Geology of the Early Arikareean Sharps Formation on the Pine Ridge Indian Reservation and Surrounding Areas of South Dakota and Nebraska

Based on geologic mapping, measured sections, and lithologic correlations, the local features of the upper and lower type areas of the Early Arikareean (30.8–20.6 million years ago) Sharps Formation are revised and correlated. The Sharps Formation above the basal Rockyford Member is divided into two members of distinct lithotypes. The upper 233 feet of massive siltstones and sandy siltstones is named the Gooseneck Road Member. The middle member, 161 feet of eolian volcaniclastic siltstones with fluvially reworked volcaniclastic lenses and sandy siltstone sheets, is named the Wolff Camp Member. An ashey zone at the base of the Sharps Formation is described and defined as the Rockyford Ash Zone (RAZ) in the same stratigraphic position as the Nonpareil Ash Zone (NPAZ) in Nebraska. Widespread marker beds of fresh water limestones at 130 feet above the base of the Sharps Formation and a widespread reddish-brown clayey siltstone at 165 feet above the base of the Sharps Formation are described. The Brown Siltstone Beds of Nebraska are shown to be a southern correlative of the Wolff Camp Member and the Rockyford Member of the Sharps Formation. Early attempts to correlate strata in the Great Plains were slow in developing. Recognition of the implications of the paleomagnetic and lithologic correlations of this paper will provide an added datum assisting researchers in future biostratigraphic studies. Based on similar lithologies, the Sharps Formation, currently assigned to the Arikaree Group, should be reassigned to the White River Group.     

A New Jawless Vertebrate from the Middle Devonian of Scotland

A new jawless vertebrate, Cornovichthys blaauweni gen. et sp. nov., is described from a single complete specimen from the Achanarras fish bed at Achanarras Quarry in Caithness, northern Scotland. The Achanarras fish bed consists of lacustrine laminites and was deposited in a major deep-water phase of the Orcadian lake during the deposition of the cyclic Caithness Flagstone Group. The Achanarras fish bed is of Middle Devonian (Eifelian) age. The new animal compares closely with Euphanerops, one ofthe Frasnian 'anaspids' (Hyperoartii) of the Escuminac Formation at Miguasha, Quebec, Canada.     

First records and potential palaeoecological significance of Dianella (Xanthorrhoeaceae), an extinct representative of the native flora of Rapa Nui (Easter Island)

Easter Island, a remote island in the Pacific Ocean, is currently primarily covered by grasslands, but palaeoecological studies have shown the former presence of different vegetation. Much of its original biota has been removed during the last two millennia, most likely by human activities, and little is known about the native flora. Macrofossil and pollen analyses of a sediment core from the Raraku crater lake have revealed the occurrence of a plant that is currently extinct from the island: Dianella cf. intermedia/adenanthera (Xanthorrhoeaceae), which grew and disappeared at the Raraku site long before human arrival. The occurrence of Dianella within the Raraku sedimentary sequence (between 9.4 and 5.4 cal. kyr b.p.) could have been linked to the existence of favorable palaeoenvironmental conditions (peatland rather than the present-day lacustrine environment) during the early to mid Holocene. This finding contributes new knowledge about indigenous plant diversity on Easter Island and reinforces the usefulness of further macrofossil and pollen analyses to identify native species on Easter Island and elsewhere.     

Cretaceous (Albian to Turonian) radiolarians from chert blocks of the Moni Mélange (Southern Cyprus)

Well-preserved Cretaceous (Albian–Turonian) radiolarians were extracted from radiolarian-bearing chert olistoliths of the Monagroulli Member within the Moni Mélange (Campanian-Maastrichtian, Southern Cyprus). Four assemblages were distinguished: Middle Albian–Lower Cenomanian (Thanarla spoletoensis Zone), Upper Albian–Lower Cenomanian (Thanarla spoletoensis Zone, Dorypyle? anisa Subzone), lowermost Turonian (base of Alievium superbum Zone) and Lower Turonian (Alievium superbum Zone). The radiolarian assemblages are diverse and have taxonomic composition similar to coeval assemblages of Italy and Spain. The sediments of the Monagroulli Member differ from coeval rocks of the Mamonia Complex (western Cyprus) by the more common presence of radiolarian cherts and may have been formed in the distal part of a continental margin with less input of clastic material. A new spicular radiolarian genus Cyprothamnus with 2 new species (C. multifurcatus and C. moniensis) is described from the Lower Turonian strata.     

