Origin of ore fluids in the Muruntau gold system: Constraints from noble gas, carbon isotope and halogen data   总被引：6，自引：0，他引：6  

Torsten Graupner  Samuel Niedermann  Reiner Klemd  Achim Bechtel 《Geochimica et cosmochimica acta》2006,70(21):5356-5370

Hydrothermal vein minerals directly associated with native gold mineralization in the Muruntau vein system (Uzbekistan) have been studied for noble gas, carbon isotope and halogen chemistry of the trapped ore-related fluids. Helium trapped in early arsenopyrite 1, which has preserved the original fluid signature better than associated scheelite and quartz, indicates a small input from a mantle source (?5% of total He). However, the overwhelming majority of the He in the fluid (∼95%) is from crustal sources. The noble gases Ne, Kr and Xe in the sample fluids are dominated by gases of atmospheric origin. The carbon isotope (δ¹³C: −2.1‰ to −5.3‰) and halogen characteristics of the fluids (log Br/Cl: −2.64 to −3.23) lend further support for the activity of juvenile fluids during the main ore stage. The high proportion of crustal components in the ore-forming fluids may be explained by intense fluid-rock interaction and is also supported by previous Nd and Sr isotope studies. The involvement of a juvenile fluid component during the main stage of hydrothermal activity at Muruntau (∼275 Ma) can be linked to the emplacement of lamprophyric dikes at Muruntau, due to apparently overlapping ages for high-temperature alteration, related ore vein formation and intrusion of the dikes. The input of mantle-derived fluids, possibly related to the Hercynian collisional event in the western Tien Shan, stimulated intense fluid-rock interaction in the crust. In this context, the mantle-derived fluid should be considered as one possible carrier of metals. Significant amounts of external meteoric fluids circulating in fracture systems are interpreted to have modified the noble gas signature of fluid in quartz, mostly during late, low temperature fluid circulation.  相似文献   

Correlation between hydrogen isotope ratios of lipid biomarkers and sediment maturity     

Jens Radke  Achim Bechtel  Wilhelm Püttmann  Dirk Sachse 《Geochimica et cosmochimica acta》2005,69(23):5517-5530

We investigated the influence of thermal maturity on the hydrogen isotope ratios of sedimentary hydrocarbons to prove that the isotope ratio of hydrocarbons mirrors paleoclimate signatures. δD values from n-alkanes and acyclic isoprenoids of two sediment sections (Kupferschiefer [KS], 258 Ma, and Posidonienschiefer [PS], 184 Ma) with different maturation history were investigated. Both covered thermal maturity from 0.48 to 1.3 R_c (vitrinite reflectance and reflectance calculated from MPI1). Sediment burial up to 4500 m caused thermal maturation of organic matter in the KS horizon from the Early Zechstein basin of Poland, whereas contact metamorphic thermal maturation originated in the Early Toarcian PS (Posidonienschiefer) of the North German Vlotho Massif. The δD values of the extracted n-alkanes positively correlate with thermal maturity in the KS (y = 56‰ × MPI1[x] − 160‰ [VSMOW]) and in the PS (y = 104‰ × MPI1[x] − 200‰ [VSMOW]). The δD values of isoprenoids (i.e., pristane, phytane) were even more enriched with increasing maturity (y = 179‰ × MPI1[x] − 341‰ [VSMOW] in the KS; y = 300‰ × MPI1[x] − 415‰ [VSMOW] in PS).These results explain why isotope ratios of n-alkanes and isoprenoids in mature sediments are generally enriched in D and do not have the expected isotopic difference between n-alkanes and isoprenoids of ∼190‰. Moreover, the correlation between sediment maturity parameters and δD values suggests that after correction the δD values of n-alkanes can be used to reconstruct climate and environment in the geological past.  相似文献   

Spontaneous self-combustion of organic-rich lateglacial lake sediments after freeze-drying     

Nadine Dräger  Achim Brauer  Brian Brademann  Rik Tjallingii  Michał Słowiński  Mirosław Błaszkiewicz  Norbert Schlaak 《Journal of Paleolimnology》2016,55(2):185-194

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Palynology of Triassic–Jurassic boundary sections in northern Switzerland     

Elke Schneebeli-Hermann  Nathan Looser  Peter A. Hochuli  Heinz Furrer  Achim G. Reisdorf  Andreas Wetzel  Stefano M. Bernasconi 《Swiss Journal of Geoscience》2018,111(1-2):99-115

