Palaeoenvironmental Interpretation Research Articles

Mixed axial and transverse deep‐water systems: The Cretaceous post‐rift Lysing Formation, offshore Norway

AbstractDeep‐water stratigraphic successions from syn‐ to post‐rift stages are an archive of evolving physiographic configurations, and can record axial and transverse sedimentary sources. The healing of topography decreases the influence of syn‐rift structures on sedimentation patterns and transport processes over time, which leads to a long‐term transition from dominantly axial to transverse dispersal patterns. The Halten and Dønna terraces, offshore mid‐Norway, comprise a series of rift‐related sub‐basins established during the Jurassic, which were infilled with sediments during the Cretaceous. The Cretaceous Lysing Formation developed as slope‐ and basin‐floor fans within a series of weakly confined post‐rift sub‐basins with some shallow marine deposits interpreted on the basin margins. A deep‐water setting is supported by seismic interpretation, and bed type and architectural element analysis in all cored and uncored wells in the area. We document that an axial submarine fan system was active throughout the post‐rift stage due to subtle inherited topography from syn‐rift structures, which interacted with locally sourced transverse sediment sources. This led to a complicated stratigraphic architecture, with lobe fringe deposits of the axial fan system juxtaposed with channel‐fills and channel‐lobe transition zone deposits of transverse systems. The refined palaeogeographic reconstruction of the Lysing Formation illustrates how subtle topography can impact sediment routing patterns many millions of years after the end of rifting and can be used for palaeoenvironmental interpretations in other post‐rift settings.

Discussion of the paper by Yahya et al. 2018 entitled “Paleoenvironmental and paleoclimatic conditions during the deposition of the bauxite layer (Upper Cretaceous) using multi-proxy geochemical and palynological analyses, in the Zabirah Area, Northern Saudi Arabia” (Arabian Journal of Geosciences v.11, Article No.15)

Yahya et al. (2018) interpreted the palaeoenvironmental and palaeoclimatic conditions prevalent during the formation of the Late Cretaceous Az Zabirah Bauxite in Northern Saudi Arabia. They suggest that claystones associated with the bauxite profile are of Maastrichtian age based on palynology. This age interpretation is counter to the evidence of decades of detailed mapping and biostratigraphic analyses conducted by specialists from the Bureau de Recherches Geologiques et Minieres (BRGM) that demonstrate an Albian to Cenomanian age for the Az Zabirah Bauxite. This older age is even reported in Yahya et al.’s text quoting BRGM and Arabian American Oil Company palynology reports yet, for reasons that remain obscure, was rejected in favour of an unsubstantiated Maastrichtian age. More recent publications on the Cretaceous stratigraphy of Saudi Arabia were not cited. Furthermore, the palynology presented in the paper does not confirm their age interpretation. A second bauxite horizon, the “Pre-Aruma Bauxite” is present nearby but all descriptions and illustrations in the paper suggest that this is not the studied horizon. Moreover, recent Sr isotope dating suggests that the “Pre-Aruma Bauxite” is older than Middle Campanian. The value of sedimentological, palaeoclimatic and palaeoenvironmental interpretations requires them to be placed in their correct stratigraphic context. The authors have singularly failed to achieve this in their publication.

Phytolith transport and its influence factor in different soil types in northern temperate region

Increasing use is being made of phytoliths for quantitative palaeovegetation and palaeoclimatic reconstruction, and consequently studies of phytolith transport are attracting increasing attention. In this context, we conducted a detailed study of factors affecting the soil phytolith transport in six representative natural soil types in Northeast China. We define a phytolith transport index (T) which indicates that transport rates are the lowest in chernozem and chestnut soils, intermediate in dark brown and albic soils, and obviously higher in black and alluvial soils. Additionally, there are differences in the vertical transport of different phytolith types in the soils; however, the transport characteristics are essentially the same among the different soil types. Transport rates are lowest for tabular and blocky phytoliths, followed by bulliform phytolith. By contrast, the rates for short cell, lanceolate and elongate phytoliths are significantly higher, and, notably, these phytolith types have different size and aspect ratios. The transport of phytoliths is also mainly influenced by mean annual precipitation (MAP), soil pH and soil clay content. Climatic factors, especially MAP, are a more significant factor for phytolith transport than phytolith size and aspect ratio. Overall, our findings are significant for the palaeoenvironmental interpretation of soil phytolith assemblages in topsoils.

