Regressive Episodes Research Articles

Shifting Tides in South Asia: Sri Lanka’s Postwar Descent

Abstract: While many had hoped that the end of Sri Lanka’s long-running civil war in May 2009 might bring about a restoration of the rule of law and reconciliation between the Sinhalese majority and the Tamil minority, the government under President Mahinda Rajapaksa has continued its march down the authoritarian path. By further centralizing power under his office and family, by transforming the parliament and judiciary into veritable arms of the executive, and by promoting a culture of impunity whereby political elites and military personnel face little or no consequences for their blatant violations of human rights and malfeasance, the Rajapaksa regime has presided over one of the island’s worst episodes of democratic regression.

Discontinuity surfaces in Upper Cretaceous to Paleogene carbonates of central Dalmatia (Croatia): Glossifungites ichnofacies, biogenic calcretes, and stratigraphic implications

Substrate-controlled ichnofacies and biogenic calcretes represent key features for identification and interpretation of discontinuities in the carbonate rock record, which are of great significance for stratigraphic interpretations and correlations. Intraformational firmground and composite surfaces, as well as a regional Cretaceous to Paleogene (K–Pg) subaerial unconformity, developed in Upper Cretaceous to Paleogene intra-platform peritidal successions in central Dalmatia, Croatia (Adriatic-Dinaridic Carbonate Platform, ADCP), were analyzed for their trace fossil and subaerial exposure features. Thalassinoides (probably T. paradoxicus) box-work burrow systems of the substrate-controlled Glossifungites ichnofacies characterize the two documented firmgrounds and one composite (polygenic) surface. Rhizogenic laminar calcretes developed subsequently inside burrows of the composite surface through diagenetic overprint of marine sediment that passively infilled the burrows. While the formation of the two firmgrounds was probably caused by cessation of precipitation and/or deposition of calcium carbonate due to relative sea-level fall, the recorded trace fossils associated with the composite surface indicate that this surface developed through both submarine firmground and subaerial exposure stages probably caused by several episodes of regression and transgression, and exemplifies the general complexity of hiatal surfaces in shallow-marine carbonate successions. The regional K–Pg subaerial unconformity is characterized by biogenic (beta microfabric) calcretes with rhizoliths including Microcodium aggregates, root tubules, as well as alveolar-septal structures. Laminar calcretes and pisoids, together with in situ and resedimented speleothems, and bauxitic deposits, were also recorded. The unconformity developed due to formation of a forebulge in front of the approaching Dinaridic orogen. Ichnological and subaerial exposure features, together with stratigraphic implications derived from the analyzed discontinuities, serve as examples that can be applied to discontinuities present in carbonate successions elsewhere.

Late Wenlock sequence and bentonite stratigraphy in the Malvern, Suckley and Abberley Hills, England

The Late Wenlock Series (Homerian Stage) of the central Midland Platform occupies an area stretching from Ledbury to the Malvern, Suckley and Abberley Hills. Based upon the establishment of a sequence stratigraphic framework for the Much Wenlock Limestone Formation, and the immediately under- and over-lying Coalbrookdale and Lower Elton Formations, comparisons can now be made with key sections across the northern Midland Platform and beyond. These correlations have been strengthened by the determination of apatite rare earth element (REE) geochemical signatures obtained from four volcanic ash layers (bentonites) at Whitman's Hill Quarry (Herefordshire), which allow for comparisons with published coeval sections at Wren's Nest Hill (West Midlands) and Wenlock Edge (Shropshire), as well as with bentonites described from the Island of Gotland (Sweden).Across the study area fifteen parasequences associated with two pronounced regressive episodes, separated by a marked transgression, can be identified. The lithological responses to these relative sea-level changes are the same as those reported from the West Midlands, including the threefold division of the Much Wenlock Limestone Formation into Lower Quarried Limestone, Nodular Beds and Upper Quarried Limestone Members. Apatite REE geochemical signatures from Whitman's Hill Quarry identify three bentonites which probably originated from a granodiorite magmatic source, while a fourth bentonite has a distinctively mafic composition, more akin to that of a gabbro or syenite. This distinctively mafic bentonite is preserved on a marked flooding surface within the Nodular Beds Member and appears compositionally and stratigraphically equivalent to a bentonite at Wren's Nest Hill (West Midlands). Furthermore in both sections this bentonite is of notable thickness (120–200mm) allowing for its identification in other sections across the region. Comparisons with Gotland identify three closely spaced bentonites of a similar mafic composition to the bentonite described from the Midland Platform. While similarities in stratigraphic position and composition do not, at present, allow for the identification of a single ash fall event covering both the Midland Platform and Gotland, they are indicative of a shared source region, which may offer the possibility for future bentonite correlation between these regions.

