No description available.

Deep-marine levees are areally extensive features that border submarine channel systems. Compared to the adjacent channel, where episodes of erosion and bypass are commonplace, levees are mostly depositional features that experience little erosion, and therefore high preservation potential of individual beds, and presumably provide a nearly continuous depositional record of transport events down deep-marine slopes. Nevertheless, despite their size, volumetric prominence, and interpretive significance, deep-marine levees have received much less research attention compared to the adjacent channels. Accordingly, the spatial and temporal evolution of levee stratigraphy is much less well understood, in part because of the typically recessive nature of levee deposits exposed in outcrop in the ancient sedimentary record, and insufficient seismic resolution seismic in the modern. Also, although modern deep-marine levees have been shown to sequester a large proportion of the world’s total buried organic carbon, few studies have attempted to assess carbon deposition and preservation in ancient deep-marine levee deposits. In the Isaac Formation of the Windermere Supergroup (Neoproterozoic) of east-central British Columbia, Canada, well-exposed levee deposits display a systematic organization on several dimensional scales. Levee packages (decameter-scale) are interpreted to be due to cyclic changes in the granulometric makeup of sediment being supplied to the system, whereas bedsets (centimeter- to meter-scale) are interpreted to represent systematic and recurring pulses or surges during a single flow event. Furthermore, physical and geochemical characterization of levee strata at Castle Creek has shown that the unique depositional processes in levees can result in the concentration and enrichment of sedimentary marine organic matter (OM), which occurs mostly in banded, mud-rich sandstones deposited under oxic conditions. Organic carbon occurs primarily as nano-scale coatings on clay particles and uncommon sand-sized organomineralic aggregates and discrete sand-sized amorphous grains. The distribution of this OM in levee strata is controlled by a combination of primary productivity, sea level, and rates of continental runoff and detrital terrigenous influx, which collectively are principally controlled by climate. Understanding the stacking patterns, geochemistry, and organic content of ancient levee deposits is important for assessing sedimentation patterns, depositional processes, event frequency and magnitude, paleoenvironmental conditions, and the evolution of ancient ocean and climate systems.

The Lower Tertiary Balder Formation in the Beryl Embayment, North Sea, consists of sands interbedded with claystones and tuffs. The sands are massive and well sorted and can be up to 400 feet (122 m) thick, and are highly porous and permeable hydrocarbon reservoirs. The sands form large lobate and circular bodies of sands a few kilometres in diameter, with steep sides that are sometimes controlled by fault planes. The margins of the sands sometimes display thick sand wings extending up along fault planes. The sands display dewatering structures such as sills and dykes have a complex geometrical relationship with the surrounding sediments. Hydrothermal mineralisation is displayed as nodules, concretions and cementation of the sands within the Balder interval. The concept of seismic pumping, which postulates the rapid upward migration of deep fluids as the result of fault movement, was introduced to the literature some eighteen years ago, but fell into disrepute. However, it is argued here that re-shear of normal faults in the reverse direction can under certain critical physical conditions cause seismic pumping and can transport large quantities of deep seated fluids rapidly. This gives rise to the expulsion of fluid from depth into conventionally deposited massive sands of submarine fan environments, belonging to the Balder Formation, and thus in the fluidisation of the sediments. These sands have been intruded into the surrounding rocks and along fault planes forming a complex distribution of in situ and remobilised sands, thereby giving rise to the observed sand geometries and structures.

