The relative controls on forest fires and fuel source fluctuations in the Holocene deciduous forests of southern Wisconsin,USA          下载免费PDF全文

JOSHUA R. MUELLER  COLIN J. LONG  JOSEPH J. WILLIAMS  ANDREA NURSE  KENDRA K. MCLAUCHLAN 《第四纪科学杂志》2014,29(6):561-569

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Variability of Summer Monsoon Rainfall in India on Inter-Annual and Decadal Time Scales   总被引：1，自引：0，他引：1       下载免费PDF全文

Porathur Vareed JOSEPH  Bindu GOKULAPALAN  Archana NAIR  Shinu Sheela WILSON 《大气和海洋科学快报》2013,6(5):398-403

Indian Summer Monsoon Rainfall(ISMR)exhibits a prominent inter-annual variability known as troposphere biennial oscillation.A season of deficient June to September monsoon rainfall in India is followed by warm sea surface temperature(SST)anomalies over the tropical Indian Ocean and cold SST anomalies over the western Pacific Ocean.These anomalies persist until the following monsoon,which yields normal or excessive rainfall.Monsoon rainfall in India has shown decadal variability in the form of 30 year epochs of alternately occurring frequent and infrequent drought monsoons since1841,when rainfall measurements began in India.Decadal oscillations of monsoon rainfall and the well known decadal oscillations in SSTs of the Atlantic and Pacific oceans have the same period of approximately 60 years and nearly the same temporal phase.In both of these variabilities,anomalies in monsoon heat source,such as deep convection,and middle latitude westerlies of the upper troposphere over south Asia have prominent roles.  相似文献   

印度喀拉拉邦雨影区流域系统形态分析及其水文意义(英文)     

Jobin THOMAS  Sabu JOSEPH  K.P. THRIVIKRAMJI  George ABE 《地理学报(英文版)》2011,21(6)

The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin (PRB) lies on the rain shadow region of the southern Western Ghats, India, where climate showed marked intra-basin variation. A morphometric analysis was done to evaluate the drainage characteristics of PRB using topographical maps and digital elevation data. PRB was divided into eighteen 4th order basins (SB1-SB18), distributed along various climatic...  相似文献   

Rossby waves in May and the Indian summer monsoon rainfall     

P. V. JOSEPH  J. SRINIVASAN 《地球，A辑:动力气象学与海洋学》1999,51(5):854-864

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A TRIBUTE TO WILBUR ZELINSKY*     

JOSEPH S. WOOD 《Geographical review》2006,96(2):iii-vii

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Monazite-Xenotime Thermochronometry and Al2SiO5 Reaction Textures in the Picuris Range, Northern New Mexico, USA: New Evidence for a 1450-1400 Ma Orogenic Event     

DANIEL  CHRISTOPHER G.; PYLE  JOSEPH M. 《Journal of Petrology》2006,47(1):97-118

Al₂SiO₅ reaction textures in aluminous schist and quartziteof the northern Picuris range, north-central New Mexico, recorda paragenetic sequence of kyanite to sillimanite to andalusite,consistent with a clockwise P–T loop, with minor decompressionnear the Al₂SiO₅ triple-point. Peak metamorphic temperaturesare estimated at 510–525°C, at 4·0–4·2kbar. Kyanite and fibrolite are strongly deformed; some prismaticsillimanite, and all andalusite are relatively undeformed. Monaziteoccurs as inclusions within kyanite, mats of sillimanite andcentimetre-scale porphyroblasts of andalusite, and is typicallyaligned subparallel to the dominant regional foliation (S₀/S₁or S₂) and extension lineation (L₁). Back-scatter electron imagesand X-ray maps of monazite reveal distinct core, intermediateand rim compositional domains. Monazite–xenotime thermometryfrom the intermediate and rim domains yields temperatures of405–470°C (±50°C) and 500–520°C(±50°C), respectively, consistent with the progradeto peak metamorphic growth of monazite. In situ, ion microprobeanalyses from five monazites yield an upper intercept age of1417 ± 9 Ma. Near-concordant to concordant analyses yield²⁰⁷Pb–²⁰⁶Pb ages from 1434 ± 12 Ma (core) to 1390± 20 Ma (rim). We find no evidence of older regionalmetamorphism related to the 1650 Ma Mazatzal Orogeny. KEY WORDS: Al₂SiO₅; metamorphism; monazite; thermochronometry; triple-point  相似文献   

Deformation structures and an alteration zone linked to deposition of volcanogenic sulphate in an ancient playa (Oligocene of Nebraska, USA)     

