Timing of Proterozoic magmatism in the Sunsas belt,Bolivian Precambrian Shield,SW Amazonian Craton     

Ingrid M.Nedel  Reinhardt A.Fuck  Amarildo S.Ruiz  Gerardo R.Matos-Salinas  Alanielson da C.D.Ferreira 《地学前缘(英文版)》2021,12(6):277-293

We present new U-Pb zircon and monazite ages from the Sunsas belt granitic magmatism in Bolivia,SW Amazonian Craton.The geochronological results revealed four major magmatic events recorded along the Sunsas belt domains.The older igneous event formed a granitic basement coeval to the Rio Apa Terrane(1.95-1.85 Ga)in the southern domain.The second magmatic episode is represented by 1.68 Ga granites associated to the Paraguá Terrane(1.69-1.66 Ga)in the northern domain.The 1.37-1.34 Ga granites related to San Ignacio orogeny represent the third and more pervasive magmatic event,recorded throughout the Sunsas belt.Moreover,magmatic ages of～1.42 Ga revealed that the granitogenesis asso-ciated to the Santa Helena orogeny also affected the Sunsas belt,indicating that it was not restricted to the Jauru Terrane.Lastly,the 1.10-1.04 Ga youngest magmatism was developed during the Sunsas oro-geny and represents the final magmatic evolution related to Rodinia assembly.Likewise,the 1.95-1.85 and 1.68 Ga inherited zircon cores obtained in the～1.3 Ga and 1.0 Ga granite samples suggest strong par-tial melting of the Paleoproterozoic sources.The 1079±14 Ma and 1018±6 Ma monazite crystallization ages can be correlated to the collisional tectono-thermal event of the Sunsas orogeny,associated to reac-tions of medium-to high-grade metamorphism.Thus,the Sunsas belt was built by heterogeneous 1.95-1.85 Ga and 1.68 Ga crustal fragments that were reworked at 1.37-1.34 Ga and 1.10-1.04 Ga related to orogenic collages.Furthermore,the 1.01 Ga monazite age suggests that granites previously dated by zir-con can bear evidence of a younger thermal history.Therefore,the geochronological evolution of the Sunsas belt may have been more complex than previously thought.  相似文献   

Oceanic micrometeorological field experiments: An historical perspective     

Lutz Hasse 《Boundary-Layer Meteorology》1990,50(1-4):139-146

This paper provides an historical perspective on micrometeorological field experiments designed to evaluate air-sea interaction processes. Of course, marine meteorology is much older, and air-sea interaction has always been an inevitable part of it. But only in this century have the tools been developed to go from qualitative understanding towards quantitative measurements of interactions.  相似文献   

Bestimmung gelöster und suspendierter Schwermetalle in der Elbe     

Prof. Dr. Lutz Brügmann 《Ocean Dynamics》1990,43(3):127-135

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Lattice vibration spectra. LXVIII. Single-crystal Raman spectra of marcasite-type iron chalcogenides and pnictides,FeX2 (X=S,Se, Te; P,As, Sb)     

H. D. Lutz  B. Müller 《Physics and Chemistry of Minerals》1991,18(4):265-268

Single-crystal Raman spectra of marcasite-type FeS₂, FeSe₂, and FeTe₂ and loellingite-type FeP₂, FeAs₂, and FeSb₂ are presented and discussed with reference to the energies of the two X-X stretching modes v _x-x (A _g, B _1g) and the four X₂ librations Rx₂ (A _g, B _1g, B _2g, B _3g). The main results obtained are that (i) the intraionic X-X bonds of FeS₂ marcasite and FeS₂ pyrite are nearly equal in strengths (mean values of the S-S stretching modes 418 and 420 cm^-1, respectively) and (ii) the interactions of the metal ions and the dumbbell-like X₂ units increase on going from the chalcogenides to the respective pnictides and from FeS₂ marcasite to pyrite (as shown from the frequencies of the X₂ librations).  相似文献   

Selective feeding and grazing rates of oyster (Crassostrea virginica) larvae on natural phytoplankton assemblages     

