31 research outputs found

    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
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