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111.
112.
Josué Camargo Mendes 《International Journal of Earth Sciences》1957,45(3):540-547
Summary This article is a brief résumé of the geology of the marine Upper Carboniferous beds (Itaituba series) of the Amazonian basin. The unfolded sediments cover a large area of the basin and are constituted of limestones, shales and sandstones. The macrofauna includes brachiopods, pelecypoda, corals, bryozoa, etc., from which the brachiopods are the better known by the present. The microfauna includes two genera of fusulinids:Millerella andFusulinella.According to the age as given by the fusulinids the sediments are Pennsylvanian (Upper Carboniferous), and not Permian as it has been supposed by some authors. So, the correlation with the Andean (Bolivia and Peru) permian groups is no more valid. Correlation with Tarma Group (Upper Carboniferous from Peru) and with the marine carboniferous of the MaranhÃo-Piauí (Brazil) is possible but not very well established. 相似文献
113.
114.
Dr. René Gächter Ken Lum-Shue-Chan Y. K. Chau 《Aquatic Sciences - Research Across Boundaries》1973,35(2):252-261
The toxic effect of copper on phytoplankton production is investigated in waters having different complexing capacities. It is demonstrated that a water’s complexing capacity does not guarantee that an equivalent amount of copper could be tolerated without adversely affecting algal production. Possible explanations for these findings are offered and discussed. It is deduced that ionic copper probably is already toxic to planktonic algae at concentrations of about 10?10 mole/l. 相似文献
115.
André Cailleux 《International Journal of Earth Sciences》1954,42(2):246-248
Sans résumé 相似文献
116.
Diego Gómez Pablo Salvador Julia Sanz Mikhail Urbazaev José Luis Casanova 《地理信息系统科学与遥感》2020,57(6):813-829
ABSTRACT The climate in southern Iceland has warmed over the last 70 years, resulting in accelerated glacier dynamics at the Solheimajoküll glacier. In this study, we compare glacier terminus locations from 1973 to 2018, to changes in climate across the study area, and we derive ice-surface velocities (2015–2018) from satellite remote-sensing imagery (Sentinel-1) using the offset-tracking method. There have been two regional temperature trends in the study period: cooling (1973–1979) and warming (1980–2018). Our results indicate a time lag of about 20 years between the onset of glacier retreat (?53 m/year since 2000) and the inception of the warming period. Seasonally, the velocity time series suggest acceleration during the summer melt season since 2016, whereas glacier velocities during accumulation months were constant. The highest velocities were observed at high elevations where the ice-surface slope is the steepest. We tested several scenarios to assess the hydrological time response to glacier accelerations, with the highest correlations being found between one and 30 days after the velocity estimates. Monthly correlation analyses indicated inter-annual and intra-annual variability in the glacier dynamics. Additionally, we investigate the linkage between glacier velocities and meltwater outflow parameters as they provide useful information about internal processes in the glacier. Velocity estimates positively correlate with water level and negatively correlate with water conductivity between April and August. There is also a disruption in the correlation trend between water conductivity and ice velocity in June, potentially due to a seasonal release of geothermal water. 相似文献
117.
J. René Roy 《Solar physics》1973,28(1):95-114
High resolution on- and off-band Hα filtergrams of disk solar surges obtained with the Vacuum Tower Telescope of the Sacramento Peak Observatory have been compared to magnetic data.
- Surges constitute clusters of very fine dark (sometimes bright) filaments where each thread connects to an Ellerman bomb brightening. If the magnetic map reveals the existence of a satellite polarity as defined by Rust (1968), the bomb(s) lies over it.
- Although a large fraction of surges is not associated with clearly detectable satellite polarities, events are strongly favored in regions of evolving magnetic features, characterized by dimensions of about 10 000 km and significant flux change over a period of less than a day. A flux change rate of 3 × 1015 Mx s?1 has been measured along at least three homologous bomb-surge events in a satellite of region MW 18594. Surges appear to be related to rising flux of one polarity into a region of stronger opposite flux.
- The trajectories of surges are matched by magnetic lines of force computed in the current-free approximation.
118.
A thermal study of the formation of oceanic crust 总被引:1,自引:0,他引:1
119.
Manuel R. Palacios-Fest Ana Luisa Carreño José R. Ortega-Ramírez Guillermo Alvarado-Valdéz 《Journal of Paleolimnology》2002,27(2):185-206
Paleoecology of Laguna Babícora, Chihuahua, Mexico was reconstructed using ostracode faunal assemblages and shell chemistry. The paleolimnological record is used to show the magnitude of paleoclimatic changes in the area from 25,000 years to the present.Faunal assemblages consist of four species of the genus Limnocythere: L. sappaensis, L. ceriotuberosa, L. bradburyi and L. platyforma, all associated with Candona caudata, Candona patzcuaro and Cypridopsis vidua. A paleosalinity index developed from these assemblages indicates that the lake's salinity fluctuated frequently from oligo- to meso-haline conditions during the last 25,000 years. This pattern and low salinity range are in good agreement with modern TDS (here used as an indicator of salinity) values recorded from 26 wells and one spring from the area (258–975 mg l–1). To estimate paleotemperature we examined the trace element content (Mg/Ca ratios) from individual valves of L. ceriotuberosa and L. platyforma, the two species most commonly recorded in Laguna Babícora.Shell Mg/Ca ratios of 204 specimens of these two species were used to estimate water temperature (Mg/Ca) by means of experimental standard coefficients. Our data show that paleowater temperature ranged from 5.6–21.3 °C (with 2 values ranging from 0.2–4.8 °C), which suggest a close correlation with atmospheric temperatures around the lake. These results are in good agreement with a modern mean winter temperature (3.5 °C) and mean summer temperature (20 °C) recorded in the area between 1970 and 1980. 相似文献
120.
We present the discovery and spectroscopic identification of two very high proper-motion ancient white dwarf stars, found in a systematic proper-motion survey. Their kinematics and apparent magnitude clearly indicate that they are halo members, while their optical spectra are almost identical to the recently identified cool halo white dwarf WD 0346+246. Canonical stellar halo models predict a white dwarf volume density that is 2 orders of magnitude less than the rho approximately 7x10-4 M middle dot in circle pc-3 inferred from this survey. With the caveat that the sample size is very small, it appears that a significant fraction, approximately 10%, of the local dark matter halo is in the form of very old, cool, white dwarfs. 相似文献