Diet and reproductive biology of the Starred Agama,Laudakia stellio (Linnaeus, 1758) (Squamata: Agamidae), in the northern Sinai,Egypt

We quantified sexual size dimorphism, diet and reproduction in the Starred Agama, Laudakia stellio, in northern Sinai. Males were larger than females in snout-vent length and head index. The species is a sit-and-wait predator and feeds on insects, mainly coleopterans. About 30% of stomachs included plant material. No difference between sexes existed in terms of prey size preference. The reproductive season is seen to be year round with no distinctive seasonality. The smallest sexually mature female measured 92 mm SVL, whereas the smallest sexually reproductive male was 89 mm SVL. Clutch size ranged from 6 to 18 eggs.     

Platform environments, microfacies and systems tracts of the upper Cenomanian-lower Santonian of Sinai, Egypt

Summary Factors controlling grain composition and depositional environments of upper Cenomanian—Santonian limestones of Sinai are discussed. The mainly shallow-water, inner-platform setting investigated is subdivided into five major facies belts, each represented by several microfacies types (MFTs). Their lateral distribution patterns and their composition underline aclear relation between depositional environment and platform position. The facies belts include sandstones and quartzose packstones of siliciclastic shorefaces, mudstones and bioclastic wackestones of restricted lagoons, shallow-subtidal packstones with diverse benthic foraminifera and calcareous algae, bioclastic and/or oolitic grainstones of inner-platform shoals, and wackestones of deep open-marine environments. The microfacies distribution patterns of the Cenomanian-Santonian strata are evaluated with respect to local and regional large-scale environmental changes. While protected shallow-subtidal environments with only subordinate ooids and oncoids prevail during the late Cenomanian, high-energy oolithic shoals and carbonate sands occur locally during the middle and late Turonian. They were probably related to a change of the platform morphology and a reorganisation of the platform after a late Cenomanian drowning. In the Coniacian-Santonian, the lack of ooids, oncoids, and the decrease of calcareous algae versus an increase in siliciclastics indicate a shift to lower water temperature and to a more humid climate. Especially in the Turonian, the interplay between sea-level changes, accommodation, hydrodynamics, and siliciclastic input is reflected by lithofacies and biofacies interrelation-ships that are elaborated within individual systems tracts. In particular, increasing accommodation intensified circulation and wave-agitation and controlled the distribution of high-energy environments of the middle and upper Turonian trans-gressive systems tracts. During highstands protected innerplatform environments prevailed.     

Lithostratigraphy and facies development of upper cretaceous carbonates in east central Sinai,Egypt

Summary The Upper Cretaceous exposures in east central Sinai are represented by carbonate-dominated successions interbedding few sandstone, chert, shale and marl horizons. The recognised rock units are correlated with their counterparts commonly used in the Gulf of Suez region and central Sinai including from base to top: the Raha Formation, Abu Qada Formation, Wata Formation, Matulla Formation and the Sudr Chalk. Twelve limestone microfacies are encountered and are categorised as mudstones (pelmicrite and ostracod micrite), wackestones (pelagic biomicrite and foraminiferal biomicrite), grainstones (foraminiferal biopelsparite and oosparite), boundstones (bindstone and framestone), floatstones (coated-grained biomicrudite, rudist biomicrudite and shelly biomicrudite) and rudstones (shelly biosparudite). The dolostone microfacies include fine-medium crystalline ostracod dolostones and shelly dolostones. These microfacies have been compared with the Standard Microfacies Types and their depositional environments are discussed. The encountered litho- and biofacies suggest that the Cenomanian shallow transgressive sea had covered east central Sinai as far south as the Dahab region. By the advent of the Turonian, open marine subtidal conditions prevailed. This was followed by transitional conditions with shoals and tidal bars in the Late Turonian pointing to a regressive phase more pronounced at the southern localities. The rocks of the Matulla Formation were deposited in an oscillating environment of shallow subtidal to intertidal conditions during Coniacian-Santonian. In the Late Santonian and during most of the Campanian-Maastrichtian, sedimentation was influenced by open marine conditions with low sedimentation rates; local shallow subtidal regressive events occurred.     

