Ries crater and suevite revisited—Observations and modeling Part I: Observations     

Dieter Stöffler  Natalia A. Artemieva  Kai Wünnemann  W. Uwe Reimold  Juliane Jacob  Birgit K. Hansen  Iona A. T. Summerson 《Meteoritics & planetary science》2013,48(4):515-589

We report results of an interdisciplinary project devoted to the 26 km‐diameter Ries crater and to the genesis of suevite. Recent laboratory analyses of “crater suevite” occurring within the central crater basin and of “outer suevite” on top of the continuous ejecta blanket, as well as data accumulated during the past 50 years, are interpreted within the boundary conditions imposed by a comprehensive new effort to model the crater formation and its ejecta deposits by computer code calculations (Artemieva et al. 2013). The properties of suevite are considered on all scales from megascopic to submicroscopic in the context of its geological setting. In a new approach, we reconstruct the minimum/maximum volumes of all allochthonous impact formations (108/116 km³), of suevite (14/22 km³), and the total volume of impact melt (4.9/8.0 km³) produced by the Ries impact event prior to erosion. These volumes are reasonably compatible with corresponding values obtained by numerical modeling. Taking all data on modal composition, texture, chemistry, and shock metamorphism of suevite, and the results of modeling into account, we arrive at a new empirical model implying five main consecutive phases of crater formation and ejecta emplacement. Numerical modeling indicates that only a very small fraction of suevite can be derived from the “primary ejecta plume,” which is possibly represented by the fine‐grained basal layer of outer suevite. The main mass of suevite was deposited from a “secondary plume” induced by an explosive reaction (“fuel‐coolant interaction”) of impact melt with water and volatile‐rich sedimentary rocks within a clast‐laden temporary melt pool. Both melt pool and plume appear to be heterogeneous in space and time. Outer suevite appears to be derived from an early formed, melt‐rich and clast‐poor plume region rich in strongly shocked components (melt ? clasts) and originating from an upper, more marginal zone of the melt pool. Crater suevite is obviously deposited from later formed, clast‐rich and melt‐poor plumes dominated by unshocked and weakly shocked clasts and derived from a deeper, central zone of the melt pool. Genetically, we distinguish between “primary suevite” which includes dike suevite, the lower sublayer of crater suevite, and possibly a basal layer of outer suevite, and “secondary suevite” represented by the massive upper sublayer of crater suevite and the main mass of outer suevite.  相似文献   

Water fluxes through the Cretan Arc Straits, Eastern Mediterranean Sea: March 1994 to June 1995     

Harilaos Kontoyiannis  Alexander Theocharis  Efstathios Balopoulos  Soterios Kioroglou  Vassilios Papadopoulos  Michael Collins  Antonios F. Velegrakis  Athanasia Iona 《Progress in Oceanography》1999,44(4):58

Five research cruises were undertaken incorporating ADCP sections along the Cretan Arc Straits and CTD surveys covering the entire area of the Straits and the Cretan Sea. In addition, six moorings (with 15 current meters) were deployed within the Straits, which monitored flows in the surface (50 m), intermediate (250 m), and deep (50 m from the bottom) layers. The ADCP, CM, and CTD datasets enable the derivation of water transports through the Cretan Arc Straits to be assessed. Flow structure through the Cretan Arc Straits is not the typical flow regime with a surface inflow and deep outflow, instead there is a persistent deep outflow of Cretan Deep Water (CDW) (σ_θ>29.2) with an annual mean of ˜0.6 Sv, through the Antikithira and Kassos Straits at depths below 400 m and 500 m, respectively. CDW outflowing transports are higher (˜0.8 Sv) in April–June, and lower (˜0.3 Sv) in October–December. Within the upper water layer (0–˜400 m), the transport and the water exchanges through the Straits are controlled by local circulation features, which weaken substantially below 200 m. The Asia Minor Current (AMC) influences the Rhodes and the Karpathos Straits, resulting in a net inflow of water. In contrast, the Mirtoan/West Cretan Cyclone influences the Antikithira and Kithira Straits, where there is a net outflow. In the Kassos Strait, there is a complex interaction between the East Cretan Cyclone, the Ierapetra Anticyclone and the westward extension of the Rhodes Gyre, which results in a variable flow regime. There is a net inflow in autumn and early winter, and a switch to a net outflow in early spring and summer. The total inflow and outflow, throughout all of the Straits, ranged from ˜2 to ˜3.5 Sv, with higher values in autumn and early winter and lower in summer. The AMC carries ˜2 Sv of inflow through the Rhodes and Karpathos Straits, and this accounts for 60–80% of the total inflow. About 10–15% of the total outflow is of CDW, and a further 45–70% occurs through the upper 400 m of the Kithira and Antikithira Straits. The Kassos Strait exhibits a net inflow of ˜0.7 Sv in autumn and early winter, with a net outflow of ˜0.5 Sv in early spring and summer.  相似文献   

