• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 27
  • 27
  • 8
  • 8
  • 8
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Coal facies and palaeoenvironments of the middle eocene to early oligocene Bowmans and Lochiel deposits, Northern St. Vincent Basin, South Australia.

Springbett, Gavin January 2007 (has links)
Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / The middle eocene to early oligocene Bowmans and Lochiel coal deposits of the northern St. Vincent Basin, South Australia have been studied to elucidate their depositional environments. These coals occur within predominantly fluvio-lacustrine transgressive system tract sequences that formed during the initial phase of basin infill. The aforementioned facies are unevenly distributed and their stratigraphic succession highlights evolutionary changes in local palaeoenvironments. Within individual seams the transition from subaquatic to topogenous forest swamps and ultimately ombrogenous conditions is most common. However, over the coal sequence as a whole, conditions evolved from exclusively terrestrial through mixed terrestrial and subaquatic to open water. Also detected were multiple rapid reversals of the water table, especially higher in the sequence, and cyclic patterns reflecting a brief basal subaquatic phase prior to the onset of sustained terrestrial conditions. These patterns suggest a fluctuating, although progressively rising, water table and a balance between accommodation and accumulation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1280880 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007
22

Coal facies and palaeoenvironments of the middle eocene to early oligocene Bowmans and Lochiel deposits, Northern St. Vincent Basin, South Australia.

Springbett, Gavin January 2007 (has links)
Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / The middle eocene to early oligocene Bowmans and Lochiel coal deposits of the northern St. Vincent Basin, South Australia have been studied to elucidate their depositional environments. These coals occur within predominantly fluvio-lacustrine transgressive system tract sequences that formed during the initial phase of basin infill. The aforementioned facies are unevenly distributed and their stratigraphic succession highlights evolutionary changes in local palaeoenvironments. Within individual seams the transition from subaquatic to topogenous forest swamps and ultimately ombrogenous conditions is most common. However, over the coal sequence as a whole, conditions evolved from exclusively terrestrial through mixed terrestrial and subaquatic to open water. Also detected were multiple rapid reversals of the water table, especially higher in the sequence, and cyclic patterns reflecting a brief basal subaquatic phase prior to the onset of sustained terrestrial conditions. These patterns suggest a fluctuating, although progressively rising, water table and a balance between accommodation and accumulation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1280880 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007
23

Deposiotional systems of the permian Vryheid formation highveld coalfield, South Africa: their relationship to coal seam occurence and distribution

Cadle, Anthony Burnard January 1995 (has links)
The Permo-Carboniferous Dwyka Group and Vryheid Formation of the Karoo. Sequence in the Highveld Coalfield are analysed to determine the depositional systems operative during sedimentation. The investigation involves the processing of "629" borehole cores and logs in an area of 860km2.[Abbreviated Abstract. Open document to view full version] / AC2017
24

Cleat mineralogy of later permian coal measures, Bowen Basin, Queensland, Australia

Faraj, Basim Said. Unknown Date (has links)
No description available.
25

Cleat mineralogy of later permian coal measures, Bowen Basin, Queensland, Australia

Faraj, Basim Said. Unknown Date (has links)
No description available.
26

Development and application of some quantitative stratigraphic techniques to the Coos Bay coalfield, a Tertiary fluvio-deltaic complex in southwestern Oregon

Titus, Willard Sidney, III 01 January 1987 (has links)
A computer technique for interpreting geophysical logs of drill-holes in quantitative lithologic terms has been developed and tested on the deposits of the late Eocene Coaledo Formation, a well-studied fluvio-deltaic complex in southwestern Oregon. The technique involves the use of induced and natural gamma logs for separation of coal and claystone from coarse-grained detrital rocks and the use of the ratio of resistivity and natural gamma responses (defined here as the "grain size index") to divide the coarse elastic rocks into a series of textural classes corresponding to the Wentworth-Odden particle size scale.
27

