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21.
A New Fossil Termite(Isoptera,Stolotermitidae,Stolotermes)from the Early Miocene of Otago,New Zealand 总被引:1,自引:1,他引:0
<正>The forewing of a termite from Early Miocene lake sediments in Otago,southern New Zealand is figured and described.It exhibits the generic characters of the damp-wood termite Stolotermes Hagen,but differs from forewings of the known species in size and venation pattern and is described as Stolotermes kupe sp.nov.S.kupe represents the first confident record of fossil Stolotermitidae and extends the fossil record of the family back to the Early Miocene.It also is the first direct evidence of fossil Isoptera from New Zealand,though silicified termite faecal pellets,referable to Kalotermes brauni,have been previously described.S.kupe indicates that Stolotermitidae has been present in the Australasian region since at least the Early Miocene. 相似文献
22.
23.
Thermochronometric constraints on the tectonic evolution of the Serifos detachment, Aegean Sea, Greece 总被引:1,自引:0,他引:1
Stephanie Brichau Stuart Thomson Uwe Ring 《International Journal of Earth Sciences》2010,99(2):379-393
We constrain the timing and kinematics of the Serifos detachment in the southwestern Cyclades, Greece, using low-temperature
thermochronometry. Fission-track dating shows that the Serifos detachment was active between ~13 and 6 Ma and that the Serifos
granodiorite in its footwall intruded at or before ~12–11 Ma into the extensional shear zone and initially cooled very rapidly
at rates >180°C per million year. The mylonite zone at the top of the granodiorite and mylonitic structures in its country
rocks record a consistent top-SSW shear sense in the ductile crust. In the brittle regime top-NNE shear-sense indicators occur
as well. Conjugate top-SSW and top-NNE high-angle normal faults are the youngest deformational features and cut across the
detachment. Age–distance relationships for the fission-track data display a relatively flat pattern. We discuss a model advocating
initial top-SSW movement on the Serifos detachment before and during emplacement of the granodiorite. Updoming of the detachment
during exhumation and cooling caused subsequent bivergent extension in the brittle crust. 相似文献
24.
25.
Alexander Deutsch Christian Koeberl Joel D. Blum Bevan M. French Billy P. Glass Richard Grieve Peter Horn Elmar K. Jessberger Gero Kurat Wolf Uwe Reimold Jan Smit Dieter Stöffler Stuart Ross Taylor 《地学学报》1994,6(6):644-650
In a recent article in Terra Nova, Kristan-Tollmann and Tollmann (1994) suggested that the Biblical Flood can be explained by seven fragments of a comet that impacted the ocean at seven locations on Earth at 03.00h (C.E.T.) on 23 September, 9545 yr BP. We demonstrate that all the ‘geological proofs’ that allegedly support their conclusions are not supported by the available data on impact cratering. Their hypothesis is based on insufficient and ambiguous data, selective citation, and incomplete comprehension of previous research. 相似文献
26.
Matthias Lankhorst David Fratantoni Michel Ollitrault Philip Richardson Uwe Send Walter Zenk 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(10):1615-1632
A comprehensive analysis of velocity data from subsurface floats in the northwestern tropical Atlantic at two depth layers is presented: one representing the Antarctic Intermediate Water (AAIW, pressure range 600–1050 dbar), the other the upper North Atlantic Deep Water (uNADW, pressure range 1200–2050 dbar). New data from three independent research programs are combined with previously available data to achieve blanket coverage in space for the AAIW layer, while coverage in the uNADW remains more intermittent. Results from the AAIW mainly confirm previous studies on the mean flow, namely the equatorial zonal and the boundary currents, but clarify details on pathways, mostly by virtue of the spatial data coverage that sets float observations apart from e.g. shipborne or mooring observations. Mean transports in each of five zonal equatorial current bands is found to be between 2.7 and 4.5 Sv. Pathways carrying AAIW northward beyond the North Brazil Undercurrent are clearly visible in the mean velocity field, in particular a northward transport of 3.7 Sv across 16°N between the Antilles islands and the Mid-Atlantic Ridge. New maps of Lagrangian eddy kinetic energy and integral time scales are presented to quantify mesoscale activity. For the uNADW, mean flow and mesoscale properties are discussed as data availability allows. Trajectories in the uNADW east of the Lesser Antilles reveal interactions between the Deep Western Boundary Current (DWBC) and the basin interior, which can explain recent hydrographic observations of changes in composition of DWBC water along its southward flow. 相似文献
27.