Colonization and bionomics of the sandfly Phlebotomus kazeruni from Sinai, Egypt

Phlebotomuius kazeruni (Diptera: Psychodidae) females were collected by light-trap in southern Sinai, Egypt, and this sandfly species was colonized for the first time as a laboratory strain, maintained by the procedures of Modi & Tesh (1983). Laboratory-reared females did not lay eggs autogenously; they blood-fed more readily (P=0.02) on a hamster (37%) than a human (22%) during 1 h exposure. Fecundity of hamster-fed females was significantly greater than for those fed on human blood: 69.4 +/- 5.8 vs. 45.2 +/- 8.1 eggs/female from the first gonotrophic cycle. Pre-oviposition and egg incubation periods were significantly less for females fed on hamster compared with human blood, but the larval development and pupation periods were not affected by this difference in bloodmeal source. Egg to adult survival was equivalent (38%) for progeny of females blood-fed on hamster or human. The mean generation time of progeny from females fed on hamster (51.9 +/- 1.0 days) or human (53.3 +/- 1.7 days) was not significantly different. The sex ratio of adult male:female progeny was similar (P=0.2) for both hosts: 42:58% from hamster, 46:54% from human blood-fed female parents. Evidently P. kazeruni from Sinai is sufficiently anthropophagic to be a potential vector of Leishmania from rodents to humans.     

Sedimentary response to basin inversion: Mid cretaceous-early tertiary pre- to syndeformational deposition at the Areif El Naqa anticline (Sinai, Egypt)

Summary The Areif El Naqa domal anticline in northeastern Sinai is part of the ‘Syrian Arc’ which represents an intraplate orogen that has been formed since the late Cretaceous by inversion of an older half-gaben system as a consequence of the collision of the African and Eurasian plates. The here studied pre- and syn-deformational Upper Albian to Lower Eocene sedimentary succession in the anticline was formed under shallow marine to hemipelagic conditions resulting in predominantly carbonate lithologies with only subordinate siliciclastic intercalations. The depositional history at Areif El Naqa has been reconstructed in terms of sequence stratigraphy on the basis of detailed sedimentological, biostratigraphical, and paleoecological investigations of ten sections including comparisons with age-equivalent successions further north and south as well as published data. Following a late Triassic-early Cretaceous extensional period, tectonically rather quiet conditions prevailed during deposition of the Albian-Turonian successions. Inversion started around the Coniacian. Three main phases of uplift have been determined for the Areif El Naqa anticline on the basis of evidence from lateral facies and thickness changes, local development of pronounced hiatuses, and in comparison to the sequence stratigraphic development in the tectonically quiet region of central east Sinai. The first major compressional phase is interpreted to have taken place in Coniacian-early Santonian times. It is characterized by pronounced facies and thickness changes which were documented in an earlier study byBartov et al. (1980). Nevertheless, inter-regional sea level changes still controlled deposition at Areif El Naqa during this period. The second pulse of tectonic uplift is indicated for the late Campanian-early Maastrichtian. This is based on siliciclastic deposits which are interpreted as having been reworked from older siliciclastic rocks uplifted in the anticlinal core. The third compressional pulse is inferred to be of middle Paleocene to early Eocene age as evidenced by a major hiatus in sections on the northern anticlinal flank. The uplift history at Areif El Naqa has been compared with the tectonic development in other parts of the Syrian Arc and in general seems to reflect major movements which occurred throughout the anticlines of the fold belt.     

