119 research outputs found

    GEO-ELECTRICAL MAPPING OF BEACHROCK IN VATERA BEACH, LESVOS

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    Tο Beachrock (Br ή παραλιακοί ψαμμίτες) εμφανίζεται σε παράκτιες ζώνες και έχει σύνθετο ρόλο όσον αφορά στη μορφοδυναμική εξέλιξη τους. Αν και το Br έχει μελετηθεί ευρέως, ωστόσο, δύο βασικά θέματα χρήζουν επιπρόσθετης έρευνας. Το πρώτο αφορά στη σημασία της αλληλεπίδρασης του δυναμικά μεταβαλλόμενου παράκτιου περιβάλλοντος με την χρονικά μεταβαλλόμενη επιφανειακή και υπόγεια υδρογεωλογική ισορροπία. Το δεύτερο θέμα έχει να κάνει με τη χωρική κατανομή και την εξέλιξη του Br σε σχέση με συγκεκριμένο περιβάλλον που το “φιλοξενεί”. H παρούσα εργασία αναδεικνύει τη μέθοδο της ειδικής ηλεκτρικής αντίστασης του υπεδάφους, ως ένα σύγχρονο εργαλείο που μπορεί να συμβάλει στη μελέτη των παραπάνω προβληματισμών. Η έρευνα περιέλαβε μετρήσεις με τη γεωηλεκτρική μέθοδο συνεχούς ρεύματος κατά μήκος δύο τομών στην παραλία των Βατερών της Λέσβου, όπου παρατηρούνται σημαντικές επιφανειακές εμφανίσεις Br. Πραγματοποιήθηκαν δώδεκα γεωηλεκτρικές βυθοσκοπήσεις, με ανάπτυγμα ηλεκτροδίων Axial Pole-Dipole. Οι μετρήσεις της ειδικής ηλεκτρικής αντίστασης επέτρεψαν μία έμμεση εκτίμηση του TDS, το οποίο απεικονίζει την διεπιφάνεια γλυκού-θαλασσινού νερού. Κατά την ερμηνεία του γεωηλεκτρικού μοντέλου αναδείχθηκαν δύο σχηματισμοί που αντιστοιχούν σε Br. Ο πρώτος αποτελεί επέκταση του Br προς την ξηρά και ο δεύτερος πιστεύεται ότι είναι Br σε πρώιμο στάδιο ωρίμανσης.Beachrock (Br) is encountered on the coastal zones, playing an important but also complex role in their morphodynamic evolution. Although Br has been widely studied, two important issues require further investigation. The first concerns the importance of the interaction of the dynamically changing coastal environment with the temporal changing surficial and underground hydrogeological balance. The second has to do with the spatial distribution and the evolution of Br with respect to the specific “host” coastal zone geo environment. This paper designates the electrical resistivity method as a tool that contribute in arguing in the abovementioned issues. The research comprised subsurface measurements with the DC resistivity method along two profiles located on Vatera beach (Lesvos Island), where there is a significant Br outcrops. Twelve geoelectric soundings were carried out using the Axial Pole-Dipole electrode array. The electrical resistively measurements permitted an indirect estimation of TDS, which depicts the coastal interface of fresh water - sea water. The interpreted geoelectric model shows two thin formations attributed to Br. The first is the inland extension of the Br outcrop and the second it is believed to be a primary stage of Br build up

    Climate controlled aggradation and cyclicity ofcontinental siliciclastic sediments in Wolfcampian cyclothems, Permian, Hugoton embayment U.S.A. - Data Repository

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    The purpose of the Data Repository (DR) is twofold: 1) provide additional tables and figures and associated text that directly supplement the material provided in the paper, and 2) provide background material not available through publications or other channels. Two digital files, one for each purpose, are provided in the DR. The file covering background material is the appendix to Dubois Ph.D. dissertation, Ramp-scale geomodel for reservoir and stratigraphic analysis of the Hugoton field (Wolfcampian, midcontinent U.S.A.), completed in 2007. Two of the three dissertation' chapters have been published (Dubois et al., 2006a, 2006b) and the third is the current paper under review.Climate controlled aggradation and cyclicity of continental siliciclastic sediments in Wolfcampian cyclothems, Permian, Hugoton embayment U.S.A. is an outcome of a larger study focused on the Wolfcampian gas resource in the Hugoton field. That comprehensive multi-discipline study represents nearly a decade of effort by Kansas Geological Survey and industry scientists. It included the building of a vast 3D geocellular model of the entire Wolfcampian volume over the study area. The finely-layered 108-million-cell model provided a 3D view of the distribution of marine and continental siliciclastic lithofacies. Readers interested in details on Hugoton geomodel construction and a more thorough discussion of the marine portion of the cyclothems in this study were directed to published work (Dubois et al. 2006b, 2007)

