The Ocoee Supergroup is a sequence of Neoproterozoic, immature, continental rift facies clastic sediments. Potential source rocks were tested by analyzing modes of detrital framework minerals, detrital mineral chemistry, whole rock geochemistry and detrital zircon U/Pb geochronology by LA-ICP-MS for Ocoee siltstone-sandstone dominated formations. Ocoee units are arkosic to subarkosic siltstones/sandstones, and ternary tectonic discrimination diagrams confirm a continental basement uplift source. Alkali feldspar predominates over plagioclase feldspar. Detrital feldspar compositions of Ocoee sediments as a group are similar to feldspar in local basement granitic rocks except for high-Ca plagioclase grains present locally in basement granitic rocks. The high alkali content of the detrital feldspars in the Ocoee Supergroup is consistent with derivation from an A-type granite source terrane. Normative Q-A-P values, calculated from wholerock chemistry, and trace element diagrams are also supportive of an A-type granite source for these rocks. The siltstones and sandstones of the Snowbird Group contain high abundances of heavy minerals (zircon, titanite, ilmenite, epidote and apatite), which are dispersed among other detrital grains and as concentrations of heavy minerals in discrete laminae. ZTR index and titanite mineral chemistry suggest a granitic source for these sediments. Detrital zircon geochronology in Ocoee sediments indicates a dominantly Grenville (1000 to 1300 Ma) source for these sediments. The youngest zircon age in the basal Ocoee Wading Branch Formation (639±8 Ma) is related to rift magmatism and provides a minimum depositional age for the Ocoee Supergroup.

Following the 2010 Deepwater Horizon (DWH) spill, sediment cores were analyzed from marshes at various levels of oiling to determine how deeply oil penetrated sediment in these marsh environments, and if at these sites it had quantifiably affected benthic ecosystems. Minimum mixing depths were determined from penetration of the lithogenic radionuclide 234Th, which ranged from 0.25 to 4.5 cm. Sediment accumulation rates were determined using 210Pb, with verification from 137Cs in selected cores. Lead-210 profiles revealed long-term (decadal) mixing. Bay Jimmy, Louisiana was significantly affected by the DWH oil spill, as indicated by total polycyclic aromatic hydrocarbon concentrations of up to 21,913 ppb. This is far above the level at which adverse biological effects occur (4,022 ppb). Benthic foraminifera responded to the heavy oiling by decreases to standing stock and depth of habitation relative to unoiled sites, as well as exhibiting deformities. These data clearly show that oil can be quickly mixed into salt marsh sediments, with demonstrable impacts on indigenous benthos. Further, radioisotope inventories indicated that most of the sampled sites are in a net erosional state. Should marshes containing trapped DWH oil be submerged by rising sea level, there is a great potential for the remobilization of oil.

The Fraser delta hosts a population of over 500,000 including the municipalities of Richmond and Delta and the Vancouver International Airport. The main arm of the Fraser River has been fixed in place by construction of a jetty focusing sediment deposition on the Sand Heads area. There is a history of submarine slide events at the delta crest which pose substantial risk to coastal infrastructure near the delta front. A submarine channel, characterized by prominent levee deposits, extends seaward from the Sand Heads area. In this study, sand beds in cores from levee overspill deposits are dated using excess 210Pb activity. They are interpreted as the downstream deposits of channelized turbidity currents generated by liquefied slide material. Sedimentation is characterized by sandy mud, interpreted to be deposited continuously by river plume suspension fall-out, and two distinct kinds of sand beds which represent two genetically different processes. The first type of sand bed (Facies 6) is thick, sharp based and clean, often showing classic Bouma turbidite elements including a massive sand base with laminated sands fining up to a mud top and is interpreted as the deposit from slides involving large volumes of material at the upper reaches of the tributary channels. The second type of sand bed (Facies 5) is characterized by muddy sand, has gradational contacts, and is interpreted as a low density deposit from either river generated turbidity currents or distal turbidites from smaller slide events. Facies 6 sand beds often occur as sets of 2 to 4 beds and individual bed sets have been dated to approximately the same ages of known large-scale slide events. Facies 5 sand beds occur more frequently and generally occur after periods with high flow. Sediment cores show three distinct phases of levee growth within the past 100 years approximately. A basal phase consists of very thick beds of medium sand that are interpreted to represent the early stage of channel-levee evolution when continuous overspill occurs during turbidity current events. The second stage is characterized by thick sets of frequent Facies 6 fine grained sand beds separated by less than one year of mud deposition. These sand beds are interpreted as representing a period of levee growth where channel relief is low and overspill events occur often. The third phase is characterized by thick mud intervals with less frequent fine sand beds. Phase 3 is interpreted to reflect a state when levee growth has increased channel relief to a height greater than that of the typical channelized turbidity current. In the third phase, sediment bypass is common and only larger density flows are capable of spilling onto the levees. Deposits interpreted to represent large slides have a return interval of 10 to 15 years during the past 40 years. Deposits of smaller events occur on average every four to five years. Event ages are compared to large spring floods from the Fraser River and seismic activity to determine any causal relationship. There is some relationship between ages of event beds and river flood years, but the largest sand beds do not correspond to unusually large flood years or seismic activity. It is concluded that there are likely a combination of factors which contribute to slope failure including over steepening and increased pore pressure. / Graduate / 0372 / cooper.stacey@nrcan.gc.ca

