نتایج جستجو برای: zircon
تعداد نتایج: 3386 فیلتر نتایج به سال:
A mural excavated at the Neolithic Çatalhöyük site (Central Anatolia, Turkey) has been interpreted as the oldest known map. Dating to ∼6600 BCE, it putatively depicts an explosive summit eruption of the Hasan Dağı twin-peaks volcano located ∼130 km northeast of Çatalhöyük, and a birds-eye view of a town plan in the foreground. This interpretation, however, has remained controversial not least b...
Zircon (ZrSiO4) is a small mineral highly resistant to chemical changes; this robustness has led it to be used for estimating earth conditions eons ago. It has been used to date geologic events, measuring its radiogenic Pb, U and Th isotopes. The oldest dated mineral on Earth is a zircon from Australia, and its oxygen isotope value suggests Earth’s crust was cool and wet as long ago as 4.3 bill...
mard-abad calc-alkaline granite formed along the margin of active pull-apart or intra-continental plates, and it is post-collision granite type. granophyric, perthitic and myrmekitic are main textures that could form from crystallization of hypersolvus source magma, which occurred under water vapor pressure of approximately 2 kb. during this study the temperature of formation of these granites ...
The Stirling Range Formation of southwestern Australia contains discoidal impressions and trace-like fossils in tidal sandstones. The various disks have previously been linked to the Ediacaran biota, younger than 600 million years old. From this unit, we report U-Th-Pb geochronology of detrital zircon and monazite, as well as low-grade metamorphic monazite, constraining the depositional age to ...
The Bi'r Umq suture zone (BUSZ) in western Saudi Arabia comprises Neoproterozoic oceanic-arc plutonic, volcanosedimentary, and ophiolitic rocks that record some of the earliest magmatic and tectonic events of the East African Orogen in the Arabian–Nubian Shield (ANS). New Nd isotopic analyses are combined with data on zircon inheritance and published isotopic studies to establish the case that ...
Mard-abad calc-alkaline granite formed along the margin of active pull-apart or intra-continental plates, and it is post-collision granite type. Granophyric, perthitic and myrmekitic are main textures that could form from crystallization of hypersolvus source magma, which occurred under water vapor pressure of approximately 2 kb. During this study the temperature of formation of these granites ...
U-Pb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the ...
Rhyolite lavas and xenoliths from the Salton Sea geothermal field (Southern California) provide insights into crustal compositions and processes during continental rupture and incipient formation of oceanic crust. Salton Buttes rhyolite lavas contain xenoliths that include granophyres, fine-grained altered rhyolites (“felsite”), and amphibole-bearing basalts. Zircon is present in lavas and xeno...
A woman (38 years) with tetracycline-stained maxillary anterior teeth came to dental office to improve her appearance. The porcelain veneers and zircon-porcelain crowns were selected as the best treatment option to mask the stained teeth. Medial line, occlusal line, level of gingival margin and frontal plane alignment of maxillary anterior teeth was analysed. Direct composite laminates were pla...
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