A synthesis of the circulation and hydrography of the South Aegean Sea and the Straits of the Cretan Arc (March 1994–January 1995)     

Alexander Theocharis  Efstathios Balopoulos  Soterios Kioroglou  Harilaos Kontoyiannis  Athanassia Iona 《Progress in Oceanography》1999,44(4):1

Four seasonal oceanographic cruises were carried out in the Eastern Mediterranean Sea, within the framework of the CEC/MAST-MTP Project PELAGOS, during 1994–1995. The surveys covered the South Aegean Sea and the adjacent open sea regions (southeastern Ionian, northwestern Levantine). Analysis of CTD data revealed that a multiscaled circulation pattern prevails in the area. It differs from the circulations detected during the 1986–87, thus indicating interannual variability. Cyclonic and anticyclonic gyres and eddies are interconnected by currents and jets variable in space and time. Most of the features are persistent, others seem transitional or recurrent. The hydrological structure is also complex and apart from the upper layer does not present basinwide any significant seasonality. Dynamical and hydrological regimes are variable in the upper and intermediate layers at the Straits of the Cretan Arc, while the deep regime seems rather constant. Topographic control is evident on the flows through the straits. The new very dense deep water mass, namely the Cretan Deep Water (CDW) and a well-defined intermediate layer of minimum temperature and salinity, the so-called Transition Mediterranean Water (TMW), consists the new important structural elements of the South Aegean Sea. The CDW outflows towards the deep and bottom layers of the Eastern Mediterranean, thus considerably contributing to the formation of the new, denser Deep and Bottom Water of the Eastern Mediterranean, which sinks and displaces the Eastern Mediterranean Deep Water of Adriatic origin in the adjacent sea regions outside the Aegean Sea.  相似文献   

Direct Conversion of Food Waste into 3D Porous Carbon Traps for Selective Adsorption of Cationic Dyes     

Anitha Senthamizhan  Brabu Balusamy  Doriana Debellis  Jose Alejandro Heredia-Guerrero  Giorgio Mancini  Riccardo Carzino  Luca Ceseracciu  Athanassia Athanassiou  Despina Fragouli 《洁净——土壤、空气、水》2023,51(1):2200284

Conversion of waste biomass into valuable functional materials accomplishes the concept of circular economy in the development of sustainable waste management, and also recovery of such resources possibly reduces the requirement of feedstocks. In this scenario, the development of methodologies toward the direct conversion of the raw biomass into solid adsorbent materials without the use of any templates is highly desirable, but exceptionally challenging due to the complexity of the process. Here the direct synthesis of 3D porous carbon traps by a simple, cost-effective, and template-free process starting from a kitchen-based recipe and fermented food waste is described. Precisely, a robust carbon trap is formed with a spongy structure and highly interconnected hierarchical pores after the pyrolysis of a rice-based foam in the air. The developed materials float on water and interact efficiently with cationic dyes at static conditions. Importantly, such performance of the 3D carbon traps is not affected in the presence of anionic dyes, indicating the excellent selectivity towards the adsorption of cationic dyes. The adsorbent can be easily recovered and reused for up to 3 cycles without releasing any byproducts, thus, without causing hazardous risk of any secondary pollution to the environment.  相似文献   

Texture development of polycrystalline anhydrite experimentally deformed in torsion     

Florian Heidelbach  Iona C. Stretton  Karsten Kunze 《International Journal of Earth Sciences》2001,90(1):118-126

A polycrystalline aggregate of anhydrite was deformed in torsion to a maximum shear strain of 8.1 at 700°C and a maximum shear strain rate of 5᎒^-3 s^-1. The crystallographic preferred orientation (CPO or texture) was investigated as a function of shear strain/shear strain rate in a radial profile from the centre to the edge of the sample. A deformation texture developed at shear strains of 1.5-2 (corresponding to shear strain rates of 1 to 1.3᎒^-3 s^-1) and reached a stable position relative to the kinematic frame at a shear strain of 3.7 (2.3᎒^-3 s^-1). Further shear strain only led to a small increase in texture strength but no change in the orientation relative to the kinematic frame. The CPO is very similar to naturally observed textures and can be explained by the activity of the {001}<010> and {012}<121> slip systems. Although independent mechanical data indicate that a change of mechanism from dislocation- to diffusion-controlled creep occurred at a shear strain of approximately 1.5, the texture does not weaken, but rather increases, in strength with higher shear strains.  相似文献   

Hydrology and circulation in the Southern Cretan Sea during the CINCS experiment (May 1994–September 1995)     

D. Georgopoulos  G. Chronis  V. Zervakis  V. Lykousis  S. Poulos  A. Iona 《Progress in Oceanography》2000,46(2-4)

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