The stratigraphy and sedimentology of Mesozoic carbonate platform-margins cropping out in southern Italy are investigated. New strati graphic data are presented from northern and eastern slopes of the Apennine carbonate platform, based on locallycorrelated field sections. Thin-section petrography is used to demonstrate the spatial and temporal distribution of derived lithoclasts. Results indicate that southern Apennine platforms underwent repeated erosion during Cretaceous time and possible reasons for this are discussed. Petrographic studies also provided outline sediment parageneses for slopes and platforms, with special reference to the detailed geochemistry of secondary dolomite formation on the eastern margin of the Apulian platform, whose growth is indicated by proton microprobe microanalysis to have been influenced by redox changes. The sedimentary facies and sediment geometries of Upper Cretaceous to Lower Tertiary slope sediments mapped in the Frosolone area are discussed in a case-study. Cross-sections showing geometries of key beds are presented, and depositional controls are discussed. Outcrop data suggest an Early to Middle Jurassic age of basin formation of this sector of the Lagonegro-Molise basin. A further case study from the Mesozoic slope in the Gran Sasso shows sediment geometries at reflection seismic scale, and relates them to possible depositional control by relative sea-level fluctuations. Finally, data from southern Apennine platforms and basins are combined in a tentative sequence stratigraphic framework for the Middle Cretaceous. The results of onedimensional subsidence modelling are presented in order to separate and describe the signals of local tectonics and relative sea-level fluctuations affecting the southern passive-margin of Mesozoic Tethys.

Planorbis to Turneri Zone sedimentary rocks were studied at outcrops on Skye, Raasay, Applecross, Ardnamurchan, Morvern and Mull. A proposed lithostratigraphy includes two Groups, four Formations and seventeen Members. Increased faunal diversity in Mull and Skye reflects environmental stability during the Angulata and Semicostatum Zones; low diversity in the Bucklandi and Turneri Zones signifies lower stability. Species abundance in Mull and their decrease in Skye during Angulata-Bucklandi Zone times signifies a northward increase in environmental instability. Smectites are present in the Planorbis-Bucklandi Zone shales. The Semicostatum-Turneri Zones are composed of non expanding clays; the smectite formed by erosion of previously exposed alkaline igneous rocks under warm, alkaline, low rainfall conditions. Progressive transgression covered the source area and a change to more acidic conditions with higher rainfall also promoted the formation of "ironstones" and chlorites. The Angulata and Bucklandi Zones comprise bioclastic, oolitic, carbonate and siliciclastic sediments signifying shallow marginal marine semi-enclosed basins. Thin laterally impersistent beds of coarse,poorly sorted pebbles signify an unstable hinterland; during the Semicostatum and Turneri Zones fully marine conditions were established. Ferruginous beds are oolitic in Skye. They probably formed as "mud balls" and due to acid leaching of feldspars. Phosphatic nodules are calciumhydroxyapatite. The limestone/shale "rhythms" are explained by a combined primary and diagenetic origin. The limestones consist of low-Mg calcite Both ferroan and non ferroan calcite are present. Tectonic stresses and diagenesis deformed crystals and formed veins. Sr⁺² values show a decline as the carbonate fraction increases. Three different ranges are distinguished for three facies and ages. Sr concentration is bimodal and probably inherited from the original sediments. The northern and southern basins evolved separately, sedimentation was controlled by differential tilting, uplift and subsidence. Palaeoslopes were gentle, to the west-northwest and south-southwest. Local topography (e.g. Central Strath High) modified the slopes; no movement occurred along the main faults of the area. Sedimentation relates to the "taphrogenic rifting stage" proposed for the North Sea Mesozoic.

