Grey Beds Research Articles

Field Description and Lithostratigraphic Study of Sargelu Formation in Rania and Sargelu sections, Northern Iraq

The Sargule Formation was deposited during the Middle Jurassic, representing one of the most important source rocks in Iraq and surrounding areas.
 Jurassic successions are commonly exposed as an isolated patch at some eroded anticline’s cores and limbs in the High Folded Zone, Imbricate Zone, and Thrust Zones of northern Iraq. The Sargelu section is located in Sargelu village at Surdash anticline, while the Rania section is located in Rania city near Hanjira village at Shaweri anticline. Fieldwork in Rania and Sargelu Sections allow to divide Sargelu Formation lithostratigraphically into many subdivisions as follow:
 The Sargelu Formation in the Rania section is about 40 m and can be divided into two lithologic units; the upper thin to medium bituminous limestone beds alternated with thin chert beds, and the lower thin to medium bituminous limestone beds alternated with fissile gray shale beds.
 the The Sargelu section comprises 180m and is divided into three units; the upper unit consists of dark gray limestone beds and thin brownish-black of laminated shale. The middle unit includes dark chert alternated with dark gray bituminous limestone and brownish-black laminated shale. At the same time, the lower unit consists of dark gray bituminous limestone beds alternated with medium brownish-black laminated shale beds.

Through my eyes.

When I first saw you, I thought of the colour grey. Grey walls, grey bed, grey skin. I was afraid. I felt small and powerless before you — you, whose eyes looked as though they had seen beyond the edge of the universe. I was trembling, my skin clammy. I felt naive, like a child to whom Death was a

Интерпретация строения пойменного аллювия: на примере разрезов геоархеологического объекта Остров Лиственичный (Северо-Восточное Приангарье)

This paper examines characteristic features of floodplain accumulation at geoarchaeological site Ostrov Listvenichnyi, located on the Angara River at the same-name island (Northeast Angara region, Baikal Siberia). The problems of interpretation of topographic and lithological data, island architecture, glacial and postglacial natural climatic insights (MIS 2–MIS 1) are also touched upon. The accumulation of sediments at a series of 16 archaeological test pits recorded along the northwestern side of the island was analyzed by using pedolithological method. Island formation history included the upbuilding of the origin island based on river point bar, further transformation into “east” pre-island and final articulation of ancient “east” pre-island and younger “west” pre-island. The primary differences in alluvium composition of ancient pre-island (red beds, clay loam) and Holocene sedimentations (grey beds, sandy loam), both situated at the same level, were identified and explained. Detailed analysis of floodplain accumulation revealed eight distinct lithological layers varying by the structure and the composition. The following conclusions were reached based on the data available: lithological strata 1–5 have formed in Sartan, lithological strata 6–8 have formed in Holocene. Every layer contains the information on the changing climate and environment: signals of floods (high flood stages in 7 layer, “dry” stages in 3 layer), different phases of humification (humusless strata 1–4, first fragile humus horizons in layer 5, more pronounced humus horizons a, b, c, d in layer 4, and humus background in strata 7–8), epigenetic markers of сryogenic processes in strata 3–5. Analysis suggest also three chronologically differentiated floodplain benches: lower 1,5–2 meter bench (top of layer 3) associated with Middle Sartan; middle 2,5–3 meter bench (top of layer 5) associated with Final Sartan; top 4,5–5 meter bench (top of layer 8) associated with modern time.

Reconstruction of nearshore chemical conditions in the Mesoproterozoic: evidence from red and grey beds of the Yangzhuang formation, North China Craton