DAVID B. LOOPE  JOSEPH A. MASON†  HUIMING BAO‡  RICHARD M. KETTLER  C. WILLIAM ZANNER¶ 《Sedimentology》2005,52(1):123-139

Historic, sulphur-rich volcanic eruptions have altered global climate for as much as five years, and much larger events are known from the geologic record. At Scotts Bluff, Nebraska, Early Oligocene strata of the lower Arikaree Group contain a tephra bed with abundant calcite pseudomorphs after gypsum. Previous work has shown sulphate from the pseudomorphs in this tephra bears a high ¹⁷O anomaly indicative of oxidation of sulphur gases by ozone or hydrogen peroxide in the atmosphere. Possible sources of the tephra were caldera eruptions at about 28 Ma in the San Juan volcanic field of south-western Colorado (∼500 km SW of the study site) and the eastern Great Basin (∼1000 km WSW). The present sedimentological study shows that tephra and volcanogenic sulphate were deposited and preserved within a small, surface-discharging playa that developed on the irregular upper surface of aeolian siltstones of the subjacent White River Group. Sulphate solutions (including perhaps sulphuric acid) percolated downward within the vadose zone, dissolving early formed smectite cement within underlying volcaniclastic sandstones, reddening these rocks along an irregular alteration front. Preserved fine-scale stratification within the sandstones precludes the possibility that reddening took place during pedogenesis. Displacive growth of gypsum at the playa centre folded tephra beds and forced tephra into underlying sandstones, forming elongate cones. The large mass fraction of gypsum (now replaced by calcite) in the playa sediments suggests a huge, long-distance delivery of sulphate aerosols. Some of the sulphate and tephra may have come from the same eruption, or the fine-grained tephra may simply have aided preservation of dry-fog sulphate derived from an unrelated, effusive eruption of lava.  相似文献   

Adakite-like Lavas from Antisana Volcano (Ecuador): Evidence for Slab Melt Metasomatism Beneath Andean Northern Volcanic Zone   总被引：6，自引：1，他引：6  

BOURDON  ERWAN; EISSEN  JEAN-PHILIPPE; MONZIER  MICHEL; ROBIN  CLAUDE; MARTIN  HERVE; COTTEN  JOSEPH; HALL  MINARD L. 《Journal of Petrology》2002,43(2):199-217

Extensive sampling of the Antisana volcano in Ecuador (NorthernVolcanic Zone of the Andes) has revealed the presence of adakite-likerocks throughout the edifice, i.e. rocks with geochemical characteristicsclose, but not identical, to those of slab melts. Two main volcanicgroups have been distinguished, characterized by two distinctevolutionary trends. The AND group, mostly composed of andesites,shows the clearest adakitic characteristics such as high La/Yband Sr/Y ratios and low heavy rare earth element (HREE) contents.The CAK group, composed of high-K andesites and dacites, displaysless pronounced adakitic-like characteristics. Although themore basic rocks of each group are difficult to distinguishon many geochemical diagrams, a geochemical study shows thatthe evolution of the AND and CAK groups is dominated by differentpetrogenetic processes. The isotopic characteristics of theCAK rocks suggest that evolution of this group is dominatedby a limited assimilation–fractional crystallization processwithin the granitic continental basement of the cordillera.In the AND group, the abundances of incompatible elements, suchas Nb or HREE, suggest that the series was produced by a partialmelting process in a mantle rich in garnet, amphibole and/orclinopyroxene. Such a mantle source has been demonstrated (experimentallyand by exhumed mantle xenoliths) to be produced in subductionzones where slab melts react with and metasomatize the mantlewedge. In Ecuador, magmas erupted in the Western Cordillera(trenchward relative to Antisana volcano) are true adakites,suggesting that slab melts can be responsible for the metasomatismof the mantle wedge beneath the NVZ in Ecuador. If mantle convectioncan drag down this modified mantle beneath Antisana volcano,destabilization of metasomatic amphibole at appropriate pressuresin this modified garnetiferous mantle can adequately explainthe formation and the geochemical features of Antisana lavas. KEY WORDS: subduction; adakite; metasomatism; Ecuador; AFC; Sr and Nd isotopes  相似文献   

Monazite-Xenotime-Garnet Equilibrium in Metapelites and a New Monazite-Garnet Thermometer   总被引：9，自引：0，他引：9  

PYLE  JOSEPH M.; SPEAR  FRANK S.; RUDNICK  ROBERTA L.; McDONOUGH  WILLIAM F. 《Journal of Petrology》2001,42(11):2083-2107

Prograde suites of pelitic rocks were examined with electronmicroprobe and laser ablation inductively coupled plasma massspectrometry to determine the systematics of element partitioningbetween coexisting monazite, xenotime, and garnet. Monazitegrains that grew in equilibrium with xenotime are enriched inY and Dy compared with monazite that grew in xenotime-absentassemblages. Y and heavy rare earth element contents of monazitecoexisting with xenotime increase with rising temperature. Monazite–xenotimeY–Gd and Y–Dy partitioning is systematic withina metamorphic grade, and increases slightly with increasingmetamorphic grade, suggesting that monazite–xenotime pairsapproached partitioning equilibrium. Garnet and monazite inboth xenotime-bearing and xenotime-absent assemblages show astrong ( R² = 0·94) systematic relationship between inversetemperature and ln(K_Eq) for the net-transfer equilibrium YAG+ OH-Ap + (25/4)Qtz = (5/4)Grs + (5/4)An + 3YPO₄-Mnz + 1/2H₂O,suggesting that garnet and monazite crystallized in compositionalequilibrium. The following temperature–K_Eq relationshipfor the equilibrium above has been derived:   相似文献   

Simulations of terrestrial carbon metabolism and atmospheric CO₂ in a general circulation model     

A. SCOTT DENNING  G. JAMES COLLATZ  CHANGAN ZHANG  DAVID A. RANDALL  JOSEPH A. BERRY  PIERS J. SELLERS  GREG D. COLELL  DONALD A. DAZLICH 《Tellus. Series B, Chemical and physical meteorology》1996,48(4):521-542

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