A multidisciplinary study and palaeoenvironmental interpretation of middle Miocene Keles lignite (Harmancık Basin, NW Turkey), with emphasis on syngenetic zeolite formation

The Harmancık Basin, in the north-easternmost Miocene graben in western Anatolia, hosts a 12.6-m-thick coal seam located in the Keles coalfield, in which coals are being exploited by open-cast mining methods. Syngenetic clinoptilolite/heulandite-type zeolite formation in the upper part of coal seam and carbonaceous clayey diatomite as a roof rock have been identified for the first time, and the palaeoenviromental reconstruction of the coal seam was conducted using a multidisciplinary approach. The coal facies and palynological data show that vegetation and depositional changes took place during the middle Miocene, which resulted in vertical variations in elemental and mineralogical compositions. During the initial stages of mire development woody vegetation (e.g. pollen with affinity to Cupressaceae) prevailed, telmatic conditions were common, and preservation of organic matter was high due to anoxic conditions. Thus, relatively low-ash yield was observed in the lower and middle parts of the coal seam. Furthermore, the presence of kaolinite and smectite-type clay mineral aggregates in these parts of the coal seam suggests that alteration of synchronous volcanic inputs took place under weak acidic to neutral conditions. In contrast, limnotelmatic conditions prevailed during the late stages of peat-accumulation, and macrophytes coinciding with herbaceous peat-forming vegetation (e.g. Osmundaceae, Polypodiaceae, and Nymphaeaceae) were dominant. The elevated Gelification Index (GI) values in the uppermost parts of the coal seam could be related to development of alkaline conditions in the palaeomires, which also caused formation of syngenetic clinoptilolite/heulandite-type zeolite from the alkaline activations of synchronous volcanic inputs. Even though palynological data points to the prevalence of freshwater conditions during peat-accumulation, B enrichments along Sr/Ba ratio higher than 1.0 could point to possible marine influence; however, no Neogene marine deposits have been identified in the Harmacik Basin. Nevertheless, the SEM-EDX data show the presence of traceable Ba and Sr in clinoptilolite/heulandite grains, and Sr-bearing barite around feldspar grains in the studied samples from the upper parts of the coal seam. This implies K-feldspars and K-rich alkali-feldspars, derived from synchronous volcanic ash fall, altered under alkaline conditions. Moreover, alginite proportions increased towards the upper parts of the seam, while relatively high Hydrogen Index (HI) values were reached in the uppermost part of coal seam and carbonaceous clayey diatomite roof-rock sample. Furthermore, palynolgical data imply that vegetation changes towards the roof of the coal seam reflect the progressive development of more humid conditions and nutrient-rich surface waters, which favoured increased algal activity.

Palynology of Miocene sediments in Brunei Darussalam: first SEM investigations of pollen and spores, and their taxonomy and palaeoenvironmental interpretation

Palynology of Miocene sediments in Brunei Darussalam: first SEM investigations of pollen and spores, and their taxonomy and palaeoenvironmental interpretation

Micropalaeontological analysis and palaeoenvironmental interpretation of the upper sedimentary sequence of Corinth Marl (Corinth Isthmus, Greece)