Η λιμνοθάλασσα Πρόκοπος βρίσκεται στα βορειοδυτικά της Πελοποννήσου και αποτελεί μια πολύ σημαντική περιοχή με μοναδική πολιτιστική και οικολογική κληρονομιά όχι μόνο για τη συγκεκριμένη περιοχή, αλλά και για την Ελλάδα γενικότερα. Η λιμνοθάλασσα και ο υδροβιότοπο γύρω από αυτή έχει αναγνωριστεί από διεθνείς συνθήκες (RAMSAR), ευρωπαϊκά προγράμματα για την προστασία της φύσης (NATURA 2000) και της βιοποικιλότητας. Η λιμνοθάλασσα είναι ένας ενιαίος υγροβιότοπος, όμως το μεγαλύτερο μέρος της έκτασης της έχει μικρό βάθος (περίπου 30 cm) και καλύπτεται από πυκνούς καλαμιώνες, ιδιαίτερα κατά την θερινή περίοδο Στην εργασία αυτή παρουσιάζονται τα αποτελέσματα της μελέτης των ιζημάτολογικών χαρακτηριστικών της λιμνοθάλασσας μέσα από την ιζηματολογική και γεωχημική ανάλυση δειγμάτων ιζημάτων τα οποία συλλέχθηκαν από έξι θέσεις με πυρήνες βαρύτητας. Συνολικά 31 δείγματα αναλύθηκαν ως προς το κοκκομετρικό τους μέγεθος, τον ολικό οργανικό άνθρακα (TOC) και τα κύρια στοιχεία και ιχνοστοιχεία. Η κοκκομετρική ανάλυση πραγματοποιήθηκε για το αδρομερές υλικό με κόσκινα ενώ για το λεπτομερές κλάσμα χρησιμοποιώντας τον αναλυτή Malvern Mastersizer 2000 Hydro. Ο προσδιορισμός του ολικού οργανικού άνθρακα έγινε με την τροποποιημένη μέθοδο της τιτλοδότησης Walkley-Black ενώ ο προσδιορισμός των κυρίως στοιχείων και ιχνοστοιχείων, Al, Ca, Fe, K, Mg, Mn, Na, P, Cd, Cr, Cu, Ni, Pb, V και Ζn με φασματοσκοπία πλάσματος ατομικής εκπομπής Thermo Scientific iCAP 6000 ICP-OES. Για την αξιολόγηση των φυσικοχημικών παραμέτρων των υδάτων χρησιμοποιήθηκαν τα στοιχεία των σταθμών τηλεμετρίας (πολυαισθητήρας YSI6600), που έχουν εγκατασταθεί στην λιμνοθάλασσα του Πρόκοπου και τα οποία καλύπτουν περίοδο παρακολούθησης ενός έτους. Οι φυσικοχημικές παράμετροι οι οποίοι παρουσιάζονται και αξιολογούνται είναι το pH, θερμοκρασία (0C), διαλυμένο οξυγόνο (DO-mg/L) και αλατότητα (S ‰). Από την μελέτη των ανωτέρω παραμέτρων πρόεκυψε ότι τα ιζήματα της λιμνοθάλασσας αποτελούνται από πολύ πτωχά έως πτωχά ταξιθετημένη, πολύ λεπτόκοκκη άμμο έως αδρομερή πηλό και από υψηλές συγκεντρώσεις ολικού οργανικού άνθρακα >3%. Από τις εποχικές διακυμάνσεις των φυσικοχημικών παραμέτρων καταγράφηκαν περίοδοι με πολύ χαμηλές έως μηδενικές συγκεντρώσεις διαλυμένου οξυγόνου, τη θερινή περίοδο δείχνοντας υποξικές συνθήκες και ανοξικές κρίσης. Με βάση την θέση των σταθμών διακρίνουμε ότι η αλατότητα παρουσιάζει σημαντική διακύμανση, η οποία δημιουργείται από τη διαδικασία εισόδου-εξόδου του θαλάσσιου και γλυκού νερού στη λιμνοθάλασσα. Το pH παρουσιάζει μια φυσική ημερήσια διακύμανση του συντελεστή 0,5 το οποίο είναι ανάλογο προς τη θερμοκρασία και τη συγκέντρωση του οξυγόνου διαλύματος. Για την αξιολόγηση της περιβαλλοντικής κατάστασης της λιμνοθάλασσας από τις γεωχημικές αναλύσεις, χρησιμοποιήσαμε γεω-περιβαλλοντικούς δείκτες ώστε να προσδιορίσουμε τον εμπλουτισμό ή τον απεμπλουτισμό των ιζημάτων του πυθμένα σε βαρέα μέταλλα στην λιμνοθάλασσα. Για τον σκοπό αυτό χρησιμοποιήσαμε τον δείκτη γεω-συσσώρευσης (index of geo-accumulation), τον δείκτη μόλυνσης (contamination factor), τον δείκτη εμπλουτισμού (enrichment factor) που υπολογίσθηκαν σε σχέση με τιμές βάσεις των υπό εξέταση μετάλλων στα ιζήματα από την διεθνή βιβλιογραφία. Από την πιο πάνω ανάλυση φαίνεται ότι με βάση τους γεω-περιβαλλοντικούς δείκτες που υπολογίσθηκαν, τα υπό εξέταση ιζήματα στην περιοχή μελέτης δεν εμφανίζουν χαρακτηριστικά φαινόμενα ρύπανσης. / The Prokopos Lagoon is located in the north-western part of Peloponessus and is one of the most important ecological are of Greece. It is protected by the environmental international convention Ramsar and is listed in the Nature 2000 European network as special protected area. The lagoon is very shallow with mean depth of 30 cm while parts of it are consist of reed-bed forests and marshes. In this study we present the sedimentological characteristics of the bottom lagoon sediments using sedimentological and geochemical techniques. The analyzed samples were collected from six locations with gravity cores. A total number of 31 samples were analyzed for their grain size, total organic carbon (TOC) and major and trace elements. The particle size analysis was performed on the coarse material by sieving while the fine fraction was analyzed using the Malvern Mastersizer 2000 Hydro and moment measures were calculated using GRADISTAT software. The determination of the total organic carbon was made according to the modified titration method of Walkley-Black while the identification of the major and trace elements, Al, Ca, Fe, K, Mg, Mn, Na, P, Cd, Cr, Cu, Ni, Pb , V and Zn with plasma atomic emission spectroscopy Thermo Scientific iCAP 6000 ICP-OES. In order to evaluate the water physicochemical parameters, data from two telemetric stations (with multi parameter sensors YSI6600) were analyzed covering a period of one year monitoring. The physicochemical parameters that are presented and assessed are the pH, temperature (0C), dissolved oxygen (DO - mg/L) and salinity (S ‰). The study of the above parameters revealed that the bottom lagoon sediments consist of poorly to very poorly sorted, very fine sand to coarse silt and are characterized by high content of total organic carbon (>3%). The seasonal variations of physicochemical parameters indicate periods (summer) with very low to zero dissolved oxygen concentrations, showing hypoxic conditions and anoxic crisis. Salinity variations are the result of the process exchange of marine and freshwater into the lagoon via the narrow inlet. The pH variations follow proportionally the temperature and the oxygen concentration trend of the lagoon water. For the assessment of the environmental status of the lagoon and based on the geochemical analyses, we used geo-environmental indices to determine the enrichment or depletion of the bottom sediments heavy metals concentrations. For this purpose we used the geo-accumulation index, the index of contamination, the enrichment factor, compared to the bibliography values of baseline concentration. From the above analysis and based on thee geo-environmental indices we conclude that the bottom lagoon sediments are not polluted.

