We suggest a new explanation for the presence of crustally derived zircons in the upper-mantle rocks of ophiolitic complexes, as an alternative to subduction-related models. Integrated isotopic (U-Pb, Hf, and O isotopes) and trace-element data for zircons from the Tumut ophiolitic complex (southeast Australia) indicate that these grains are related to granitic magmatism and were introduced into...

marine sequences within several orogenic belts in YunWe report petrological and geochemical data on ultramafic pillow nan, SW China (Figs 1 and 2; Fang et al., 1996). These lavas from Late Palaeozoic marine sequences in Yunnan, SW lavas have been interpreted to be oceanic plateaux or China. These lavas have >26 wt % MgO, euhedral to subhedral seamount eruptive rocks associated with mantle plume...

The East Harrison Lake belt (EHLB) refers to a northwest-trending belt of rocks occurring to the east of Harrison Lake in southwest British Columbia (Figure 1) which is currently the focus of exploration for ultramafic-related Cu-Ni (PGE). The geology of the EHLB will also be summarized as a 1: 50 000-scale compilation map (Ash et al., in preparation) incorporating both published and unpublishe...

across) and UI-21 (1.5 cm across). UI-3 is a websterite, composed of augite (gray), orthopyroxene (white) and spinel (brown); at the top is the host basalt. UI-21 is a spinel lherzolite; spinel is brown, other phases near-white. MINERALOGY DETERMINATIONS BY CHEMIN XRD, TESTED ON ULTRAMAFIC ROCKS (MANTLE XENOLITHS). A. H. Treiman, K. L. Robinson, D. F. Blake, and D. Bish. Lunar and Planetary Ins...

Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition...

The occurrence and genesis of Ca(OH)2 and Mg(OH)2 deposits associated with hyperalkaline groundwater from partly serpentinized ultramafic rocks in Northern Oman is reported. Two types of Ca(OH)2 deposit are differentiated; crystalline portlandite formed by the evaporation of Ca 2 + 2 O H spring waters, and a form of amorphous gel, not previously known in nature. The latter is a product of prese...

Introduction: Shocked rocks are known from various planetary bodies of the solar system including Earth, Moon, Mars, and several types of asteroids. It was first recognized on Earth that stages of progressive shock metamorphism can be defined [1,2,3,4] and this concept was later on confirmed for lunar rocks [5] and meteorites [6,7,8]. Initiated by the IUGS “Subcommission on the Classification o...

A quartz-pyroxene rock interpreted as a banded iron formation (BIF) from the island of Akilia, southwest Greenland, contains (13)C-depleted graphite that has been claimed as evidence for the oldest (>3850 million years ago) life on Earth. Field relationships on Akilia document multiple intense deformation events that have resulted in parallel transposition of Early Archean rocks and significant...

Ultramafic soils are originated from ultramafic rocks such as peridotite and serpentinite highly enriched in metals (e.g., Ni, Cr, Co) depleted plant nutrients P, K, Ca). Such characteristics make these unfavorable for agriculture have raised environmental concerns on metal release to the environment. From another perspective, host a diverse flora with higher endemism than surrounding non-ultra...

The Wadi Hodein area in the south Eastern Desert of Egypt is occupied by Neoproterozoic Pan-African (Precambrian) basement rocks including metamorphic and intrusive assemblages. The metamorphic assemblage comprises dismembered ophiolitic metamorphosed ultramafic rocks and island-arc calc-alkaline metavolcanics. On the other hand, the intrusive assemblage rocks include syn-tectonic tonalite-gran...