Language Regression Associated With Autistic Regression and Electroencephalographic (EEG) Abnormalities

We report a boy, referred at 25 months following a dramatic isolated language regression antedating autistic-like symptomatology. His sleep electroencephalogram (EEG) showed persistent focal epileptiform activity over the left parietal and vertex areas never associated with clinical seizures. He was started on adrenocorticotropic hormone (ACTH) with a significant improvement in language, behavior, and in EEG discharges in rapid eye movement (REM) sleep. Later course was characterized by fluctuations/regressions in language and behavior abilities, in phase with recrudescence of EEG abnormalities prompting additional ACTH courses that led to remarkable decrease in EEG abnormalities, improvement in language, and to a lesser degree, in autistic behavior. The timely documentation of regression episodes suggesting an "atypical" autistic regression, striking therapy-induced improvement, fluctuation of symptomatology over time could be ascribed to recurrent and persisting EEG abnormalities.

The origin of coexisting carbonates in banded iron formations: A micro-mineralogical study of the 2.4 Ga Itabira Group, Brazil

This is the first petrographic and chemical study on the origin of co-existing calcite, dolomite, ankerite and sideroplesite in the 2.4Ga Itabira Group, Brazil. The Itabira Group hosts silicic and dolomitic BIFs, known as quartz itabirites and carbonate itabirites, which are composed of micritic quartz and dolomite with inclusions of nano- and micro-hematite. Nanometric Si-bearing ferrihydrite clusters are observed in the micritic dolomite. Mineralogical and textural features indicate a primary oxidising depositional environment for the Itabira Group at 2.4Ga. Limestones of the Itabira Group include early diagenetic hematite nodules intergrown with dolomite. Silica in the ferrihydrite structure increases its stability up to 500°C, and the nano- and micro-hematite included in dolomite and quartz were partially protected from later transformation by being enclosed within the dolomite and quartz crystals.Positive Eu and Y anomalies and heavy rare earth element enrichments of all lithofacies, along with their low terrestrial element abundance (excluding the shales), indicate their primary precipitation from a mixed hydrothermal-marine environment. In the case of the carbonate itabirites, fluids were CO2 rich. Dolomite precipitated abiotically due to higher temperatures (∼100°C) and high Mg/Ca ratios. The facies changes from carbonate-rich to quartz-rich are attributed to transgression and regression episodes and/or a change in the upwelling hydrothermal fluid composition.Post depositional reductive dissolution affected the quartz itabirites facilitating the precipitation of ankerite, sideroplesite and magnetite/sulphides from a reducing diagenetic solution, rich in Mn, Mg and Fe, either as lenses or disseminated, in the quartz itabirites and shales. The sideroplesite-richest samples have the most negative δ13C values (quartz itabirite: −9.49‰; shale: −5.76‰), indicating that at least part of the C is of organic origin, either through the oxidation of organic matter or introduced via the diagenetic fluids. Specularite is replacive and likely related to a post-depositional hydrothermal event.This study shows that careful mineralogical investigations combined with REE+Y and trace element geochemistry is necessary in order to decipher the depositional environments, which are oxidising, mixed marine-hydrothermal. Post-depositional reductive diagenesis masks in part these primary conditions.