The current study performs a detailed micropalaeontological analysis, in terms of ostracods, benthic foraminifera and calcareous nannoplankton, in order to reconstruct the palaeoenvironmental history of the sedimentary sequence exposed in the central part of Corinth Isthmus. Twenty one samples from two lateral sections were studied, on both sides of a westwards dipping normal fault at the west end of the central horst, which are part of the same stratigraphical sequence. The calcareous nannofossil analysis provided for the first time dating evidence for the upper Corinth Marl sequence, revealing that Section A (at the footwall block of the fault/the upper part of the Corinth Marl) is attributed to the Early Pleistocene /Calabrian (nannofossil biozone MNN19f) and that Section B (at the hanging wall of the fault) is assigned to the Middle Pleistocene /Chibanian (MNN20). Both parts of the studied sequence not only differentiate in age but bear notably separated species composition of the main ostracod assemblages as well. The combined study of ostracod and benthic foraminiferal microfaunas indicated that at least since Early Pleistocene the Corinth Marl deposits at the central part of Corinth Isthmus corresponded to a shallow, restricted, oligohaline lagoon with salinity alternations expressed as layers enriched in nannofossil content. Towards Middle Pleistocene the lagoon presented increased salinity and signs of shoaling. The studied sequence closes upwards with a bed of Middle Pleistocene age, rich in marine molluscs and corals indicating a radical environmental change: the opening of the lagoon and the establishment of a shallow marine coastal environment.

Miocene Foraminifera Biostratigraphy and Interpretation North Deep Sea Block of the Congolese Atlantic Basin

This work is the subject of the biostratigraphic and palaeoenvironmental study of the North Deep Sea area of the Congolese Miocene Atlantic Basin. This study is made from samples of lateral cores, drill cuttings and electrical logs. Lithology generally exhibits an irregular alternation of weakly indurated grey clay, light grey siltstones, and whitish, quartzitic sand, medium to coarse-grained, sub-angular to rounded. The presence of glaucony indicates that sediments have been deposited in a calm and reducing environment. The entire formation is fossiliferous. Micropaleontological analysis revealed 120 species of foraminifera including 98 planktonic (81.67%) and 22 benthic (18.33%) species used for biozonation, dating and interpretation of palaeoenvironments. Similarly, the bio-events of plankton foraminiferal, characterized by the level of the first appearance of certain species, have made it possible to identify fifteen biozones (Globorotalia plesiotumida, Globorotalia merotumida, Globorotalia acostaensis, Globorotalia menardii, Globigerina nepenthes, Globorotalia siakensis, Globorotalia fohsi, Globorotalia praefohsi, Globorotalia peripheroacuta, Globorotalia peripheroronda, Praeorbulina sicana, Catapsydrax dissimilis, Globigerinatella insueta, Paragloborotalia kugleri and Globorotalia kugleri) corresponding to age between Aquitanian and Lower Pliocene. Biofacies analysis of foraminifera has identified palaeoenvironments that vary from open marine environments, bathyal to abyssal.

Recurrent volcanic activity recorded in araucarian wood from the Lower Cretaceous Springhill Formation, Patagonia, Argentina: Palaeoenvironmental interpretations

Recurrent volcanic activity recorded in araucarian wood from the Lower Cretaceous Springhill Formation, Patagonia, Argentina: Palaeoenvironmental interpretations

Benthic Foraminifera from the Saïda clay formation (Djebel Brame, northwestern Algeria) biostratigraphy and paleoecology

The analysis of benthic foraminiferal assemblages was performed in the Oxfordian deposits of the “Argile de Saida” in northwestern Algeria. This formation consists mainly of clay and sandstone alternations of the Upper Jurassic. It is located in the western part of the Tlemcenian domain. The first results of the micropaleontological study of Djebel Brame indicated that the microfauna of Foraminifera was quite original and widely abundant during that period. In addition, their biostratigraphic distribution exhibited three microfaunal associations, largely dominated by Nodosariidae. These results also revealed the renewal of the assemblage composition and allowed identifying several species of biostratigraphic divisions which were found consistent with those established for the ammonites. In addition, the palaeoenvironmental interpretations were based on the spatio-temporal distribution of benthic foraminiferal associations with hyaline and agglutinated tests. Besides, the geochemical analyses (calcimetry) reflected the basin infill during the Late Oxfordian.

