The Merzbacher & Eggler (1984) Geohygrometer: a Cautionary Note on its Suitability for High-K Suites     

SCHMITT  A. K.; DE SILVA  S. L. 《Journal of Petrology》2000,41(3):357-362

The use of the popular Merzbacher & Eggler (1984, Geology12, 587–590) experimental geohygrometer for calcalkalineandesites and dacites is critically evaluated and two pitfallsare found. First, calculation of the correct projection parametersis problematic because two endmember calculation schemes arefound in the literature; Baker & Eggler (1983, Journal ofVolcanology and Geothermal Research 18, 387–404) and Walkeret al. (1979, Contributions to Mineralogy and Petrology 70,111–125). Although related, these two schemes have crucialdifferences that can result in very different projection parametersfor the plagioclase component. This is most crucial for high-Kcompositions; H₂O contents estimated using the Walker et al.(1979) scheme can be as much as 100% higher than those estimatedusing the Baker & Eggler (1983) projection. Incorrect projectionparameter calculation has led to overestimation of water contentsin high-K andesites and dacites from the Central Andes. Second,for medium-K and high-K andesitic–dacitic compositionswater contents derived using the Merzbacher & Eggler (1984)geohygrometer deviate considerably from water contents estimatedusing other methods. Experimental data from the literature,and our studies of water contents inferred from melt inclusionsand plagioclase–melt equilibrium for dacites from theAltiplano–Puna Volcanic Complex of the Central Andes indicatethat the Merzbacher & Eggler (1984) geohygrometer shouldnot be applied to compositions with K₂O >1·9 wt %,as originally calibrated. KEY WORDS: magmatic volatiles; pre-eruptive water; experimental geohygrometer; high-K suites; melt inclusion  相似文献   

The sedimentary expression of oceanic anoxic event 1b in the North Atlantic     

JOÃO TRABUCHO ALEXANDRE  JUAN PEDRO RODRÍGUEZ‐LÓPEZ  POPPE L. DE BOER 《Sedimentology》2011,58(5):1217-1246

The Aptian/Albian oceanic anoxic event 1b contains the record of several perturbations in the global carbon cycle and multiple black shale levels, particularly in the Western Tethys. The local lithological expression of an oceanic anoxic event depends on palaeogeographical and depositional setting as well as on regional palaeoclimate. Marine sediments at a particular location may therefore be more or less organic‐rich (or not at all) and they may consist of different lithologies. In most studies, however, much of the lithological variability associated with oceanic anoxic events is left unaccounted for and, thus, the exact processes leading to the enrichment of organic matter in these marine sediments and their subsequent preservation in the geological record are unknown. This study focuses on the local sedimentary processes behind the deposition of organic‐rich sediments at Deep Sea Drilling Project Site 545 and Ocean Drilling Program Sites 1049 and 1276 in the North Atlantic during oceanic anoxic event 1b. Although specifically dealing with the sediments deposited during this particular event at these localities, it is expected that the same processes were responsible for determining the exact sedimentary products at localities in similar settings, as well as during other similar events in the Mesozoic. Here, it is shown that the deposition of organic‐rich sediments during oceanic anoxic event 1b was a consequence of the enhanced productivity favoured by upwelling and by riverine nutrient input, or aeolian fertilization of the euphotic zone depending on geographical location. Slope instability processes resulted in the transfer of part of these organic‐rich sediments from the shelf to deep sea depocentres as mud‐laden organic‐rich turbidites, especially in the northern North Atlantic. The so‐called ‘black shales’ are much more varied than their name implies. The end product of sedimentation during an oceanic anoxic event at a particular location is commonly the result of several equifinal processes acting on a local scale rather than the direct result of basinal or even global mechanisms.  相似文献   

Middle and Late Quaternary depositional sequences and cycles in the eastern Mediterranean     

G. J. DE  LANGE  J. J. MIDDELBURG  P. A. PRUYSERS 《Sedimentology》1989,36(1):151-156

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Tidal averaging and models for anisotropic dispersion in coastal waters     

J. M. DE KOK 《地球，A辑:动力气象学与海洋学》1994,46(2):160-177

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Definition and character of the Regency Interglacial and Early-Middle Pleistocene stratigraphy in the King Valley, western Tasmania, Australia     