Activation of Snake in a serine protease cascade that defines the dorsoventral axis is atypical and pipe-independent in Drosophila embryos

During Drosophila embryogenesis, establishment of ventral and lateral cell fates requires spatial regulation of an extracellular serine protease cascade composed of Nudel, Gastrulation Defective (GD), Snake, and Easter. Pipe, a sulfotransferase expressed ventrally during oogenesis, sulfates secreted targets that somehow confer positive spatial input to this cascade. Nudel and GD activation are pipe-independent, while Easter activation requires pipe. The effect of pipe on Snake activation has been unknown. Here we show that Snake activation is cascade-dependent but pipe-independent. These findings support a conclusion that Snake’s activation of Easter is the first spatially regulated step in the dorsoventral protease cascade.     

Geochemical evidence for the formation of a large miocene “travertine” mound at a sublacustrine spring in a soda lake (Wallerstein castle rock, nördlinger ries, Germany)

Summary “Travertines” (tufa pinnacles) of the Miocene Riescrater basin have been investigated to test whether carbon, oxygen and strontium isotopes can be used for the recognition of fossil subaquatic spring deposits in high-alkalinity settings. The Ries basin “travertines” have so far been interpreted as a product of subaerial to sublacustrine artesian springs discharging calcareous groundwater into a freshwater or slightly saline lake. However, recent studies on microfacies and fabric development propose a formation at Ca²⁺-supplying sublacustrine springs of a soda lake. Geochemical analysis of “travertines” of the castle rock Wallerstein, including “sickle-cell” limestones, thrombolites, non-skeletal stromatolites, and speleothems, now support the latter interpretation. High Sr contents surpassing that of the contemporaneously formed dolomitic algal biocherms of the lake shore point to an aragonitic composition of primary precipitates. the δ¹³C values of diagenetically moderately to weakly altered “travertine” facies types are in the same range of the impact-brecciated Upper Jurassic limestones, thus, are inconsistent with a mixture of soil-derived CO₂ and CO₃ ²⁻ from the Jurassic limestones. In addition, the δ¹⁸O values are too high to support a significant contribution of CO₃ ²⁻ by meteoric waters seeping through marine Jurassic limestones. Instead the δ¹³C and δ¹⁸O values indicate an origin of the CO₃ ²⁻ from a lake water body characterized by evaporation. This is consistent with a sodium-rich lake water as indicated by high sodium contents of aragonitic algal bioherms of the lake shore. The⁸⁷Sr/⁸⁶Sr isotope ratio of the “travertine” mound carbonates are consistent with calculated mixing of spring waters discharging from the crystalline basement and lake water high in dissolved inorganic carbon. This points to an origin of the divalent cations from sublacustrine spring waters. In turn,⁸⁷Sr/⁸⁶Sr isotope ratios of green algal reef carbonates of the lake shore are closer to that of the Upper Jurassic carbonates, due to surface run-off from surrounding limestone uplands.     

Ecological Release and Venom Evolution of a Predatory Marine Snail at Easter Island

Background

Ecological release is coupled with adaptive radiation and ecological diversification yet little is known about the molecular basis of phenotypic changes associated with this phenomenon. The venomous, predatory marine gastropod Conus miliaris has undergone ecological release and exhibits increased dietary breadth at Easter Island.

Methodology/Principal Findings

We examined the extent of genetic differentiation of two genes expressed in the venom of C. miliaris among samples from Easter Island, American Samoa and Guam. The population from Easter Island exhibits unique frequencies of alleles that encode distinct peptides at both loci. Levels of divergence at these loci exceed observed levels of divergence observed at a mitochondrial gene region at Easter Island.

Conclusions/Significance

Patterns of genetic variation at two genes expressed in the venom of this C. miliaris suggest that selection has operated at these genes and contributed to the divergence of venom composition at Easter Island. These results show that ecological release is associated with strong selection pressures that promote the evolution of new phenotypes.     