Sequence stratigraphic analysis of Cenomanian greenhouse palaeosols: A case study from southern Patagonia, Argentina

The aim of this contribution is to analyse extrinsic (i.e., tectonics, climate and eustasy) and intrinsic (i.e., palaeotopography, palaeodrainage and relative sedimentation rates) factors that controlled palaeosol development in the Cenomanian Mata Amarilla Formation (Austral foreland basin, southwestern Patagonia, Argentina). Detailed sedimentological logs, facies analysis, pedofeatures and palaeosol horizon identification led to the definition of six pedotypes, which represent Histosols, acid sulphate Histosols, Vertisols, hydromorphic Vertisols, Inceptisols and vertic Alfisols.Small- and large-scale changes in palaeosol development were recognised throughout the units. Small-scale or high-frequency variations, identified within the middle section are represented by the lateral and vertical superimposition of Inceptisols, Vertisols and hydromorphic Vertisols. Lateral changes are interpreted as the result of intrinsic factors to the depositional systems, such as the relative position within the floodplain and the distance from the main channels, that condition the nature of parent material, the sedimentation rate and eventually the palaeotopographic position. Vertical stacking of different soil types is linked to avulsion processes and the relatively abrupt change in the distance to main channels as the system aggraded.The large-scale or low-frequency vertical variations in palaeosol type occurring in the Mata Amarilla Formation are related to long-term changes in depositional environments. The lower and upper sections of the studied logs are characterised by Histosols and acid sulphate Histosols, and few hydromorphic Vertisols associated with low-gradient coastal environments (i.e., lagoons, estuaries and distal fluvial systems). At the lower boundary of the middle section, a thick palaeosol succession composed of vertic Alfisols occurs. The rest of the middle section is characterised by Vertisols, hydromorphic Vertisols and Inceptisols occurring on distal and proximal fluvial floodplains, respectively.The palaeosol succession for the Mata Amarilla Formation can be analysed within a sequence stratigraphic scheme considering changes in depositional environments in relation to accommodation/supply conditions. The results contrast with classical models, mainly in that the palaeosols of the Mata Amarilla Formation are relatively well-developed throughout the whole sequence, including transgressive periods of relatively high aggradation rate. Also, even when during regressive episodes, when a thick palaeosol succession that marks the sequence boundary is developed in the classical models, the lack of incised valleys in this succession led to the preservation of thick palaeosol successions during lowstand conditions. The vertical and lateral palaeosol distribution identified in the Mata Amarilla Formation could be eventually extrapolated to other sequences deposited during climate optimums.

Novel Infantile-Onset Leukoencephalopathy With High Lactate Level and Slow Improvement

To describe a novel pattern of magnetic resonance imaging (MRI) abnormalities as well as the associated clinical and laboratory findings. The MRIs of more than 3000 patients with an unclassified leukoencephalopathy were systematically reviewed.Clinical and laboratory data were retrospectively collected. University hospital. Seven patients (3 male) shared similar MRI abnormalities and clinical features. Pattern of MRI abnormalities and clinical and laboratory findings. The MRIs showed signal abnormalities of the deep cerebral white matter, corpus callosum, thalamus, basal ganglia,brainstem, and cerebellar white matter between the ages of 9 months and 2 years. On follow-up, abnormalities gradually improved. Clinical regression occurred in the second half-year of life with spasticity and loss of milestones.From the second year on, clinical improvement occurred.So far, no second episode of regression has happened.Lactate levels were elevated during clinical regression. These patients represent a single novel leukoencephalopathy,probably caused by a mitochondrial defect.

Diversity Dynamics of Callovian-Albian Brachiopods in the Northern Caucasus (Northern Neo-Tethys) and a Jurassic/Cretaceous Mass Extinction

The fossil records of the Northern Caucasus (southwestern Russia) provide an exceptional opportunity to reveal the evolution of brachiopods during the Callovian-Albian time interval and to evaluate the regional evidence for a Jurassic/Cretaceous mass extinction. Stratigraphic ranges of 119 species, 52 genera, 25 families, 13 superfamilies, and 2 orders of brachiopods are considered to document the main patterns of their diversity dynamics. The total number of taxa was high in the Callovian-Oxfordian, then dropped in the Kimmeridgian, increased again in the Tithonian, decreased significantly in the Berriasian, and remained relatively low until the end of the Early Cretaceous except for a minor peak in the Barremian. Species, genera, families, and superfamilies of brachiopods declined remarkably in the Northern Caucasus in the Berriasian, which is regional evidence for a Jurassic/Cretaceous mass extinction. Both an acceleration in disappearance rate and a drop in appearance rate contributed to this collapse. Recovery began in the Valanginian-Hauterivian, but it was not completed at the level of species. Transgressions/regressions, growth of the carbonate platform, a salinity crisis, and oxygen depletion were important controls on the brachiopod diversity dynamics in the Northern Caucasus. A regressive episode around the Jurassic-Cretaceous transition seems to be a plausible cause of the relevant brachiopod decline. A comparison of changes in the total number of brachiopod taxa between the Neo-Tethys Ocean and the Alpine Tethys Ocean shows some difference, but both domains provide evidence for a Jurassic/Cretaceous mass extinction, which was less severe in the Swiss Alps and the Jura Mountains (Alpine Tethys) than in the Northern Caucasus (Neo-Tethys).

