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

We present the first finding of continental crust-derived Precambrian zircons in garnet/spinel pyroxenite veins within mantle xenoliths carried by the Neogene Hannuoba basalt in the central zone of the North China Craton (NCC). Petrological and geochemical features indicate that these mantle-derived composite xenoliths were formed by silicic melt^lherzolite interaction. The Precambrian zircon ages can be classified into three age groups of 2·4^2·5 Ga, 1·6^2·2 Ga and 0·6^1·2 Ga, coinciding with major geological events in the NCC. These Precambrian zircons fall in the field of continental granitoid rocks in plots of U/Yb vs Hf and Y. Their igneous-type REE patterns and metamorphic zircon type CL images indicate that they were not crystallized during melt^peridotite interaction and subsequent high-pressure metamorphism.The 2·5 Ga zircons have positive eHf(t) values (2·9^10·6), whereas the younger Precambrian zircons are dominated by negative eHf(t) values, indicating an ancient continental crustal origin.These observations suggest that the Precambrian zircons were xenocrysts that survived melting of recycled continental crustal rocks and were then injected with silicate melt into the host peridotite. In addition to the Precambrian zircons, igneous zircons of 315 3 Ma (2 ), 80^170 Ma and 48^64 Ma were separated from the garnet/spinel pyroxenite veins; these provide evidence for lower continental crust and oceanic crust recycling-induced multi-episodic melt^peridotite interactions in the central zone of the NCC. The combination of the positive eHf(t) values (2·91^24·6) of the 315 Ma zircons with the rare occurrence of 302^324 Ma subduction-related diorite^granite plutons in the northern margin of the NCC implies that the 315 Ma igneous zircons might record melt^peridotite interactions in the lithospheric mantle induced by Palaeo-Asian oceanic crust subduction. Igneous zircons of age 80^170 Ma generally coexist with the Precambrian metamorphic zircons and have lower Ce/Yb and Th/U ratios, higher U/Yb ratios and greater negative Eu anomalies.The eHf(t) values of these zircons vary greatly from ^47·6 to 24·6.The 170^110 Ma zircons are generally characterized by negative eHf(t) values, whereas the 110^100 Ma zircons have positive eHf(t) values.These observations suggest that melt^peridotite interactions at 80^170 Ma were induced by partial melting of recycled continental crust. The 48^64 Ma igneous zircons are characterized by negligible Ce anomalies, unusually high REE, U and Th contents, and positive eHf(t) values.These features imply that the melt^peridotite interactions at 48^64 Ma could be associated with a depleted mantle-derived carbonate melt or fluid.

Continental and Oceanic Crust Recycling-induced Melt^Peridotite Interactions in the Trans-North China Orogen: U^Pb Dating, Hf Isotopes and Trace Elements in Zircons from Mantle Xenoliths

A revised regular solution-type thermodynamic model for twelve-component silicate liquids in the system SiO2-TiO2-Al2O3-Fe2O3-Cr2O3-FeO-MgO-CaO-Na2O-K2O-P2O5-H2O is calibrated. The model is referenced to previously published standard state thermodynamic properties and is derived from a set of internally consistent thermodynamic models for solid solutions of the igneous rock forming minerals, including: (Mg,Fe2+,Ca)-olivines, (Na,Mg,Fe2+,Ca)M2 (Mg,Fe2+, Ti, Fe3+, Al)M1 (Fe3+, Al,Si)2TETO6-pyroxenes, (Na,Ca,K)-feldspars, (Mg,Fe2+) (Fe3+, Al, Cr)2O4-(Mg,Fe2+)2 TiO4 spinels and (Fe2+, Mg, Mn2+)TiO3-Fe2O3 rhombohedral oxides. The calibration utilizes over 2,500 experimentally determined compositions of silicate liquids coexisting at known temperatures, pressures and oxygen fugacities with apatite ±feldspar ±leucite ±olivine ±pyroxene ±quartz ±rhombohedral oxides ±spinel ±whitlockite ±water. The model is applicable to natural magmatic compositions (both hydrous and anhydrous), ranging from potash ankaratrites to rhyolites, over the temperature (T) range 900°–1700°C and pressures (P) up to 4 GPa. The model is implemented as a software package (MELTS) which may be used to simulate igneous processes such as (1) equilibrium or fractional crystallization, (2) isothermal, isenthalpic or isochoric assimilation, and (3) degassing of volatiles. Phase equilibria are predicted using the MELTS package by specifying bulk composition of the system and either (1) T and P, (2) enthalpy (H) and P, (3) entropy (S) and P, or (4) T and volume (V). Phase relations in systems open to oxygen are determined by directly specifying the fo2 or the T-P-fo2 (or equivalently H-P-fo2, S-P-fo2, T-V-fo2) evolution path. Calculations are performed by constrained minimization of the appropriate thermodynamic potential. Compositions and proportions of solids and liquids in the equilibrium assemblage are computed.