A New Naked Jawless Vertebrate From The Middle Devonian Of Scotland

A new jawless vertebrate, Achanarella trewini gen. et sp. nov., is described from some recently discovered, relatively well–preserved specimens from the Achanarras fish bed at Achanarras Quarry, northern Scotland. The Achanarras fish bed is of Middle Devonian (Eifelian) age. Achanarella is a torpedo–shaped jawless vertebrate with a strongly hypocercal tail and well–developed anal fin. It has at least 13 branchial openings with possibly more than 20. It is scaleless. Achanarella compares well with the Frasnian Euphaneropidae of the Escuminac Formation in Quebec, Canada, and Cornovichthys blaauweni Newman and Trewin, 2001, also from the Achanarras fish bed. It differs from these forms mainly in being extremely long and thin and having a very small head compared with body length.     

Favositidae (Tabulata) from Emsian to Middle Devonian limestones of the Tamworth Group (N.S.W., Australia)

Several different species and species groups of the familiy Favositidae from the Emsian and Middle Devonian limestones of the Tamworth Group (N.S.W., Australia) are described. The Emsian Sulcor Limestone Member yieldedFavosites sp. aff.F. basalticus (Goldfuss, 1826),Favosites sp. aff.F. salebrosus Etheridge, 1899,Favosites stellaris Chernyshev, 1937,Squameofavosites nitidus (Chapman, 1914),Sq. bryani (Jones, 1937),Pachyfavosites rariporosus Dubatolov, 1963, andP. tumulosus Yanet, 1965. The Middle Devonian Moore Creek Limestone Member yieldedFavosites ex gr.goldfussi D’Orbigny, 1850, exclusively. In the Emsian limestones occur favositids in a wide array of different facies, with most being found in stratified biostromes and in bedded nodular limestones. In the Middle Devonian most favositids are found in nodular and lumpy limestones which occur at the base and at the top of some successions      

Pliocene facies and fossil contents of Qaret El-Muluk formation at Wadi El-Natrun depression, Western Desert, Egypt

Summary A sequence of late Pliocene sediments (Qaret El-Muluk Formation) covers large areas within Wadi El-Natrun depression; at the western periphery of the Nile Delta. The exposed sequence is composed of friable sands. mudstones, shales and minor limestones with combined total thickness of approximately 50 m. The fossil content consists of fresh and brackish water elements; charophytes, ostracods, gastropods, oysters and benthonic foraminifera. Planktonic forams which suggest marine influence have been also recorded. Terrestrial and aquatic continental vertebrate fauna includes mammals, reptiles, fish and aves. Several subtypes of ichthyoliths have been discovered in this study. Both lithological and paleontological data testify to a depositional environment which belongs to a marginal region where fluvial and marine deposition meet in shallow brackish lagoons. The sediments display changes from channelled fluvial sands to deltaic interbedded sands and mudstones to lagoonal shales and limestones to lacustrine chara limestones. Vertical stacking of facies is indicative of a series of transgressive-regressive events. The transgression brought shallow lagoonal conditions to the area. The transgressions were incomplete due to high rate of fluvial input. The lagoon dried up intermittently and calcretes and red brown soils were formed. Each regression is indicated by river generated clastic influx. During periods of active fluvial input, fluvial sediments prograded lagoonward. The clastic material was probably a mixture of reworked detritus from older sediments. An admixture of first cycle material from the basement rocks of the Red Sea hills cannot be ruled out. The diversity of provenance argues for several channels of a large river which existed during the late Pliocene.     

Late Carboniferous hydrocarbon-seep carbonates from the glaciomarine Dwyka Group,southern Namibia

Limestone deposits with columnar to lenticular geometry (max. 3.2 m in height and 1.5 m in diameter) occur within the uppermost part of the Ganigobis Shale Member, a marine mudstone unit capping the second deglaciation sequence of the glaciomarine Dwyka Group in southern Namibia. The limestones mainly consist of four authigenic carbonate phases (microspar, banded/botryoidal cement, yellow calcite, spheroidal calcite). Extremely negative δ¹³C values (as low as ? 51‰ VPDB) indicate a hydrocarbon-derived origin of the carbonates with biogenic methane being the most likely carbon source. The limestones contain a low-diversity but high-abundance faunal assemblage of tubular fossils. These fossils closely resemble the tubes of modern and fossil seep-dwelling vestimentiferan tube worms in terms of size, shape, arrangement, and taphonomical patterns.     

