Silicon-rutile — An ultra-high pressure (UHP) mineral from an ophiolite *

Yang, Jingsui; Bai, Wangfeng; Fang, Q.; Binggang, Yan; Nicheng, Shi; Ma, Zhesheng; Dai, Mingquan; Ming, Xiong

doi:10.1080/10020070312331343970

Cited by 14 publications

(17 citation statements)

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“…Obviously, there is very little substitution of Si 4+ in olivine by Ti 4+ in rutile. Yang et al (2003) reported a high-silicon rutile, in which SiO 2 content is high up to about 15 wt.%. The Si-rutile was thought to have formed at high pressure in the transition zone or lower mantle through substitution of TiO 2 by SiO 2 .…”

Section: Discussionmentioning

confidence: 98%

“…A silicon-bearing rutile grain was found as an inclusion in chromite (Yang et al, 2003). It is 50 μm×50 μm×200 μm in size, and has a composition of (11.17-15.36) wt.% SiO 2 and (85.09-88.83) wt.% TiO 2 by EDS analysis.…”

Section: Introductionmentioning

confidence: 99%

“…The unit cell dimensions and parameters are: a=4.591 (2) Å, c=2.946 (2) Å, v=62.09 (5) Å 3 , c/a= 0.641 5. The silicon-bearing rutile is calculated to have a unit cell about 5% smaller than normal rutile (JCPDS, 21-1276) (Yang et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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SiO2 solubility in rutile at high temperature and high pressure

et al. 2009

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Silicon-bearing rutile has been found in chromitite from the Luobusa (罗布莎) ophiolite, Tibet. However, the extent of SiO 2 solubility in rutile and the nature of its origin are still unclear. At high pressure, SiO 2 takes a rutile structure with Si in 6-fold coordination. Thus, high pressures may enhance its solubility in rutile because of possible isovalent exchange in the octahedral site. In this study, we report new experimental results on SiO 2 solubility in rutile up to 23 GPa and 2 000 ℃. Starting materials were mixtures of powdered pure rutile and pure quartz, with compositions of (Ti 0.5 Si 0.5 )O 2 , (Ti 0.93 Si 0.07 )O 2 , and (Ti 0.75 Si 0.25 )O 2 . The mixtures were loaded into either platinum capsules (for a 10/5 assembly) or rhenium capsules (for an 8/3 assembly). The experiments were carried out using multi-anvil high-pressure apparatus with a rhenium resistance heater. Sample temperatures were measured with a W5%Re-W26%Re thermocouple and were controlled within ±1 ℃ of the set temperature. TiO 2 -rich and SiO 2 -rich phases were produced in all the quenched samples. Microprobe analyses of the phases show that the solubility of SiO 2 in rutile increases with increasing pressure, from 1.5 wt.% SiO 2 at 10 GPa to 3.8 wt.% SiO 2 at 23 GPa at a temperature of 1 800 ℃. The solubility also increases with increasing temperature from 0.5 wt.% SiO 2 at 1 500 ℃ to 4.5 wt.% SiO 2 at 2 000 ℃ at a pressure of 18 GPa. On the other hand, the solubility of TiO 2 in coesite or stishovite is very limited, with an average of 0.6 wt.% TiO 2 over the experimental P-T ranges. Temperature has a much larger effect on the solubility of SiO 2 in rutile than pressure. At high pressure, the melting point of SiO 2 is definitely higher than that of TiO 2 and the eutectic point moves towards SiO 2 in the TiO 2 -SiO 2 system. Lower oxygen fugacity decreases the solubility of SiO 2 in rutile, whereas water has little effect on the solubility. Our experimental data are extremely useful for determining the depth of origin of the SiO 2 -bearing rutile found in nature.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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SiO2 solubility in rutile at high temperature and high pressure

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“…Si-rutile, a mineral only discovered in diamond-bearing UHP rocks [69] , has been found in the Songpan-Garzê Triassic sandstones [57] . It implies that a UHP mineral assemblage with much higher metamorphic conditions may exist in the central Qiangtang metamorphic belt.…”

Section: Perspects For the Futurementioning

confidence: 99%

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

Zhang

Tang

2009

Sci. Bull.

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“…Xu et al (this issue) reported thousands of diamond along with over 40 kinds of minerals discovered from the Kangjinla chromitite deposit in the Luobusa ophiolite, providing new key evidence for discussing the origin of the diamond and the hosted chromitite and ophiolite. Silicon-bearing rutile has been found in chromitite from the Luobusa ophiolite, Tibet (Yang et al, 2003). Ren et al (this issue) reported new experimental results on SiO 2 solubility in rutile up to 23 GPa and 2 000 ℃.…”

Section: (Ultra) High-pressure Metamorphic Rocks Ophiolite and Subdumentioning

confidence: 85%

Foreword

Yang

Robinson

2009

J. Earth Sci.

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The Qinghai-Tibet plateau is a fast uplifting area that constitutes the world's highest and thickest, and newest piece of continental plate which has unusual geometric configurations and landscapes. The Qinghai-Tibet plateau consists of multiple terranes, with a complex geological history, including the evolution of the Tethys Ocean basin, the convergence of terranes and island arcs, multiple subductions, multiple collisions and multiple orogens, over a long period of action of continental dynamic processes. Before the Indian and the Asian plates collided, during the Early Paleozoic, it was already a large orogen and terrane collision complex. As a result of the collision of the Indian and Asian plates, the fast uplift of QinghaiTibet plateau became the most magnificent event on the earth during the Cenozoic. It formed a vast, seemingly boundless high plateau with borders consisting of mountain chains with very high peaks, and steep gorges.Twenty articles collected in this special issue on Continental Dynamics of the Qinghai-Tibet Plateau are based on the exploration of continental structures, crustal development features, and driving forces. These include studies on the microscopic and the macroscopic, materials and mechanics, determination and quantities, geometry, kinematics and dynamics near the surface and at depth, geology, geochemistry, and geophysics. Information obtained by these approaches has been used to establish the basic tectonic structure, the terrane configuration and terrane boundaries, the mechanism of structural distortion, as *Corresponding author: yangjingsui@yahoo.com.cn well as the relative movements of tectonic units, the history of the opening and closing of small oceanic basins, terranes before and after the collisions of the Indian and Asian plates, of the orogens themselves, of the huge strike slip faults, and of the uplift of the plateau, the formation of the adjacent orogenic zones of the margins coupled with the exploration of the deep crust and mantle structures and recognition of the dynamic forces. (ULTRA) HIGH-PRESSURE METAMORPHIC ROCKS, OPHIOLITE AND SUBDUCTION RELATED ROCKSThe discovery and description of (ultra) highpressure metamorphic (HPM) zones and ophiolites are the key to the understanding of the terrane margins of the Qinghai-Tibet plateau and the tectonic structure of the plateau. In this issue, Li C et al. (this issue) ) constructed a quantitative P-T path based on interpretation of reaction textures, chemical zoning of minerals in the Danba domal metamorphic terrane, eastern Tibet, and thus provided important constraints on the crustal thickening processes in the Danba area of the Songpan-Ganze orogenic belt. These are not only contributed to the knowledge of HPM zones in the Qinghai-Tibet plateau, but also to other places in China and the rest of the world. In turn, these discoveries will have an important impact on the further understanding of the tectonic structure and the characteristic configuration of the Qinghai-Tibet plateau, and the converging dynami...

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Silicon-rutile — An ultra-high pressure (UHP) mineral from an ophiolite *

Cited by 14 publications

References 2 publications

SiO2 solubility in rutile at high temperature and high pressure

SiO2 solubility in rutile at high temperature and high pressure

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

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