Chemical mass transfer in magmatic processes IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures

羟氨苄青霉素引起大疱性类天疱疮样疹

Knowledge of temperature and pressure, however qualitative, has been central to our views of geology since at least the early 19th century. In 1822, for example, Charles Daubeny presented what may be the very first “Geological Thermometer,” comparing temperatures of various geologic processes (Torrens 2006). Daubeny (1835) may even have been the first to measure the temperature of a lava flow, by laying a thermometer on the top of a flow at Vesuvius—albeit several months following the eruption, after intervening rain (his estimate was 390°F). In any case, pressure ( P ) and temperature ( T ) estimation lie at the heart of fundamental questions: How hot is Earth, and at what rate has the planet cooled. Are volcanoes the products of thermally driven mantle plumes? Where are magmas stored, and how are they transported to the surface—and how do storage and transport relate to plate tectonics? Well-calibrated thermometers and barometers are essential tools if we are to fully appreciate the driving forces and inner workings of volcanic systems.

This chapter presents methods to estimate the P-T conditions of volcanic and other igneous processes. The coverage includes a review of existing geothermometers and geobarometers, and a presentation of approximately 30 new models, including a new plagioclase-liquid hygrometer. Our emphasis is on experimentally calibrated “thermobarometers,” based on analytic expressions using P or T as dependent variables. For numerical reasons (touched on below) such expressions will always provide the most accurate means of P-T estimation, and are also most easily employed. Analytical expressions also allow error to be ascertained; in the absence of estimates of error, P-T estimates are nearly meaningless. This chapter is intended to complement the chapters by Anderson et al. (2008), who cover granitic systems, and by Blundy and Cashman (2008) and Hansteen and Klugel (2008), who consider additional methods …

Thermometers and Barometers for Volcanic Systems

CrxRe1−xO2 oxides with different rutile-like structures: changes in the electronic configuration and resulting physical properties

Caldera de los Marteles (lat 27 ~ 57' 25\" N, long t 1 ~ 50' 40\" V~r), La Calderil la (lat 27 ~ 57' 40\" N, long 1t ~ 52' 30\" W), and Caldera de B a n d a m a Oat 28 ~ 02' N, long 1 t ~ 46' ~u are th ree p r o m i n e n t cra ters of Recen t age on Gran Canar ia fo rmed by p h r e a t o m a g m a t i c e rup t ions accompan i ed b y subs idence . E leva t ion (crater bo t tom) above sea level, d i ame t e r and p resen t dep th to p re -e rup t ion sur face are, in me te r s : Marteles (t458, 550, 84), Calderil la (1765, 200, 60), B a n d a m a (2t7, 750, t40). All c ra te rs are r i m m e d b y 5-50 m th i ck f low-deposi ted and air-fail pyroclas t ics of acc identa l rock f r a g m e n t s and juveni le s ideromelane , over la in or i n t e rbedded wi th ves icu la ted ash, lapilli, and spa t te r . Depos i t ion of beds d o m i n a t e d b y accidenta l f r a g m e n t s was m a i n l y b y base surge, as ev idenced by the following fea tures : concent r ic d i s t r ibu t ion along cra ter r ims b u t con f inemen t to val leys f a r the r away ; p las te r ing of s t i cky ma te r i a l aga ins t obstacles and val ley walls; poor sor t ing; lowangle c rossbedding; absence of i m p a c t sags b e n e a t h large blocks. Addi t iona l evidence of t he presence of wa te r and /o r s t e a m is p rov ided by the a b u n d a n c e of dense s ideromelane Iapilli, acc re t ionary and a rmored lapilli, ves icu la ted tuf ts , and d i scon t inons bedding. The smal les t crater , Calderilla, has a t h i ck tu f f r ing wi th juveni le exceeding acc identa l f r agmen t s , m a x i m u m block size being less t h a n 50 cm, wi th good sor t ing a n d ex t r eme th i cken ing on t he downwi nd side ( trade wind di rec t ions a s s u m e d cons tan t ) . The ini t ial c ra te r fo rmed a t t h e edge of a smal l p l a t eau where a s t r e a m flowed down the r im. The th i ck tuf f r ing h a d blocked off and d iver ted r u n n i n g surface water , so t h a t a 80 m h i gh spa t te r , b o m b and l ava cone fo rmed di rect ly a f te rwards , 250 m d o w n s t r e a m (SE) f rom the init ial crater , p robab ly above the s ame fissure. Marteles is s i t ua t ed in l ine wi th five o ther e rup t ive centers a long a f i s s u r e o r en-echelon sets of f i s s u r e s t o t a l l i n g 2.5 k m in length . The five o the r e rup t ive centers h a v e emi t t ed vesicu la ted ash, spa t t e r and /o r l ava flows and form low cones, all s i t ua t ed on h igh m o u n t a i n tops or h igh p la teaus . P roduc t s f rom all s ix centers overlap, ind ica t ing n e a r s y n c h r o n o u s ac t iv i ty . Marteles, a deep circular c ra ter r i m m e d b y basesurge deposits , fo rmed r igh t in t he cen te r of a s teep-s ided val ley (Barranco de Guayadeque) . This s t rong ly sugges t s t h a t sur face wa te r ga ined access to a m a g m a t i c h e a t source when a f issure opened in the s t r e a m valley, leading to powerful p h r e a t o m a g m a t i c e rup t ions (blocks are up to 2 m in d iameter) . A dwind l ing wa te r supp l y due to u p s t r e a m blocking b y depos is ts f rom th i s a nd o ther pa r t s of t he act ive f issure caused the fo rma t ion of \" a g g l u t i n a t e Iapill i\", sub rounded , only s l ight ly vesicular lapilIi con ta in ing cores of c o u n t r y rock. Such an i n t i m a t e m i x t u r e of m a g m a wi th c o u n t r y rock is found a t m a n y o ther m a a r s (H.-U. Schmincke , unpubl . ) and is t h o u g h t to be due to v io lent c h u r n i n g in t he m a g m a c h a m b e r w h e n the cra ter is par t ia l ly open, r o u n d i n g being effected du r ing u p w a r d gas t r anspor t . F ina l ac t iv i ty a t Marteles resul ted in ves icu la ted ash and lapilli, sugges t ing comple te b locking of wa te r access. Bandama--studied in reconna i ssance o n l y i s no t inside a deep va l ley and m a y owe i ts f o rma t ion to the con tac t of g r o u n d r a the r t h a n sur face wa t e r wi th m a g m a , a sugges t ion fu r t he r suppor t ed b y t he g rea t dep t h of t he crater . T he v o l u m e of i ts pyroclas t ics is larger t h a n t h a t of t he o ther two craters , and m a x i m u m block size exceeds 2 In.