The Middle Pleistocene Al Mahrúqah Formation in the Murzuq Basin,northern Sahara,Libya evidence for orbitally-forced humid episodes during the last 500,000 years

Geological and geomorphological work in the endorheic Murzuq Basin (Fezzan) in the northern Sahara Desert, SW Libya, has revealed that the Middle Pleistocene Al Mahrúqah Formation consists of at least four limestone beds at four distinct elevations. The corresponding limestone beds are named (from oldest to youngest) the Antalkhatá Member, the Brak Member, the Bi'r az Zallaf Member, and the Aqar Member. The four members are interpreted as lacustrine deposits, and they are well distinguished by their spatial extent and lithology. Twenty-five radiometric and thermal ionisation mass spectrometric (TIMS) ²³⁰Th/U ages ranging from about 490–130 ka have been determined on these lacustrine limestones. According to these radiometric ²³⁰Th/U ages, the accumulation of the four limestone members of the Al Mahrúqah Formation followed the orbitally-forced (Milankovitch) eccentricity cycle of 100 ka during at least the last 400 ka. The four members formed in humid episodes of several tens of thousands of years' duration, when large lakes might have existed. The δ¹³C and δ¹⁸O values from samples of the four members of the Al Mahrúqah Formation provide independent genetic evidence on the lacustrine origin of the deposits in the Murzuq Basin. The spatial extent of the limestone deposits, and thus the intensity of the humid episodes, decreases at least from the Brak Member to the Aqar Member from about 52,000 km² to 1400 km², respectively. In spite of the limited precision and reliability of the new ²³⁰Th/U ages, it seems possible that short humid episodes interrupted the intervening arid episodes. Other long-term palaeohydrological records from northern and southern Africa as well as the Mediterranean region support the palaeoclimatic results from the Murzuq Basin.     

Biogene fluvio-lakustrine Sedimentation im Rotliegend des permokarbonen Saar-Nahe-Beckens (SW-Deutschland)

Fuviatile-lacustrine and alluvial clastic sediments about 3500 m thick have developed during the Lower Permian (Rotliegend) in the Saar-Nahe Basin (SW-Germany). In the lower part of the Rotliegend (Kusel, Lebach and Tholey Groups) fluviatile-lacustrine sequences predominate, whereas in the upper part (the Nahe Group) alluvial-playa/sabkha sequences occur. The biogenic sediments consists of fluviatile and lacustrine limestones, autoththonous fluviatile and lacustrine coals as well as allochthonous coal seams and lacustrine black shales. Ostracod andSpirorbis limestones are rather rare. Biogenic sediments are especially known from the Kusel and the Lebach Group. Only a few biogenic sediments have developed in the Nahe Group. This change in the sedimentological development indicates a distinct change of climate during the Rotliegend.     

Environmental change in the Early Permian of NE Svalbard: from a warm-water carbonate platform (Gipshuken Formation) to a temperate,mixed siliciclastic-carbonate ramp (Kapp Starostin Formation)

A detailed facies study of Early Permian strata within NE Svalbard reveals a fundamental change of the depositional setting, from a restricted-marine, warm-water carbonate platform to an open-marine, temperate-water, mixed siliciclastic-carbonate ramp. The uppermost strata of the Gipshuken Formation (Templet and Sørfonna members; Sakmarian–early Artinskian?) consist of microbialites (algal mats), mudstones, bioclastic/peloidal limestones, carbonate breccias and Microcodium facies reflecting peritidal platform areas and supratidal sabkhas. A mixed heterozoan/reduced photozoan assemblage indicates temperate-water conditions within neighboring deeper, open-marine mid-platform areas, while warm-water conditions still prevailed within inner platform zones. In contrast, the lowermost strata of the overlying Kapp Starostin Formation (Vøringen Member; late Artinskian?–Kungurian) show a fully heterozoan biotic assemblage reflecting temperate water conditions within open-marine, storm-dominated, nearshore to transitional offshore areas of a mixed carbonate-siliciclastic ramp. The Vøringen Member comprises three facies associations, which form a shallowing-upward sequence subsequent to an initial transgression. The sediments reflect bryozoan bioherms in most distal areas, followed by stacked tempestites of sandy brachiopodal shell banks and Skolithos piperocks, grading into broad sand flats in most proximal areas of the inner ramp. The above environmental change is regarded as a regional event taken place across the entire shelf along the northern margin of Pangea and is attributed to paleoclimatic, paleoceanographic, as well as paleogeographic changes, possibly related to the overall northwards drift of the supercontinent. An abrupt increase in terrigenous input coinciding with this change is ascribed to the uplift of a new local source area, probably to the north or east of the investigation area.     

