Paleozoic

The present study is a detailed structural analysis of 3D seismic data in the Selis Ridge in the western Loppa High in the Norwegian Barents Sea, to which new seismic attributes and spectral decomposition were applied. The analysis reveals that pre-Devonian basement rocks are crosscut by a 40–50 kilometers wide, several kilometers thick, E–W- to WNW–ESE-striking fold-and-thrust belt, including a steep, kilometer-thick, top-SSW shear zone. The folds display dome- and trough-shaped geometries, the thrusts appear to have been reactivated dominantly as top-west structures, and the main shear zone warps over the top of the Selis Ridge. The fold-and-thrust belt is interpreted as part of the latest Neoproterozoic (ca. 650–550 Ma) Timanian Orogeny, which potentially reworked preexisting Neoproterozoic rift basins and highs, and was reworked during E–W Caledonian contraction in the Ordovician–Silurian. The results are analogous to recent findings in the northern Norwegian Barents Sea and Sva...

The Eastern Alps are characterised by the presence of three main tectonic units, such as the Lower, Middle and Upper Austroalpine, which overlie the Penninicum (Tollmann, 1977). The Upper Austroalpine unit consists of the Northern Calcareous Alps (NCA) overlying the Greywacke zone and corresponding to the Graz Paleozoic, Murau Paleozoic and the Gurktal Nappe. Evaporitic rocks are lacking in the later ones. The Northern Calcareous Alps are a detached fold and thrust belt. The sedimentation started in the Late Carboniferous or Early Permian, the age of the youngest sediments being Eocene. The NCA are divided into the Bajuvaric, Tirolic and Juvavic nappe complexes. The evaporitic Haselgebirge Formation occurs in connection with the Juvavic nappe complex at the base of the Tirolic units (Leitner et al., 2013). The Haselgebirge Formation consists mainly of salt, shales, gypsum and anhydrite and includes the oldest sediments of the NCA. The age of the Haselgebirge Formation, established b...

The lives and works of Dr Elga Mark‐Kurik and Dr Valentina Karatajute‐Talimaa, Estonian and Lithuanian palaeontologists, respectively, are presented as part of their celebration at the 11th Symposium on Early/Lower Vertebrates at Uppsala. Both graduated from the university of their home town, Tartu and Vilnius, respectively. Elga became a Researcher at the Institute of Geology of the Estonian S.S.R. Academy of Sciences, in Tallinn, whereas Valentina worked for the Institute of Geology, Vilnius. Both were mentored by D. V. Obruchev of Moscow. Elga chose placoderms and psammosteid heterostracans as main research objects. Valentina also began with whole fish, antiarch placoderms, but then chose fish microfossils with W. Gross as mentor and discovered the oldest chondrichthyans. Both work as palaeobiologists understanding the implications of their fossils for functional interpretation and palaeogeography; their main contribution is in biostratigraphy (over 50% of their publications). In...

Harvestmen (Arachnida: Opiliones) were among the earliest terrestrial arthropods but their unmineralized exoskeletons are scarce and often fragmentary as fossils (Palencia et al. 2019). Consequently, the discovery and interpretations of fossil harvestmen from the early Palaeozoic can have disproportionate effects on the understanding of evolution in Opiliones. Recently, Devonopilio hutchinsoni Tihelka, Tian & Cai, 2020, was described as a new fossil harvestman from the well-known Rhynie chert deposits of Scotland, an important source of information on freshwater and terrestrial ecosystems of the early Devonian (Tihelka et al. 2020). This species would be one of the earliest records of harvestmen. The description was based on a single slide showing fragments of arthropod cuticle, which Tihelka et al. interpreted as a harvestmen penis and unspecified associated body parts. As specialists on harvestman morphology and systematics, we were intrigued by these conclusions. However, based o...

The geological map coverage of Greenland at scale 1:500 000 is nearing completion, with the Kane Basin sheet of north-western Greenland the last to be compiled (sheet 6 between 78°–81°N; Fig. 1). Sporadic work by the Survey since the 1970s identified the main geological provinces and structure of the region but the lithologies of the Precambrian shield were not sufficiently mapped inland to warrant final compilation. Project Kane Basin 1999 was designed to provide this knowledge; the optimal use of logistics enabled a range of geological activities to be undertaken, as well as other scientific disciplines.