Age determination of the Oligocene Qom Formation and interpretation of palaeoenvironments in the Qom back-arc basin (northern Neotethys) using benthic foraminifera

Age determination of the Oligocene Qom Formation and interpretation of palaeoenvironments in the Qom back-arc basin (northern Neotethys) using benthic foraminifera

Revised Middle and Late Pleistocene interglacial and interstadial records from the glaciated eastern Fennoscandia

The Middle to Late Pleistocene palaeoenvironmental record from the repeatedly glaciated central and eastern Fennoscandia is poorly known. The majority of the glacial and warm interval records have been interpreted to represent only the last, Weichselian, glacial cycle (119–11.7 ka). We have revised the crucial part of the existing stratigraphic documentation in central and southern Finland. Our findings show that a considerable part of the depositional record extends further back in time and is more complete than previously thought. One record may reach the Middle Pleistocene Holsteinian Interglacial (≈MIS 11), 424-374 ka ago, and a large number of records are tentatively attributed to the Middle Pleistocene Röpersdorf-Schöningen Interglacial (≈MIS 7) 243-191 ka ago. During this possible Röpersdorf-Schöningen Interglacial, the Gulf of Bothnia hosted larger alkaline and smaller dystrophic lakes surrounded by boreal pine forests in a continental climate with warmer summers and colder winters than today. The Eemian (≈MIS 5e) 131-119 ka sea coastal records show detailed evidence of the widespread intermixing of continental fresh and marine waters. During the Early Weichselian Brörup Interstadial (≈MIS 5c) 109-96 ka, central and southern Finland seem to have supported open birch forest tundra, later invaded by spruce; not boreal pine forest as earlier thought. The early birch vegetation faced a tundra phase which may be the Montaigu cooling event c. 103 ka ago. The revised palaeoenvironmental interpretation shows that the development during the three discussed warmer intervals is well in line with the central European vegetational development. Our palaeoenvironmental interpretations concerning Röpersdorf-Schöningen and Brörup warm intervals are preliminary and will need further investigations. No indisputable Middle Weichselian (≈MIS 3, 57-29 ka) sedimentary record seems to have been recorded in the studied area.

Pleistocene ostracods from central and southern Greece: The marine and brackish record

Ostracods are important palaeoenvironmental tools and for this reason the study of their palaeoecology and geographic distribution must be enhanced in the frame of a unified geographic approach. The PLOSTRAC’s project (Study of Pleistocene ostracods from central and southern Greece: Digital imaging of a palaeoenvironmental tool) main aim is to study the Pleistocene ostracods deriving from sedimentary successions from central and southern Greece and provide a bibliographic database of Pleistocene ostracod-bearing sequences in the study area accompanied by SEM pictures of the identified species. This output can be used as a reference point for future studies not only in Greece but also in the Eastern Mediterranean region as well. This work presents new data from brackish and marine Pleistocene sequences in Peloponnesus, the Ionian Islands (Zakynthos and Cephalonia) and Crete. A total number of 166 taxa were identified from the processed samples. The ostracods belong mainly to the families Trachyleberididae and Hemicytheridae. The studied sedimentary sequences cover the entire Pleistocene Age and range between purely brackish to deep marine assemblages. Moreover, according to both the palaeoenvironmental interpretation of the studied sections and the published literature, across Northern Peloponnesus during the Pleistocene mostly brackish to shallow marine conditions prevailed. Moving to the south and also to the Ionian Islands and Crete deep marine palaeoenvironments were observed.

