Stable isotope studies of fluid inclusions in speleothems and their paleoclimatic significance     

Henry P Schwarcz  Russell S Harmon  Peter Thompson  Derek C Ford 《Geochimica et cosmochimica acta》1976,40(6):657-665

Fluid inclusions found trapped in speleothems (cave deposited travertine) are interpreted as samples of seepage water from which enclosing calcium carbonate was deposited. The inclusions are assumed to have preserved their D/H ratios since the time of deposition. Initial ¹⁸O/¹⁶O ratios can be inferred from δD because rain- and snow-derived seepage waters fall on the meteoric water line (δD = 8δ¹⁸O + 10). Estimates of temperature of deposition of the carbonate can be calculated from inclusion D/H ratios and δ¹⁸O of enclosing calcite in Pleistocene speleothems. For most speleothems investigated (0–200,000 yr old) δ¹⁸O of calcite appears to have decreased with increasing temperature of deposition indicating that the dominant cause of climate-dependent change in δ¹⁸O of calcite was the change in K_cw, the isotope fractionation equilibrium constant, with temperature; δ¹⁸O of meteoric precipitation generally increased with increasing temperature, but not sufficiently to compensate for the decrease in K_cw.  相似文献   

Oldest Atlantic seafloor     

W. B. Bryan  F. A. Frey  G. Thompson 《Contributions to Mineralogy and Petrology》1977,64(2):223-242

Basalt recovered beneath Jurassic sediments in the western Atlantic at Deep Sea Drilling Project sites 100 and 105 of leg 11 has petrographic features characteristic of water-quenched basalt extruded along modern ocean ridges. Site 100 basalt appears to represent two or three massive cooling units, and an extrusive emplacement is probable. Site 105 basalt is less altered and appears to be a compositionally homogeneous pillow lava sequence related to a single eruptive episode.Although the leg 11 basalts are much more closely related in time to the Triassic lavas and intrusives of eastern continental North America, their geochemical features are closely comparable to those of modern Mid-Atlantic Ridge basalts unrelated to postulated mantle plume activity. Projection of leg 11 sites back along accepted spreading flow lines to their presumed points of origin shows that these origins are also outside the influence of modern plume activity. Thus, these oldest Atlantic seafloor basalts provide no information on the time of initiation of these plumes. The Triassic continental diabases show north to south compositional variations in Rb, Ba, La, and Sr which lie within the range of plume-related basalt on the Mid-Atlantic Ridge (20 °–40 °N). This suggests that these diabases had mantle sources similar in composition to those beneath the present Mid-Atlantic Ridge. Plumes related to deep mantle sources may have contributed to the LIL-element enrichment in the Triassic diabase and may alos have been instrumental in initiating the rifting of the North Atlantic. Systematically high values for K and Sr⁸⁷/Sr⁸⁶ in the Triassic diabases may reflect superimposed effects of crustal contamination in the Triassic magmas.Contribution Number 3953 from the Woods Hole Oceanographic Institution  相似文献   

Land-derived pollutant hydrocarbons     

B.S. Cooper  R.C. Harris  S. Thompson 《Marine pollution bulletin》1974,5(1):15-16

Evidence is given for the derivation of oil pollution from on-shore sources and for a possible relation between its concentration in estuarine sediment and in the lipids of the sediment biomass.  相似文献   

GLAST large area telescope multiwavelength planning     

O. Reimer  P. F. Michelson  R. A. Cameron  S. W. Digel  D. J. Thompson  K. S. Wood 《Astrophysics and Space Science》2007,309(1-4):523-526

Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.   相似文献   

The linkage between velocity patterns and sediment entrainment in a forced‐pool and riffle unit     