Long-term deforestation in NW Spain: linking the Holocene fire history to vegetation change and human activities

The Holocene fire regime is thought to have had a key role in deforestation and shrubland expansion in Galicia (NW Spain) but the contribution of past societies to vegetation burning remains poorly understood. This may be, in part, due to the fact that detailed fire records from areas in close proximity to archaeological sites are scarce. To fill this gap, we performed charcoal analysis in five colluvial soils from an archaeological area (Campo Lameiro) and compared the results to earlier studies from this area and palaeo-ecological literature from NW Spain. This analysis allowed for the reconstruction of the vegetation and fire dynamics in the area during the last ca 11 000 yrs. In the Early Holocene, Fabaceae and Betula sp. were dominant in the charcoal record. Quercus sp. started to replace these species around 10 000 cal BP, forming a deciduous forest that prevailed during the Holocene Thermal Maximum until ∼5500 cal BP. Following that, several cycles of potentially fire-induced forest regression with subsequent incomplete recovery eventually led to the formation of an open landscape dominated by shrubs (Erica sp. and Fabaceae). Major episodes of forest regression were (1) ∼5500–5000 cal BP, which marks the mid-Holocene cooling after the Holocene Thermal Maximum, but also the period during which agropastoral activities in NW Spain became widespread, and (2) ∼2000–1500 cal BP, which corresponds roughly to the end of the Roman Warm Period and the transition from the Roman to the Germanic period. The low degree of chronological precision, which is inherent in fire history reconstructions from colluvial soils, made it impossible to distinguish climatic from human-induced fires. Nonetheless, the abundance of synanthropic pollen indicators (e.g. Plantago lanceolata and Urtica dioica) since at least ∼6000 cal BP strongly suggests that humans used fire to generate and maintain pasture.

The global Taghanic Biocrisis (Givetian) in the eastern Anti-Atlas, Morocco

In the Tafilalt of the eastern Anti-Atlas, Morocco, the impact of the polyphase global Taghanic Crisis (upper part of Middle Givetian) on facies and faunas was studied in more than twenty successions of a strongly condensed hemipelagic platform (northern and central Tafilalt), of a more neritic to biostromal area with interspersed shale basins (southern Tafilalt, Amessoui Syncline), and in a predominantly hypoxic basin (southeastern Tafilalt). In the pre-crisis interval, a deepening (Depophase If-Win) and increased nutrient supply allowed faunal blooms of macrofauna, especially of goniatites ( Maenioceras), resulting in the deposition of the fossiliferous Maenioceras Marls (middle part of ansatus Zone) on the platform and of correlative dark goniatite shales in the SE. In the Amessoui Syncline, shales alternate with small-sized but widespread coral-stromatoporoid biostromes. In the western Tafilalt thin styliolinites indicate eutrophic peaks at the top. A significant pre-Taghanic regressive trend (top of Depophase If) is recorded by disconformity-bound, shallowing upwards cycles at the base, within, and at the top of the Upper Sellagoniatites Bed (higher part of ansatus Zone with Polygnathus ovatinodosus) and by corresponding biostromes and calcareous sandstones in the S and SE. The regressive episode allowed the local re-appearance of shallow-water conodonts (youngest known Bipennatus), culminated in an iron-encrusted hardground or intraclastic reworked unit, and caused local extinctions of ammonoids and of reefal fauna. The initial Taghanic Onlap (base of Depophase IIa-Tagh; upper part of ansatus Zone with rare “Po.” alveoliposticus) led to the return of marls and styliolinid-rich nodular limestones or of hypoxic shales in the S and SE. Equivalents of the Lower and Middle Tully Limestones of the North American Taghanic type area can be recognized, may display subcycles, and are separated by a minor regressive phase. A disconformity or distinctive sea-level fall, associated with the final extinction of Sobolewiidae and other goniatites, separates equivalents of the Upper Tully Limestone. The subsequent aff. amplexum Bed (base of Depophase IIa-UT) is characterized by an initial radiation of Pharciceratidae and of some conodonts ( Oz. semialternans Zone), by blooms in branching tabulate corals (youngest known Bainbridgia) and phacopid trilobites, and by a positive carbon isotope excursion. The final extinction of Maenioceratidae and Agoniatitina ( Sellagoniatites) coincided with a minor regression at the top of the Taghanic Crisis interval. Uniquely in the eastern Tafilalt, with the most complete sedimentary record, a thin bioclastic conodont lag is preserved at the base of the Upper Givetian and below the deepening of Depophase IIa-Gen. The post-Taghanic radiation of ammonoids and especially of conodonts falls in the nodular Mzerrebites erraticus Beds ( hermanni Zone) of the platform and in correlative hypoxic goniatite shales and marls of the S and SE. Radiation continued in the subsequent, haematite-rich Lunupharciceras nodules of the platform and in the widespread Lower Marker Bed (both cristatus ectypus Zone) that are separated by disconformities. The Tafilalt record confirms that the Taghanic Crisis was a second order global overturn of pelagic and reefal biota that progressed in at least three distinctive steps over several hundred thousand years. The detailed event stratigraphy allows global correlations and comparisons with other regions (New York type area, Dra Valley, France, Germany) that have been investigated in similar detail. It is assumed that the Taghanic Crisis was primarily driven by repeated and fast eustatic fluctuations and climate change (greenhouse overheating pulses), which were probably linked. Hypoxia/anoxia played only a local role in extinctions. The crisis can be recognized globally but it had very different effects regionally leading variably to faunal migrations, blooms, and extinctions.

