap between the granulite facies metamorphism and granitoid plutonism in the region (420–410 Ma) indicates that the dated granulite is unlikely to represent residue after partial melting and magma extraction that generated the regional granitoids. It is suggested that these ages may record a relatively slow cooling following the cessation of mafic magmatic intrusion that formed the xenolith protoliths and that was probably the heat source responsible for granite production. At about 25 km, this thermal relaxation accounts for the change from an olivine + plagioclase + 2-pyroxene gabbroic assemblage into the granulite facies 2-pyroxene + plagioclase + spinel field. Received: 17 May 1995 / Accepted: 24 March 1997  相似文献   

Changes in Volatile Organic Chemical Concentrations After Purging Slowly Recovering Wells     

Beverly L. Herzog  Sheng-Fu J. Chou  John R. Valkenburg  Robert A. Griffin 《Ground Water Monitoring & Remediation》1988,8(4):93-99

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