Coupled magmatic and tectonic activity plays an important role in high-temperature hydrothermal circulation at mid-ocean ridges. The circulation patterns for such systems have been elucidated by microearthquakes and geochemical data over a broad spectrum of spreading rates, but such data have not been generally available for ultra-slow spreading ridges. Here we report new geophysical and fluid geochemical data for high-temperature active hydrothermal venting at Dragon Horn area (49.7°E) on the Southwest Indian Ridge. Twin detachment faults penetrating to the depth of 13 ± 2 km below the seafloor were identified based on the microearthquakes. The geochemical composition of the hydrothermal fluids suggests a long reaction path involving both mafic and ultramafic lithologies. Combined with numerical simulations, our results demonstrate that these hydrothermal fluids could circulate~6 km deeper than the Moho boundary and to much greater depths than those at TransAtlantic Geotraverse and Logachev-1 hydrothermal fields on the Mid-Atlantic Ridge.

The Khondalite Belt within the Inner Mongolia Suture Zone (IMSZ) in the North China Craton is a classic example for Paleoproterozoic ultrahigh-temperature (UHT) metamorphism. Here we report new spinel-bearing metapelitic granulites from a new locality at Xumayao within the southern domain of the IMSZ. Petrological studies and thermodynamic modeling of the spinel þ quartz-bearing assemblage shows that these rocks experienced extreme metamorphism at UHT conditions. Spinel occurs in two textural settings: 1) high X Zn (Zn/(Mg þ Fe II þ Zn) Z 0.071e0.232) spinel with perthitic K-feldspar, sillimanite and quartz in the rock matrix; and 2) low X Zn (0.045e0.070) spinel as inclusions within garnet porphyroblasts in association with quartz and sillimanite.Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks: 1) near-isobaric cooling from 975 C to 875 C around 8 kbar, represented by the formation of * Corresponding author. Tel.: þ86 15120092441 (mobile). GEOSCIENCE FRONTIERSjournal homepage: www.elsevier.com/locate/gsf GEOSCIENCE FRONTIERS 3(5) (2012) 603e611 garnet porphyroblasts from spinel and quartz; and 2) cooling and decompression from 850 C, 8 kbar to below 750 C, 6.5 kbar, represented by the break-down of garnet. The spinel þ quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indicating a near isothermal compression process. Our study confirms the regional extent of UHT metamorphism within the IMSZ associated with the Paleoproterozoic subduction-collision process. ª 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

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Flexible magnetoelectric device is one of the indispensable elements. However, the complicated fabrication process and low sensitivity hinders the practical applications. Here, flexible NiFe anisotropic magnetoelastic composites were prepared by cluster–supersonic expansion method assistant with polyvinylidene fluoride (PVDF) substrates. The NiFe/PVDF composites possess sensitive angle–resolution magnetoelectric coupling coefficient at room temperature, and the value can reach 0.66 μV/deg. The strong anisotropic magnetoelasticity phenomenon is reminiscent of the short–range ordered cluster structure. The anisotropic magnetoelastic coefficient can be deduced by temperature– and magnetic field strength–dependent anisotropic magnetoresistance. The magnetic torque results also prove the strong anisotropic magnetoelastic trait. The coupling between piezoelectricity and anisotropic magnetostrictive effect endows great possibilities toward flexible electronic compass. These results shed light on future in non–invasive tracking of vital biological health via wearable electronic devices.

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