Presence of Hypolagus Dice, 1917 (Mammalia, Lagomorpha) in the Neogene of the Balearic Islands (Western Mediterranean): Description of Hypolagus balearicus nov. sp.

In this paper we describe a new species of Hypolagus coming from an early Pliocene karstic deposit near Caló den Rafelino (Manacor, Mallorca). It represents the westernmost European record for the genus. The faunal assemblage of this deposit represents an early phase of the second insular faunal episode of Mallorca, related with the Messinian regressive episode (latest Miocene). Although the postcranial are relatively robust, the size of all these elements is included in the range of continental leporids. It is unknown if they display significant allometric changes, as occurred in other insular leporids. p3 is small and displays a markedly trapezoidal outline and a deep hypoflexid (between 54 and 56% of the total tooth width). The presence of Hypolagus in the Neogene of the Balearic Islands is in agreement with the faunal scenario for the European continent during the late Miocene and the Pliocene, where this genus is abundant and widely distributed.

No global-scale transgressive–regressive cycles in the Thanetian (Paleocene): Evidence from interregional correlation

A detailed examination of transgressions and regressions that occurred during the Thanetian (58.7–55.8 Ma) may provide an important constraint on the global palaeoenvironment. Seven tectonically “stable” regions (the eastern Russian Platform, Northwestern Europe, Northwestern Africa, Northeastern Africa, the Arabian Platform, the northern Gulf of Mexico, and Southern Australia), represent exceptional records of transgressive–regressive (T–R) cyclicity. Their chronostratigraphic frameworks are sufficiently well constrained to permit accurate correlation. Surprisingly, except for a generally regressive trend occurring in the late Thanetian, no common T–R cycles can be delineated, which indicates an absence of global-scale T–R cyclicity during the Thanetian. Furthermore, we find no clear correspondence between documented T–R patterns and previously reported eustatic changes. We suggest that a warm climate and an absence of major glaciations in the early-middle Thanetian, coupled with only slow eustatic change expected from tectonic processes, stabilized Thanetian eustatic sea level. Regional subsidence or uplift, possibly generated by mantle flow in the form of dynamic topography, governed transgressions and regressions locally and resulted in an inconsistency between T–R cycles in different parts of the globe. The late Thanetian regressive episode, which preceded the Paleocene–Eocene Thermal Maximum, may be linked to an advance of glaciation.

