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1.
Analyses of primary and early diagenetic fluid inclusions in the halite from the Late Ordovician Mallowa Salt, Canning Basin, Western Australia indicate a Ca‐rich composition and high concentration of parent brines in the basin which were close to sylvite and carnallite precipitation. The salt‐bearing series in the sampled interval was overheated up to 62 °C. The recorded differences in gas compositions result from the input of several gas sources including dispersed organic matter in the salt series and hydrocarbon deposits in the underlying rocks. The high concentration of the brines in fluid inclusions does not allow quantitative reconstruction of the chemical composition of Late Ordovician parent seawater. Using the information from Early Cambrian and Late Silurian basins as a proxy, however, the new data indicate that Late Ordovician seawater was undoubtedly Ca‐rich and, in comparison with modern seawater, had a similar K content, considerably lower Mg content (c. 30%), approximately three times the Ca content and one‐third the SO4 content. 相似文献
2.
Łukasz Wiejaczka Lakpa Tamang Danuta Piróg Paweł Prokop 《Environmental Earth Sciences》2018,77(20):718
The present study focuses on the Balason river running through the Himalayan piedmont zone (near Siliguri, India). The objective of the study is an assessment of the environmental effects of river bed material extraction by humans and the dependence of indigenous people on the river and its ecosystem services. The analysis is based on results of field work consisting of geodetic measurements of the river channel and interviews among the local community from the Nimtijot village. Historical hydrological data were also used for the study. The results of the investigation show that the Balason river is heavily affected by excessive exploitation of river bed material during dry season and the replenishment of extracted material in a monsoon season is not always sufficient. It leads to channel deepening. The local community working in the river heavily depends for its livelihood on continuing this activity. A decreasing amount of bed material to be extracted may lead to degradation of the strong relationship between the local community and their natural environment (river). 相似文献
3.
Christian Pfister Rudolf Brázdil Rüdiger Glaser Anita Bokwa Franz Holawe Danuta Limanowka Oldřich Kotyza Jan Munzar Lajos Rácz Elisabeth Strömmer Gabriela Schwarz-Zanetti 《Climatic change》1999,43(1):111-150
Thirty-two weather diaries written in astronomical calendars in central Europe in the late fifteenth and sixteenth centuries are presented and discussed. Systematic weather observations were promoted by the rise of planetary astronomy and its application in astro-meteorology. The practice of keeping weather diaries spread from Cracow (Poland) to Ingolstadt (Germany) and from there to other universities. The data obtained from these sources provided the backbone for setting up series of precipitation indices for Poland, Germany and Switzerland. Monthly statistics of days with precipitation, snowfall and frost were computed by counting the relevant entries in the most important diaries. The results were compared with either those obtained from instrumental measurements in the same place or with those from modern instrumental measurements in a neighbouring place. The final results show that autumn was considerably colder in the early sixteenth century. April was considerably drier and July was wetter during the period 1508-1531 than during 1901-1960. In order to highlight the impact of weather patterns on grain prices in a year of crisis, the timing of wet and dry spells in southern Poland and southern Germany is compared for the year 1529. Winters became 1.7°C colder from 1564 to 1576 and the month of July tended to be wetter than in 1901-1960. Details noted in the diaries kept between 1585 and 1600 by the astronomers Brahe (near Copenhagen) and Fabricius (in the Ostfriesland region of northwestern Germany) closely agree. It rained more often in June and July and temperatures dropped. The winter months were more frequently dominated by winds from easterly directions, the frequency of snowfall was higher and a deficit occurred in precipitation. This points to a higher frequency of high pressure in the Fennoscandian area with cold air advection from the east or northeast. 相似文献
4.