Palaeoenvironmental reconstitutions at the Carboniferous–Permian transition south of the Paris Basin, France: implications on the stratigraphic evolution and basin geometry

The late Carboniferous-to-Permian coal-bearing Decize-La Machine Basin, and more specifically the Lucenay-les-Aix area, located south of the Paris Basin, has been investigated to reassess the palaeoenvironmental evolution and the basin architecture. The detailed sedimentological study has been carried out based on core data and digitised old mining data, i.e., seismic profiles and well-logs. An interpretation of well-logs without core data is proposed, based on a palaeoenvironmental interpretation from cores and their respective well-log data, and three depositional environments have been defined: an alluvial plain, an alluvial-fan, and deltaic and lacustrine environments. Correlations between wells have been performed using markers identified in seismic profiles, paired with sequence stratigraphic interpretations from well-log and core data. An evolution in seven major progradational–retrogradational stratigraphic cycles is proposed based on the evolution of the depositional environment observed at the basin scale, leading to a reconstruction of palaeogeographic maps at the Carboniferous–Permian transition. This new viewpoint shows that through time, the deposits, proximal at the base of the succession with coal preservation, become more lacustrine with the delta prograding into the basin. In consequence, the basin evolution shows a general retrogradational trend with increasing lacustrine deposits at the top of the succession eroded by the Permian–Triassic unconformity. Therefore, the current borders of the basin in the Lucenay-les-Aix area are not representative of those at the time of the sedimentary filling, and thus, this area could be part of a larger one, perhaps encompassing all north-eastern French Massif Central late Carboniferous-to-Permian basins.

Modern pollen assemblages of the Neotropics

AbstractAimModern pollen assemblages provide a means to calibrate fossil pollen data and to provide a translation from habitat and vegetation type to pollen representation. Here we provide a database of modern pollen abundances from a broad range of neotropical habitats and locations.LocationThe Neotropics, especially western Amazonia, the Andes, The Galápagos, Central America, Puerto Rico and Mexico.TaxonAngiosperms and GymnospermsMethodsOver a 30‐year period, mud–water interface samples, moss polsters, soils and pollen traps were used to assay modern pollen assemblages. Standard extraction methods were used, and a minimum of 300 terrestrial pollen grains were counted and identified in each sample. Bioclimatic data were assigned to each location, and sexual traits and pollination syndromes are provided for some genera. A detrended correspondence analysis (DCA) shows the structuring of the data relative to mean annual temperatures (MAT), mean annual precipitation (MAP) and precipitation of the driest quarter (PDQ). Probability density functions of distances among samples are calculated within and between Holdridge Life Zones, based on sample DCA scores.ResultsThe modern pollen of 636 locations are documented, with >500 pollen types identified. The dataset spans settings with MAT <5°C to > 25°C, and with MAP ranging from c. 500 to 5,000 mm, and PDQ from 80 to 1,500 mm. Ordination of the dataset provides evidence that assemblages differ according to temperature and precipitation, although historical biogeography also shapes pollen rains. The pollen grains of zoophilous species contribute important information to habitat descriptions, but they are under‐represented in the dataset.Main conclusionsThe dataset covers a broad environmental range and can help inform biogeographical and palaeoenvironmental interpretation of palaeoecological records. Some caution in using the data is needed as the field of tropical palynology is maturing and the data gathered 30 years ago are less detailed than those gathered recently. Although anemophilous taxa tend to be over‐represented in neotropical pollen spectra, the majority of pollen identified in each sample are from zoophilous species.

A Unique Coincidence of Geomorphological, Geological, and Geoarchaeological Features in the Valley of Camels (Dakhla Oasis, Western Desert, Egypt)

Geosites constitute important natural resource of Egypt. Field investigations in the Dakhla Oasis of the Western Desert have permitted to assess unique geomorphological, geological, and geoarchaeological features co-occurring in the Valley of Camels. These features are assigned to geomorphological type (animal-shaped landforms sculptured by differential erosion), palaeogeographical type (continental facies of the Cretaceous sandstones and petroglyphs left by the past societies and partly suitable to palaeoenvironmental interpretations), sedimentary type (cross-bedding and multiple truncation planes in sandstones), and hydrogeological type (Roman wells). The Valley of Camels is a globally ranked geosite of complex type. It demonstrates coincidence of essentially different features. For instance, the Toutam landform is notable by its unusual shape resulting from weathering, it exhibits cross-bedding and multiple parallel truncation planes typical for continental sandstones, and it bears petroglyphs near its base. In the Valley of Camels, the geoheritage can be used as the resource for (geo)education and (geo)tourism. Excellent visibility and high aesthetic properties make the proposed geosite suitable to tourists with different geological knowledge or even without it. Geotourism development in the Valley of Camels can contribute to the local sustainable development via providing socio-economic benefits to the local community and strengthening the oasis integration into the Egyptian economy.

