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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
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Alfred A. Gübeli Peter A. Hochuli Walter Wildi 《International Journal of Earth Sciences》1984,73(3):1081-1114
The paper describes the palynology, stratigraphy, sedimentology and palaeogeographic setting of Lower Cretaceous turbiditic and terrigenous deep-sea sediments at the Tethyan margins of Africa and Alboran (External Domain of the Rif, and Flysch Nappes). During the Early Cretaceous terrigenous turbiditic deep-water sedimentation characterizes two different palaeogeographic domains in the southern part of the western Tethys: In the northern area of the External Domain (Ketama Unit of the Rif) alternating turbiditic arenites and pelites are interpreted as sediments of a distal part of a fan system on the Tethyan margin of Africa. The main sources for the terrigenous material were situated in Central and Western Algeria; only little sand transited through the Prerif and the Mesorif zones of Morocco. The terrigenous sedimentation began in the Hauterivian, but the main turbiditic cycles are of Aptian to Lower and Middle Albian age. The Flysch Domain probably was situated far to the Northeast with respect to the Rif basin, at the western and southern margins of the Alboran microplate. Relatively proximal turbidites form most of the Tisirène Nappe, whereas more distal turbidites constitute the series of the Melloussa and the Chouamat Nappes. The existence of two different source areas is demonstrated, one to the NE and the other to the NW of the depositional area. The turbidites probably were deposited on a E-W oriented fan system which progradated into a longitudinal trench-like trough. In the Central Rif area, the Tisirène Flysch is of Valanginian to Albian (pre-Vraconian) age. In the Western Rif and in the Melloussa and Chouamat Nappes of the whole area no sediments older than Aptian have been found. The stratigraphy of the investigated series is based on a new tentative palynostratigraphic zonation, using pollen, spores and dinoflagellate cysts. Rich and well preserved assemblages have been found in the Western Rif only, whereas the samples of the Tisirène Nappe and the Chouamat Nappe in the Central and Eastern Rif have been affected by some thermal alteration. Black and mostly opaque palynomorphs from the Ketama Unit reflect the strong thermal influence in the External Domain of the Central and Eastern Rif. 相似文献
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U. Heimhofer S. P. Hesselbo R. D. Pancost D. M. Martill P. A. Hochuli J. V. P. Guzzo 《地学学报》2008,20(5):347-354
Organic matter from two black shale units in the Santana Formation, Araripe Basin, NE Brazil, has been studied to investigate the palaeoenvironmental conditions prevailing during formation of this famous fossil lagerstätte. Optical and organic geochemical analyses indicate a predominantly autochthonous source with very limited terrestrial input. Molecular fossils of green sulphur bacteria show that the water column was stratified with euxinic conditions reaching up into the photic zone. Thus, mass‐mortality events of fish may be explained by intrusion of sulphide‐containing waters. The low quantity of material derived from land plants in this interior marine setting is interpreted to reflect a consequence of enhanced marine productivity, resulting in dilution of the continental signal. Different depositional scenarios are proposed to explain our findings including (1) coastal erosion and nutrient leaching during a transgressive event, (2) intrusion of euxinic waters during an early Albian OAE or (3) an estuarine circulation pattern associated with thermohaline stratification. 相似文献
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Pavle TAN?I? Radovan DIMITRIJEVI? Maja POZNANOVI? Aleksandar PA?EVSKI Slobodanka SUDAR 《《地质学报》英文版》2012,86(6):1524-1538
The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) ?; b=12.3109(2) ?; c=3.03712(7) ?; and V=345.91(1) ?3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-Al3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01(Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples. 相似文献
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The study of palynomorphs and calcareous nannofossils from the Albian–Campanian Napo Group in the Pungarayacu 30 well in the Subandean Zone of Ecuador has led to a new biostratigraphic framework revealing the existence of several hiatuses for this area. The palynological and palynofacies data are used together with other fossils and lithological evidence to define a sequence stratigraphic framework. The distribution of palynomorphs and palynofacies indicates a strong terrestrial input for the lower part of the Napo Group (Napo Basal and Lower Napo formations). In the upper part (Middle and Upper Napo formations), terrestrial input is reduced and a restricted marine environment with several dysoxic–anoxic intervals can be inferred. The hydrocarbons present in the well studied have traditionally been regarded as locally sourced. However, several lines of evidence (TAS, Tmax and VR) prove the immature stage of the source rock in this borehole as well as in a larger area. 相似文献
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A palynology and organic matter study has been carried out on samples of the Upper Triassic Raibl beds from an Upper Austroalpine
thrust sheet, preserved in the area of the Iberg Klippen (Laucherenst?ckli). The palynological assemblages indicate an early
Carnian (Julian) age. Comparison with well calibrated successions from the Southern Alps suggests a correlation with the Late
Julian ammonoid zone Austrotrachyceras austriacum.
The lithofacies of the studied sections suggests a substantial similarity to Raibl beds of the Upper Austroalpine of the Northern
Calcareous Alps and those of the Silvretta- and the S-charl nappe of the Grisons. The minute Upper Austroalpine thrust sheet
represents the westward extension of series with similar facies, which are still preserved in the Northern Calcareous Alps
of Liechtenstein and western Austria (Vorarlberg).
According to the Thermal Alteration Scale (TAS) of Batten (1996) the observed medium brown colors of the pollen grains correspond
to a value of 4/5, which is equivalent to vitrinite reflectance (VR) values of 0.7–0.9 %Ro. In comparison with other sites in Liechtenstein, Vorarlberg and the Upper Austroalpine of Central Grisons (Silvretta and
S-charl nappe) with measured VR values of > 2%Ro the organic matter of the studied samples shows only minor thermal alteration, indicating that the Upper Austroalpine thrust
sheets of Iberg represent the highest part of the nappe stack in Central Switzerland, formerly covered by a comparatively
thin overburden.
相似文献
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Ulrich Heimhofer Thierry Adatte Peter A. Hochuli Stefan Burla Helmut Weissert 《International Journal of Earth Sciences》2008,97(4):785-797
The Late Aptian to Early Albian transition has previously been identified as a possible example of substantial climate cooling
within the mid-Cretaceous greenhouse period. To study the response of continental weathering and terrestrial vegetation to
this cooling episode at low- to mid-latitudes, marine nearshore deposits from the Algarve Basin (SW Portugal) have been investigated
with a combined approach including palynology, clay mineralogy and bulk-rock geochemistry. In the Lower Aptian part of the
succession, quartz-rich sandstone facies is accompanied by high abundances of early diagenetic kaolinite, which is interpreted
to reflect episodes of enhanced humidity and high meteoric flow-through. In contrast, the Late Aptian to Early Albian deposits
are characterized by high abundances of detrital clay minerals (mica and chlorite) indicating the dominance of physical weathering
processes in the source area, most probably related to low precipitation rates in conjunction with tectonically enhanced erosion.
Palynological data show a strong dominance of Classopollis pollen associated with low pteridophyte spore abundances, suggesting warm semi-arid to arid palaeoenvironments. Changes in
sedimentation patterns from varicoloured lagoonal marls to thick-bedded shallow-water carbonates are neither expressed in
the spore-pollen assemblages nor in the distributions of clay minerals which both remain essentially stable throughout the
Late Aptian to Early Albian. These relatively stable patterns are in contrast with various lines of evidence, predominantly
from high-latitude areas, that suggest a significant cooling during this time interval. Our study demonstrates that terrestrial
environments of low- to mid-latitude regions were not significantly affected by the Late Aptian - Early Albian “cold snap”. 相似文献