SEAN J. FITZSIMONS  ERIC A. COLHOUN  GUUS VAN DE GEER  ROBERT S. HILL 《Boreas: An International Journal of Quaternary Research》1990,19(1):1-15

Interpretation of weathered glacial and interglacial deposits in the lower King Valley suggests that the Early Pleistocene Thureau Formation is conformably overlain by the Regency Formation. Pollen analysis of the Regency Formation provides evidence of a new climatic stage, the Regency Interglacial. The interglacial deposit consists of humified peat overlain by drifted wood and leaves. The pollen analysis shows a transition from montane scrub rainforest to lowland temperate rainforest dominated by Lagarostrobos franklinii, Nothofagus cunninghamii and Phyllocladus aspleniifolius. Trace quantities of the species Quintinia psi-latispora and Gothanipollis perplexus , now both extinct in Tasmania, were also recorded. On the basis of intense chemical weathering and correlation with sediments that have a reversed magnetization the weathered glacial deposits of the Thureau Formation are thought to be older than 730,000 B.P. The eroded interglacial deposit rests on the weathered deposits and is buried by outwash gravels of the David Formation, which was deposited during an ice advance of the Middle Pleistocene Henty Glaciation (c. 150,000 B.P.). Comparison of the Regency site with a site 2 km to the south at Baxter Rivulet shows that the unconformity between the interglacial deposit and the overlying outwash gravel represents the erosion of the evidence for the Middle Pleistocene Moore Glaciation.  相似文献   

Radar observations of asteroid 25143 Itokawa (1998 SF36)     

Steven J. OSTRO  Lance A. M. BENNER  Michael C. NOLAN  Christopher MAGRI  Jon D. GIORGINI  Daniel J. SCHEERES  Stephen B. BROSCHART  Mikko KAASALAINEN  David VOKROUHLICKÝ  Steven R. CHESLEY  Jean‐Luc MARGOT  Raymond F. JURGENS  Randy ROSE  Donald K. YEOMANS  Shigeru SUZUKI  Eric M. de JONG 《Meteoritics & planetary science》2004,39(3):407-424

Abstract— We observed 25143 Itokawa, the target of Japan's Hayabusa (MUSES‐C) sample‐return mission, during its 2001 close approach at Arecibo on twelve dates during March 18‐April 9 and at Goldstone on nine dates during March 20‐April 2. We obtained delay‐Doppler images with range resolutions of 100 ns (15 m) at Arecibo and 125 ns (19 m) at Goldstone. Itokawa's average circular polarization ratio at 13 cm, 0.26 ± 0.04, is comparable to that of Eros, so its cm‐to‐m surface roughness probably is comparable to that on Eros. Itokawa's radar reflectivity and polarization properties indicate a near‐surface bulk density within 20% of 2.5 g cm^?3. We present a preliminary estimate of Itokawa's shape, reconstructed from images with rather limited rotation‐phase coverage, using the method of Hudson (1993) and assuming the lightcurve‐derived spin period (12.132 hr) and pole direction (ecliptic long., lat. = 355°, ?84°) of Kaasalainen et al. (2003). The model can be described as a slightly asymmetrical, slightly flattened ellipsoid with extents along its principal axes of 548 times 312 times 276 m ± 10%. Itokawa's topography is very subdued compared to that of other asteroids for which spacecraft images or radar reconstructions are available. Similarly, gravitational slopes on our Itokawa model average only 9° and everywhere are less than 27°. The radar‐refined orbit allows accurate identification of Itokawa's close planetary approaches through 2170. If radar ranging planned for Itokawa's 2004 apparition succeeds, then tracking of Hayabusa during its 2005 rendezvous should reveal Yarkovsky perturbation of the asteroid's orbit.  相似文献   

Arc parallel extension in Higher and Lesser Himalayas, evidence from western Arunachal Himalaya, India     

SHARMISTHA DE SARKAR  GEORGE MATHEW  KANCHAN PANDE 《Journal of Earth System Science》2013,122(3):715-727

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Simulation of sediment transport during flood events: laboratory work and field experiments     