A first palynostratigraphic scheme of Upper Triassic deposits in northern Switzerland was established based on spore-pollen associations and dinoflagellate cyst records from the upper part of the Upper Triassic Klettgau Formation and the lower part of the Lower Jurassic Staffelegg Formation. Drill cores from the Adlerberg region (Basel Tabular Jura) and from Weiach (northern part of Canton Zurich) as well as from an outcrop at the Chilchzimmersattel (Basel Folded Jura) were studied and five informal palynological associations are distinguished. These palynological associations correlate with palynological association of the Central European Epicontinental Basin and the Tethyan realm and provide a stratigraphic framework for the uppermost Triassic sediments in northern Switzerland. Throughout the uppermost Triassic to Jurassic palynological succession a remarkable prominence of Classopollis spp. is observed. Besides Classopollis spp. the three Rhaetian palynological associations A to C from the Upper Triassic Belchen Member include typical Rhaetian spore-pollen and dinoflagellate taxa (e.g., Rhaetipollis germanicus, Geopollis zwolinskae, Rhaetogonyaulax rhaetica, and Dapcodinium priscum). Association B differs from association A in a higher relative abundance of the sporomorph taxa Perinopollenites spp. and the consistent occurrence of Granuloperculatipollis rudis and Ricciisporites tuberculatus. Spore diversity is highest in the late Rhaetian palynological association C and includes Polypodiisporites polymicroforatus. A Rhaetian age for the Belchen Member is confirmed by palynological associations A–C, but there is no record of the latest Rhaetian and the earliest Jurassic. In contrast to the Rhaetian palynological associations the Early Jurassic associations W and D include Pinuspollenites spp., Trachysporites fuscus (in association W), and Ischyosporites variegatus. In the view of the end-Triassic mass extinction and contemporaneous environmental changes the described palynofloral succession represents the pre-extinction phase (associations A and B) including a distinct transgression, the extinction phase (association C) associated with a regression, and the post-extinction phase (association W).  相似文献   

The multiple chronological techniques applied to the Lake Suigetsu SG06 sediment core,central Japan     

Richard A. Staff  Takeshi Nakagawa  Gordon Schlolaut  Michael H. Marshall  Achim Brauer  Henry F. Lamb  Christopher Bronk Ramsey  Charlotte L. Bryant  Fiona Brock  Hiroyuki Kitagawa  Johannes van der Plicht  Rebecca L. Payne  Victoria C. Smith  Darren F. Mark  Alison Macleod  Simon P. E. Blockley  Jean‐Luc Schwenninger  Pavel E. Tarasov  Tsuyoshi Haraguchi  Katsuya Gotanda  Hitoshi Yonenobu  Yusuke Yokoyama  Suigetsu Project Members 《Boreas: An International Journal of Quaternary Research》2013,42(2):259-266

The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high‐resolution, multi‐proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well‐constrained chronology is required. This paper outlines the multiple geochronological techniques being applied – namely varve counting, radiocarbon dating, tephrochronology (including argon–argon dating) and optically stimulated luminescence (OSL) – and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu (SG06) varve chronology and the absolute (IntCal09 tree‐ring) time scale, as derived using radiocarbon data from the uppermost (non‐varved) portion of the core. This tie‐point, defined as a distinct (flood) marker horizon in SG06 (event layer B‐07–08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 IntCal09 cal. years BP (68.2% probability range).  相似文献   

Determination of Geopotential Differences between Local Vertical Datums and Realization of a World Height System   总被引：2，自引：0，他引：2  

Burša  Milan  Kouba  Jan  Müller  Achim  Raděj  Karel  True  Scott A.  Vatrt  Viliam  Vojtíšková  Marie 《Studia Geophysica et Geodaetica》2001,45(2):127-132

The methodology developed for connecting Local Vertical Datums (LVD) was applied to the Australian Height Datum (AHD) and the North American Vertical Datum (NAVD88). The geopotential values at AHD and NAVD88 were computed and the corresponding vertical offset of 974 mm with rms 51 mm was obtained between the zero reference surfaces defined by AHD and NAVD88. The solution is based on the four primary geodetic parameters, the GPS/levelling sites and the geopotential model EGM96. The Global Height System (or the Major Vertical Datum) can be defined by a geoidal geopotential value used in the solution as the reference value, or by the geopotential value of the LVD, e.g. NAVD88.  相似文献   

Data processing in biology and geology: CUTBILL,J.L. ed. (1971): Proceedings of a Symposium held at the Department of Geology,University of Cambridge,September 24–26,1969. XV, 346, pp. London: Academic Press. (Published for the systematics association). Cloth, £ 5.00.     

Achim Schneider 《Geoforum》1972,3(2):105-106

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Differences between Mean Sea Levels for the Pacific,Atlantic and Indian Oceans From Topex/Poseidon Altimetry     

Burša  Milan  Kouba  Jan  Müller  Achim  Raděj  Karel  True  Scott A.  Vatrt  Viliam  Vojtíšková  Marie 《Studia Geophysica et Geodaetica》1999,43(1):1-6

Geopotential values W of the mean equipotential surfaces representing the mean ocean topography were computed on the basis of four years (1993 - 1996) TOPEX/POSEIDON altimeter data: W = 62 636 854.10m ² s ^–2 for the Pacific (P), W = 62 636 858.20m ² s ^–2 for the Atlantic (A), W = 62 636 856.28m ²s^–2 for the Indian (I) Oceans. The corresponding mean separations between the ocean levels were obtained as follows: A – P = – 42 cm, I– P = – 22 cm, I – A = 20 cm, the rms errors came out at about 0.3 cm. No sea surface topography model was used in the solution.  相似文献   

Palaeomagnetic Studies of Miocene Ignimbrites from Nevada     

Wulf Achim Gose 《Geophysical Journal International》1970,20(3):241-252

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Mervyn S. Paterson and Teng-fong Wong, Experimental Rock Deformation – The Brittle Field, 2005     

Achim Kopf 《Surveys in Geophysics》2006,27(4):487-488

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