Quantitative analysis of accommodation patterns in carbonate platforms: an example from the mid-Cretaceous of SE Spain

For sequence stratigraphic analysis of extensive carbonate platforms (hundreds of kilometres wide) developed in greenhouse climates on broad, passive margins, less emphasis should be placed on large-scale seismic geometries, and more attention paid to sequence stratigraphic correlation of stratigraphic sections based usually on isolated outcrops. To this end, quantitative analysis of accommodation emerges as a simple, useful tool, that allows detailed architectural reconstructions, regional chronostratigraphical correlation and systems tract interpretation. In this paper, a quantitative analysis of accommodation was applied to the wide platforms that developed in the southern passive continental margin of Iberia during the mid-Cretaceous (late Albian to early middle Cenomanian interval). This analysis was based on several integrated techniques including: (1) construction of total accommodation curves with the aid of backstripping techniques for calculating decompacted sedimentary accumulation through time, (2) mathematical analysis of these curves and characterisation of second- and third-order accommodation patterns, and (3) analysis of parasequence stacking patterns in peritidal cyclic successions by means of Fischer plots. By applying these techniques to eight individual sections logged at the decimetre scale in outcrops of the External Zones of the Betic orogenic belt, it was possible to characterise the second- and third-order accommodation signal for this interval in the basin. The second-order curve defines a long-term sigmoidal pattern of nearly six million years, with low rates of accommodation generation in the first and the last part of the interval, and high rates in the mid-interval. The third-order signal defines six accommodation events of one million years average duration, which controlled the development of six successive depositional sequences and their systems tracts. On the basis of this new sequence stratigraphic framework, a high-resolution, 2-D platform transect, showing the spatial distribution of facies, was erected and analysed. The results notably complete previous qualitative sequence stratigraphic data on the platform and contribute to a better understanding of the nature of systems tracts and their boundaries in response to overlapping of second- and third-order accommodation patterns.     

Bio-seismic and sequence stratigraphy of the Neogene of the Northwest Damietta Concession,Nile Delta,Egypt

The stratigraphic framework of the Neogene sequence drilled by two offshore wells located in the north-eastern shore of the Nile Delta (the wells Sekhmet-1 and Sekhmet-2) has been established. The lithostratigraphic units with their sequences, from older to younger, are as follows: the Sidi Salim Formation (including Sr1 SB, Sr2 SB, Sr2 MFS, Sr3 SB and Sr3 MFS), a sequence representing the uppermost part of the Sidi Salim and most of the lower part of the Qawasim Formations (including Tor 1.1 SB, Tor 1.2 SB, Tor 1.3 SB, Tor 1.4 SB and ?Tor 2 SB), a sequence representing the uppermost part of Qawasim and the lower part of the Abu Madi Formations (including ?Me1 SB, Me2 SB and Me2 MFS), the Kafr El Sheikh Formation (including alternatively Za 1 and 2 SB and MFS and Ge 1 SB and MFS), the El Wastani Formation (including Ge 2 SB and MFS) and a Quaternary sequence represented by the topmost part of El Wastani and Mit Ghamr/Bilqas Formation (including alternatively ?Cala 1 and 2 SB and MFS and ?Io 2 SB). The lower part of the Qawasim in well Sekhmet-2 includes two LST: Tor 2 LST and Me 1 LST.     

Coralline-algal assemblages of a Burdigalian platform slope: implications for carbonate platform reconstruction (northern Sardinia,western Mediterranean Sea)

The rhodolithic slope deposits of a Burdigalian carbonate platform in Sardinia near Sedini were analyzed to reconstruct facies and palaeobathymetry. There is a distinct red-algal growth zonation along the platform slope. The clinoform rollover area consists of coralline-algal bindstones, which downslope change into a zone where rhodoliths are locally fused by progressive encrustation. Mid-slope rhodoliths are moderately branched, and downslope rhodoliths have fruticose protuberances, resulting in branching rhodolith growth patterns. There is a sharp change from the rhodolitic rudstones to the basinal, bivalve-dominated rudstones at the clinoform bottomsets. Red-algal genera identified include Sporolithon, Lithophyllum, Spongites, Hydrolithon, Mesophyllum, Lithoporella, Neogoniolithon, and other mastophoroids and melobesioids. Genera and subfamilies show a zonation along the clinoforms, allowing palaeobathymetric estimates. The clinoform rollovers formed at a water depth of around 40 m and the bottomsets around 60 m. Results from geometrical reconstruction show that coral reefs in the inner platform formed at water depths of around 20 m. Therefore, the Sedini carbonate platform is an example of a reef-bearing platform in which the edge or the platform-interior reefs do not build up to sea level.     