RENAAT DE SUTTER  RONNY VERHOEVEN  ANDREAS KREIN 《水文科学杂志》2013,58(4):599-610

Abstract

This paper aims at initiating a fundamental understanding of the suspended load transport of river sediment in unsteady flow. Laboratory erosion tests as well as artificial flood experiments are used to evaluate the influence of the transient regime on the transport efficiency of the flow. The erosion experiments reveal that the transport capacity is augmented when the unsteadiness of the flow increases. However, the influence of the transient regime is counteracted by the cohesive properties of the river bed. Field experiments with artificial floods released from a reservoir into a small canal confirm these findings and show a relationship between the friction velocity and the suspended load transport. An appropriate parameter β is proposed to evaluate the impact of the transient regime on the transport of suspended sediment.  相似文献   

Technology transfer in the Clean Development Mechanism     

HELEEN DE CONINCK  FRAUKE HAAKE  NICO VAN DER LINDEN 《Climate Policy》2013,13(5):444-456

Technology transfer is often mentioned as an ancillary benefit of the Kyoto Protocol's Clean Development Mechanism (CDM), but this claim has hardly been researched or substantiated. The question of technology transfer is important, both for developing countries in need for new technology and knowledge and for industrialized countries, as it provides export potential for climate-friendly technologies. To determine what technology transfer means, whether it is occurring through the CDM, and what the value of the associated capital flows is, this article examines technology transfer in the 63 CDM projects that were registered up until 1 January 2006. Technology hardware originates from outside the host country in almost 50% of the evaluated projects, particularly in non-CO₂ greenhouse gas projects, wind energy projects, and a substantial share of the hydropower projects. Bioenergy and projects in the agricultural sector mainly use local technology. The investment value associated with the CDM projects that transferred technology is estimated to be around €470 million, with about €390 million coming from the EU. As the non-CO₂ greenhouse gas projects had very low capital costs, the investment value was highest in the more capital-intensive wind energy and hydropower projects. We also found substantial soft technology transfer, but uncertainties for this finding are greater.  相似文献   

Sedimentology,palaeoenvironments and biostratigraphy of the Pliocene–Pleistocene carbonate platform of Grande‐Terre (Guadeloupe,Lesser Antilles forearc)     

JEAN‐JACQUES CORNÉE  JEAN‐LÈN LÉTICÉE  PHILIPPE MÜNCH  FRÉDÉRIC QUILLÉVÉRÉ  JEAN‐FRÉDÉRIC LEBRUN  PIERRE MOISSETTE  JUAN‐CARLOS BRAGA  MIHAELA MELINTE‐DOBRINESCU  LYVANE DE MIN  JULIEN OUDET  AURAN RANDRIANASOLO 《Sedimentology》2012,59(5):1426-1451

Pliocene and Pleistocene deposits from Grande‐Terre (Guadeloupe archipelago, French Lesser Antilles) provide a remarkable example of an isolated carbonate system built in an active margin setting, with sedimentation controlled by both rapid sea‐level changes and tectonic movements. Based on new field, sedimentological and palaeontological analyses, these deposits have been organized into four sedimentary sequences (S1 to S4) separated by three subaerial erosion surfaces (SB0, SB1 and SB2). Sequences S1 and S2 (‘Calcaires inférieurs à rhodolithes’) deposited during the Late Zanclean to Early Gelasian (planktonic foraminiferal Zones PL2 to PL5) in low subsidence conditions, on a distally steepened ramp dipping eastward. Red algal‐rich deposits, which dominate the western part of Grande‐Terre, change to planktonic foraminifer‐rich deposits eastward. Vertical movements of tens of metres were responsible for the formation of SB0 and SB1. Sequence S3 (‘Formation volcano‐sédimentaire’, ‘Calcaires supérieurs à rhodolithes’ and ‘Calcaires à Agaricia’) was deposited during the Late Piacenzian to Early Calabrian (Zones PL5 to PT1a) on a distally steepened, red algal‐dominated ramp that changes upward into a homoclinal, coral‐dominated ramp. Deposition of Sequence S3 occurred during a eustatic cycle in quiet tectonic conditions. Its uppermost boundary, the major erosion surface SB2, is related to the Cala1 eustatic sea‐level fall. Finally, Sequence S4 (‘Calcaires à Acropora’) probably formed during the Calabrian, developing as a coral‐dominated platform during a eustatic cycle in quiet tectonic conditions. The final emergence of the island could then have occurred in Late Calabrian times.  相似文献