Biostratigraphy and palaeoenvironmental interpretation of the Dalichai Formation (Lower Cretaceous) in the eastern and central Alborz Mountains (North Iran) based on calcareous nannofossils

Calcareous nannofossils are described from 4 sections of the Lower Cretaceous Dalichai Formation from the Eastern (Tepal, Talu and Lavan sections) and central Alborz Mountains (Yonjezar section), Iran. Forty-two species belonging to 18 genera have been identified from the 4 sections studied, including 13 species belonging to 8 genera of ascidian didemnids only from the Tepal section. These taxa indicate the CC1–CC5 biozones of Sissingh’s (1977) biozonation and an age of Berriasian to Early Barremian. The nannofossils recorded from the Dalichai Formation are generally Tethyan and cosmopolitan, while the presence of some Boreal taxa (Nannoconus abundans and N. borealis) may reflect connection between the Boreal and Tethyan realms in the Early Barremian. The sedimentary basin of the Dalichai Formation of the Tepal, Talu, and Yonjezar sections was located at low latitudes of the Tethyan realm with warm surface water. Also, trends of increasing depth and productivity, of a shift from r-selected to k-selected strategies and of a change from low-to-high mesotrophic to oligotrophic conditions, were deduced. A change from unstable to stable conditions towards the tops of sections is inferred for these localities. Laterally in the Dalichai Basin from the eastern to central Alborz, there was an increase in depth and productivity, and also a trend towards oligotrophic conditions and a dominance of low-stress conditions.

Facies architecture and palaeoenvironmental constraints of subaqueous felsic volcanism in the Iberian Pyrite Belt: The Paymogo Volcano-Sedimentary Alignment

The Paymogo Volcano-Sedimentary Alignment (PVSA) is an essentially igneous sequence associated with VHMS deposits of the Iberian Pyrite Belt. Unlike other areas of this mining district, where mafic igneous rocks are abundant, in the PVSA these are essentially felsic. Two facies associations have been distinguished based on petrographic and chemical features: a lower dacite facies association and an upper rhyolite facies association. The main ore horizons appear related to volcanic breccias of the rhyolite facies association. A detailed petrographic study of these breccias suggests they are resedimented hyaloclastite deposits. The analysis of volcanic facies indicates that the volcanism developed at water depths deeper than 500 m, consistent with the minimum depth at which VHMS deposits can form. We conclude that detailed volcanological studies provide effective constraints to palaeoenvironmental interpretations, which are relevant in assessing regional stratigraphy and area selection for VHMS exploration.

Quantifying the three‐dimensional stratigraphic expression of cyclic steps by integrating seafloor and deep‐water outcrop observations