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.     

Oligocene larger foraminifera from United Arab Emirates,Oman and Western Desert of Egypt

An early Oligocene (Rupelian) diagnostic larger foraminiferal assemblage is described and illustrated from marls and limestones of the Asmari Formation, at Jabals Hafit and Malaqet in the UAE. An equivalent assemblage is identified in the mudstones of the Tahwah Formation, Wadi Suq, Oman. Although Nummulites intermedius (D'Archiac 1846) and N. fichteli are fully synonymous (e.g. Roveda 1970; Schaub 1981; Sirel 2003), in this study both species are biometrically differentiated, distinct and both names are valid. N. fichteli Michelotti 1841, N. intermedius (D'Archiac 1846) and N. emiratus n. sp., which are index for the early Oligocene (Rupelian), and they are replacing each others competitively and environmentally.

The presence of Blondeauina bouillei n.gen., N. emiratus n.sp., N. intermedius, N. fichteli, Planoperculina complanata (Defrance 1822) and Austrotrillina asmariensis Adams 1968 ascribed the section of the Asmari Formation to the early Oligocene (Rupelian). The studied marls and limestones were deposited in outer and inner shelf environments, respectively. The Asmari Formation in the area studied consists mainly of marl in its lower portion and reefal limestone in its upper part, indicating a major marine regression. The Tahwah Formation in Oman is composed of bioturbated silty and muddy marls and is a facies equivalent to the Asmari Formation marls. The Asmari Formation facies change probably relates to a mid-Oligocene fall in global sea level.

In this study, the Dabaa Formation, a subsurface unit of late Eocene–Oligocene marine shales in the north Western Desert of Egypt, was chosen to correlate with the Oligocene of Emirates and Oman. The Dabaa Formation comprises Spiroclypeus ornatus (Henson 1937) and Eulepidina dilatata (Michelotti 1861). The environment of deposition was inner shelf to littoral, which become estuarine towards the top in many areas. This Oligocene Dabaa sequence is correlatable with Wadi El Arish sequence recently discovered by Kuss and Boukhary (2008) from Risan Aneiza, Northern Sinai, Egypt.     

Facies arrangement and cyclostratigraphic architecture of a shallow-marine,warm-water carbonate platform: the Late Carboniferous Ny Friesland Platform in eastern Spitsbergen (Pyefjellet Beds,Wordiekammen Formation,Gipsdalen Group)

During the Late Carboniferous, a spacious warm-water carbonate platform developed across the eastern part of the present Arctic archipelago of Svalbard. The platform initiated in the Moscovian on an uplifted fault block (Ny Friesland High) and progradated during the Late Moscovian to Early Kasimovian into the adjacent Campbellryggen Basin (central Spitsbergen). The fossiliferous platform strata are characterized by a pronounced cyclicity formed by stacked parasequences, which consist of defined, subtidal to supratidal facies-set successions reflecting a general shallowing of the depositional area. Up to 17 of these shallowing-upward cycles, bounded by distinct discontinuity (marine flooding) surfaces due to the recurrent emersion and subsequent flooding of the platform surface, have been recognized within the platform strata. The stacked cycles are the result of global, glacio-eustatic, high-frequent and high-amplitudinal sea-level fluctuations with eccentricity periodicities caused by ice volume changes during the Gondwana Land glaciation. Based on systematic changes of the cycles (thickness and internal facies composition), the upper part of the platform strata is interpreted as a progradational parasequence set of a late highstand system tract. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Distribution and environmental control of coral assemblages in northern Safaga Bay (Red Sea, Egypt)