    Ichnotaxonomy of the Cambrian Spence Shale Member of the Langston Formation, Wellsville Mountains, Northern Utah, USA

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    The Spence Shale of northern Utah is the oldest North American middle Cambrian (~506–505 Ma) Burgess Shale-type (BST) deposit and, unlike previously thought for BST deposits, has a very diverse ichnofauna. Twenty-four ichnogenera and 35 ichnospecies were identified: Archaeonassa (A. fossulata and A. jamisoni isp. nov.), Arenicolites carbonaria, Aulichnites, Bergaueria (B. hemispherica and B.aff. perata), Conichnus conicus, Cruziana (C. barbata and C. problematica), Dimorphichnus, Diplichnites (D. cf. binatus, D. gouldi, andD.cf. govenderi), Gordia marnia, Gyrophyllites kwassizensis, Halopoa aff. imbricata, Lockeia siliquaria, Monomorphichnus (M. bilinearis,M.lineatus, and M. cf. multilineatus), Nereites cf. macleayi, Phycodes curvipalmatum, Phycosiphon incertum, Planolites (P. annularius, P.beverleyensis, and P. montanus), Protovirgularia (P. dichotoma and P. cf. pennatus), Rusophycus (R. carbonarius, R. cf. pudicus, and R. cf.cerecedensis), Sagittichnus lincki, Scolicia, Taenidium cf. satanassi, Teichichnus cf. nodosus, and Treptichnus (T. bifurcus, T. pedum, and T.vagans). The ichnofossils comprise three ichnocoenoses—Rusophycus-Cruziana, Sagittichnus, and Arenicolites-Conichnus—representingdwelling, deposit- and filter-feeding, grazing, locomotion, and predation behaviors of organisms (e.g., annelid worms and trilobites).Two ichnofossil associations are suggestive of predation: (1) Planolites terminating at a Rusophycus; and (2) Archaeonassa crosscuttinga Taenidium. The Spence Shale ichnofauna represent a distal Cruziana Ichnofacies and depauperate, distal Skolithos Ichnofacies. Anew ichnospecies of Archaeonassa is proposed, A. jamisoni isp. nov., and Ptychoplasma (Protovirgularia) vagans is herein transferred toTreptichnus. This study is the first ichnotaxonomic study of the Spence Shale and North American BST deposits and shows highlydiverse ichnofaunas can be present in BST deposits

    Fluvial Trace Fossils in the Middle Siwalik (Sarmatian-Pontian) of Darjeeling Himalayas, India

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    Trace fossils that record animal and plant activity are described for the first time from the Middle Siwalik, Neogene deposits of Darjeeling Himalaya. Sedimentary facies association attests to a channel– interchannel floodplain fluviatile setting. The intimate association of the burrows with phytoliths, rhizoliths, leaf compressions and coal lenses suggest that the tracemakers dominated a floodplain habitat. Point bar deposits host a low diversity Planolites-Naktodemasis-Macanopsis-Cylindricum equilibrium ichnocoenosis in the heterolithic fine sandstone-siltstone-shale facies that alternates with dense, monospecific colonization of Planolites as opportunistic pioneers relocating under stressed condition. Interlayered floodplain deposits in the fluvial successions preserve enigmatic large diameter, vertical tubes within thin to thick-bedded, dark silty shale facies. These tubes bear mixed characters assignable to both crayfish burrows and large-diameter rhizoliths. Further work on these tubes is necessary to make more accurate interpretations of those structures. Shallow to moderate burrow depths; intermittent, short-lived colonization events and preservation of rhizoliths and rhizohalos under fluctuating moisture content indicate short-term fluctuations of a relatively high water table (close to the paleosurface) in an imperfectly drained proximal floodplain setting. Ichnotaxa distribution and their inferred ethology provide significant faunal data that may put constraints on the reconstruction of Middle Siwalik depositional environment

    Effects of experience and body size on refuge choice in the crayfish Orconectes immunis