ABSTRACT Mesoproterozoic red beds near ancient coasts have not aroused extensive interest. A new geochemical study of the alternating red and grey dolostones from the Yangzhuang Formation provides a better understanding of the redox conditions of nearshore sedimentary environments. In this contribution, whole-rock samples are characterized by positive correlations of rare earth elements (REE) vs. Th and FeT vs. Th and flat-type REE distribution patterns, indicating massive terrigenous input, which is considered to be inherited from felsic rocks. Relatively high (Femag+Feox)/FeT and Fe3+/Fe2+ ratios in red beds indicate more oxidized conditions in supratidal environments compared with the lower oxygen contents in intertidal environments. Under these two distinct chemical sedimentary conditions, acetic acid-leached red and grey samples both have HREE-depleted distributions, suggesting significant freshwater invasion. Moreover, limited terrigenous redox-sensitive elements (RSEs) can reach the coast where the red beds are deposited, whereas relatively high RSE enrichment factors originating from shallow oceans are recorded in grey beds. In the Mesoproterozoic, limited oxidative weathering, shallow seawater desalination, and low organic production occurred near the coast. Meanwhile, a prolonged period of low Mo and U availability preserved in carbonate minerals confirmed that marine oxygen levels failed to satisfy the deposition of offshore red beds. During the regression, potentially exposed sediments connected to atmospheric oxygen guaranteed the oxidation of iron and the formation of red beds, and these events were coupled with negative δ13Ccarb shifts in the Yanliao rift zone.

LOWER TRIASSIC (INDUAN TO OLENEKIAN) CONODONTS, FORAMINIFERA AND BIVALVES FROM THE AL MAMALIH AREA, DEAD SEA, JORDAN: CONSTRAINTS ON THE P-T BOUNDARY

Upper Permian to Lower Triassic successions exposed in the Al Mamalih area, east of the Dead Sea, Jordan record the transition between the alluvial Umm Irna Formation (Upper Permian) and the overlying shallow marine Ma’in Formation (Lower Triassic). The Permian-Triassic boundary is constrained either within a hiatus represented by a sequence boundary between these formations or within ca 15 m of shallow marine beds overlying the boundary. Above the sequence boundary reddened, shallow-marine beds (Himara Member) mark the initial Triassic (presumed early Induan) marine transgression (Himara Member). Absence of both body fossils and vertical infaunal burrows indicates low-diversity, ecosystems following the Permian-Triassic extinction event. A gradational upward increase in grey, green and yellow siltstones beds (Nimra Member), accompanied by a concomitant increase in bioturbation (surface traces and infaunal vertical burrows), bivalves and brachiopods, stromatolites, conchostracans and lingulids in the lower part of the Nimra Member indicates colonisation of the substrate under shallow marine conditions during the recovery phase. Shallow-water carbonates in the Nimra Member yielded an abundant, low diversity assemblage of conodonts (e.g. Hd. aequabilis and H. agordina) and a foraminifera assemblage (Postcladella gr. kalhori-Earlandia spp.-Ammodiscus jordanensis n. sp.) that are interpreted as euryhaline recovery taxa that characterise the the mid-late Induan. Abundant new material has allowed revision of the conodont apparatus and the foraminifera include a new species Ammodiscus jordanensis n. sp. of Induan age. The discovery of the bivalves Claraia bittneri (C. aurita group) and Eumorphotis multiformis is worthy to note. Upper Permian alluvial lithofacies (Jordan) pass basinwards, about 50 km to the northwest, to coeval shallow marine siliciclastic and carbonates in the Negev and Mediterranean coast of Israel.

Magnetization age from paleomagnetism of the Copper Harbor red beds, Northern Michigan, USA, and its Keweenawan geologic consequences

The Copper Harbor Formation on Lake Superior’s Keweenaw Peninsula records the transition from volcanic to sedimentary infilling of North America’s 1.1 Ga Keweenawan rift. Radiometric dating shows that the formation’s primary mafic sediments and interbedded “Lake Shore” flows were deposited between ∼1092 and ∼1082 Ma. Our regional paleomagnetic results for the Copper Harbor’s red beds yield a dominantly prefolding normal-polarity secondary chemical characteristic remanent magnetization in hematite at 18 of 21 sites with a mean direction of declination = 274.9°, inclination = +10.9° (k = 69.5, α95= 4.2°), and a paleopole at 7.4°N, 181.7°E (A95= 3.3°). Using paleopoles from Keweenawan volcanic rocks with U–Pb zircon age dates, an apparent polar wander path is constructed from 1106 ± 2 to 1087 ± 2 Ma. Extrapolation of this path dates oxidation of the Copper Harbor’s primary gray beds to red beds at 1060 ± 5 Ma. The path implies an apparent polar wander rate of ∼18 cm per year from ∼1108 to 1096 Ma and of 6.8 cm per year from 1096 to 1087 Ma, along with a consistent clockwise rotation of 0.30 ± 0.05°per million years for the Laurentian Shield from ∼1108 to ∼1160 Ma. Further, most Keweenawan volcanic rocks around the Lake Superior region carry an endemic ∼1060 Ma normal-polarity hematite remanence overprint, acquired during the initial stages of Grenvillian tectonic uplift, that has caused asymmetry in a unit’s normal and reverse paleopoles. Also, the Copper Harbor paleopole dates emplacement of the White Pine stratiform sedimentary copper mineralization more precisely at 1060 ± 5 Ma.