The laminated lake sediments of the Eckfeld maar (Middle Eocene, Germany): Types of stratification and role of organic matter

Summary The Middle Eocene lake sediments of the Eckfeld maar are situated on the southwestern margin of the Tertiary High-Eifel volcanic field (Germany) and are well known for excellently preserved fossil remains. During a driling campaign in 1996 six well sections were cored at three different locations. Three cores (E1/96, E2/96 and E3/96) penetrated deposition of the central lake facies, which is dominated by laminated organic-rich pelites within the uppermost 40 m. It is the aim of this paper to present a brief survey over the main types of stratification observed within the organic-rich portions of the Eckfeld lake sediments. Based on the varying distribution of mineral and organic matter three sediment sequences are distinguished representing different phases of lake development. The “minerogenic laminites” represent the purely clastic mineral sedimentation in a lake, which was surrounded during this early phase by a tephra rim barren of vegetation. The gradual overgrowth of the tephra rim by vegetation is reflected by the predominance of land plant detritus in the sediments of the “transtion beds”, though the siliciclastic input is still significant. In contrast, the succeeding sequence of the “biogenic laminites” is characterised by the frequent occurrence of centric diatoms (mainly of the planktonic speciesAulacoseira cf.granulata) and Chlorophyceae (mainlyBotryococcus andTetraedron) documenting the increase in autochthonous organic sedimentation in a meromictic lake.     

Données nouvelles sur les mammifères et les nummulites de l'éocène supérieur subalpin (synclinaux du Charbon et d'entrevernes,Bauges, Savoie et Haute-Savoie)

Vertebrate remains and nummulites have been investigated from the Late Eocene—Early Oligocene transgressive sequence of the «Chaînes subalpines south of the lake Annecy. The sedimentary environments range from fluvio-lacustrine shales and conglomerates at the base to hemipelagic Globigerina shales at the top. The fluvio-lacustrine white marls contain mammals of the upper, probably terminal Ludian, with affinities to the assemblage of Saint-Capraise. The brackish Cerithium beds have furnished charophytes of the Bembridge zone. The nummulite limestones are not dated precisely, but isolated, probably redeposited nummulites from the base of the Globigerina shales are of terminal Eocene or basal Oligocene age. The Globigerina shales themselves belong to the Oligocene.     

Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: implications for the age of the hominin fossils and stone tool industries

Palaeomagnetic analysis was conducted on speleothems from Members 1-5 at Sterkfontein Cave, South Africa. Palaeomagnetic analysis of siltstone and speleothem from the bulk of Member 4 indicate a reversed magnetic polarity that dates the deposits and its Australopithecus africanus fossils to between 2.58 and ∼2.16 Ma. Further confirmation of this age comes in the form of two short normal polarity events correlated to the Rèunion (∼2.16 Ma) and Huckleberry Ridge (∼2.05 Ma) events in speleothem capping the bulk of Member 4 and coeval with deposition of the final phase of Member 4, including A. africanus fossil Sts 5. At ∼2.16-2.05 Ma, Sts 5 is the youngest representative of A. africanus yet discovered. Palaeomagnetic analysis of the Silberberg Grotto deposits identifies a single short geomagnetic field event in flowstone overlying the StW 573 Australopithecus fossil, which is suggested to represent the Rèunion event at ∼2.16 Ma. This further supports the uranium lead age estimates of 2.3-2.2 Ma for the StW 573 fossil. Based on a reversed polarity for the deposits below the skeleton it cannot be older than 2.58 Ma. If StW 573 is considered to be a second species of Australopithecus then this indicates that two species of Australopithecus are present at Sterkfontein between 2.6 and 2.0 Ma. All of the Member 5 deposits date to less than 1.8 Ma based on a comparison of palaeomagnetic, faunal, and electron spin resonance age estimates. The StW 53 fossil bearing infill (M5A) is intermediate in age between Member 4 and the rest of Member 5 (B-C) at around 1.78-1.49 Ma. The rest of Member 5 (B-C) containing Oldowan and Acheulian stone tools and Homo and Paranthropus fossils was deposited gradually between 1.40 and 1.07 Ma, much younger than previously suggested.     

