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51.
Fumiko Higashino Daniela Rubatto Tetsuo Kawakami Anne‐Sophie Bouvier Lukas P. Baumgartner 《Journal of Metamorphic Geology》2019,37(7):1037-1048
In situ analysis of a garnet porphyroblast from a granulite facies gneiss from Sør Rondane Mountains, East Antarctica, reveals discontinuous step‐wise zoning in phosphorus and large δ18O variations from the phosphorus‐rich core to the phosphorus‐poor rim. The gradually decreasing profile of oxygen isotope from the core (δ18O = ~15‰) to the rim (δ18O = ~11‰) suggests that the 18O/16O zoning was originally step‐wise, and modified by diffusion after the garnet rim formation at ~800°C and 0.8 GPa. Fitting of the 18O/16O data to the diffusion equation constrains a duration of the high‐T event (~800°C) to c. 0.5–40 Ma after the garnet rim formation. The low δ18O value of the garnet rim, together with the previously reported low δ18O values in metacarbonates, indicates regional infiltration, probably along a detachment fault, of low δ18O fluid/melt possibly derived from meta‐mafic to ultramafic rocks. 相似文献
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To explore planetary evolution, we provide conductive cooling profiles that account for planet size, phonon diffusivity and various internal heating scenarios. Our new analytical solution for simple cooling of spheres reveals that heat is removed from only Earth's outermost ~1000 km over geological time. Numerical models with decaying heat production show that any upward concentration of radionuclides causes high temperatures at shallow depths, forcing interior temperatures to increase with time while producing a thermal gradient that forbids lower mantle convection. Hence, differentiation drives upper mantle magmatism and tectonics, leaving a quiescent but hot deep interior, while slowly melting the core. 相似文献
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We performed seismic waveform inversions and numerical landslide simulations of deep-seated landslides in Japan to understand the dynamic evolution of friction of the landslides. By comparing the forces obtained from a numerical simulation to those resolved from seismic waveform inversion, the coefficient of friction during sliding was well-constrained between 0.3 and 0.4 for landslides with volumes of 2–8 ×106 m3. We obtained similar coefficients of friction for landslides with similar scale and geology, and they are consistent with the empirical relationship between the volume and dynamic coefficient of friction obtained from the past studies. This hybrid method of the numerical simulation and seismic waveform inversion shows the possibility of reproducing or predicting the movement of a large-scale landslide. Our numerical simulation allows us to estimate the velocity distribution for each time step. The maximum velocity at the center of mass is 12–36 m/s and is proportional to the square root of the elevation change at the center of mass of the landslide body, which suggests that they can be estimated from the initial DEMs. About 20% of the total potential energy is transferred to the kinetic energy in our volume range. The combination of the seismic waveform inversion and the numerical simulation helps to obtain the well-constrained dynamic coefficients of friction and velocity distribution during sliding, which will be used in numerical models to estimate the hazard of potential landslides. 相似文献
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Anne Klöppel Martin Pfannkuchen Annika Putz Peter Proksch & Franz Brümmer 《Marine Ecology》2008,29(2):259-272
Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms – the sponge itself or associated microorganisms – are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites. 相似文献
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Managing by principle: A critical analysis of the European principles of Integrated Coastal Zone Management (ICZM) 总被引:2,自引:2,他引:0
A set of eight principles is contained in the European Recommendation on Integrated Coastal Zone Management. The principles have been adopted with the minimum of critical review. The six core principles form two groups, one concerned with strategic goals and one that has a local focus. The principles are presented as a menu of free-standing options, with no prioritization either within or between groups. This can produce irreconcilable differences in strategy. The principles require clarification, prioritization of the strategic principles and recognition that they are an indivisible integrated set which should not be used to select principles to advance a particular agenda. 相似文献