Paleomagnetic and rock magnetic study of Lower Devonian red beds from Podolia: remagnetization problems

Results of paleomagnetic studies of red bed Early Devonian deposits of Podolia, which make the Dniester series (southwestern Ukraine, the Dniester basin) have been given. As a result two components of natural remanent magnetization have been subdivided in addition to viscous one. The first one has got south-southwestern declination and negative inclination, it is identified in almost all samples within the limits of deblocking temperatures from 150—200°С to 530—630°С. Its corresponding paleomagnetic pole (47°S, 351,5°E) is close to the Permian fragment of APWP for the Baltic/Stabile Europe. Its bearers are newly-formed magnetic minerals (secondary authigenous hematite), responsible for production of “late” chemical magnetization. The second component is subdivided in some samples within the limits from 590—610°С to 680—690°С, it has got southwestern declination and positive inclination. Its corresponding paleomagnetic pole (2.3°S, 338.4°E) is drawn towards Early Devonian fragment of APWP This component is caused by presence of detritic grains of hematite. There are solid grounds for consideration of this magnetization to be primary one, which reflects the direction of the Devonian field. New results are in good agreement with paleomagnetic directions obtained earlier in this area for red beds and grey beds of Early Devonian.

Metallogenesis of the sediment-hosted stratiform Cu deposits of the Ravar Copper Belt (RCB), Central Iran

The Ravar Copper Belt (RCB) is located in the north of Kerman in the Central Iran. This belt is a part of the Tabas Block which is 450km long and 50km wide. It is bounded by Kuhbanan- Kalmard Fault in the west and Nayband Fault in the east. The main lithological units in the RCB are Mesozoic sedimentary rocks. The stratigraphic sequence includes evaporites, continental red beds and limestone, similar to other sedimentary Cu belts around the world. Sandstone is the most common host rock in the RCB and has arenite composition which was formed in fluvial to deltaic environment related to foreland basin. Mineralization is closely related to plant fossils and the main ore minerals include chalcocite, bornite, pyrite, marcasite, argentite, spionkopite, covellite, malachite, etc. Replacement, dissemination, banding and veinlet are the most common ore textures which suggest an epigenetic origin related to the early diagenetic stage. Geochemical signatures indicate that RCB is a Cu-Ag-U Red bed type sediment-hosted copper belt similar to Paradox basin and Central Andes deposits. In addition to Cu (3%), minor amounts of Ag, U, Hg, Pb and Au are also existed. Negative values of δ34S show that sulfur is introduced by BRS process and is more derived from organic maters destruction. It is proposed that meteoric and ground waters achieved high salinity while passing through the lower evaporite sequences, thus being able to leach metals from thick red beds as chloride complexes during upward flows. Ore deposition occurred when the metal bearing solution reached to the organic rich gray bed.

THE PERMIAN -TRIASSIC BOUNDARY, DEAD SEA, JORDAN: TRANSITIONAL ALLUVIAL TO MARINE DEPOSITIONAL SEQUENCES AND BIOSTRATIGRAPHY

