The ∼2 ka subplinian eruption of Montaña Blanca,Tenerife     

G. J. Ablay  G. G. J. Ernst  J. Marti  R. S. J. Sparks 《Bulletin of Volcanology》1995,57(5):337-355

The latest cycle of volcanism on Tenerife has involved the construction of two stratovolcanoes, Teide and Pico Viejo (PV), and numerous flank vent systems on the floor of the Las Cañadas Caldera, which has been partially infilled by magmatic products of the basanite-phonolite series. The only known substantial post-caldera explosive eruption occurred 2 ka bp from satellite vents at Montaña Blanca (MB), to the east of Teide and at PV. The MB eruption began with extrusion of 0.022 km³ of phonolite lava (unit I) from a WNW-ESE fissure system. The eruption then entered an explosive subplinian phase. Over a 7–11 hour period, 0.25 km³ (DRE) of phonolitic pumice (unit II) was deposited from a 15 km high subplinian column, dispersed to the NE by 10 m/s winds. Pyroclastic activity also occurred from vents near PV to the west of Teide. Fire-fountaining towards the end of the explosive phase formed a proximal welded spatter facies. The eruption closed with extrusion of small volume domes and lavas (0.025 km³) at both vent systems. Geochemical, petrological data and Fe-Ti oxide geothermometry indicate the eruption of a chemically and thermally stratified magma system. The most mafic and hottest (875°C) unit I magma can yield the more evolved and cooler (755–825°C) phonolites of units II and III by between 7 and 11% fractional crystallization of an assemblage dominated by alkali feldspar. Analyses of glass inclusions from phenocrysts by ion microprobe show that the pumice was derived from the water-saturated roof zone of a chamber containing 3.0–4.5 wt.% H₂O and abundant halogens (F0.35wt.%). Hotter, more mafic tephritic magma intermingled with the evolved phonolites in banded pumice, indicating the injection of mafic magma into the system during or just before eruption. Reconstruction ot the event indicates a small chamber chemically stratified by in situ (side-wall) crystallization at a depth of 3–4 km below PV. Although phonolite is the dominant product of the youngest activity of the Teide-PV system, there has been no eruption of phonolitic magma for at least 500 years from teide itself and for 2000 years from the PV system. Therefore there could be a large volume of highly evolved, volatile-rich magma accumulating in these magma systems. An eruption of fluorine-rich magma comparable with MB would have major damaging effects on the island.  相似文献   

Preface: The Abee Consortium     

Kurt Marti 《Earth and Planetary Science Letters》1983,62(1):116-117

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Noble gas components in clasts and separates of the Abee meteorite     

John F. Wacker  Kurt Marti 《Earth and Planetary Science Letters》1983,62(1):147-158

The noble gas components and their distributions were studied in a variety of clasts and in separated phases of clast 2,2 using a detailed stepwise release program. The results show the presence of two distinct trapped components: one appears to be similar to Kenna-type gas [28], the other is characterized by element ratios³⁶Ar/⁸⁴Kr < 370 and³⁶Ar/¹³²Xe ≥ 900 and is termed Ar-rich component. Silicate phases are identified as carriers of both components; but since they are differentially released, the results imply that multiple carrier phases are required. Unlike results from other meteorites, HF attack removes all but 15% of the xenon. Substantial amounts of trapped and, in many cases, unfractionated air were observed, apparently in reaction products of reduced and easily oxidized minerals. The¹²⁹Xe_r release systematics imply the presence of two distinct carriers of extinct¹²⁹I and suggest lithophilic behavior of I in Abee. The U/Th-⁴He and K-⁴⁰Ar data are consistent with a 4.5 Gy age. Amounts of spallogenic He, Ne and Ar yield a cosmic ray exposure age of 8 My. We compare the Ar-rich component to noble gas abundances in planetary atmospheres and we discuss a suggested model of origin.  相似文献   

Noble gas components in planetary atmospheres and interiors in relation to solar wind and meteorites     

K. Marti  K. J. Mathew 《Journal of Earth System Science》1998,107(4):425-431

We discuss observed xenon isotopic signatures in solar system reservoirs and possible relationships. The predominant trapped xenon component in ordinary chondrites (OC) is OC-Xe and its isotopic signature differs from Xe in ureilites, in carbonaceous chondrites, in the atmospheres of Earth and Mars, and in the solar wind. Additional minor Xe components were identified in type 3 chondrites and in the metal phase of chondrites. The OC-Xe and ureilite signatures are both consistent with varying mixtures of HL-Xe and slightly mass fractionated solar-type Xe. Xenon in the Martian atmosphere is found to be strongly mass fractionated by 37.7‰ per amu, relative to solar Xe, favoring the heavy isotopes. Xenon in SNC’s from the Martian mantle show admixture of solar-type Xe, which belongs to an elementally strongly fractionated component. The origin of the isotopic signatures of Ne and Xe in the terrestrial atmosphere are discussed in the light of evidence that the Xe isotopic fractionations in the Martian and terrestrial atmospheres are consistent. However, in the terrestrial atmospheric Xe component excesses are observed for¹³²Xe and also for^129,131Xe, relative to fractionated solar Xe. The suggested chemically fractionated fission Xe component (CFF-Xe) seems to closely match the above excesses. We discuss models of origin for planetary volatiles and possible processes driving their evolution to present day compositions.  相似文献   