Tadeusz M. Peryt M.Sc. 《International Journal of Earth Sciences》1975,64(1):143-158
When interpreting the depositional environment of the Buntsandstein sequence, thin stromatolite layers, if present, were often overlooked or given short shrift. The present paper provides evidence of value of stromatolites for the environmental interpretation of the Buntsandstein rocks. Algal stromatolites found in western Poland occur in form of thrombolites, LLH-type structures, SH-type structures, and rarely as oncolites. Stromatolites are usually associated with oolites. Very often stromatolites show important traces of scouring and channelling action of water. Since stromatolites occurred in the zone of clastic-carbonate deposition they were covered up by continuous sheet of detrital grains. Periodic catastrophic erosion and deposition was produced by hurricanes and severe storms in the peritidal and shallow subtidal zone. It is possible to distinguish the peritidal and subtidal stromatolites. In the vicinity of stromatolites are of frequent occurrence spirorbids, conchostracs, gastropods, and rare foraminifers. Besides, spirorbids are associated with stromatolites — they constituted the initial hard substratum for the stromatolitic structures and sometimes they also occur inside stromatolites. The not-hypersaline sedimentary environment of the Buntsandstein rocks can be compared with modern environments of the Persian Gulf and the Gulf of Aqaba. 相似文献
5.
The previous study showed that the Zechstein (Upper Permian) anhydrites have about 0.2% strontium with a remarkably small sample scatter. Our study of three lower Zechstein anhydrite units (Lower Anhydrite, Upper Anhydrite and Basal Anhydrite) from West Poland indicate that although often the Sr content is 0.1–0.2%, there are common deviations. In particular, a considerable part (28%) of the studied samples is characterized by lower values (<0.1%), and on the other hand ca. 15% of samples are Sr-enriched, and in those samples celestite was recorded. Particular anhydrite levels differ especially in the frequency of samples showing great Sr content. The greatest variation was found in the Lower Anhydrite. This agrees well with the conclusion derived from the sedimentological studies indicating that there was the greatest differentiation of depositional environments during the deposition of the Lower Anhydrite. The Sr content is a good indicator of brine concentration during the gypsum precipitation and it seems that the subsequent gypsum–anhydrite transformation itself does not affect the strontium distribution. The histograms of Sr content in the Basal Anhydrite indicate a slightly higher brine concentration than it was during the Lower Anhydrite deposition, and the latter in turn was higher than brine concentration during the Upper Anhydrite sedimentation. Celestite veins are clearly diagenetic in origin. The form of celestite occurrence and the increased strontium content (1% or more) indicate an additional source of ions that occurred outside the anhydrite series. In the case of the Lower Anhydrite, the supposed additional source of Sr was related to aragonite-to-calcite transition and squeezing of CaCl2 brines from reefs into anhydrite series due to increased pressure. For the Basal Anhydrite this source could be related to brines derived from the Older Halite deposits. 相似文献
6.
The present paper is concerned with the study of the evolution of regular patterns of shear bands observed experimentally (cf. Milligan, 1974), and provides an extension of the previous work published by the same authors. The purpose of this paper is to present an improved version of a simple theoretical model, derived basically from a classical equilibrium of the Coulomb wedge. This model constitutes a modified version of an extension of the classical Coulomb wedge analysis by assuming that soil parameters are varying during the deformation process and the initial configuration at which limit equilibrium occurs evolves toward a new equilibrium configuration. The application of the model in the analysis of shear band pattern observed in dredged model tests on cantilever walls provided realistic simulation of consecutive shear band formation. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
7.
Strontium isotope composition of Middle Miocene primary gypsum (Badenian of the Polish Carpathian Foredeep Basin): evidence for continual non‐marine inflow of radiogenic strontium into evaporite basin 
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下载免费PDF全文 Strontium isotope compositions of ancient sulphate deposits not only provide chemostratigraphic information but also offer insight into the system in which the evaporites precipitated. Primary gypsum from two Middle Miocene (Badenian) sections in southern Poland shows steadily higher 87Sr/86Sr ratios than those expected from a marine‐derived formation. The ratios are interpreted as the result of increasing inflow into the basin at the time of gypsum precipitation. Palaeogeographic reconstructions suggest that riverine runoff sources were situated in the West and East European platforms (to the north and east, respectively) and the Carpathians (to the south), which are mostly composed of Mesozoic sedimentary rocks; their dissolution cannot be responsible for the higher 87Sr/86Sr ratios recorded. We conclude that Archaean and Palaeoproterozoic igneous and supracrustal rocks of the Ukrainian Shield were the source of the higher 87Sr/86Sr ratios recorded in the Badenian primary gypsum. A distinctive decreasing trend of 87Sr/86Sr ratios from western Ukraine to southern Poland is explained by a consistent direction of brine inflow during gypsum crystallization (typical cyclonic circulation controlled by the Coriolis effect). 相似文献
8.