Authors : Ahmad Helman Hamdani, Diana Putri Hamdiana Abstract : The Sajau coal measures of Berau Basin, northeastern Kalimantan were deposited within a range of facies associations spanning a spectrum of settings from fluvial to marine. The transitional to terrestrial coal measures are dominated by siliciclastics, but they also contain three laterally extensive marine bands (mudstone). These bands act as marker horizons that enable correlation between fully marine and terrestrial facies. Examination of this range of facies and their sedimentology has enabled the development of a high-resolution sequence stratigraphic framework. Set against the established backdrop of third-order Sajau transgression, nine fourth-order sequences are recognized. Results show that, in the composite sequences, peat accumulation predominantly correlates in transitional areas with early transgressive sequence sets (TSS) and highstand sequence set (HSS), while in more landward areas it correlates with the m...

In the Manang area (north Annapurna Range; Nepal Himalaya), the Permo-Carboniferous succession is 1000 to 1500 m thick. Crinoidal biocalcarenites (Tilicho Lake Fm.) pass upward to alternating black shales and sharp-based white quartzose sandstones (Thini Chu Group). Detailed stratigraphic analysis of this unit allowed us to recognize and establish 5 new formations and 8 new members. The Marsyandi Fm., of Visean age, records an increase of subarkosic terrigenous detritus during the initial stage of Neotethyan rifting, and is capped by two sequences "Syringotbyris  beds") characterized by transgressive sandstones rich in Serpukhovian brachiopods. The overlying black shales with subordinate quartzarenites (Col Noir Shale) are followed in the more proximal Bangba section by diamictites yielding dolostone rock fragments, documenting the first advance of glacial ice on rift shoulders, actively uplifted since the Bashkirian-Moscovian (Bangba Fm.). Next, glaciomarine to transgress...

The Late Palaeozoic–Early Mesozoic Tethyan development of the Eastern Mediterranean region remains debatable, especially in Turkey, where alternative northward and southward subduction hypotheses are proposed. Relevant to this debate, new whole-rock geochemical data are provided here for early Carboniferous (Late Tournaisian-Late Visean; c. 340–350 Ma) tuffaceous sedimentary rocks within the Çataloturan thrust sheet (Aladağ nappe), eastern Taurides. The tuffs accumulated from evolved alkaline volcanism, variably mixed with terrigenous and radiolarian-rich sediments. In addition, Late Palaeozoic meta-volcanic rocks, c. 150 km farther NE, within the Binboğa (= Malatya) metamorphics (a low-grade high-pressure unit), are indicative of a within-plate setting. An impersistent geochemical subduction signature in these volcanics may represent an inherited, rather than contemporaneous, subduction influence, mainly because of the absence of a continental margin arc or of arc-derived tuff. Bot...

Abstract: Seeped oil-to-source correlation requires sophisticated geochemical fingerprinting techniques and an understanding of their limitations. Through the past several decades, studies have used EOM composition, biomarkers, diamondoids, and multi-elemental analyses to correlate oils in reservoir studies; yet only EOM composition and biomarkers are routinely used to correlate seeped oils. Thus, in the current study, seven seeped oils (Soxhlet-extracted, mainly Type III (terrestrial origin) and Type II/III (mixed) of organic matter in the source rock, API values = 35 - 40°) from a single basin (consisting of five Blocks: A, B, D, E, and F) and EOM from a background sample (from Block C) were analyzed using the aforementioned techniques and data therein was correlated to investigate the utility of these as advanced geochemical seep hunting tools. The extracted oils (from Blocks A, B, D, and E) varied between light condensates and black oils. Variations on the seeped oils may be attributed to oil fractionation, thermal maturation, chemical interactions during the upward migration of hydrocarbons, and / or biodegradation. Biomarkers results confirmed a Tertiary to Late Cretaceous Type III, low hydrogen kerogen source, and Type II/III consisting of high 18a(H)-oleanane (average Ol/H30=0.50), Gammacerane, a high (C29)/(C28+C27) sterane ratio, and low abundance of C30 steranes. Diamondoid analysis complemented these findings by targeting light hydrocarbon compounds, which are biodegraded in areas of passive or microseepage. High adamantane:diamantane ratios were consistently observed across the basin's seeped oil extracts, suggestive of light condensate oil. According to the results, diamondoids are a better indicator of maturity than biomarker parameters, especially for biodegraded hydrocarbons. The study also helped to find relation among elements, which could be of interest in correlating oils from similar/different sources when looking at seeps. Lastly, a logical workflow strategy is provided that can be used to determine which fingerprinting techniques are merited for seeped oil samples.