AbstractDeep‐water deposits are important archives of Earth’s history including the occurrence of powerful flow events and the transfer of large volumes of terrestrial detritus into the world’s oceans. However the interpretation of depositional processes and palaeoflow conditions from the deep‐water sedimentary record has been limited due to a lack of direct observations from modern depositional systems. Recent seafloor studies have resulted in novel findings, including the presence of upslope‐migrating bedforms such as cyclic steps formed by supercritical turbidity currents that produce distinct depositional signatures. This study builds on process to product relationships for cyclic steps using modern and ancient datasets by providing sedimentological and quantitative, three‐dimensional architectural analyses of their deposits, which are required for recognition and palaeoflow interpretations of sedimentary structures in the rock record. Repeat‐bathymetric surveys from two modern environments (Squamish prodelta, Canada, and Monterey Canyon, USA) were used to examine the stratigraphic evolution connected with relatively small‐scale (average 40 to 55 m wavelengths and 1.5 to 3.0 m wave heights) upslope‐migrating bedforms interpreted to be cyclic steps within submarine channels and lobes. These results are integrated to interpret a succession of Late Cretaceous Nanaimo Group deep‐water slope deposits exposed on Gabriola Island, Canada. Similar deposit dimensions, facies and architecture are observed in all datasets, which span different turbidite‐dominated settings (prodelta, upper submarine canyon and deep‐water slope) and timescales (days, years or thousands of years). Bedform deposits are typically tens of metres long/wide, <1 m thick and make up successions of low‐angle, backstepping trough‐shaped lenses composed of massive sands/sandstones. These results support process‐based relationships for these deposits, associated with similar cyclic step bedforms formed by turbidity currents with dense basal layers under low‐aggradation conditions. Modern to ancient comparisons reveal the stratigraphic expression of globally prevalent, small‐scale, sandy upslope‐migrating bedforms on the seafloor, which can be applied to enhance palaeoenvironmental interpretations and understand long‐term preservation from ancient deep‐water deposits.

δ18O and δ13C of Cyprideis torosa from coastal lakes: Modern systematics and down-core interpretation

Stable isotope analyses of ostracod shells are a commonly-used proxy for palaeoenvironmental reconstruction. Although the fundamental controls on isotope composition of ostracod shells are well understood and, in some instances, quantifiable, the paleoclimatic and palaeoenvironmental interpretation of records from lake sediments depends strongly on the characteristics of individual lakes including the climatic setting, depth, volume, hydrology, aquatic vegetation and catchment properties. This is particularly important for coastal lakes where physio-chemical variations may occur on diurnal timescales. Here, we combine variations in δ 18 O water , δ 18 O ostracod and δ 13 C ostracod , hourly water temperature, and Mg/Ca ostracod inferred water temperatures (constraining calcification temperature) to improve palaeoenvironmental interpretation and provide insights into lake carbon cycle. The dataset improves understanding of complex coastal lake site systematics and downcore interpretation of stable isotopes from C. torosa , a geographically widespread brackish water ostracod. The δ 18 O ostracod values show a complex relationship with temperature and suggest, in most circumstances, that δ 18 O water is the dominant control on δ 18 O ostracod . During times of fresher water, δ 13 C ostracod increases, suggesting increasing aquatic productivity. Above a certain δ 18 O water threshold however, aquatic productivity begins to decline. The interpretation of δ 13 C ostracod in some coastal lakes, may therefore be dependent on understanding of the range of expected δ 18 O water . Due to short-term (diurnal to seasonal) variations that cause large ranges in δ 18 O water and δ 18 O ostracod , stable isotope analyses of C. torosa should be: (1) undertaken on multiple single shells (2) where carapaces are preserved, paired with trace-element/Ca analyses on the same individual; and (3) undertaken alongside a study of the modern lake system. • In most circumstances, δ 18 O water is the dominant control on δ 18 O ostracod . • δ 13 C ostracod is likely controlled by productivity and the oxidation of terrestrial organic matter. • Samples that show a relationship with temperature have higher δ 18 O and a decreasing trend with δ 13 C. • Only some valves in a palaeo-dataset with mixed seasonal signals may relate to palaeo-temperature.

Palaeoenvironmental interpretation of the structures and textures of the Miocene sediments in the Strymon basin, Northern Greece

Abstract For the purpose of lithological analysis the Miocene sedimentary sequences in the Strymon basin, Northern Greece have been observed and described in detail concluding in subdividing them into a new lithostratigraphic shape. These investigations in this analysis, through the study of data of the sedimentary structures and textures led to the interpretation of the depositional environments in the Miocene basin.