No description available.

The Palaeoproterozoic Dannemora inlier is situated in the north-eastern Bergslagen region. The inlier consists of primary and reworked volcanic deposits, stromatolitic limestone and skarn that have been subjected to upper greenschist facies metamorphism. Thicknesses of the different volcanic deposits indicate deposition within a caldera, where syn-volcanic alkali alteration was strong. The deposition was submarine and below wave base in the eastern part of the inlier, but above wave base in the central part where erosion channels together with cross-bedding occurs frequently. The Dannemora Formation is the volcanosedimentary succession of the inlier. Two borehole profiles, a northern and a southern, cover the whole Formation and show different alteration patterns. A strong depletion of Na2O and enrichment of K2O dominate in the southern profile, whereas this pattern is not as evident in the northern profile. The uppermost section of the totally eight constituting the Formation, is intercalated with ore-bearing dolomitic limestone and skarn, and has experienced at least two episodes of alteration. An anticline has been established lithogeochemically from immobile element ratios and the reoccurrence of an accretionary lapilli bed. Numerous altered sub-alkaline, calc-alkaline and basaltic dykes have been recorded in the Dannemora inlier. They are the result of mixing and fractionation of at least three magmatic sources and carry a mixed signature of subduction zone and within-plate volcanic tectonic setting. A seismic profile across the Dannemora inlier images a strong reflector package that dips c. 50° E to the east of the inlier. This package coincides with the polyphase, E-up reverse, brittle-ductile Österbybruk deformation zone (ÖDZ). Yet another steep reflector in the Dannemora ore-field extends to a depth of more than two kilometres. This reflector might represent either a deep-seated iron deposit or a fluid-bearing fault zone.

No description available.

The whole Mediterranean was a site of carbonate deposition during Miocene. Unlike other Miocene basins in the Mediteranean, the importance of Mut Basin lies in its tectonically undisturbed nature that provides excellent exposures to study sequence stratigraphic architecture and carbonate sedimentology. Opening of Mut Basin began during Oligocene / carbonate deposition started during Early Miocene. The pre-Miocene rocks are characterized by (from bottom to top), 1. ophiolites and Mesozoic limestones, 2. Eocene lacustrine limestones, 3. Burdigalian fluvial sandstones and conglomerates. The carbonate deposition began in Miocene, settling on the preexisting topography. Carbonates have been deposited in a ramp setting, where several sequences formed. The ramp was partly subaerially exposed during Early Miocene due to relative sea level fall / however, no significant lowstand deposits were developed. The subsequent sea level rise caused transgressive deposits to overlie this ramp sequence. The patch reefs on this ramp exhibit a keep-up type depositional setting. As the transgression continued, the basin topography controlled the type of depositional setting. Hence, a transition from ramp to reefal margin type setting occurred. In landward direction the topographically low areas became back reef lagoonal part of this reefal margin. A mature reefal environment formed during highstand times, which is characterized by a rich coral fauna / algal flora in the basinward side. Some of the patch reefs of the ramp transformed into pinnacle reefs. Diagenetic alterations are mostly related to duration and degree of sea level fall, and therefore related to sequence boundaries. The Miocene carbonates in the study area consist of six sequences which may be used for correlation with other Miocene carbonates of the Mediterranean region.

The Oligocene Brac Formation is the oldest part of the Bluff Group that is exposed on Cayman Brac. Sediments of the Brac Formation were deposited on a small, open bank in shallow marine waters. Today, the formation is composed of limestone, finely crystalline dolostone, and coarsely crystalline sucrosic dolostone. The Pollard Bay member, defined herein, comprises the sucrosic dolomite that is exposed only on the south coast of Cayman Brac. Changes in sea level and subsequent groundwater chemistry mediated a complex diagenetic evolution that is responsible for the lithological heterogeneity that now characterizes the formation. Field, petrographic, and geochemical analyses indicate that dolomitization was probably mediated by normal to slightly modified seawater. Multiphase dolomite crystals represent different stages of textural and geochemical maturity, and attest to time-transgressive dolomitization processes that evolved in various hydrologic regimes through time.