A review of the geologic history of the Himalayan-Tibetan orogen suggests that at least 1400 km of north-south shortening has been absorbed by the orogen since the onset of the Indo-Asian collision at about 70 Ma. Significant crustal shortening, which leads to eventual construction of the Cenozoic Tibetan plateau, began more or less synchronously in the Eocene (50–40 Ma) in the Tethyan Himalaya in the south, and in the Kunlun Shan and the Qilian Shan some 1000–1400 km in the north. The Paleozoic and Mesozoic tectonic histories in the Himalayan-Tibetan orogen exerted a strong control over the Cenozoic strain history and strain distribution. The presence of widespread Triassic flysch complex in the Songpan-Ganzi-Hoh Xil and the Qiangtang terranes can be spatially correlated with Cenozoic volcanism and thrusting in central Tibet. The marked difference in seismic properties of the crust and the upper mantle between southern and central Tibet is a manifestation of both Mesozoic and Cenozoic tectonics. The form...

Geologic Evolution of the Himalayan-Tibetan Orogen

The thermodynamic properties of 154 mineral end-members, 13 silicate liquid end-members and 22 aqueous fluid species are presented in a revised and updated data set. The use of a temperature-dependent thermal expansion and bulk modulus, and the use of high-pressure equations of state for solids and fluids, allows calculation of mineral–fluid equilibria to 100 kbar pressure or higher. A pressure-dependent Landau model for order–disorder permits extension of disordering transitions to high pressures, and, in particular, allows the alpha–beta quartz transition to be handled more satisfactorily. Several melt end-members have been included to enable calculation of simple phase equilibria and as a first stage in developing melt mixing models in NCKFMASH. The simple aqueous species density model has been extended to enable speciation calculations and mineral solubility determination involving minerals and aqueous species at high temperatures and pressures. The data set has also been improved by incorporation of many new phase equilibrium constraints, calorimetric studies and new measurements of molar volume, thermal expansion and compressibility. This has led to a significant improvement in the level of agreement with the available experimental phase equilibria, and to greater flexibility in calculation of complex mineral equilibria. It is also shown that there is very good agreement between the data set and the most recent available calorimetric data.

An internally consistent thermodynamic data set for phases of petrological interest

Two end member models of how the high elevations in Tibet formed are (i) continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and (ii) time-dependent, localized shear between coherent lithospheric blocks. Recent studies of Cenozoic deformation, magmatism, and seismic structure lend support to the latter. Since India collided with Asia ∼55 million years ago, the rise of the high Tibetan plateau likely occurred in three main steps, by successive growth and uplift of 300- to 500-kilometer-wide crustal thrust-wedges. The crust thickened, while the mantle, decoupled beneath gently dipping shear zones, did not. Sediment infilling, bathtub-like, of dammed intermontane basins formed flat high plains at each step. The existence of magmatic belts younging northward implies that slabs of Asian mantle subducted one after another under ranges north of the Himalayas. Subduction was oblique and accompanied by extrusion along the left lateral strike-slip faults that slice Tibet's east side. These mechanisms, akin to plate tectonics hidden by thickening crust, with slip-partitioning, account for the dominant growth of the Tibet Plateau toward the east and northeast.

http://science.sciencemag.org/content/sci/294/5547/1671.full.pdf

Oblique Stepwise Rise and Growth of the Tibet Plateau

The thermodynamic properties of 254 end-members, including 210 mineral end-members, 18 silicate liquid end-members and 26 aqueous fluid species are presented in a revised and updated internally consistent thermodynamic data set. The PVT properties of the data set phases are now based on a modified Tait equation of state (EOS) for the solids and the Pitzer & Sterner (1995) equation for gaseous components. Thermal expansion and compressibility are linked within the modified Tait EOS (TEOS) by a thermal pressure formulation using an Einstein temperature to model the temperature dependence of both the thermal expansion and bulk modulus in a consistent way. The new EOS has led to improved fitting of the phase equilibrium experiments. Many new end-members have been added, including several deep mantle phases and, for the first time, sulphur-bearing minerals. Silicate liquid end-members are in good agreement with both phase equilibrium experiments and measured heat of melting. The new dataset considerably enhances the capabilities for thermodynamic calculation on rocks, melts and aqueous fluids under crustal to deep mantle conditions. Implementations are already available in thermocalc to take advantage of the new data set and its methodologies, as illustrated by example calculations on sapphirine-bearing equilibria, sulphur-bearing equilibria and calculations to 300 kbar and 2000 °C to extend to lower mantle conditions.

An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids

[1] The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ∼1% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire ∼1000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2-year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products.