D. M. Thompson  E. E. Wohl 《地球表面变化过程与地形》2009,34(2):177-192

A field‐based project was initiated in order to characterize velocities and sediment entrainment in a forced‐pool and riffle sequence. Three‐dimensional velocities and turbulence intensities were measured with an acoustic Doppler velocimeter at 222 different points at three similar flows that averaged approximately 4·35 m³ s⁻¹ within a large pool–riffle unit on North Saint Vrain Creek, Colorado. Sediment‐sorting patterns were observed with the introduction of 500 tracer particles painted according to initial seeding location. Tracer particles moved sporadically during a 113 day period in response to the annual snowmelt peak flow, which reached a maximum level of 14·8 m³ s⁻¹. Velocity data indicate high instantaneous velocities and turbulence levels in the centre of pools. Patterns of sediment deposition support the notion that stream competence is higher in the pool than the downstream riffle. Flow convergence around a large channel constriction appears to play a major role in multiple processes that include helical flow development and sediment routing, and backwater development with low velocities and turbulence levels above the constriction that may locally limit sediment supply. Jet flow, flow separation, vortex scour and turbulence generation enhance scour in the centre of pools. Ultimately, multiple processes appear to play some role in maintenance of this forced pool and the associated riffle. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

High-resolution imaging of the anomalous flux ratio gravitational lens system CLASS B2045+265: dark or luminous satellites?     

J. P. McKean  L. V. E. Koopmans  C. E. Flack  C. D. Fassnacht  D. Thompson  K. Matthews  R. D. Blandford  A. C. S. Readhead  B. T. Soifer 《Monthly notices of the Royal Astronomical Society》2007,378(1):109-118

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Late-Holocene paleoenvironmental change at mid-elevation on the Caribbean slope of the Cordillera Central,Dominican Republic: a multi-site,multi-proxy analysis     

Chad S. Lane  Sally P. Horn  Claudia I. Mora  Kenneth H. Orvis 《Quaternary Science Reviews》2009,28(23-24):2239-2260

High-resolution proxy records from the circum-Caribbean region indicate significant variation in Late Holocene climate, especially precipitation, attributed primarily to shifts in the mean annual position of the Intertropical Convergence Zone (ITCZ). The paleoenvironmental and cultural impacts of this Late-Holocene climate variability have been analyzed intensively in the western Caribbean, and to a lesser extent in the southern Caribbean. However, the occurrence and impacts of Late Holocene climate shifts in the eastern Caribbean, especially in island interiors, has not been well documented. Here we present sediment records of Late-Holocene paleoenvironmental change from two lakes located on the Caribbean slope of the Cordillera Central in the Dominican Republic that span the last ～3000 years. Sediment characteristics, pollen, charcoal, biogenic carbonate assemblages and isotopic composition, and bulk sedimentary carbon isotope values in Laguna Castilla and Laguna de Salvador indicate extreme shifts in hydrology, vegetation, and disturbance regimes in response to climate change and human activity in the lake watersheds. Close correspondence between the hydrological histories of the lakes and trace metal concentrations in sediments of the Cariaco Basin indicate that precipitation variability here responds to the same controls, and may similarly reflect shifts in the mean annual position of the ITCZ. Human occupation of the watersheds appears to be closely linked to severe dry periods and may indicate larger scale cultural responses to precipitation variability on the island of Hispaniola. Prehistoric human populations strongly affected vegetation and disturbance regimes in the lake watersheds. Impacts may have lasted several centuries and may have been more severe than impacts of modern populations.  相似文献   

SECOND ORDER CORRECTIONS TO PHOTOGRAPHIC CO-ORDINATES     

E. H. Thompson 《The Photogrammetric Record》1974,8(44):210-216

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Towards improving the framework for probabilistic forecast evaluation   总被引：1，自引：0，他引：1  

Leonard A. Smith  Emma B. Suckling  Erica L. Thompson  Trevor Maynard  Hailiang Du 《Climatic change》2015,132(1):31-45

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Ethical and normative implications of weather event attribution for policy discussions concerning loss and damage     

Allen Thompson  Friederike E. L. Otto 《Climatic change》2015,130(3):439-452

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