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    We investigated whether refuge size or experience with a refuge affected the refuge use of male Orconectes immunis crayfish. Individuals were given choices among seven refuges for 10 consecutive days. Refuges were formed from equal length but different diameter PVC pipe and placed in an array in a random sequence. Three treatments were used. In the Novel Refuge treatment, individuals were placed in a new test arena with a new arrangement of cleaned refuges every day. In the Nonremoval treatment, individuals were left in the same arena with the same set of refuges each day. In the Removal treatment, individuals were removed from the refuges each day but placed back in the same arena with the same set of refuges after the refuges had been cleaned. We found that refuge occupation was correlated with an individual\u27s size; smaller crayfish tended to use smaller refuges than larger crayfish, even though all crayfish could fit in all of the different sized refuges. When first tested, individuals initially chose larger refuges than they would subsequently settle in, suggesting that under duress, they were not as particular about refuge characteristics. Individuals in the Nonremoval and Removal treatments were significantly more consistent in their refuge use than those in the Novel Refuge treatment, suggesting that experience with a particular refuge increased use of that refuge. Individuals from the Novel Refuge treatment that were housed for a month with a single refuge did not increase their use of that sized refuge more than those that were housed without a refuge, indicating that simply occupying a refuge of a given size did not affect refuge preference

    New Mediterranean Biodiversity Records (July 2016)

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    This contribution forms part of a series of collective articles published regularly in Mediterranean Marine Science that report on new biodiversity records from the Mediterranean basin. The current article presents 51 geographically distinct records for 21 taxa belonging to 6 Phyla, extending from the western Mediterranean to the Levantine. The new records, per country, are as follows: Spain: the cryptogenic calcareous sponge Paraleucilla magna is reported from a new location in the Alicante region. Algeria: the rare Atlanto-Mediterranean bivalve Cardium indicum is reported from Annaba. Tunisia: new distribution records for the Indo-Pacific lionfish Pterois miles from Zembra Island and Cape Bon. Italy: the ark clam Anadara transversa is reported from mussel cultures in the Gulf of Naples, while the amphipod Caprella scaura and the isopods Paracerceis sculpta and Paranthura japonica are reported as associated to the –also allochthonous–bryozoan Amathia verticillata in the Adriatic Sea; in the latter region, the cosmopolitan Atlantic tripletail Lobotes surinamensisis also reported, a rare finding for the Mediterranean. Slovenia: a new record of the non-indigenous nudibranch Polycera hedgpethi in the Adriatic. Greece: several new reports of the introduced scleractinian Oculina patagonica, the fangtooth moray Enchelycore anatina, the blunthead puffer Sphoeroides pachygaster (all Atlantic), and the lionfish Pterois miles (Indo-Pacific) suggest their ongoing establishment in the Aegean Sea; the deepest bathymetric record of the invasive alga Caulerpa cylindracea in the Mediterranean Sea is also registered in the Kyklades, at depths exceeding 70 m. Turkey: new distribution records for two non indigenous crustaceans, the blue crab Callinectes sapidus (Atlantic origin) and the moon crab Matuta victor (Indo-Pacific origin) from the Bay of Izmir and Antalya, respectively; in the latter region, the Red Sea goatfish Parupeneus forsskali, is also reported. Lebanon: an array of records of 5 alien and one native Mediterranean species is reported by citizen-scientists; the Pacific jellyfish Phyllorhiza punctata and the Indo-Pacific teleosteans Tylerius spinosissimus, Ostracion cubicus, and Lutjanus argentimaculatus are reported from the Lebanese coast, the latter notably being the second record for the species in the Mediterranean Sea since 1977; the native sand snake-eel Ophisurus serpens, rare in the eastern Mediterranean, is reported for the first time from Lebanon, this being its easternmost distribution range; finally, a substantial number of sightings of the lionfish Pterois miles further confirm the current establishment of this lessepsian species in the Levantine

    New Specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia

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    Two new specimens of the oviraptorid theropod Nemegtomaia barsboldi from the Nemegt Basin of southern Mongolia are described. Specimen MPC-D 107/15 was collected from the upper beds of the Baruungoyot Formation (Campanian-Maastrichtian), and is a nest of eggs with the skeleton of the assumed parent of Nemegtomaia on top in brooding position. Much of the skeleton was damaged by colonies of dermestid coleopterans prior to its complete burial. However, diagnostic characters are recovered from the parts preserved, including the skull, partial forelimbs (including the left hand), legs, and distal portions of both feet. Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs. The second new specimen, MPC-D 107/16, was collected a few kilometers to the east in basal deposits of the Nemegt Formation, and includes both hands and femora of a smaller Nemegtomaia individual. The two formations and their diverse fossil assemblages have been considered to represent sequential time periods and different environments, but data presented here indicate partial overlap across the Baruungoyot-Nemegt transition. All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments. However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies
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