Holocene relative sea‐level changes in Harris, Outer Hebrides, Scotland, UK

AbstractEvidence for relative sea‐level changes during the middle and late Holocene is examined from two locations on the Atlantic coast of Harris, Outer Hebrides, Scotland, using morphological mapping and survey, stratigraphical, grain size and diatom analysis, and radiocarbon dating. The earliest event identified is a marine flood, which occurred after 7982–8348 cal. a (7370 ± 80 14C a) BP, when the sea crossed a threshold lying at −0.08 m Ordnance Datum Newlyn (OD) (−2.17 m mean high water springs (MHWS)) before withdrawing. This could have been due to a storm or to the Holocene Storegga Slide tsunami. By 6407–6122 cal. a (5500 ± 60 14C a) BP, relative sea levels had begun to fall from a sandflat surface with an indicated MHWS level of between 0.08 and −1.96 m (−2.01 to −4.05 m). This fall reached between −0.30 and −2.35 m (−2.39 to −4.44 m) after 5841–5050 cal. a (4760 ± 130 14C a) BP, but was succeeded by a relative sea‐level rise which reached between 0.54 and −1.57 m (−1.55 to −3.66 m) by 5450–4861 cal. a (4500 ± 100 14C a) BP. This rise continued, possibly with an interruption, until a second sandflat surface was reached between 2.34 and −0.26 m (0.25 to −2.35 m) between 2952–3375 cal. a (3000 ± 80 14C a) and 1948–2325 cal. a (2130 ± 70 14C a) BP, before present levels were reached. The regressive episode from the earliest sandflat is correlated with the abandonment of the Main Postglacial Shoreline. It is maintained that the fluctuations in relative sea level recorded can be correlated with similar events elsewhere on the periphery of the glacio‐isostatic centre and may therefore reflect secular changes in nearshore sea surface levels. Despite published evidence from trim lines of differential ice sheet loading across the area, no evidence of variations in uplift between the locations concerned could be found. Copyright © 2009 John Wiley & Sons, Ltd.

Climate variability in the Stephanian B based on environmental record of the Mšec Lake deposits (Kladno–Rakovník Basin, Czech Republic)

In the Stephanian B in eastern equatorial Pangaea, a large freshwater lake was formed in the continental basins of the west, central and northeast Bohemia, Czech Republic with a total area estimated at 5000–10,000 km 2 and a lifetime of 50 to 500 ky. Its size exceeded that of any Permian–Carboniferous lake in the European basins of that period so far described. Continual sedimentation of organic-rich, seasonally laminated clayey–silty lake deposits produced a unique high-resolution record of part of the Stephanian B climate in the studied region. An extraordinarily large trophic web of fish assemblages also proves the temporal stability of this meromictic oligotrophic lake. The lake hydrology was inferred from the chemical and isotopic analyses of the autochthonous carbonates, particularly siderite, and analysis of organic matter. The environmental and weathering conditions in the lake watershed were inferred from analysis of palynospectra and detrital clay minerals. The lake passed through several stages of development including an initial highstand with peak productivity, a stepwise increase in mineralization accompanying gradual lake regression, a lowstand in the middle part of its lifetime, a partial lake recovery, and then a final transition to a shallow lacustrine-deltaic system. Lake regression was triggered by a long-term decrease in the P/E ratio coupled with increasing seasonality and accompanied by a decrease in intensity of chemical weathering in the drainage basin. Considerable vegetation response to fluctuating lake levels suggests complex environmental changes. During the initial lake highstand, abundant and diversified assemblages of xerophilous elements prevailed, spores of ferns prevailed during the regressive episode, and spores of lycopsids abruptly increased at the lowstand and remained dominant in the palynospectra of the second lake highstand. Final transition to a lacustrine-deltaic system was associated with pronounced increase in sphenopsids and ferns. These changes can be attributed to Milankovitch-like climate change from warm–wet to warm–seasonal dry, and may be inferred to have been responsible for Stephanian continental cyclothems. The entire Stephanian B period was more humid than the preceding Barruelian and subsequent Stephanian C in the Czech basins, thus revealing a climate cycle at a timescale of several million years, which is discussed in relation to southern Gondwana ice sheet stability.