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Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE)

INTRODUCTION Experimental studies were carried out to evaluate phase relations involving titanite–F–Al-titanite solid solution in the system CaSiO3– Geological background Al2SiO5–TiO2–CaF2. The experiments were conducted at Titanite is a common accessory mineral in mafic, pelitic 900–1000°C and 1·1–4·0 GPa. The average F/Al ratio in and granitic rocks from many geological environments titanite solid solution in the experimental run products is 1·01 ± (Higgins & Ribbe, 1976; Ribbe, 1982; Enami et al., 0·06, and XAl ranges from 0·33 ± 0·02 to 0·91 ± 0·05, 1993). Titanite may deviate significantly from its ideal consistent with the substitution [TiO]–1[AlF ]1. Analysis of composition by the substitution Al and F for Ti and O the phase relations indicates that titanite solid solutions coexisting (Hollabaugh, 1980; Franz & Spear, 1985; Bernau et al., with rutile are always low in XAl , whereas the maximum XAl of 1986; Fehr, 1991; Oberti et al., 1991; Carswell et al., titanite solid solution occurs with fluorite and either anorthite or 1996). The Al + OH ⇔ Ti + O substitution leads Al2SiO5. Reaction displacement experiments were performed by to the Al–OH end-member vuagnatite CaAlSiO4(OH), adding fluorite to the assemblage anorthite + rutile = titanite + which has a different structure from titanite (McNear et kyanite. The reaction shifts from 1·60 GPa to 1·15 ± 0·05 al., 1976) and is typical of low-temperature geological GPa at 900°C, from 1·79 GPa to 1·375 ± 0·025 GPa at environments (Enami et al., 1993). By contrast, the F–Al 1000°C, and from 1·98 GPa to 1·575 ± 0·025 GPa at substitution is isostructural and is common at high meta1100°C. The data show that the activity of CaTiSiO4O is very morphic temperatures (>500–600°C) and pressures. For close to the ideal molecular activity model (XTi ) at 1100°C, but example, up to 55 mol % F–Al substitution has been shows a negative deviation at 1000°C and 900°C. The results reported from highand ultra-high-pressure metaconstrain G°f,298·15 of CaAlSiO4F to be −2595 ± 3 kJ/mol morphic rocks (Franz & Spear, 1985; Sobolev & Shatsky, and S°298·15 to be in the range of 105·2–109·6 J/mol K, which 1991; Carswell et al., 1996). The common association of in turn can be used to calculate petrogenetic grids involving titanite F–Al-rich titanites with high-pressure environments has solid solutions in the system CaTiSiO4O–CaAlSiO4F. led to the suggestion that equilibria involving titanite solid solution may be useful for constraining pressure, temperature and/or F2 fugacity during metamorphism (Smith, 1977; Franz & Spear, 1985; Gibert et al., 1990;

http://www2.ess.ucla.edu/~manning/pdfs/t02.pdf

The Substitution of Al and F in Titanite at High Pressure and Temperature: Experimental Constraints on Phase Relations and Solid Solution Properties

http://www2.ess.ucla.edu/~manning/pdfs/tm07a.pdf

The solubility of corundum in H2O at high pressure and temperature and its implications for Al mobility in the deep crust and upper mantle

http://www2.ess.ucla.edu/~manning/pdfs/ammn14.pdf

Dehydration melting and the relationship between granites and granulites

Fluid-rock interaction is important in a wide range of settings in the middle crust to the upper mantle. Fluids are liberated in the crust during prograde metamorphism in convergent-margin settings. At greater depth, devolatilization of subducting lithosphere plays a major role in global element cycling, metasomatic alteration of the mantle, and the genesis of arc magmas. Mafic magmas produced in these settings may stall in the lower crust and liberate volatiles that metasomatize surrounding rocks and trigger production of silicic magmas of crustal derivation. Mounting evidence points to an important role for metasomatic alteration by saline brines in the genesis of some lower-crustal granulite-facies metamorphic terranes.

Unlike shallow geothermal systems or low-grade metamorphic environments, there has been only limited progress in modeling the fluid-rock interaction that characterizes the deeper geologic systems enumerated above. Such phase-equilibrium models require as input the chemical potential, μ i μ i ≡ ( ∂ G i ∂ n i ) P , T (1) 
of the participating phases or species i , where G i is the Gibbs free energy of i , n i is the number of moles of i , P is pressure, and T is temperature. At the P and T of interest,

 μ i = μ i ∘ + R T l n a i (2) 
Where μ° is standard state chemical potential, a is activity, R is the gas constant, and T is absolute temperature.

It is challenging to quantify the right-hand terms in Equation (2) at P and T ranging from the middle crust to the upper mantle. This is chiefly because of (1) limitations in our quantitative knowledge of key properties of relevant solutes and H2O, and (2) uncertainty in how properly to model solute activities at the requisite conditions. As a consequence, aqueous geochemists have been discouraged from plying their trade in the numerous deep geologic systems in which fluid-rock interaction may play a major role in the Earth’s chemical and physical evolution. …

/pdf/thermodynamic-modeling-of-fluid-rock-interaction-at-mid-9wcb8u6nc9.pdf

Thermodynamic Modeling of Fluid-Rock Interaction at Mid-Crustal to Upper-Mantle Conditions

http://www2.ess.ucla.edu/~manning/pdfs/nm08.pdf

Craig E. Manning

Papers

The Substitution of Al and F in Titanite at High Pressure and Temperature: Experimental Constraints on Phase Relations and Solid Solution Properties

The solubility of corundum in H2O at high pressure and temperature and its implications for Al mobility in the deep crust and upper mantle

Dehydration melting and the relationship between granites and granulites

Thermodynamic Modeling of Fluid-Rock Interaction at Mid-Crustal to Upper-Mantle Conditions

Solubility of corundum in the system Al2O3–SiO2–H2O–NaCl at 800 °C and 10 kbar