Soils disturbed by strip mining practices may have increased colloid loads moving to groundwater resources, also enhancing the transport of contaminants into our water resources. We hypothesize that contaminant transport within soils following mining is enhanced by colloid mobility. Two sites were chosen for this study, a 30-year old reclaimed strip mine in southwest Virginia and a recently mined area from eastern Kentucky. Intact reclaimed soil monoliths were retrieved from sandstone derived soils in southwestern Virginia. Reclaimed monoliths from eastern Kentucky were recreated in the lab. Intact undisturbed (native) soil monoliths representing the soils before mining were also sampled for comparison. Biosolids were added to an additional reclaimed monolith at a rate of 20 T/acre. Leaching experiments with deionized water at a rate of 1.0 cm/h involved 6 cycles of 8 hours each, giving each monolith at least 2 pore volumes of leaching. Native soil monoliths from Virginia had an average colloid elution of 857 mg over all cycles, reclaimed soil monoliths had an elution of 1460 mg, reclaimed soil monoliths with spoil material had a colloid elution of 76 mg, and when biosolids were amended to reclaimed soil and spoil monoliths, 870 mg colloids were eluted. Native soil monoliths from eastern Kentucky eluted 7269 mg colloids, reclaimed monoliths from eastern Kentucky eluted 10,935 mg colloids, and reclaimed soils with spoil material eluted no colloids. Lime stabilized biosolids enhanced colloid elution due to high pH dispersing material within the monoliths, while spoil materials with high density and salt content reduced colloid elution. Metal loads in solution were mobilized by DOC, particularly in low sulfate environments, while colloid bound metals increased the total metal loads in the order of Pb > Ni > Cu > Cd > Zn > Cr.

The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.

No description available.