Routine trace-element geochemistry suggests that components in putative marine halite evaporites may be partly of nonmarine origin, but such interpretations are commonly ambiguous. Stable chlorine isotopes may provide a less-ambiguous marker of chloride origin where δ37 Cl departs from the range predicted for evaporite formation from seawater. Bedded halite with primary sedimentary textures preserves original δ37 Cl values. Measurable change in δ37 Cl can be generated by incongruent dissolution of halite, but only if less than half the original halite remains. Badenian (middle Miocene) halite from the Forecarpathian and from the East Slovakian and Transcarpathian basins has a δ37 Cl range of – 0.2 to 0.8‰. Two phenomena cannot be explained by simple evaporation of 0.0‰ seawater. At Wieliczka, the Shaft Salt has distinctive δ37 Cl values (– 0.2 to 0.0‰) relative to neighbouring salt beds (0.2 to 0.6‰), requiring a large, abrupt input of brine with negative δ37 Cl. Halite with high (0.6 – 0.8‰) δ37 Cl near the base of the East Slovakian and Transcarpathian evaporites requires a large input of chloride with positive δ37 Cl into the basins. Expulsion of basin brine with non-0‰δ37 Cl into the evaporite basins may account for the nonmarine chloride sources. 相似文献
9.
Danuta Peryt Krystyna Wyrwicka Charles Orth Moses Attrep Jr Leonard R. Quintana 《地学学报》1994,6(2):158-165
Two sections of the Upper Cenomanian and Lower Turonian in central and south-east Poland were investigated for foraminifers, CaCO3 content, carbon content insoluble in HCl (Corg ) and in the carbonates (Ccarb ), carbon and oxygen isotopic composition of bulk-rock carbonates and elemental abundances. The Cenomanian/Turonian boundary interval is characterized by the appearance of more marly facies, a δ13 C and δ18 O stable isotope anomaly, a considerable increase in Corg content and decrease in Ccarb content and substantial changes in the foraminiferal assemblages. A major carbon stable isotope excursion with a shift of +2 (PDB) occurs in the lowermost Whiteinella archaeocretacea Zone. The late Cenomanian δ13 C anomaly is associated with heavy δ18 O values. The peak value of δ13 C corresponds to the minima in P/B ratio and in diversity of foraminiferal assemblages. A late Cenomanian anoxic event is thought to be responsible for changes in foraminiferal assemblages. However, elemental abundance analyses do not show changes in the concentrations of trace elements. This may be explained by the long distance between studied area and a source of enrichment which was probably located in the western hemisphere. 相似文献
10.
James O. Sickman Danuta M. Bennett Delores M. Lucero Thomas J. Whitmore William F. Kenney 《Journal of Paleolimnology》2013,50(2):159-174
We investigated relationships among modern diatom species composition and physical and chemical characteristics of high-elevation lakes of the Sierra Nevada (California), to develop transfer functions that can be used to infer historic lake conditions. Data were collected from 50 lakes in National Parks and Forests of the central and southern Sierra Nevada. Multivariate statistical methods revealed that acid neutralizing capacity (ANC) and nitrate accounted for significant variation in diatom taxa. A training set with 242 modern diatom taxa from a subset of 41 lakes was used to develop transfer functions for ANC and nitrate using weighted averaging techniques. ANC and nitrate calibration ranges were 23.0–137 μEq/L and 0.18–9.5 μM, respectively. Coefficients of determination for the models were: ANC: R2 = 0.76, and R jackknife 2 = 0.44; NO3: R2 = 0.67, and R jackknife 2 = 0.27. The ANC model was applied to the top 50 cm of sediments in Moat Lake to reconstruct ANC from ca. AD 350 to 2005. The reconstruction suggests that ANC declined by about 40 % (101–60 μEq/L) between the 1920s and the 1960s and then recovered to pre-1920s levels during 1980–2000. The magnitude of this ANC excursion was the largest observed during the past 1,600 years. We hypothesize that temporal variations in ANC were influenced by: (1) changes in rates of acid deposition, especially nitric acid and (2) variations in the timing and magnitude of snowmelt runoff. 相似文献