Craters of phreatomagmatic origin on Gran Canaria, Canary Islands

Redox melting and composition of near liquidus melts of C–O–H-bearing peridotite

In this study we present a fresh isotopic data, as well as U–Pb ages from different REE-minerals in carbonatites and phoscorites of Guli massif using in situ LA-ICPMS technique. The analyses were conducted on apatites and perovskites from calcio-carbonatite and phoscorite units, as well as on pyrochlores and baddeleyites from the carbonatites. The 87Sr/86Sr ratios obtained from apatites and perovskites from the phoscorites are 0.70308–0.70314 and 0.70306–0.70313, respectively; and 0.70310–0.70325 and 0.70314–0.70327, for the pyrochlores and apatites from the carbonatites, respectively. Furthermore, the in situ laser ablation analyses of apatites and perovskites from the phoscorite yield eNd from 3.6 (±1) to 5.1 (±0.5) and from 3.8 (±0.5) to 4.9 (±0.5), respectively; eNd of apatites, perovskites and pyrochlores from carbonatite ranges from 3.2 (±0.7) to 4.9 (±0.9), 3.9 (±0.6) to 4.5 (±0.8) and 3.2 (±0.4) to 4.4 (±0.8), respectively. Laser ablation analyses of baddeleyites yielded an eHf(t)d of +8.5 (± 0.18); prior to this study Hf isotopic characteristic of Guli massif was not known. Our new in situ eNd, 87Sr/86Sr and eHf data on minerals in the Guli carbonatites imply a depleted source with a long time integrated high Lu/Hf, Sm/Nd, Sr/Rb ratios. In situ U–Pb age determination was performed on perovskites from the carbonatites and phoscorites and also on pyrochlores and baddeleyites from carbonatites. The co-existing pyrochlores, perovskites and baddeleyites in carbonatites yielded ages of 252.3 ± 1.9, 252.5 ± 1.5 and 250.8 ± 1.4 Ma, respectively. The perovskites from the phoscorites yielded an age of 253.8 ± 1.9 Ma. The obtained age for Guli carbonatites and phoscorites lies within the range of ages previously reported for the Siberian Flood Basalts and suggest essentially synchronous emplacement with the Permian-Triassic boundary.

Gerhard P. Brey

Papers

CrxRe1−xO2 oxides with different rutile-like structures: changes in the electronic configuration and resulting physical properties

Craters of phreatomagmatic origin on Gran Canaria, Canary Islands

Redox melting and composition of near liquidus melts of C–O–H-bearing peridotite

In situ LA-ICPMS Isotopic and Geochronological Studies on Carbonatites and Phoscorites from the Guli Massif, Maymecha-Kotuy, Polar Siberia

Metallic Re–Re bond formation in different MRe2O6 (MFe, Co, Ni) rutile-like polymorphs: The role of temperature in high-pressure synthesis