The Permian to Triassic transition in Jordan is characterised by a sequence boundary underlain by red-bed, alluvial lithofacies deposited in a humid-tropical climate by low-sinuosity rivers, and overlain by shallow marine siliciclastics with thin carbonates. The low-gradient alluvial floodplain was repeatedly subjected to the development of ferralitic and pisolitic paleosols on the interfluves. In contrast, dysaerobic environments in the fluvial channels and abandoned lakes resulted in the preservation of a prolific flora of macro-plants and palynomorphs that indicate a probable range from Mid- to Late Permian age, though the abundant presence of the distinctive pollen Pretricolpipollenites bharadwajii indicates the youngest part of that range. Above the sequence boundary, reddened shallow-marine beds characterised by ripple cross-laminated, siltstones/sandstone with desiccation cracks and sparse surface burrows mark the initial Triassic marine transgression in the region (Arabian Plate Tr 10). These are followed by two thin limestone (packstone) beds with shallow scours and bivalve shell lags, that have yielded a low diversity assemblage of conodonts (e.g. Hadrodontina aequabilis ) and foraminifera (“ Cornuspira ” mahajeri ) that are interpreted as euryhaline taxa characterising the early Induan (Early Triassic). Thus the absence of body fossils and vertical infaunal burrows in the lowest marine beds may reflect low-diversity ecosystems following the Permian-Triassic extinction event, or be a result of stressed shallow marine environments. A gradational upward increase in grey, green and yellow siltstones beds accompanied by a concomitant increase in bioturbation (and infaunal vertical burrows) and thin-shelled bivalves about 15 m above the boundary indicates colonisation of the substrate under more normal shallow marine conditions perhaps indicating recovery phase following the extinction event.

Sedimentology of the lower Serpukhovian (upper Mississippian) Mabou Group in the Cumberland Basin of eastern Canada: tectonic, halokinetic, and climatic implications

The Visean–Serpukhovian transition in Atlantic Canada was marked by a general humidification of the climate as the region drifted towards equatorial latitudes. It also corresponds to a time when ice volume was increasing on Gondwana, which marked the end of Mississippian marine incursions in the region. Glacioeustatic fluctuations of greater magnitude are thought to have increased the response of the regional climate to third-order cyclicity from orbital forcing. In the Cumberland Basin, fluvial grey beds of the lower Serpukhovian Shepody Formation were deposited in sub-humid conditions during highstands, whereas red playa deposits of the same unit were deposited under semi-arid conditions during lowstands. Basin reconstruction suggests that this unit was sourced from the fault-bounded Cobequid and Caledonia highlands and deposited in two separate salt-withdrawal minibasins. This fluvial system was seemingly discharging to the north into the broad lake that deposited the contemporaneous Hastings Formation. A disconformity separates the Shepody Formation from mid-Serpukhovian red beds of the Claremont Formation and is tentatively associated with another increase in ice volume on Gondwana followed by a recrudescence of fault activity and basin subsidence. A prolonged time of aridity, floral crisis, non-deposition, deep weathering and karstification in late Serpukhovian to early Bashkirian times is contemporaneous with abundant glacial deposits in higher latitudes, suggesting that globally low sea levels may have been at play in creating a situation of greater continentality in the study area.

Neuropterid fossil plants from the basal part of the Middle Carboniferous Manhang Formation in the Taebaek area, Korea and their significance

Some well-preserved neuropterid fossil plants were abundantly found in dark gray shale beds of lowermost basal part of the Middle Carboniferous Manhang Formation, which occur in the road cuts of Route 35 near the Hyeobsim Bridge in the Jangseong area, Taebaek City, Gangwon Province, Korea. The fossil plants include three species of Paripteris Gothan: P. gigantea (Sternberg), P. kaipingiana (Sze), and P. otozamioides (Sze and Lee). The latter two species were newly discovered and firstly described from the Korean Peninsula. The present fossil plants are the oldest land vascular plant fossils in the Republic of Korea. Based on the world-wide geologic range of these fossil plants, the basal part of the Manhang Formation in the Taebaek area corresponds to the upper Namurian stage of the Middle Carboniferous Period in age. This age assignment means that the deposition of the Manhang Formation started when the Middle Carboniferous sea transgressed on the Sino-Korean Craton.

Read, Write, Play, Learn: Literacy Instruction in Today's KindergartenLori JamisonRog (2011) Newark, DE: International Reading Association. ISBN-13: 978-0872078475; 214pp, £22.50

LiteracyVolume 48, Issue 2 p. 112-112 Review Read, Write, Play, Learn: Literacy Instruction in Today's Kindergarten , Lori Jamison Rog (2011) Newark, DE: International Reading Association. ISBN-13: 978-0872078475; 214pp, £22.50 Fiona Gray, Fiona Gray 4th-Year BEd studentSearch for more papers by this author Fiona Gray, Fiona Gray 4th-Year BEd studentSearch for more papers by this author First published: 16 October 2012 https://doi.org/10.1111/j.1741-4369.2012.00673.xRead the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume48, Issue2July 2014Pages 112-112 RelatedInformation

