Vented sediments and tsunami deposits in the Puget Lowland,Washington – differentiating sedimentary processes     

MARIA ELIZABETH MARTIN  JOANNE BOURGEOIS 《Sedimentology》2012,59(2):419-444

The sandy deposits produced by tsunamis and liquefaction share many sedimentary features, and distinctions between the two are important in seismically active coastal zones. Both types of deposits are present in the wetlands bordering Puget Sound, where one or more earthquakes about 1100 years ago caused both tsunami flooding and sediment venting. This co‐occurrence allows an examination of the resulting deposits and a comparison with tsunami and liquefaction features of modern events. Vented sediments occur at four of five wetland field localities and tsunami deposits at two. In comparison with tsunami deposits, vented sediments in this study and from other studies tend to be thicker (although they can be thin). Vented sediments also have more variable thickness at both outcrop and map scale, are associated with injected dykes and contain clasts derived from underlying deposits. Further, vented sediments tend to contain a greater variety of sedimentary structures, and these structures vary laterally over metres. Tsunami deposits compared with vented sediments are commonly thinner, fine and thin landward more consistently, have more uniform thickness on outcrop and map scales, and have the potential of containing coarser clasts, up to boulders. For both tsunami deposits and vented sediments, the availability and grain size of source material condition the characteristics of the deposit. In the cases presented in this paper, both foraminifera and diatom assemblages within tsunami deposits and vented sediments consisted of brackish and marine species, and no distinction between processes could be made based on microfossils. In summary, this study indicates a need for more careful analysis and mapping of coastal sediments associated with earthquakes to avoid misidentification of processes and misevaluation of hazards.  相似文献   

A combined biogeochemical and palaeobotanical approach to study permafrost environments and past dynamics          下载免费PDF全文

TIINA RONKAINEN  MINNA VÄLIRANTA  ERIN MCCLYMONT  CHRISTINA BIASI  SAKARI SALONEN  SONIA FONTANA  EEVA‐STIINA TUITTILA 《第四纪科学杂志》2015,30(3):189-200

  相似文献   

An investigation of suspended sediment rating curves in western and northern Greece     

MARIA MIMIKOU 《水文科学杂志》2013,58(3):369-383

ABSTRACT

The suspended sediment rating curves for six stations on four rivers in western and northern Greece are investigated. For each station the suspended sediment load is a power function of the water discharge, which may be distinguished according to wet and dry seasons; the latter yields higher sediment loads for a given discharge than the former. This is due to the higher erosivity of dry season rainfall compared to wet season rainfall producing the same runoff. All rating curve exponents b lie in the range 2.5–3.5 for the wet and 2.0–3.0 for the dry season and are related to the constants a of the curves by empirical equations. The variation in a and b is explained in terms of the annual precipitation and area of the basin, the hypsometric fall, the main channel length, and the average bedslope of the river from the basin divide to the station, through empirical relationships, which also permit the prediction of rating curves for ungauged basins.  相似文献   

Climate and landscape during Heinrich Event 3 in south‐western Europe: the small‐vertebrate association from Galls Carboners cave (Mont‐ral,Tarragona, north‐eastern Iberia)          下载免费PDF全文

JUAN MANUEL LÓPEZ‐GARCÍA  HUGUES‐ALEXANDRE BLAIN  MARIA BENNÀSAR  JOSEP ANTONI ALCOVER  SANDRA BAÑULS‐CARDONA  MÓNICA FERNÁNDEZ‐GARCÍA  MARTA FONTANALS  PATRICIA MARTÍN  JUAN IGNACIO MORALES  LAURA MUÑOZ  MIREIA PEDRO  JOSEP MARÍA VERGÉS 《第四纪科学杂志》2014,29(2):130-140

  相似文献   

Nitrogen oxides concentrations and soil emission fluxes in the Po Valley     

M. KESSEL  J. GRIESER  W. WOBROCK  W. JAESCHKE  S. FUZZI  M. C. FACCHINI  G. ORSI 《Tellus. Series B, Chemical and physical meteorology》1992,44(5):522-532

  相似文献   

ECOPLANNING AND ENVIRONMENTAL REFORM IN A METROPOLITAN FRINGE: SANT SADURNÍ D'ANOIA,CATALONIA*     

MARIA ÀNGELS ALIÓ  LILIANA FRACASSO  SANDRA ESTRELLA 《Geographical review》2012,102(2):245-258

  相似文献   

The Po Valley Fog Experiment 1989   总被引：13，自引：0，他引：13  

S. FUZZI  M. C. FACCHINI  G. ORSI  J. A. LIND  W. WOBROCK  M. KESSEL  R. MASER  W. JAESCHKE  K. H. ENDERLE  B. G. ARENDS  A. BERNER  I. SOLLY  C. KRUISZ  G. REISCHL  S. PAHL  U. KAMINSKI  P. WINKLER  J. A. OGREN^  K. J. NOONE•  A. HALLBERG  H. FIERLINGER-OBERLINNINGER  H. PUXBAUM  A. MARZORATI  H.-C. HANSSON  A. WIEDENSOHLER  I. B. SVENNINGSSON  B. G. MARTINSSON  D. SCHELL  H. W. GEORGII 《Tellus. Series B, Chemical and physical meteorology》1992,44(5):448-468