L. W. Fritz  R. A. Lutz  M. A. Foote  C. L. van Dover  J. W. Ewart 《Estuaries and Coasts》1984,7(4):513-518

Results of laboratory feeding experiments suggest that oyster (Crassostrea virginica) larvae select small phytoplanktonic organisms (<10 μm) over larger-celled forms from natural estuarine assemblages, but that little selection occurs within the small phytoplankton fraction. Laboratory-reared larvae grazed each of five small-celled phytoplankton groups enumerated (coccoids, centrate diatoms, pennate diatoms, dinoflagellates, and flagellates) at rates proportional to phytoplankton group densities in controls (no larvae added). Larval grazing rates (number of cells removed per larva per hour) were inversely proportional to both larval density and experimental duration.  相似文献   

Environmental oxidation rate of manganese(II): bacterial catalysis     

Steven Emerson  Susan Kalhorn  Lucinda Jacobs  Bradley M Tebo  Kenneth H Nealson  Reinhardt A Rosson 《Geochimica et cosmochimica acta》1982,46(6):1073-1079

A simple mass balance for dissolved manganese(II) in waters containing low levels of oxygen in Saanich Inlet indicates that the residence time for Mn(II) removal to the solid phase is on the order of a few days. The average oxidation state of Mn in particulate material sampled from the region of Mn removal was 2.3–2.7, and electron micrographs revealed structures characteristic of bacterially formed Mn precipitates. Radiotracer experiments utilizing ⁵⁴Mn(II) indicated that removal of Mn from solution in the region of active uptake was substantially blocked by a poison mixture, demonstrating that Mn(II) binding to particulates is catalyzed by bacteria in this environment.  相似文献   

Book reviews     

A. M. O'Connor  Fouad Ibrahim  W. F. Schmidt-Eisenlohr  Olof Nordström  Gunnar Alexandersson  Lutz Holzner  L. A. Kosiński 《GeoJournal》1978,2(5):492-494

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Heavy metal inflow into the floodplains at the mouth of the river Weiße Elster (Central Germany)     

Lutz Zerling  Christiane Hanisch  Frank W. Junge 《洁净——土壤、空气、水》2006,34(3):234-244

From 1998 to 2002 investigations were carried out to estimate both the quantity and quality (heavy metal contents) of suspended matter loads discharged into a floodplain area measuring approx. 5 km² of the Central German river Weiße Elster, a tributary of the river Saale in the Elbe river basin. Flood sediments, suspended particulate matter, and floodplain soils were investigated especially for the main pollutants Cd, Zn, Cu, Pb, Cr, and Hg. Supplementary gamma spectroscopy examinations were performed to help to identify the age of deposits in order to estimate sedimentation rates for last decades. The recent flood sediments are contaminated by up to 33 times the geogenic background (Cd). Up to 55% of the total annual SPM load of the river Weiße Elster is relocated into the investigated retention area in the flood‐stricken year 2002. The sedimentation rates for the last 50 years vary between 0.5 mm/a and 1 mm/a in far away and rarely flooded parts and between 1 mm/a and 2 mm/a in the frequently flooded parts of the inflow of the retention area.  相似文献   

Small-scale diffusion experiments in the Baltic surface-mixed layer under different weather conditions     

Prof. Dr. Friedrich Schott  Mafred Ehlers  Lutz Hubrich  Detlef Quadfasel 《Ocean Dynamics》1978,31(6):195-215

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The influence of sea waves on the wind profile     

Lutz Krügermeyer  Manfred Grünewald  Michael Dunckel 《Boundary-Layer Meteorology》1978,14(3):403-414

From wind profile and wave measurements performed during the JONSWAP II experiment, relations between the dimensionless profile slope and the significant wave height are derived. It is shown that the wind profile is distorted by the waves especially in the vicinity of the water surface. The wave influence on the profile seems to be restricted to heights below about three wave heights. Above this level, the dimensionless profile slope is an approximately constant value corresponding to a drag coefficient of about 1.15 × 10^–3.  相似文献