Modal Analysis of Artificial Granite Grinding Machine Tool Bed

Machine tool bed, which supports headstock, tailstock and other functional components, is one of the important structure parts of machine tools. Precision grinding machine tool beds are designed by the authors with artificial granite and cast iron respectively for research. Their three-dimensional models were established via software SOLIDWORKS and then imported into the finite element software (ANSYS) to simulate for the first eight modal frequencies and the corresponding vibration modes. Simulation results show that the first eight order natural frequencies of artificial granite bed are better and the corresponding maximum amplitude of vibration modes are decreased significantly than cast iron bed. The dynamical properties of artificial granite bed are obviously better than grey cast iron bed.

Mid-Paleocene event at Gabal Nezzazat, Sinai, Egypt: planktonic foraminiferal biostratigraphy, mineralogy and geochemistry

The Qreiya Beds that record the ‘mid-Paleocene event’ at Gabal Nezzazat occur within the Igorina albeari (P3b) Zone and constitute part of a 14-m thick shale succession that ranges in age from Early to Late Paleocene. They are composed of four alternating dark grey and brown shale beds, which are thinly laminated, phosphatic, organic-rich and extremely sulphidic. They are characterized by distinct enrichment and high peak anomalies in chalcophiles (Zn, Co, Ni, Cu and Pb) and organic association elements (V and Cr), especially within the brown organic-rich beds. It is concluded that these elements are incorporated into the phosphatic debris, sulphides and organic matter. In contrast, the grey beds are enriched in clay minerals and quartz. Clay mineral assemblages indicate alternating periods of warm/humid climate (high kaolinite) and dry climate (low kaolinite) during the formation of the grey and brown beds, respectively. The sediments of the Qreiya Beds yield lithological, biotic, geochemical and mineralogical data indicative of suboxic/anoxic marine environments as a result of high productivity and/or upwelling. The top metre of the succession below the Qreiya Beds is characterized by a progressive change from faunas dominated by praemurcurids to faunas dominated by Morozovilids, and by a progressive upward decrease in δ13Ccarb and δ18Ocarb values. The foraminiferal faunal change may reflect shallowing and warming preceding deposition of the Qreiya Beds. The change in isotopic values is inferred to be the result of surface weathering, fluvial input and diagenesis with no evidence of any primary change that could support presence of a hyperthermal event.

Methane seepage along the Hikurangi Margin, New Zealand: Overview of studies in 2006 and 2007 and new evidence from visual, bathymetric and hydroacoustic investigations

This paper is an introduction to and an overview of papers presented in the Special Issue of Marine Geology “Methane seeps at the Hikurangi Margin, New Zealand”. In 2006 and 2007, three research cruises to the Hikurangi Margin at the east coast of New Zealand's North Island were dedicated to studying methane seepage and gas hydrates in an area where early reports suggested they were widespread. Two cruises were carried out on RV TANGAROA and one on RV SONNE using the complete spectrum of state-of-the-art equipment for geophysics (seismic, sidescan, controlled source electromagnetics, ocean bottom seismometers and hydrophones, singlebeam and multibeam), seafloor observations (towed camera systems, ROV), sediment and biological sampling (TV-guided multi-corer, gravity-corer, grab, epibenthic sled), deployment of in-situ observatories (landers) as well as water column sampling and oceanographic studies (CTD, moorings). The scientific disciplines involved ranged from geology, geophysics, petrography, geochemistry, to oceanography, biology and microbiology. These cruises confirmed that a significant part of the Hikurangi Margin has been active with locally intense methane seepage at present and in the past, with the widespread occurrence of dead seep faunas and knoll-forming carbonate precipitations offshore and on the adjacent land. A close link to seismically detected fluid systems and the outcropping of the base of the gas hydrate stability zone can be found at some places. Pore fluid and free gas release were found to be linked to tides. Currents as well as density layers modulate the methane distribution in the water column. The paper introduces the six working areas on the Hikurangi Margin, and compiles all seep locations based on newly processed multibeam and multibeam backscatter data, water column hydroacoustic and visual data that are combined with results presented elsewhere in this Special Issue. In total, 32 new seep sites were detected that commonly show chemoherm-type carbonates or carbonate cemented sediment with fissures and cracks in which calyptogenid clams and bathymodiolid mussels together with sibloglinid tube worms live. White bacterial mats of the genus Beggiatoa and dark gray beds of heterotrophic ampharetid polychaetes typically occur at active sites. Bubble release has frequently been observed visually as well as hydroacoustically (flares) and geochemical analyses show that biogenic methane is released. All seep sites, bubbling or not, were inside the gas hydrate stability zone. Gas hydrate itself was recovered at three sites from the seafloor surface or 2.5 m core depth as fist-sized chunks or centimeter thick veins. The strong carbonate cementation that in some cases forms 50 m high knolls as well as some very large areas being paved with clam shells indicates very strong and long lasting seep activity in the past. This activity seems to be less at present but nevertheless makes the Hikurangi Margin an ideal place for methane-related seep studies in the SW-Pacific.