  相似文献   

Meteorological characteristics of the Po Valley fog   总被引：1，自引：0，他引：1  

W. WOBROCK  D. SCHELL  R. MASER  M. KESSEL  W. JAESCHKE  S. FUZZI  M. C. FACCHINI  G. ORSI  A. MARZORATI  P. WINKLER  B. G. ARENDS  J. BENDIX 《Tellus. Series B, Chemical and physical meteorology》1992,44(5):469-488

  相似文献   

Geochronology and Petrogenesis of the Cretaceous Antampombato-Ambatovy Complex and Associated Dyke Swarm, Madagascar   总被引：1，自引：0，他引：1  

MELLUSO  LEONE; MORRA  VINCENZO; BROTZU  PIETRO; TOMMASINI  SIMONE; RENNA  MARIA ROSARIA; DUNCAN  ROBERT A.; FRANCIOSI  LUIGI; D'AMELIO  FOSCO 《Journal of Petrology》2005,46(10):1963-1996

The Antampombato–Ambatovy complex is the largest intrusionin the central–eastern part of the Cretaceous flood basaltprovince of Madagascar, with an exposed surface area of about80 km². It has an ⁴⁰Ar/³⁹Ar incremental heating age of 89·9± 0·4 Ma and a U–Pb age of 90 ± 2Ma. The outcropping plutonic rocks range from dunite and wehrlite,through clinopyroxenite and gabbro, to sodic syenite. A dykeswarm cross-cutting some of the above lithologies (and the nearbyPrecambrian basement rocks) is formed of picritic basalts, alkalito transitional basalts, benmoreites and rhyolites; some ofthe latter are peralkaline. A few basaltic dykes have cumulateolivine textures, with up to 26 wt % MgO and 1200 ppm Ni, whereasothers have characteristics more akin to those of primitiveliquids (9 wt % MgO; Mg-number 0·61; 500 ppm Cr; 200ppm Ni). These basalts have relatively high TiO₂ (2·2wt %) and total iron (14 wt % as Fe₂O₃), and moderate contentsof Nb (10–11 ppm) and Zr (c. 100 ppm). Initial (at 90Ma) Sr- and Nd-isotope ratios of the clinopyroxenites and basaltdykes are 0·7030–0·7037 and 0·51290–0·51283,respectively. Syenites and peralkaline rhyolites have Sr- andNd-isotope ratios of 0·7037–0·7039 and 0·51271–0·51274,respectively. The data suggest derivation of the parental magmasfrom a time-integrated depleted mantle source, combined withsmall amounts of crustal contamination in the petrogenesis ofthe more evolved magmas. The isotopic compositions of the mafic–ultramaficrocks are most similar to those of the mid-ocean ridge basalt(MORB)-like igneous rocks of eastern Madagascar, and suggestthe existence of an isotopically ‘depleted’ componentin the source of the entire Madagascar province, even thoughthe Antampombato basalts are chemically unlike the lavas anddykes with the same depleted isotopic signature found in westernMadagascar. If this depleted component is plume-related, thissuggests that the plume has a broadly MORB-source mantle composition.The existence of isotopically more enriched magma types in theMadagascan province has several possible petrogenetic explanations,one of which could be the interaction of plume-related meltswith the deep lithospheric mantle beneath the island. KEY WORDS: geochronology; flood basalts; Antampombato–Ambatovy intrusion; Cretaceous; Madagascar  相似文献   

Lithic-volcanic sandstones derived from oceanic crust in the Franciscan Complex of California: 'sedimental memories' of source rock geochemistry     

D. K. LARUE  MARIA M. SAMPAYO 《Sedimentology》1990,37(5):879-889

The Permanente terrane, part of the Franciscan accretionary complex of California, contains an unusual fault-bounded packet bearing lithic-volcanic sandstones and conglomerates. Based on petrographical, sedimentological, stratigraphical and geochemical studies, it is concluded that these rocks were deposited on the flank of an oceanic rise or plateau by sediment gravity flows probably below the carbonate compensation depth. The bulk geochemistry of the sandstones is similar to the chemistry of greenstones in the Permanente terrane, suggesting that the greenstones or rocks similar to them represent the source of the lithic-volcanic sandstones, and that the sandstones geochemically ‘remember’ the chemistry of their source rocks. This ‘sedimental memory’ is impressive: geochemical variation in the sandstones is co-linear with presumable magmatic variation trends in the greenstones. Sandstone geochemistry, plotted on Zr/Y vs. Y and V vs. Ti diagrams, shows that compositions occupy similar fields as greenstones in the Permanente terrane and oceanic crustal compositions in general. Because oceanic crustal sequences can become accreted to continental margins, oceanic crust should be considered a potential source of sediment, especially in continental margin settings. However, differentiating sandstones derived from oceanic arcs and from oceanic crust is extremely difficult unless discriminating geochemical criteria are used.  相似文献