Long‐Term Sediment Export Estimates from Northern Jordan using Roman Cisterns as Sediment Traps     

Sabine Kraushaar  Gregor Ollesch  Christian Siebert  Hans‐Joerg Vogel  Markus Fuchs 《Geoarchaeology》2015,30(4):369-378

Roman cisterns served as rainwater storage devices for centuries and are densely distributed in parts of northern Jordan. A major earthquake hit the region ca. A.D. 750 and in a short time many settlements were abandoned. As a consequence, most cisterns were not maintained, and they filled with sediments that today provide a postabandonment depositional record. In two field surveys, we mapped the locations of more than 100 cisterns in the Wadi Al‐Arab basin and selected two for detailed stratigraphic analysis that included ¹⁴C and optically stimulated luminescence dating. Catchment basin area for each cistern was determined by differential GPS. Both cisterns filled with sediments after the great earthquake and consequent abandonment of the region. Calculated sediment volumes are translated to long‐term average sediment export rates of 2.6–6.6 t ha⁻¹a⁻¹, which are comparable to erosion and sediment yield rates from other studies within the Mediterranean region. Our pilot study suggests that this approach can be applied elsewhere to calculate long‐term sediment export rates on hill slopes containing relict cisterns.  相似文献   

Conversion Gain and Interpixel Capacitance of Cmos Hybrid Focal Plane Arrays     

Gert Finger  James W. Beletic  Reinhold Dorn  Manfred Meyer  Leander Mehrgan  Alan F. M. Moorwood  Joerg Stegmeier 《Experimental Astronomy》2005,19(1-3):135-147

The conversion gain of optical and infrared focal plane CMOS hybrid arrays is a fundamental parameter, whose value computes into the derivation of other parameters characterizing the performance of a detector. The widespread “noise squared versus signal” method used to obtain the conversion gain can overestimate the nodal capacitance of the detector pixel by more than 20% for infrared arrays and by more than 100% for Si-PIN diode arrays. This is because this method does not take account of the capacitive coupling between neighboring pixels. A simple technique has been developed to measure the nodal capacitance directly by comparing the voltage change of an external calibrated capacitor with the voltage change on the nodal capacitor of the detector pixel. The method is elaborated in detail and has been verified with a Si-PIN diode array hybridized to a Hawaii-2RG multiplexer using an Fe ⁵⁵ X-ray source. It is also in good agreement with a stochastic method based on 2D autocorrelation.  相似文献   

Relic Oceanic Crust at Sub-Arc Depth: An Example from UHP Eclogites Enclosed in Serpentinites from the Southwestern Tianshan, China     

SHEN Tingting  ZHANG Lifei  Joerg HERMANN  LIU Fenglin 《《地质学报》英文版》2017,91(Z1):35-35

Ultra-high pressure(UHP)eclogites that derive from subducted oceanic crust are rarely found at the Earth’s surface because they need to be enclosed in a buoyant host rock such as serpentinites that facilitate exhumation(Hermann et al.,2000;Guillot et al.,2001).Under normal subduction geotherms,serpentinites break down just before UHP conditions are reached and therefore most of the exhumed eclogites representing subducted oceanic crust formed under fore-arc conditions.We investigated eclogite blocks enclosed into serpentinites that occur in the southwestern Tianshan oceanic subduction,China.A previous study proved that the serpentinites derive from altered oceanic crust and experienced UHP metamorphism at low temperatures of 510-530°C(Shen et al.,2015).Three relatively fresh eclogite samples were studied in detail.Sample 129-7 shows the retrograde mineral assemblage of amphibole+biotite+albite+chlorite+minor titanite and peak metamorphic relics of omphacite+garnet±chlorite.Sample C107-23 is mainly composed of amphibole+albite+chlorite+zoisite+muscovite+minor titanite as a retrograde assemblage and garnet+phengite as the peak metamorphic relics with omphacite only found as inclusions in garnet.Similar to sample C107-23,sample C11066 preserves large-grained euhedral to subhedral garnet relics with omphacite inclusions,and epidote,diopside,amphibole,muscovite,chlorite,albite and biotite are in the matrix belong to the retrograde assemblage.These three retrograde eclogite samples were modelled using thermodynamic calculations in the Mn NCKFMSHO(Mn O-Na_2O-Ca O-K_2O-FeO-Mg O-Al_2O_3-SiO_2-H_2O-Fe_2O_3)system.Based on the peak assemblage of omphacite+garnet and the crossing of the grossular and pyrope isopleths in garnet,peak P-T conditions of~460-470oC,28-29 kbar(129-7),450-500oC,28-35 kbar(C107-23),~475-505oC,26-29 kbar(C11066)were calculated.The retrograde assemblages indicate near isothermal decompression resulting in a clockwise P-T evolution of these eclogites.The peak metamorphic pressures at 500°C are well within UHP conditions(coesite stability field)and are within error the same as peak conditions of the host serpentinites(Shen et al.,2015).This provides evidence that eclogites and serpentinites shared the same evolution.We infer that the subducted low-density serpentinites were assembled with the high-density eclogites during subdution and helped the latter to exhume back to the surface.The studied eclogites thus represent rare examples of relics of oceanic crust that was subducted to sub-arc depth.  相似文献   

