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An array of magnetic variometers has been operated in the south-east corner of the Australian mainland, observing the coast effect simultaneously in two dimensions for the first time. The observations are presented as sets of variograms in the time domain and as contour maps of certain parameters in the frequency domain. Vertical field response functions are determined for each station, and the...

Acanthomorphic acritarch fossils, including some interpreted to be the fossils of the earliest animal embryos, first appear in the lower Doushantuo Formation of the Yangtze Gorges area (YGA). Further, the complete paleontological and geochemical record for the YGA has played a central role in defining the global biological and geochemical backdrop that presaged and witnessed the dawn of diverse...

Os-, Nd-, and Pb-isotope measurements were performed on a suite of eleven Kamchatka peridotite mantle xenoliths in volcanics from the southern (Avachinsky) and central (Sheveluch and Kharchinsky) segments of the Kamchatka peninsula. Peridotites with higher Os content (1.3–5.2 ppb) show a narrow Os / Os range between 0.1182 and 0.1272 while the xenoliths with lower Os content (b1 ppb) show a wid...

The 18-km-diameter El’gygytgyn crater is located on the Chukotka peninsula, northeastern Russia. It represents the only currently known impact structure formed in siliceous volcanics, including tuffs. The impact melt rocks and target rocks provide an excellent opportunity to study shock metamorphism of volcanic rocks. The shockinduced changes observed in porphyritic volcanic rocks from El’gygyt...

Turbiditic sandstones from the mid–Late Cretaceous Tianba Flysch sequence are well exposed near Tianba in the north Nieru Valley, southern Tibet, and contain significant amounts of chrome-rich spinels. Microprobe results show that the spinels have a well-developed Fe-Ti trend and have Cr/( ) 0.4–0.65, Mg/( ) 0.3–0.9, and TiO2 2 Cr Al Mg Fe 11%. The occurrence of melt inclusions, and well above ...

Following accretion of southern Siberian microcontinents to the compositions reveal up to one order of magnitude variation of some trace elements and ratios between suites, and show a progressive Siberian craton in the Early Paleozoic, five cycles of K-rich silicic magmatism, progressively decaying in volume, occurred on batholithic change in trace element concentration with decreasing age. Pla...

Quartz porphyry of rhyolitic composition though a volumetrically minor is an important component metavolcanic successions in the Gadag schist belt western Dharwar craton. The quartz porphyries are calc-alkaline, enriched light rare earth elements (Lan/Ybn ~ 10–20) and with strong negative Eu anomaly (Eu/Eu*N=0.45–0.58). These features, coupled high K2O/Na2O (0.8 to 1.46), low Nb/Th (<1), Lan/Sm...