Summary Coral assemblages in northern Safaga Bay, Red Sea, Egypt, are qualitatively described. Nine distinct assemblages were found, which correspond to quantitatively defined community types previously described from the area off Hurghada, northern Red Sea. Their distribution within northern Safaga Bay was mapped. Strong gradient and/or steep relief assemblages were:Acropora assemblage on windward (exposed) reefs,Porites assemblage on leeward (sheltered) reefs,Millepora assemblage on current exposed reefs,Stylophora assemblage on reef flats. Low gradient and/or low relief assemblages were:Acropora dominated coral patches in areas of good circulation to a depth of 15 m,Stylophora/Acropora coral patch assemblages in shallow sheltered environments, faviid carpet in low relief areas between 10 and 25 m which with increasing turbidity turns into a depauperate faviid carpet,Porites carpet in low relief areas between 5 and 15 m with clearest water,Sarcophyton carpet in low relief areas with high suspension load, platy scleractinian assemblage in deeper water (>25 m) with low light intensity. The distribution of coral assemblages depends basically on 1) topography 2) hydrodynamics 3) light and 4) suspension load.     

Microfacies controls on weathering of carbonate building stones: Devonian (northern Sauerland,Germany)

Summary The Beisinghausen Limestone (Upper Givetian to Frasnian) in the Eslohe-Reiste area (northern Sauerland), used in the past as building stone, corresponds to proximal carbonate turbidites which have been derived from the Attendom-Elspe ‘reef’ complex. The particles of this allodapic limestone originated in different parts of the carbonate complex as shown by facies-diagnostic microfossils (foraminifera, calcisphaeres, calcareous algae, microproblematica). The fossils as well as the other dominating grain types (lumps, peloids) point to source areas located within lagoonal and slope environments. Reef-derived material is rare. The turbidites exhibit four microfacies types, differentiated by composition and size of the grains as well as by micrite content and corresponding to the common vertical and lateral textural variation of limestone turbidites. These MF types were recognized in outcrops as well as from building stones used in building the St. Pankratius church in Eslohe-Reiste (northern Sauerland) in 1849 and in the renovation of the church in 1963/64. The comparison of microfacies and the degree of the destruction of ‘old’ and ‘new” building stones by weathering (macroscopically described by the ◂Fabric Index’: Product of the ‘Rock Destruction Risk’ and the ‘Rock Preparation Destruction Degree’) shows that intrabioclastic rudstones (MF type 1) and bioclastic grainstones (MF type 2), both characterizing the basal parts of the turbidite beds, are more resistant to weathering destruction originating from freezing and thawing than packstones (MF type 4). Weathering of micritic facies types (e.g., MF 4) is more intensive due to the stronger development of joint systems affecting not only the surface of the building stones but the entire dimension stone. Porosity or the existence and amount of stylolites seem to have had no significant impact on the weathering of the building stones studied. The stronger weathering of building stones used in the original construction of the church as compared with the stones applied in this century is caused by the greater time interval available for mechanical weathering connected with freezing and thawing. The consideration of microfacies of limestone turbidites should facilitate the exploitation of weathering-resistant carbonate building stones.     

Filament lumachelle on top of Middle Jurassic oolite limestones: event deposits marking the drowning of a Tethysian carbonate platform (Subbetic,southern Spain)

Bioclastic accumulations often occur on top of Tethysian carbonate platforms and crinoids are a common constituent of these bioclastic deposits on Lower and Middle Liassic carbonate platforms. In contrast, the relevant literature contains few examples in which the main constituent of the lumachels is thin-shelled bivalves (filaments). This paper presents a study of a filament lumachelle cropping out on top of a Middle Jurassic carbonate platform. The carbonate platform is represented by the Jabalcuz Formation, found in one of the northernmost Subbetic units (south of Jaén city). The lumachelle marks the demise of the carbonate platform and has special features that characterize the drowning phase. This process has been related with the syn-rift extensional tectonics associated to the opening of the Tethys westwards. Stratigraphically, the lumachelle occurs on top of shallow-water oolite limestones (Middle Jurassic) and is overlain by radiolarian-rich pelagic and resedimented deposits (Latest Callovian–Oxfordian). It occurs as a body (about 1.5 km wide and up to 8 m thick) made up entirely of densely packed thin bivalve shells. A remarkable feature of the bivalve shell beds is stromatolite-like crumpled lamination at the outcrop. The observations made at the outcrop scale, by microscope under transmitted light, and by cathodoluminiscence favor a diagenetic origin for this striking structure. Other hypotheses, such as its possible relation with seismicity, cannot be confirmed. The filaments would have filled one of the former basins that originated in relation with syn-rift fault-block tectonics leading to the demise of the carbonate platform. Tectonics was one of the main factors setting in motion a carbonate productivity crisis and the inhibition of a diverse benthic community. Once production failed in the carbonate factory, storms and probably hurricanes as well, swept shell deposits from the shallowest areas of the shallow-water carbonate platform and accumulated them in a coevally formed small half-graben basin. At least three main depositional stages can be differentiated in the fill of this half-graben basin, which was a sediment trap for the accumulation and preservation of the tiny bivalve shells against ebb surges. The massive accumulation of valves, the shortage of micrite around the filaments, outcrop morphology and facies relationships, along with regional geology, are among the arguments supporting this interpretation.     