Τυρφογένεση και εξελικτική πορεία τυρφώνων στην Ελλάδα

Καλαϊτζίδης, Σταύρος 26 June 2008 (has links)
Στην παρούσα διατριβή διερευνώνται οι διεργασίες που λαμβάνουν χώρα στο τυρφογενές στρώμα, έτσι ώστε να ανιχνευθούν οι μεταβολές των φυσικών, πετρογραφικών και χημικών χαρακτηριστικών των οργανικών ιζημάτων συναρτήσει των παραμέτρων τυρφογένεσης, όπως το κλίμα και οι τοπικές γεωλογικές συνθήκες. Απώτερο στόχο συνιστά η μοντελοποίηση παλαιοπεριβαλλόντων γένεσης των γαιανθράκων. Τέλος αξιολογείται η συμπεριφορά των ορυκτών, η γεωχημική συγγένεια και η κινητικότητα των ιχνοστοιχείων σε ενδεχόμενη αξιοποίηση της τύρφης για ενεργειακούς σκοπούς. Η έρευνα εστιάστηκε στους τυρφώνες Φιλίππων (Ν. Καβάλας) και Νησιού (Ν. Πέλλας) στη Βόρεια Ελλάδα και στον παράκτιο τυρφώνα του Κεριού (Ν. Ζακύνθου). Εξετάστηκαν τα ποιοτικά και ποσοτικά χαρακτηριστικά των οργανικών και ανοργάνων ιζημάτων που πληρούν τους τυρφώνες, αλλά και τα αντίστοιχα τυρφογενετικά φυτικά είδη, που αναπτύσσονται στους ενεργούς τυρφώνες Νησιού και Κεριού. Συγκεκριμένα πραγματοποιήθηκαν προσεγγιστική και στοιχειακή ανάλυση, ορυκτολογικοί προσδιορισμοί, εξέταση στιλπνών τομών με ηλεκτρονική μικροσκοπία σάρωσης, αναλύσεις τόσο της ανόργανης χημικής σύστασης (XRF, ICP/OES, ICP/MS), όσο και της οργανικής χημικής σύστασης (13C CP/MAS NMR, FTIR, py-GC/MS), όπως επίσης και ανθρακοπετρογραφικοί προσδιορισμοί. Αναφορικά με τους ορυκτολογικούς προσδιορισμούς εφαρμόστηκε μέθοδος πλήρους ποσοτικοποίησης των ορυκτών φάσεων με εφαρμογή περιθλασιμετρίας ακτίνων Χ σε ξηρό δείγμα, συνυπολογίζοντας την επίδραση του οργανικού υλικού. Αξιολογήθηκε επίσης η εφαρμογή περιθλασιμετρίας ακτίνων Χ σε υπολείμματα οξείδωσης της τύρφης. Οι τυρφώνες Φιλίππων και Νησιού συνιστούν παρόμοια περιβάλλοντα τυρφογένεσης, καθώς και οι δύο αναπτύσσονται σε ενδοηπειρωτικές λεκάνες, των οποίων η βύθιση ελέγχεται κυρίως από τεκτονικούς παράγοντες, με την ανάπτυξη παρόμοιων τυρφογενετικών φυτικών ειδών, όπως Cyperaceae και ειδικότερα το ασβεστόφιλο Cladium mariscus και διάφορα Carex spp., ενώ επηρεάζονται στη σύγχρονη εξέλιξή τους τουλάχιστον και οι δύο από καρστικούς υδροφόρους, συνιστώντας τοπογενείς ποωτυρφώνες, με κύριο μορφολογικό χαρακτηριστικό την παρουσία εξάρσεων (hummocks). Αντίθετα στο Κερί η τυρφογένεση αναπτύχθηκε σε παράκτιο περιβάλλον με τη βύθιση (δηλ. το πλημμύρισμα) να ελέγχεται τόσο από τεκτονικούς παράγοντες, όσο και από τις ευστατικές κινήσεις της θάλασσας, και το πεδίο χαρακτηρίζεται ως υφάλμυρος ποωτυρφώνας. Στο Κερί πέρα από ελόφυτα γλυκών νερών, αναπτύσσονται και είδη υφάλμυρων οικολογικών συνθηκών, όπως Scirpus maritimus και Juncus maritimus, λόγω της υφαλμύρινσης του υδροφόρου ορίζοντα. Με βάση τα χαρακτηριστικά τυρφογένεσης στους τρεις τυρφώνες τροποποιήθηκαν οι δείκτες φάσεων, που χρησιμοποιούνται στη γεωλογία γαιανθράκων, έτσι ώστε να αντανακλούν καλύτερα τις συγγενετικές διεργασίες στο ακρότελμα. Επιπρόσθετα περιγράφονται τόσο ποιοτικά, όσο και ποσοτικά τα χαρακτηριστικά των ιζημάτων στο τελματικό και το λιμνοτελματικό πεδίο, ενώ εκτιμάται επίσης και η πορεία της ενανθράκωσης των υπό μελέτη οργανογενών ιζημάτων, έτσι ώστε να εξαχθούν διαγνωστικές παράμετροι εφαρμογής στα παλαιοπεριβάλλοντα τυρφογένεσης. / The present study focuses on the processes taking place in the peatigenic layer (acrotelma), in order to trace the alteration of physical, chemical and petrographical features of the organic sediments in connection with the peat-forming factors. The ulterior aim is to propose a model for interpreting the coal-forming palaeoenvorinmental conditions. Finally, the mobility of the toxic trace elements is evaluated, in case of peat utilization for power generation in the future. Cores from the peatlands of Philippi (Prefecture of Kavala) and Nissi (Prefecture of Pella) in Northern Greece and of Keri (Zakynthos Island) in Southern Greece, were examined. The objective was to determine the qualitative and quantitative characteristics of the organogenic sediments hosted in the peatlands and additionally, of the peat-forming plants that grow on the surface of the Nissi and Keri mires. A series of laboratory examinations were performed on the collected samples, including proximate and ultimate analyses, mineralogical determinations by applying X-ray diffraction and SEM, inorganic geochemical analyses using XRF, ICP-OES and ICP-MS, organic geochemical analyses using 13C CP/MAS NMR, FTIR and py-GC/MS techniques and organic petrographical examinations on intact samples. Regarding the mineralogical determinations a method for full quantification of the mineral phases has been developed taking into account the pattern of the organic phases. Additionally the application of X-ray diffraction in oxidized peat residues has been evaluated. The Philippi and Nissi peatlands comprise similar peat-forming environments, since: (a) both developed in intermontane basins, the subsidence of which is controlled mainly by the tectonic activity, (b) Cyperaceae, mainly Cladium mariscus and various Carex spp., constitutes the main peat-forming plants, (c) whereas both are affected by karstic waters. They are fens for most of the peat accumulation period. On the contrary, in Keri the peat accumulation developed in a coastal environment due to paludification controlled both by the tectonic activity and the eustatic sea level changes, and the environment is characterized as a brackish mire, where additionally Scirpus maritimus και Juncus maritimus thrive. Taking in consideration the peat-forming features in the three studied peatlands the coal facies indices were modified in order to reflect more precisely the syngenetic processes in the acrotelma. Additionally a model is provided that describes both qualitatively and quantitatively the characteristics of the organogenic sediments deposited in the telmatic and the limnotelmatic fields. Furthermore, the coalification pathways of the studied sediments are interpreted, in order to obtain diagnostic parameters that can be applied to coal palaeoenvironmental studies.

Page generated in 0.0485 seconds