Search for solar-type nitrogen in the gas-rich Pesyanoe meteorite     

S. V. S. Murty  K. Marti 《Meteoritics & planetary science》1990,25(3):227-230

Abstract— We report nitrogen isotopic data obtained from a stepwise gas release of two grain-size fractions of the gas-rich meteorite Pesyanoe. Cosmic-ray-produced ¹⁵N_c may be present in all temperature steps ≥600 °C, and we correct this component using spallation ²¹Ne data. The resulting ratios reveal the presence of more than one trapped N component. Indigenous N is released above 1000 °C with an isotopic signature of δ¹⁵N = ?33‰. This is consistent with the rather uniform signatures of indigenous nitrogen in enstatite meteorites. There is no evidence for the presence of “very light” N of δ¹⁵N ? ?200‰. On the other hand, a “heavy” nitrogen component appears in the temperature range 700–800 °C, and coincides with a major release of solar-type noble gases. For a two-component mixture, the isotopic shifts in this temperature range define a lower limit δ¹⁵N_corr = ?6‰ for the second component (e.g., solar-type nitrogen). However, for the case of a solar-type component, the calculated δ¹⁵N signature depends on the adopted elemental abundances. For example, adoption of the relative abundances of ¹⁴N and noble gases in lunar ilmenite 71501 yields δ¹⁵N ? +170, which is in the range of the heavier nitrogen signatures observed on the lunar surface.  相似文献   

James R. Arnold 1923–2012     

Kurt Marti  Devendra Lal 《Meteoritics & planetary science》2012,47(11):1884-1886

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Radial oscillations of warm cores in neutron stars     

J. M. Marti  J. A. Miralles  J. Ma Ibáñez 《Astrophysics and Space Science》1987,139(1):93-101

We have solved the relativistic equations for the radial oscillations of warm cores in neutron stars by assuming a given law for the interior distribution of temperature-the resulting from the condition of relativistic thermal equilibrium-and focussed on the properties of the fundamental modes.Our results let us to establish well-defined regions of stability in a diagram central temperature versus central density.  相似文献   

The cosmic ray record in the San Juan Capistrano meteorite     

R.C. Finkel  C.P. Kohl  K. Marti  L. Rancitelli 《Geochimica et cosmochimica acta》1978,42(3):241-250

An integrated study of the cosmic ray exposure history of the San Juan Capistrano meteorite was carried out using measurements of rare gas isotopic abundances, particle track densities and radioisotope concentrations. Spallation systematics determined for Kr isotopes in lunar samples are shown to be valid also for the San Juan Capistrano and St. Severin meteorites, thus allowing us to determine a reliable ⁸¹Kr/⁸³Kr production ratio as needed for applying the ⁸¹Kr-Kr dating method. The ⁸¹Kr-Kr age of SJC is 28.7 ± 2.0 Myr, about 35% longer than ages determined by spallation He or Ne. The minimum observed track production rate (2.6 × 10⁵ tracks/cm² · Myr) sets a minimum of 8 cm for the preatmospheric radius of an assumed spherical body. Track density gradients and the low ⁶⁰Co activity (<2.9 dpm/g Co) both set an upper limit of 10 cm to the radius. Track results show that ablation losses have averaged 6cm. The relative spallation yields of ⁷⁸Kr and ⁸³Kr, and the ratios ³He/²¹Ne and ²²Ne/²¹Ne are all compatible with a hard irradiation as would be experienced by a sample depth of about 6 cm in a body of 8–10 cm. The low activities of ⁵⁴Mn, ²²Na and ²⁶Al are also consistent with these irradiation conditions.  相似文献   

Studying monogenetic volcanoes with a terrestrial laser scanner: case study at Croscat volcano (Garrotxa Volcanic Field,Spain)     

A. Geyer  D. García-Sellés  D. Pedrazzi  S. Barde-Cabusson  J. Marti  J.A. Muñoz 《Bulletin of Volcanology》2015,77(3):1-14

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A redetermination of the isotopic abundances of atmospheric Ar   总被引：5，自引：0，他引：5  

Jee-Yon Lee  Kurt Marti  Kenji Kawamura  Hee-Soo Yoo  Jin Seog Kim 《Geochimica et cosmochimica acta》2006,70(17):4507-4512

Atmospheric argon measured on a dynamically operated mass spectrometer with an ion source magnet, indicated systematically larger ⁴⁰Ar/³⁶Ar ratios compared to the generally accepted value of Nier [Nier A.O., 1950. A redetermination of the relative abundances of the isotopes of carbon, nitrogen, oxygen, argon, and potassium. Phys. Rev. 77, 789-793], 295.5 ± 0.5, which has served as the standard for all isotopic measurements in geochemistry and cosmochemistry. Gravimetrically prepared mixtures of highly enriched ³⁶Ar and ⁴⁰Ar were utilized to redetermine the isotopic abundances of atmospheric Ar, using a dynamically operated isotope ratio mass spectrometer with minor modifications and special gas handling techniques to avoid fractionation. A new ratio ⁴⁰Ar/³⁶Ar = 298.56 ± 0.31 was obtained with a precision of 0.1%, approximately 1% higher than the previously accepted value. Combined with the ³⁸Ar/³⁶Ar (0.1885 ± 0.0003) measured with a VG5400 noble gas mass spectrometer in static operation, the percent abundances of ³⁶Ar, ³⁸Ar, and ⁴⁰Ar were determined to be 0.3336 ± 0.0004, 0.0629 ± 0.0001, and 99.6035 ± 0.0004, respectively. We calculate an atomic mass of Ar of 39.9478 ± 0.0002. Accurate Ar isotopic abundances are relevant in numerous applications, as the calibration of the mass spectrometer discrimination.  相似文献