Meteoric diagenesis of Upper Cretaceous and Paleocene-Eocene shallow-water carbonates in the Kruja Platform (Albania): geochemical evidence

Meteoric diagenesis of Upper Cretaceous and Paleocene-Eocene shallow-water carbonates in the Kruja Platform (Albania): geochemical evidenceIn the central part of the Kruja Platform (Albania) located in the Apulian passive margin, geochemical analyses (calcimetry, Sr, REE and isotopic, δ13C and δ18O) coupled with sedimentological and sequence stratigraphic study were carried out on Upper Cretaceous (CsB4, CsB5, CsB6 Biozones) and Paleocene to Middle Eocene shallow-water carbonates that crop out in the Kruje-Dajt massif (L'Escalier section) and Makareshi massif (La Route section). The lower values in Sr contents, the homogeneous δ18O values in both sections and the covariance between δ13C and δ18O values (La Route section) are attributed to diagenesis influence by a meteoric water-buffer system, supported by petrographic observations. Moreover, a new exposure surface during the Late Cretaceous time (between CsB5 and CsB6 Biozones) may be proposed according to the low or negative excursions of Sr values, the negative excursions of isotopic values in both sections and a positive peak of normalized REE values (La Route section). These variations correlate with the geochemical signal reported by the decreasing strontium isotope values of rudist shells in the Island of Brač carbonate platform (Apulia domain) during the late Middle Campanian (77.3 Ma). Also, this continental exposure is consistent with the global sea-level fall reported from the Boreal Realm, North Atlantic, and the southern Tethyan margin. This geochemical evidence is a complementary tool for the sedimentological analysis and suggests a maximum regression (a sea-level fall) at the transition between the CsB5 and CsB6 Biozones. The high values of Sr content in Middle Eocene carbonates (L'Escalier section) reflect changes in depositional environment from restricted to open marine conditions. REE values increase through transgressive systems tract, characterized by small increase of detrital input. However, anomalies of certain values in both sections suggest disturbances linked either to the changes in clay input and to diagenetic modifications. Peaks in dolomite content are linked with regressive episodes or tendencies, and dolomitic facies, as indicated by intertidal-supratidal depositional environments.

Mechanism and geochemical implications of the Late Holocene organic carbon burial event: an example from the southwest coast of India

Carbonaceous clay found in the palaeo-deposits of Meenachil River basin was analysed for the total organic carbon, nitrogen and textural characters. Radiocarbon dating of this clay formation and the embedded carbonized wood fragments was also done. The values obtained for the organic carbon, nitrogen and C/N ratio of the carbonaceous clay exhibited a very remarkable range, suggestive of different environmental conditions of formation. It is evident from the present study that since the lignin and cellulose are the dominant components of terrestrial higher plants, allochthonous and submerged organic matter have high C/N ratio. The radio carbon dating of the sediment and wood samples suggested that the palaeo-deposits of Meenachil River basin were formed as result of many transgrassive–regressive episodes, which had started even before the formation of Vembanad Lake. The formation of carbonaceous clay, as found sandwiched in palaeo-deposits, was due to the global eustatic sea-level fluctuations and tectonism.

Unusual concentration of Early Albian arthropod-bearing amber in the Basque-Cantabrian Basi (El Soplao, Cantabria, Northern Spain): Palaeoenvironmental and palaeobiological implications

The El Soplao site is a recently-discovered Early Albian locality of the Basque-Cantabrian Basin (northern Spain) that has yielded a number of amber pieces with abundant bioinclusions. The amber-bearing deposit occurs in a non-marine to transitional marine siliciclastic unit (Las Penosas Formation) that is interleaved within a regressive-transgressive, carbonate-dominated Lower Aptian-Upper Albian marine sequence. The Las Penosas Formation corresponds to the regressive stage of this sequence and in its turn it splits into two smaller regressive-transgressive cycles. The coal and amber-bearing deposits occur in deltaic-estuarine environments developed during the maximum regressive episodes of these smaller regressive-transgressive cycles. The El Soplao amber shows Fourier Transform Infrared Spectroscopy spectra similar to other Spanish Cretaceous ambers and it is characterized by the profusion of sub-aerial, stalactite-like flows. Well-preserved plant cuticles assigned to the conifer genera Frenelopsis and Mirovia are abundant in the beds associated with amber. Leaves of the ginkgoalean genera Nehvizdya and Pseudotorellia also occur occasionally. Bioinclusions mainly consist of fossil insects of the orders Blattaria, Hemiptera, Thysanoptera, Raphidioptera, Neuroptera, Coleoptera, Hymenoptera and Diptera, although some spiders and spider webs have been observed as well. Some insects belong to groups scarce in the fossil record, such as a new morphotype of the wasp Archaeromma (of the family Mymarommatidae) and the biting midge Lebanoculicoides (of the monogeneric subfamily Lebanoculicoidinae). This new amber locality constitutes a very significant finding that will contribute to improving the knowledge and comprehension of the Albian non-marine paleoarthropod fauna.