Results of our visible to near-infrared spectrophotometric observations of 41 near-Earth asteroids (NEAs) are reported. These moderate-resolution spectra, along with 14 previously published spectra from our earlier survey [Hicks, M.D., Fink, U., Grundy, W.M., 1998. Icarus 133, 69-78] show a preponderance of spectra consistent with ordinary chondrites (23 NEAs with this type of spectrum, along with 19 S-types and 13 in other taxonomic groups). There exists statistically significant evidence for orbit-dependent trends in our data. While S-type NEAs from our survey reside primarily in (1) Amor orbits or (2) Aten or Apollo orbits which do not cross the asteroid main-belt, the majority of objects with spectra consistent with ordinary chondrites in our survey are in highly eccentric Apollo orbits which enter the asteroid main-belt. This trend toward fresh, relatively unweathered NEAs with ordinary chondrite type spectra in highly eccentric Apollo orbits is attributed to one or a combination of three possible causes: (1) the chaotic nature of NEA orbits can easily result in high eccentricity orbits/large aphelion distances so that they can enter the collisionally enhanced environment in the main-belt, exposing fresh surfaces, (2) they have recently been injected into such orbits after a collision in the main-belt, or (3) such objects cross the orbits of several terrestrial planets, causing tidal disruption events that expose fresh surfaces. 相似文献
28.
A magnetospheric cavity model is presented to explain self-pulsing and frequency modulation of ducted whistler waves associated with triggered emissions. Partial reflection of these waves at the ends of the duct suggests such a magnetospheric cavity analogous to a laser cavity. 相似文献
29.
A summary is presented of our spectroscopic survey of comets extending for roughly 19 years from 1985 to 2004 comprising data for 92 comets of which 50 showed good emissions. All data were re-analyzed using consistent reduction techniques. Our observations of comets over several apparitions and comets observed over an extended period indicate no major changes in compositional classification. To our regret, no major unidentified cometary features were found in our surveyed spectral region of 5200-10400 Å. Absolute production rates for the dominant parent molecule H2O and the daughter species C2, NH2 and CN are determined within the limits of the Haser model as are values for the dust continuum, Afρ. From these data, production rate ratios are calculated for C2/H2O, NH2/H2O, CN/H2O and Afρ/H2O. Excluding the odd Comets Yanaka (1988r), 43P/Wolf-Harrington and 19P/Borrelly, with unusual spectra, our set of comets exhibited relatively uniform composition. Detailed analyses of our data resulted in four taxonomic classes:
- -
- Comets of typical composition (∼70%); exhibiting typical ratios with respect to water of C2, NH2, and CN.
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- Tempel 1 type (∼22%); having a deficiency in C2 but normal NH2 abundance.
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- G-Z type (∼6%); having both low C2 and NH2 ratios.
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- The unusual object Yanaka (1988r) (∼2%?); no detectable C2 or CN emission but normal NH2.
30.
Michael Huettner Annette Freibauer Constanze Haug Uwe Cantner 《Carbon balance and management》2010,5(1):2
The 'Copenhagen Accord' fails to deliver the political framework for a fair, ambitious and legally-binding international climate
agreement beyond 2012. The current climate policy regime dynamics are insufficient to reflect the realities of topical complexity,
actor coalitions, as well as financial, legal and institutional challenges in the light of extreme time constraints to avoid
'dangerous' climate change of more than 2°C. In this paper we analyze these stumbling blocks for international climate policy
and discuss alternatives in order to regain momentum for future negotiations. 相似文献