Nagaur — tertiary interface under Punjab-Haryana semi-desertic plains in western India

The subsurface Nagaur Basin in northwest Haryana and southwest Punjab hosts evaporite sequence, conformably overlain by Nagaur red beds and grey beds. A polymictic conglomerate intervenes the Nagaur sequence and the overlying Tertiary sequence. The focus is on the new finds of (i) distinctive ‘grey beds’ overlying ubiquitous red beds, (ii) ‘Malout conglomerate and grit’ horizon (Palaeocene-Miocene) marking an unconformity over the Nagaur Group (early Cambrian) and (iii) ‘entrapped gas and dried-up leaves/carbonaceous flakes’ in the conglomerate unit and succeeding Tertiary rocks. Palaeoenvironmental significance has been discussed. The Nagaur ‘red beds’ has been likened to ‘continental red beds’ of Schreiber (1978) and ‘reworked red beds’ of Krynine (1949). The ‘grey beds’ are channel fillings, fresh material having been derived from fresh cuttings by streams/rivers following structural grains in the Aravalli landscape where the interfluves provided weathered (oxidised) materials for the red beds. Association of continental red beds and grey beds is known in the Newark Series (Triassic) of the Eastern United States and the Keweenawan ‘late Precambrian’ of the Lake Superior region.

Diagenesis of diatomite from the Kolubara Coal Basin, Baroševac, Serbia

Diatomite associated with the Kolubara Coal Basin was studied to better understand early stage silica diagenesis of shallow water deposits. The Kolubara Basin consists of Neogene siliciclastic rocks, diatomite, marlstone and rare carbonates. Palaeozoic metamorphic and Mesozoic sedimentary and igneous basement rocks are transgressively overlain by Upper Miocene sandstone, siltstone, shale and mudstone. This Upper Miocene section is transgressively overlain by the Pontian section, which contains diatomite and coal beds. White and grey diatomite forms beds 0.7-2.2 m thick that are continuous over an area of about 2 km2. Siliceous rocks vary in composition from diatomite (81-89 per cent SiO2) to diatom-bearing shale (58-60 per cent SiO2). Siliceous deposits are laminated in places, with the laminae defined by variations in clay minerals, organic matter and diatoms. Diatomite shows only incipient diagenesis characterized by the fragmentation of diatom frustules, the minor to moderate corrosion of frustules and the formation of minor amounts of opal-A' (X-ray amorphous inorganic opal) cement. The low degree of diagenesis results from the young age of the deposits, low burial temperatures and possibly also from the presence of abundant organic matter and the dissolution of kaolinite. The presence of only weak diagenesis is also reflected by the characteristically poor consolidation of the rocks and low rank of the associated coal.

