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831.
Settlement of the puerulus stage of Jasus edwardsii (Decapoda: Palinuridae) near the shore takes place over a wide depth range. It occurs intertidally, and, as determined by crevice collectors, also takes place down to depths of at least 50 m. At sites along the east coast of the North Island of New Zealand, depth of greatest settlement found on collectors varied with locality and time, but was within the upper 11.5 m. Surface‐buoyed collectors caught fewer animals than did collectors at greater depths. Settlement levels generally increased with depth to about 10–12 m, then decreased with increasing depth and distance from shore. The ability of/, edwardsii to settle over a wide depth range may improve its chances of recruitment. A device (closing crevice collector) for measuring puerulus settlement of J. edwardsii at depth is described. 相似文献
832.
Sarah K. Appleby Martin R. Gillespie Colin M. Graham Richard W. Hinton Grahame J. H. Oliver Nigel M. Kelly 《Contributions to Mineralogy and Petrology》2010,160(1):115-132
In contrast to I-type granites, which commonly comprise infracrustal and supracrustal sources, S-type granites typically incorporate
predominantly supracrustal sources. The initial aim of this study was to identify the sources of three Scottish Caledonian
(~460 Ma) S-type granites (Kemnay, Cove and Nigg Bay) by conducting oxygen, U–Pb and Hf isotope analyses in zircon in order
to characterise one potential end-member magma involved in the genesis of the voluminous late Caledonian (~430–400 Ma) I-type
granites. Field, whole-rock geochemical and isotopic data are consistent with the generation of the S-type granites by melting
their Dalradian Supergroup country rocks. While Hf isotope compositions of magmatic zircon, U–Pb data of inherited zircons,
and high mean zircon δ18O values of 9.0 ± 2.7‰ (2SD) and 9.8 ± 2.0‰ for the Kemnay and Cove granites support this model, the Nigg Bay Granite contains
zircons with much lower δ18O values (6.8 ± 2.1‰), similar to those found in Scottish I-type granites. This suggests that the Nigg Bay Granite contains
low-δ18O material representing either altered supracrustal material, or more likely, an infracrustal source component with mantle-like
δ18O. Mixing trends in plots of δ18O vs. εHf for S-type granite zircons indicate involvement of at least two sources in all three granites. This pilot study
of Scottish Caledonian S-type granites demonstrates that, while field and whole-rock geochemical data are consistent with
local melting of only supracrustal sources, the oxygen isotopic record stored in zircon reveals a much more complex petrogenetic
evolution involving two or more magma sources. 相似文献
833.
Colin PALMER 《地球学报》2010,31(Z1):53-53
The wing of a pterosaur is unique in many ways, not least in its basic morphology, comprising a single supporting structure along the anterior edge of a flexible membrane lifting surface. No other flying vertebrate has adopted this morphology and there are no direct analogues in mechanical aerodynamics, the closest being sailboat mainsails. 相似文献
834.
Christopher I. Massey Vernon Manville Graham H. Hancox Harry J. Keys Colin Lawrence Mauri McSaveney 《Landslides》2010,7(3):303-315
The summit crater of Mt Ruapehu volcano normally hosts a 15.4-ha warm lake, whose water has been repeatedly wholly or partly
ejected by explosive and extrusive eruptions. Some of the larger eruptions have modified the lake outlet by burying it under
unconsolidated tephra (volcanic ash and blocks), creating a dam-break flood hazard independently of the occurrence of an eruption.
Eruptions in 1995 and 1996 followed this sequence; a break-out flood was anticipated and a warning system was installed to
mitigate the risk from this event and subsequent lahars in the same catchment. The 11-year filling time allowed much planning
and rehearsal. The warning system involved manual inspections of dam integrity, and seepage and lake-level monitoring to constrain
the likely failure window, and telemetered instruments including a tripwire and geophones to detect breaching of the dam and
propagation of the outbreak flood. The dam-collapse sequence, captured by a time-lapse camera, involved a series of retrogressing
landslides initiated and accelerated by seepage forces and toe scour when the lake was 1.1 m below overtopping. The barrier
failed in two phases on 18th March, 2007, beginning at 09:55 (NZST), with rapid retreat of one of the erosion scarps on the
downstream slope of the eastern barrier, initiated by internal erosion. Headward retrogression of the scarp into the barrier
formed an initial breach in the dam, after which increasing outflow led to erosion and undercutting of the wider downstream
toe of the western barrier. A final, larger dam breach occurred between 11:21 and 11:22 as slope instability caused retrogressive
failure of the remaining barrier. Five-hundred meters downstream of the dam, a large landslide was reactivated by toe scour
during the flood, contributing about a million cubic meters of solid material to the volumetric bulking of the outflow, which
reached the coast, 215 km away, 17 h later. The success of the planning and warning system allowed the whole event to occur
with little damage to infrastructure and without causing injury. 相似文献
835.
A Comparative Analysis of Four Kinds of Polysaccharides Purified from Furcellaria lumbricalis 总被引:4,自引:0,他引:4
BARROW Colin 《中国海洋大学学报(英文版)》2007,6(1):16-20
1 Introduction Carrageenan, a water-soluble sulfated polymer, usually extracted from red algae, has been widely used in food industry due to its unique properties, such as gelation, emulsification, protein stabilizer, and so on. There are at least 13 types of carrageenans defined structurally based on the content of sulfate, galactose (Gal) and 3,6-anhydro-galactose (AnG), but only three types of them are commercially available, i.e., κ-, ι- and λ-type carrageenan. Different red algae prod… 相似文献
836.
The thermal and exhumation history of late Hercynian granitoids from Calabria (Sila and Serre massifs) has been studied using thermobarometry and radiometric age determinations. The uplift and erosion which followed contractional tectonics of Tertiary age exposed in Calabria a nearly complete section of the Hercynian crust. Field data, constrained by igneous thermobarometrical data, have enabled us to draw simplified crustal profiles. In both the Sila and Serre massifs, granitoids make up the intermediate portions of the crustal sections and are stacked as tabular intrusions for up to 13 km cumulative thickness. Shallow granitoids are characterized by a weak fabric, mostly developed in the magmatic stage, whereas deep‐seated granitoids display a strong fabric developed in the magmatic state and, with decreasing temperatures, in the subsolidus state. The intrusive bodies were emplaced at 300–290 Ma, at a time when the Calabrian crust was undergoing extensional tectonics and crustal thinning. The subsequent post‐Hercynian evolution is recorded by Rb‐Sr dates of micas and fission track ages of zircon and apatite obtained from granitoids emplaced at different depths. A decrease in Rb‐Sr and fission track ages is observed as depth of emplacement increases. Data on the post‐Hercynian geological evolution of Calabria were used to model in three stages the cooling and exhumation history of deep‐seated and shallow granitoids. The first stage, in Permian to Triassic times, was characterized by slow erosion. It was followed by a second stage of extensional tectonics in Jurassic times. The third stage was exhumation during the Apenninic Orogeny. The model has generated two P–T–t arrays, one for deep‐seated and the other for shallow granitoids of the Serre massif. The T–t paths suggest that the dates of micas, zircon and apatite are cooling ages. They also show that deep‐seated granitoids remained at temperatures above the brittle–plastic transition for a long time, whereas shallow granitoids cooled rapidly. Distinct P–T–t paths explain why deep‐seated and shallow granitoids display different fabric and microstructural features. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献