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The mineral assemblages in the eclogites and meta-sediments of the Münchberg gneiss complex suggest minimum pressures of about 15 kbar, and temperatures of 600±30° C for the eclogite-facies metamorphism. Both rock types underwent a subsequent amphibolite-facies metamorphism at almost the same temperature range. In the Weissenstein borehole the eclogites and meta-sediments show an intimate interlayering on a centimetre scale. Contacts between the two rock types are often sharp and untectonized suggesting in-situ metamorphism of the eclogites. The following features indicate that the gneisses were subjected to eclogite-facies metamorphism:
  1. Phengite relics and phengite inclusions in garnet contain up to 3.45 Si per formula unit while amphibolite facies phengites have considerably lower Si-contents (3.0–3.25 p.f.u.).
  2. Omphacite relics occur in the form of Na-augite (6–9 mol% jadeite)-oligoclase symplectites.
  3. Garnets with up to 40 mol% of the pyrope component occur.
The geological and mineral-chemical data indicate that large volumes of crustal material have been buried to depths possibly exceeding 70 km. The preservation of primary eclogitic textures as well as symplectitic textures in the presence of a fluid phase, are indicative of a rapid decompression. This would suggest a tectonic uplift (e.g. underthrusting) as is also indicated by the virtually constant temperature range during the uplift.  相似文献   
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Reiner Schwarz 《GeoJournal》2004,59(3):219-225
Ecosystems lacking human induced energy input from outside are in danger to degrade if man requires any sustainable yield. The risk of failure strongly depends on the amount of exploitation. This is shown by a simple one dimensional analytical feed-back model. Natural fluctuations determine the degradation probability of productive ecosystems. The stability behaviour of the latter is demonstrated by an analytical model in the two dimensional phase space. Full quantitative evaluation of the risk needs simulation experiments. One is carried out in the thorn shrub savannah rangelands at a site in Namibia where a fully calibrated simulation model shows that the less a sustainable yield is required, the more the breakdown is delayed. In this case of highly fluctuating rainfall any sustainability sensu strictu does not exist. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
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The carbon isotopic composition of diagenetic dolomite and calcite in some sediments of the Gulf of Mexico varies between “normal-marine” (δ13C ca. 0‰) and −14.6‰ which suggests that biogenic CO2 contributed to the carbonate formation. The δ13O values of dolomite and coexisting calcite are very similar but variable down-core.Dolomite and calcite precipitated early from pore water where SO42− was not reduced. However, during (and after?) SO42− reduction dolomite and calcite still formed and there are at least two generations of carbonate minerals present.  相似文献   
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Embroygenesis of the three coregonid forms Blaufelchen, Gangfisch, and Sandfelchen from Lake Constance was observed at five different constant temperatures in a static incubation system. The relationship between temperature and the time to reach 14 developmental stages from fertilization to hatching was established for the three forms. Relative to the total incubation time, pectoral fin flutter and eye movement start earliest in Gangfisch and latest in Blaufelchen. This might allow Gangfisch to tolerate lower oxygen concentrations during the last phase of embryogenesis than Blaufelchen. Developmental rates per day as a function of temperature can be calculated by a power function. A model is presented which permits to predict the time of mass hatching for embryos which are incubated at fluctuating temperatures. The total incubation times for the three coregonids of Lake Constance are short as compared to those of other coregonids. This is interpreted as an adaptation to the specific thermal environment of each coregonid stock which helps to ensure larval survival in the respective habitat.  相似文献   
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