Regional facies trends in the lowermost beds of the Upper Triassic Charlie Lake Formation, in the subsurface of Western Canada

Abstract Regionally extensive core coverage in beds of the lowermost Upper Triassic Charlie Lake Formation — between the A marker and underlying Middle Triassic Halfway or Doig beds — in the subsurface of west-central Alberta and adjacent northeast British Columbia facilitate the interpretation of a regional depositional setting. Three broad facies assemblages are identified: 1) red beds; 2) grey beds; and 3) sandstone beds. These three assemblages occur in geographically restricted areas. The red-bed assemblage occurs mostly along the eastern margin of the basin and is interpreted as predominantly intertidal to supratidal, sabkha deposits. The grey-bed assemblage is present between the red-bed and western sandstone assemblages and consists of predominantly intertidal to shallow subtidal beds deposited in a lagoon. Sandstones occur in two locations; in the west they are part of a linear belt, and at the second location they are associated with a local paleogeographic feature, the Beatton High, located within the grey-bed assemblage north of Fort St. John, in northeast British Columbia. The western sandstones are deposits of a barrier-island complex, whereas the sandstones associated with the Beatton High are local tidal channel and fan-delta deposits sourced from the Beatton High. The west-to-east facies changes and north-northwest alignment of the facies define a western, sandy barrier-island complex behind which (to the east) was a lagoon with sabkha deposits at its eastern margin. In the lagoon, a mixture of siliciclastics, carbonates and evaporites were deposited.

New, biostratigraphically significant ammonites from the Jurassic Fernie Formation, southern Canadian Rocky Mountains

Jurassic ammonites described here for the first time come from numerous localities in the Fernie Formation in the Foothills and Front Ranges of the Rocky Mountains of north- and south-eastern British Columbia and central- and south-western Alberta, and provide useful new age data for several members of the formation. The occurrence of Orthodactylites sp. in the uppermost beds of the Red Deer Member indicates this unit extends upwards into the basal Toarcian, which will be helpful in the search for carbon-isotope excursions associated with the early Toarcian anoxic event. The presence of Hettangian and lower Pliensbachian strata in outcrop of the Gordondale Member is confirmed. Diversity of the ammonite fauna in the Grey Beds is enlarged by the presence of ? Kepplerites – ? Cadomites and Choffatia spp. These faunas also provide biostratigraphic constraints for carbon- and oxygen-isotope trends and U–Pb ages recently recorded from the Highwood Member and Grey Beds exposed in Bighorn Creek and its eastern tributary, and in Fording River. The first occurrence of Zemistephanus richardsoni from cratonic rocks, recorded here, suggests close proximity of the allochthonous terranes Wrangellia and Stikinia, the only other areas from which this species is known, to the northwest North American craton by early Bajocian time. One new species, Cardioceras (Subvertebriceras) ferniensis, is described.

PALAEGA RUGOSA, A NEW SPECIES OF FOSSIL ISOPOD (CRUSTACEA) FROM MAASTRICHTIAN ROCKS OF TUNISIA

Recent, intensive collecting for Maastrichtian ammonites in Tunisia has yielded a single small isopod specimen from the Kalaat Senaan region. The isopod is a new species of Palaega Woodward, 1870 and appears to be the first representative of the genus to be recorded from the Maastrichtian of northern Africa. A 5,000 m thick sedimentary record, ranging in age from the Aptian to the middle Ypresian, crops out in the west-central part of Tunisia, close to the Algerian border, between Kalaat Senan, Tajerouine, and Kalaa Khasba (see Robaszynski et al., 1990, 1993a, 1993b, 1993c, 2000; Hardenbol et al., 1993; Dupuis et al., 2000; and Steurbaut et al., 2000 for detailed litho- and biostratigraphy) (Fig. 1). An almost 600 m thick marly sequence of the El Haria Formation forms a low, gently undulose landscape, situated between a cliff of the 200 m thick upper limestone bar of the underlying Abiod Formation (which ranges in age from late Campanian to early Maastrichtian) and a cliff of the Eocene nummulitic limestone bar in the Metlaoui Formation. Figure 1 —Map and stratigraphic section showing the geographic and geologic position of the Tabet Zaara Section from which Palaega rugosa n. sp. was collected Numerous gullies deeply eroded into the Maastrichtian El Haria Formation between these two cliffs provide excellent exposures of the 600 m thick sequence. Several lithostratigraphic units are distinguishable within the El Haria Formation, two of which crop out in the Ain Settara section: the lowermost Ain Settara Member, consisting of dark grey jarositic marls with alternating 0.2–0.8 m thick, whitish, carbonate-rich beds, and the uppermost Sidi Nasseur Member, consisting of alternating blue grey marls and thin whitish limestone beds. The base of the Sidi Nasseur marls is defined by a 60 cm thick dark clay, …