The Late Mesozoic Bisbee basin of southeastern Arizona was an intracratonic back-arc rift basin. Extension was coupled with seafloor spreading in the Gulf of Mexico and back-arc extension behind a magmatic arc along the convergent Pacific continental margin. Tectonostratigraphic evolution of the basin occurred in three phases. Initial mid-Jurassic rifting of the basin, marked by eruption of the Canelo Hills Volcanics, may have been complicated by sinistral strike-slip motion along the Mojave-Sonora megashear. During continued rifting, from latest Jurassic to Early Cretaceous time, the Glance Conglomerate was deposited by alluvial fans and braided streams in grabens, half-grabens, and caldera-related depressions; locally interbedded volcanic rocks represent waning rift-related back-arc magmatism. The upper Bisbee Group was deposited during Early to earliest Late Cretaceous passive thermotectonic subsidence. The Bisbee Group and correlative strata occur in most mountain ranges in southeastern Arizona, and are subdivided into southeastern, northwestern, northern, and western facies. Southeastern facies were deposited in alluvial fan, meandering fluvial, estuarine, marginal marine and subtidal shelf environments as a transgressive-regressive sequence including a marine interval that was continuous with Gulf Coast assemblages during Aptian-Albian marine transgression. Northern facies were deposited in alluvial fan and braided stream environments along the northern rift shoulder of the basin. Southeastern and northern facies sandstones are dominantly quartzose, and were derived mainly from cratonic sources to the north. Subordinate volcaniclastic sandstones in the southeastern facies become more abundant to the west, proximal to eroding Jurassic and Cretaceous volcanic arcs. Basal northwestern facies arkosic strata deposited in alluvial fan, braided stream and lacustrine environments were derived from local basement uplifts, and were ponded in a northwestern depocenter by rift-related topography. A thin estuarine interval within overlying dominantly fluvial facies indicates integration of regional drainage networks by the time of maximum transgression. Transition upward to quartzose sandstone compositions reflects wearing down of local basement uplifts and increasing abundance of craton-derived sediment in the northwestern part of the basin. Western facies alluvial fan, braided stream and lacustrine intramontane deposits are composed of locally-derived arkose and lithic arkose.

Research carried out in the Ediacaran of eastern Newfoundland focused on two projects: sedimentology of the Conception and St. John’s groups exposed on the Bonavista Peninsula; and taxonomic descriptions of the small, stemmed frondose fossils at Mistaken Point on the Avalon Peninsula. Sedimentological study of the upper Conception and lower St. John's groups at Catalina Dome on Bonavista Peninsula extends our understanding of the Conception Basin, in which the oldest known complex, deep marine organisms lived, by a factor of two. Mudstone-rich turbidites dominate the succession, and a lack of wave-generated structures or other shallow-water indicators support the interpretation that the depositional environment was deep-marine. The basal part of the succession contains seismoturbidites that show no evidence of horizontal translation, implying that deposition occurred on a flat basin plain. Strata higher in the succession exhibit horizontally slumped beds, implying a transition into slope deposition. Turbidite ripple marks show a change in paleocurrent direction from eastward to southward in the Trepassey Formation, consistent with a change from convergent to strike-slip tectonics that occurred diachronously across the basin. Volcanic ash beds are more common in the Catalina Dome succession than on the Avalon Peninsula, reflecting deposition closer to the volcanic source. These volcanic beds are associated with diverse fossil assemblages rich in rangeomorphs that locally persist into the Fermeuse Formation, in contrast with the Avalon Peninsula where the Fermeuse Formation contains only simple discoid fossils. This taphonomic window lends support to the hypothesis that the form genus Aspidella represents the holdfasts of Ediacaran fronds. Stemmed small frond fossils from Mistaken Point, Avalon Peninsula, have often been informally referred to as “featherdusters”, but due to their small size and consequent poor preservation, they have not until now been formally described. The small, stemmed fronds are more diverse than previously realized, and include representatives of taxa described from elsewhere in Newfoundland, juveniles of other Mistaken Point fronds, and two new monospecific genera. This biodiversity suggests that the basal elevated tier that the small fronds occupied was competitive, with convergent evolution of frondose taxa showing distinct architecture and constructions, but broadly similar size and shape. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2013-10-30 12:12:23.297

A series of analogue flume experiments are used to investigate initiation, flow and deposition of static piles of polymict materials, the sorting during transport, and the three dimensional geometry of the resulting deposits. Sequential charges are used to investigate the effects and extent of reworking. The particle heterogeneity is designed to simulate typical PDC make-up, with analogues for juvenile pumice and lithic clasts, as well as the fine-grained pumiceous material which makes up the bulk of the flow. Analogue flume experiments are used to investigate the generation of complex facies variations typical of pyroclastic density current (PDC) deposits. Polymict charges are developed to behave as analogues for the particle size and density contrasts present in PDC (i.e. lithic and juvenile pumice clasts), and investigate the effect of granular sorting during flow on the geometry of deposit architectures. Multiple charges are used to simulate pulses or sequences of separate PDC in order to assess the extent and effects of reworking. 3D visualisation of the resulting deposits reveals stratigraphies analogous to those seen in PDC, including pumice ‘rafting' or over-passing and inverse grading of pumice, and normal grading of lithics by simple gravitational granular sorting. Reworking between differentially-coloured layers makes several complex shear-derived Kelvin-Helmholtz instability features apparent, from fully developed rotational eddies, to less developed recumbent flame structures. The implications for the formation of these in PDC are assessed, including the potential influences on temperature proxy data, radiogenic dating by included phenocrysts (40Ar/39Ar) or charcoals (14C), calculation of eruptive volumes, sedimentation rates and flow velocity.