Effects of calcium preloading on the growth of calcium carbonate crystals in the endolymphatic sac of the tree frog,Hyla arbores japonica

Summary Tree frogs, either with or without calcium chloride preloading, were maintained in a 0.8% strontium chloride solution for 1 week, then studied by X-ray microanalysis and scanning electron microscopy to determine the distribution of incorporated strontium in the endolymphatic crystals. In the absence of calcium preloading, strontium was detected on every surface of all the crystals, but after calcium preloading for 5 or 7 weeks, strontium incorporation was partially or completely inhibited, suggesting that an inhibition of the growth of the endolymphatic crystals had taken place in these preloaded specimens.     

Paleoecologic,temporal, and spatial analysis of early Silurian Reefs of the Chicotte Formation,Anticosti Island,Quebec, Canada

Summary Reefs of the Lower Silurian Chicotte Formation are the largest and most faunally diverse known on Anticosti Island, Quebec. They reach up to 25 m in thickness and 250 m in diameter and are present predominantly at two intervals, forming a lower and upper reef cluster. Remnants of bioherms are represented on the present-day wave-cut terrace as 60 to 100 m diameter, subcircular erosional depressions known as Philip structures or as outcrop. The bioherms were relatively low structures, with approximately 3 to 5 m maximum synoptic relief, some of which developed on hardgrounds and possible paleokarst surfaces of crinoidal wackestone and packstone. Dominant skeletal framework builders and sediment producers within all of the reefs are laminar to low domical stromatoporoids, colonial cerioid and fasciculate rugose corals, colonial tabulate corals, and cryptostome bryozoans. Vertical zonation of reef biota is evident within well-exposed reefs of the lower reef cluster. Three to four stages are recognizable:1) a low-diversity tabulate coral-dominatedpioneering community including large tabulate coral colonies (halysitids and favositids), and few stromatoporoids (clathrodictyids, ecclimadictyids), fasciculate rugosans, large generally monotypic stalked crinoids, and shelly benthos (brachiopods, few ostracodes and trilobites);2) an intermediate- to high-diversity, mixed tabulate coral-stromatoporoid-dominatedreef-core community;3) a slightly lower diversity stromatoporoid-tabulate coral-dominatedclimax community with laminar coenitids and alveolitids; and,4) in a few localities, a capping, low-diversity tabulatecoral-dominated (alveolitid and coenitid), and stromatoporoid-bearing community comprising laminar forms. Amelioration of Early Silurian climates, following Late Ordovician glaciation, allowed gradual reestablishment of extensive shallow-water reef growth, by mainly new and increasingly diverse genera and species of metazoans. Reef development within the Chicotte Formation coincided with global, widespread development of latest Llandovery and earliest Wenlock reefs in subtropical to tropical areas. Chicotte reefs have broad characteristics, in terms of overall biotic composition, vertical successions recognized, and paleogeographic setting, similar to those of equivalent and slightly younger age from intracratonic settings in Baltica (Gotland, Sweden and Estonia) and central and northern Laurentia (Midcontinent, U.S.A.; Hudson Bay, Canada; and North Greenland, Denmark).