Bioturbation in the deposits of the Ogre Formation at Kalnrēžas outcrop

Bakalaura darba mērķis ir raksturot bioturbāciju Ogres svītas nogulumos Kalnrēžu atsegumā. Kalnrēžu atsegumā tika sastādīti divi griezumi un izdalīti bioturbētie slāņi. Bioturbācijas intensitātes novērtēšanai nogulumos tika izmantota puskvantitatīvā ihnotekstūras indeksa metode. Pētījuma rezultātā tika noskaidrots, ka ihnotekstūras indekss 2 raksturo lielāko daļu slāņu. Visintensīvāk bioturbētie slāņi ir izvietoti griezuma apakšējā un vidusdaļā. Ihnotekstūras indekss 1 ir raksturīgākais masīvas uzbūves dolomītsmilšakmeņiem. Pilnībā pārstrādātas nogulumu primārās tekstūras netika konstatētas. Atslēgas vārdi: ihnotekstūras indekss, Ogres svīta, dolomītsmilšakmens, Kalnrēžu atsegums The aim of the bachelor thesis is to give a description of bioturbation in the deposits of the Ogre Formation at Kalnrēžas outcrop. Two geological sections were composed and bioturbated strata were eliminated. In order to document variations in the extent of bioturbation recorded in the deposits of the Ogre Formation a semiquantitative ichnofabric indices method were used. Data collected with this method reveal that ichnofabric index 2 constitutes most of the strata that were studied. The most bioturbated sediment are concentrated in the lower and middle layers of the stratigraphic section. The ichnofabric index 1 is the most common for massive dolomitic sandstones. Nearly complete to complete reworking of original physical sedimentary structures is not represented. Key words: Ichnofabric index, Ogre Formation, dolomitic sandstone, Kalnrēžas outcro

Deposits of the Devonian Eleja and Jonišķis Formations and their sedimentary environment

Pētījuma mērķis ir izdalīt un detalizēti raksturot Devona Elejas un Jonišķu svītas nogulumu fācijas un fāciju asociācijas, lai spriestu par šo nogulumu veidošanās apstākļiem. Pētījuma ietvaros ir dokumentēti 3 atsegumu un vienas urbuma serdes ģeoloģiskais griezums. Karbonātiežu fāciju izdalīšanai nogulumu sastāvs, struktūra un mikrotekstūras tika pētītas plānslīpējumos, bet Jonišķu svītas nogulumos tika noteikta arī mikrofosīliju sastopamība. Pētījumā rezultātā ir izdalītas trīs Elejas un Jonišķu svītas nogulumu fāciju asociācijas: apakšējā līdz vidējā plūdmaiņu līdzenuma ar dominējošo klastisko sedimentāciju, vidējā līdz augšējā plūdmaiņu līdzenuma ar jauktu klastisko un karbonātu sedimentāciju un apakšējā līdz vidējā plūdmaiņu līdzenuma ar dominējošo karbonātu sedimentāciju. Atslēgas vārdi: plūdmaiņas, plūdmaiņu ritmīti, fāciju analīze, plānslīpējumi, mikrofosīlijas, Famenas stāvsBukovska I. 2013. Deposits of the Devonian Eleja and Joniskis Formations and their sedimentary environment. Master thesis. Riga, University of Latvia The purpose of the thesis is to detect and to describe facies and facies associations in the Devonian Eleja and Joniškis formations to characterize their sedimentary environment. Geological sections of three outcrops and one drill-core of the Eleja and Joniškis deposits were described. The sedimentary facies were identified by composition; structure and thin section analysis were used to describe carbonate deposits, their microstructures, texture and distribution of microfossils in the Joniškis formation was characterized. Based on facies description three sedimentary facies associations are defined: subtidal to intertidal flat with dominated siliciclastic deposition, intertidal to supratidal flat with mixed siliciclastic and carbonate deposition and subtidal to intertidal flat with dominated carbonate deposition. Keywords: tides, tidal rhythmites, facies analysis, thin section, microfossils, Famennian Stag

Picking Up the PiecesHarmonising and Collating Seabed Substrate Data for European Maritime Areas

The poor access to data on the marine environment is a handicap to government decision-making, a barrier to scientific understanding and an obstacle to economic growth. In this light, the European Commission initiated the European Marine Observation and Data Network (EMODnet) in 2009 to assemble and disseminate hitherto dispersed marine data. In the ten years since then, EMODnet has become a key producer of publicly available, harmonised datasets covering broad areas. This paper describes the methodologies applied in EMODnet Geology project to produce fully populated GIS layers of seabed substrate distribution for the European marine areas. We describe steps involved in translating national seabed substrate data, conforming to various standards, into a uniform EMODnet substrate classification scheme (i.e., the Folk sediment classification). Rock and boulders form an additional substrate class. Seabed substrate data products at scales of 1:250,000 and 1:1 million, compiled using descriptions and analyses of seabed samples as well as interpreted acoustic images, cover about 20% and 65% of the European maritime areas, respectively. A simple confidence assessment, based on sample and acoustic coverage, is helpful in identifying data gaps. The harmonised seabed substrate maps are particularly useful in supraregional, transnational and pan-European marine spatial planning