The Madenli (Central Taurides) Upper Cretaceous platform carbonate succession: Benthic foraminiferal biostratigraphy and platform evolution

The Upper Cretaceous succession in the Madenli area (western Central Taurides, Southern Turkey) consists of platform carbonate rocks deposited in entirely peritidal environments, which are sensitive to sea level changes driven by global eustasy, but also strongly affected by local and regional tectonics. It includes economically important bauxite deposits. Previous works suggest different ages for bauxite formation ranging from the Albian to the Santonian. Benthic foraminiferal biostratigraphy and facies analysis of the Madenli and Doğankuzu outcrop sections allow for a more precise dating of the platform emersion periods. The footwall limestones of the bauxite deposits consist of well-bedded limestones (Unit-1), which contain a benthic foraminiferal assemblage (BFA) including mainly Biconcava bentori and Pastrikella biplana, Chrysalidina gradata (BFA I), assigned to the middle-upper Cenomanian. In the Madenli section, the first bauxite deposit occurs in the upper part of Unit-1 as a layer interbedded with pinkish sparitic and dolomitic beds (subunit-1a) deposited in supratidal environment. Subunit-1a is stratigraphically equivalent to the Doğankuzu and Mortaş bauxite deposits considered as karst-related, unconformity-type deposits. The hanging-wall limestones of the bauxite are represented by the massive limestones (Unit-2) starting locally with either the upper Cenomanian characterized mainly by the presence of Pseudolituonella reicheli or upper Campanian comprising mainly Murciella cuvillieri and Moncharmontia apenninica (BFA II). There is no field evidence of a discontinuity surface at the contact between the lower part of Unit-2, including BFA I, and the upper part of Unit-2, including BFA II. This contact is defined as a paraconformity indicating a stratigraphic gap from the Turonian to the early Campanian. The top of Unit-2 is truncated by another discontinuity surface associated with a minor bauxite deposit. The overlying Unit-3 is characterized by well-bedded, rudist-bearing limestones topped by laminated and dolomitized limestones organized in shallowing upward cycles. It is assigned to the upper Maastrichtian based on the presence of Rhapydionina liburnica (BFA III) and rudist assemblage. A third emersion period of the platform corresponds to the early Maastrichtian.     

Lipid biomarker evidence for determining the origin and distribution of organic matter in surface sediments of Lake Taihu,Eastern China

Lipid biomarkers from surface sediments of Lake Taihu (Eastern China) were analyzed in order to determine the origin and spatial distribution of sediment organic matter (OM), which is necessary to understand the regional carbon cycles and design environmental management strategies for lake systems. The results indicated significant heterogeneity in the distribution of autochthonous (algae-, photosynthetic bacteria- and macrophyte-based) and allochthonous (terrestrial plant-based) OM in sediments across the lake. Allochthonous OM inputs, indicated by long-chain n-alkane and long-chain n-alkanol biomarkers, generally declined in abundance from northwestern (Zhushan Bay and Meiliang Bay) to southeastern (East Bays) parts of the lake, suggesting a critical influence of hydrology, and in particular of inflowing rivers, which mainly enter the lake from the west and drain from the east. Autochthonous OM, on the other hand, appeared to reflect variations in overall nutrient status and habit type across the lake. Cyanobacterial OM inputs, identified by short-chain n-alkanes, were most abundant in sediment from the most severely polluted zones in Lake Taihu, namely Zhushan Bay and Meiliang Bay. OM derived from diatoms, indicated by brassicasterol and highly branched isoprenoids (HBIs), was most abundant in sediments from the East Bays, a clear-water zone with relatively low levels of nutrient input. Macrophyte OM input, indicated by the middle-chain n-alkanes and Paq ((n-C23 + n-C25)/(n-C23 + n-C25 + n-C29 + n-C31)), was only identified in sediments from the East Bays. The lowest recorded inputs for both autochthonous and allochthonous OM were in sediments from open areas with significant sediment resuspension, including Gonghu Bay, Central and Western Region. This finding might reflect degradation mineralization of OM in the water column during sediment resuspension.