Méningite et confusion fébrile à rechute : encéphalite limbique révélant une maladie d’Hodgkin

Introduction An observation of limbic encephalitis associated with Hodgkin’s disease is compared with rare cases of the literature. The clinical presentation was relapsing episodes of febrile cognitive disorders with confusion and meningitis, curable after treatment of Hodgkin’s disease. Recent concepts on limbic encephalitis are discussed. Case report A seventy-five-year-old patient was hospitalized because of relapsing feverish confusion episodes with meningitis. During the year before his admission he had experienced four spontaneously regressive episodes of feverish confusion. Exploration of these episodes disclosed a paraneoplastic limbic encephalitis due to an underlying Hodgkin’s disease. The treatment of Hodgkin’s disease led to perfect recovery of cognitive function, so that the patient could drive his car. Conclusion Lymphoproliferative disease, such as Hodgkin’s disease, is a possible diagnosis in patients with limbic encephalitis. A dysimmune process underlying Hodgkin’s disease might be operating in this association.

Jurassic maximum flooding surfaces in the Greater Caucasus basin (Northern Neo-Tethys)

Abstract The Greater Caucasus evolved in the Jurassic as a large elongated back-arc basin on the northern periphery of the Neo-Tethys Ocean. The semi-quantitative analysis of proportions between marine and continental facies for each of 67 time slices produced a detailed curve depicting transgressive and regressive episodes. Five remarkable peaks on this curve are interpreted as the maximum flooding surfaces (MFSs). They are established at the Sinemurian/Pliensbachian boundary (MFS1), in the upper Pliensbachian (MFS2), the lower Aalenian (MFS3), the upper Bajocian (MFS4) and the lower Tithonian (MFS5). All surfaces except for MFS4 occur within typical MFS-marking layers. The Jurassic MFSs of the Greater Caucasus Basin do not match transgression peaks of the 1st-order cycles of Western Europe and the MFSs of Arabia. Their correspondence to the global eustatic peaks also remains uncertain. The most unexpected event is found in MFS3, which occurs at a time of prominent global sea-level fall. Errors in constr...

Evolutionary rates of the Triassic marine macrofauna and sea-level changes: Evidences from the Northwestern Caucasus, Northern Neotethys (Russia)

A diverse Triassic marine macrofauna from the Northwestern Caucasus sheds new light on the biotic evolution after the end-Permian mass extinction. In the early Mesozoic, the study area was located on the northern margin of the Neotethys Ocean. Data on stratigraphic ranges of 130 genera of brachiopods, bivalves, ammonoids, corals, and sponges have been used to calculate the changes in two evolutionary rates, namely faunal transformation rate (FTR) and rate of transformation of the taxonomic diversity structure (TTDSR). The FTR demonstrates the changes in the generic composition of assemblages through geologic time, whereas the TTDSR indicates changes in the generic control of the species diversity. The Triassic marine macrofauna of the Northwestern Caucasus was characterized by very high FTR and TTDSR during the Early Triassic through early Late Triassic. The FTR slowed in the Middle Triassic, and accelerated again in the Carnian–Norian. In contrast, the FTR was abnormally slow in the Norian–Rhaetian. A remarkable turnover among macrofauna occurred at the Carnian–Norian transition. Regional sea-level changes were similar to the global eustatic fluctuations. It is difficult to establish their direct connections with changes in the evolutionary rates, although the turnover at the Carnian–Norian boundary coincided with a prominent regressive episode. In general, high evolutionary rates reported for the Triassic marine macrofauna of the Northwestern Caucasus may be explained as a consequence of the devastating end-Permian mass extinction.