Searching the Sinus Amoris: Using profiles of geological units,impact and volcanic features to characterize a major terrane interface on the Moon     

P. Clark  S. Joerg  R. De Hon 《Earth, Moon, and Planets》1994,64(2):165-185

Geochemical profiles of surface units, impact, and volcanic features are studied in detail to determine the underlying structure in an area of extensive mare/highland interface, Sinus Amoris. This study region includes and surrounds the northeastern embayment of Mare Tranquillitatis. The concentrations of two major rock-forming elements (Mg and Al), which were derived from the Apollo 15 orbital geochemical measurements, were used in this study. Mapped units and deposits associated with craters in the northwestern part of the region tend to have correlated low Mg and Al concentrations, indicating the presence of KREEP-enriched basalt. Found along the northeastern rim of Tranquillitatis were areas with correlated high Mg and Al concentration, indicating the presence of troctolite. Distinctive west/east and north/south trends were observed in the concentrations of Mg and Al, and, by implication, in the distribution of major rock components on the surface. Evidence for a systematic geochemical transition in highland or basin-forming units may be observed here in the form of distinctive differences in chemistry in otherwise similar units in the western and eastern portions of the study region.  相似文献   

The rectilinear restricted problem of three bodies     

Joerg Waldvogel 《Celestial Mechanics and Dynamical Astronomy》1973,8(2):189-198

In this paper we discuss some aspects of the isosceles case of the rectilinear restricted problem of three bodies, where two primaries of equal mass move on rectilinear ellipses, and the particle is confined to the symmetry axis of the system. In particular, the behaviour near a collision of the primaries and also near a collision of all three bodies is investigated. It is shown that this latter singularity is a triple collision in the sense of Siegel's theory. Furthermore, asymptotic expansions for the particle's motion during a parabolic and a hyperbolic escape are derived.Presented at the Conference on Celestial Mechanics, Oberwolfach, Germany, August 27–September 2, 1972.  相似文献   

Seismic structure of the Carnegie ridge and the nature of the Galápagos hotspot     

Valentí Sallarès  Philippe Charvis  Ernst R. Flueh  Joerg Bialas  the SALIERI Scientific Party 《Geophysical Journal International》2005,161(3):763-788

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Assessing the impact of modern recharge on a sandstone aquifer beneath a suburb of Doncaster, UK   总被引：1，自引：0，他引：1  

Brian L. Morris  W. George Darling  Aidan A. Cronin  Joerg Rueedi  Emily J. Whitehead  Daren C. Gooddy 《Hydrogeology Journal》2006,14(6):979-997

A major water quality issue in urban areas underlain by a productive aquifer is the impact of modern recharge. Using a variety of sample sources including multi-level boreholes, detectable concentrations of CFCs and SF₆ have been found throughout the upper 50 m of the saturated aquifer beneath a suburb of Doncaster, UK, indicating that modern (<50-year old) recharge has penetrated to at least this depth. Additional support for this deep penetration is provided by the detection of sulphite-reducing clostridia and faecal streptococci. Despite the upper aquifer being a poorly cemented sandstone, the residence time indicators suggest that some modern recharge is travelling via fracture systems in addition to that moving down by simple piston flow. However, the overall impact of 80 years of steady urbanisation on water quality in the aquifer beneath this suburb has in general been limited. This is attributed to a combination of factors including previous land use, dilution by direct recharge of rainfall through green-space areas including gardens, and locally high storage in the friable upper aquifer.  相似文献   

40^th European Marine Biology Symposium, Vienna 2005: Invitation to attend and call for contributions     

Joerg Ott 《Marine Ecology》2004,25(3):247-247

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青藏高原中东部第四纪冰碛物暴露年龄的测定及其意义   总被引：4，自引：0，他引：4  

赵志中  乔彦松  Joerg SCH 《地学前缘》2006,13(5):316-320

青藏高原上大面积的冰盖通常会对亚洲乃至全球气候产生深远的影响。青藏高原第四纪冰川形成的时间和范围成为人们关注的热点。本研究利用就地成因的宇宙核素暴露年龄测定方法,对唐古拉山和理塘地区的第四纪冰碛物进行了10Be、26Al和21Ne暴露年龄测定,首次获得了青藏高原的第四纪冰川核素暴露年龄。三种核素暴露年龄的一致性显示每期冰碛物沉积有一个确定的暴露时期,测试结果表明唐古拉山和理塘地区出现了两期第四纪冰期,一期形成于距今1·6~8万年,另一期形成于距今16~18万年。  相似文献   

The three-body problem near triple collision     

Joerg Waldvogel 《Celestial Mechanics and Dynamical Astronomy》1976,14(3):287-300

The behaviour of three gravitationally interacting particles in a plane, which approach each other almost on a central configuration, is studied. Linearization near a Lagrangean solution and matching methods lead to the following results: (i) After a close triple encounter in the planar problem of three bodies, one particle generally escapes with an arbitrarily large asymptotic velocity. (ii) Particular cases of actual triple collisions may be extended by the method of Easton.  相似文献