Marine Influence Research Articles

Tectonic subsidence of the southeast China coast: New evidence from Late Pleistocene transgression in Ningde bay

Subsidence of the ancient Zhejiang-Fujian Uplift (ZFU) is important to understand opening of the Chinese marginal seas and geomorphology of the east China coast. However, little was known about its subsidence history during the Quaternary. In this study we clarify three marine sedimentary layers constrained by luminescence (OSL) chronology in Ningde area of the southeast China coast, to reveal the regional subsidence evolution related to the ancient ZFU. The results show that three marine sedimentary layers above bedrock in Ningde area are formed during global sea-level highstands of MIS1, MIS3 and MIS5e, constrained by OSL datings of the three representative cores. Limited marine influence of MIS5e highstand indicated both by microfacies of the representative cores and by the paleo-shoreline outlined from 120 cores, implies that tectonic subsidence occurs here during the Late Quaternary. The offsets between the peak global sea level and the corrected paleo-shoreline elevations of MIS5e and MIS3 reveal that the average subsidence rate is ∼0.5 m/kyr since MIS5e and ∼ 0.8 m/kyr between MIS5e and MIS3 in Ningde area. This evidence suggests that the ancient ZFU possibly subsided rapidly since MIS5e and stabilized since MIS3. This study provides new insights into the subsidence history of the ancient ZFU and land-sea interaction in the tectonic subsidence region.

Sedimentology, sequence stratigraphy, palynology and diagenetic evaluation of the Triassic Jilh Formation. New insights from Saudi Arabia

The Jilh Formation (late Anisian to Carnian) was deposited on the southwestern margin of the Neotethys Ocean recording the flooding of a broad shallow marine platform, and is characterized by restricted clastic-prone mudrocks and sabkha anhydrite with interbedded shallow marine dolomitized carbonates. Within the Lower Jilh Formation, deposits encompass tidal flat to low-energy inner ramp thrombolytic microbial deposits with local anhydrite nodules and fenestrae structures interbedded with ft-scale intraclast-rich floatstones with desiccation surfaces. Within the interbedded mudrocks, land-derived miospores (including common Lunatisporites spp. and other taeniate bisaccate pollen) and clastic material are common. During the Carnian, the higher sea level resulted in a change to tidal flat bioturbated and microbially induced mudstones, along with inner ramp subtidal peloidal sand banks and skeletal wackestones with benthic foraminifera within the Upper Jilh Formation. Terrestrially derived miospores are still common (assemblage including common Camerosporites secatus, Conipollenites arabicus, Duplicisporites spp., Samaropollenites speciosus), but an increasing marine influence is also noted during the Carnian from the presence of marine palynomorphs such as acritarchs and prasinophytes (including acanthomorphic acritarchs, Veryhachium spp. and Dictyotidium spp.). The backstepping of the platform is marked by the progressive flooding of the tidal flats and the deposition of open marine facies culminating in a regional 2nd order maximum flooding surface. Petrographic and geochemical analyses show the development of fabric-replacive planar-s to planar-e dolomite fabrics associated with negative δ18O values and positive δ13C values, suggesting precipitation of the dolomite on top of 3rd and 2nd order sequences from possible transgressive reflux syn or post deposition of the Jilh Formation. Zoned dolomite rhombs lining macropores might be related to burial diagenesis and pore-filling anhydrite and calcite are locally common. The local presence of native sulfur replacing primary anhydrite nodules, along with the minor calcitization of the anhydrite also suggest the onset of thermochemical sulfate reduction during the burial history at possibly high temperature.

The sedimentology and depositional environments of the Bastians Dal and Muslingebjerg formations: evidence for the earliest phases of Jurassic rifting in North-East Greenland

The aim of this study is to elucidate the character of the earliest phases of Jurassic rifting in North-East Greenland. To achieve this, detailed sedimentological analysis and geological mapping were undertaken on the outcrops of central Kuhn Ø (74°53’55’’N,20°20’56”W). In this region the basement is overlain by the fluvial Bastians Dal Formation (Middle Jurassic) which is, in turn, overlain by the coal-bearing Muslingebjerg Formation. A maximum thickness of 140 m is calculated for the Bastians Dal Formation and mapping of stratal geometries demonstrates thinning to both the north and south, confirming that these deposits infill a palaeovalley. Predominantly south-westward palaeocurrent orientations are observed and likely reflect the orientation of the palaeovalley (NE–SW). The overlying Muslingebjerg Formation displays significant lateral variations in thickness as well as facies, thickening from a 5-m-thick coal seam in the north to 50 m in the south. Southern outcrops include two intervals of fine-grained sandstones displaying low-angle and trough cross-bedding some of which contain suggestions of tidal bundling. The arrangement of facies suggests that coal formation occurred in both fluvial- and shallow-marine (tidal?) environments. Coals are similar to those described elsewhere from the Muslingebjerg Formation and display subtle differences consistent with variable degrees of marine influence. Mapping demonstrates the presence of an NE–SW-oriented bounding fault in the south of the region into which the Muslingebjerg Formation thickens. This likely also controlled the orientation of the underlying NE–SW-aligned palaeovalley and is oblique to the proposed overall N–S orientation of faulting related to rifting through the Mid to Late Jurassic. Instead, these alignments resemble those that define pre-Jurassic phases of rifting and may therefore indicate a transitional phase of tectonism. Faulting on a similar alignment can be traced SW, cutting Lindeman Fjord and following the valleys east of the A. P. Olsen Land plateau.

Salinity indicators in sediment through the fluvial-to-marine transition (Fraser River, Canada)

Many sediment attributes have been proposed as proxies for determining salinity conditions under which sediment is deposited, and six attributes (Sr/Ba-HAc, Sr/Ba-NH4Ac, δ13Corg, C/N, and the relative abundances and concentrations of dinoflagellate cysts) are compared here. In this paper, sediment attributes from the Fraser River Delta, Canada and surrounding coastal areas are compared by depositional position along the fluvial-to-marine transition, by salinity, and by sedimentological characteristics. Along the fluvial-to-marine transition, most attributes exhibit distinct trends between parts of the river that experience sustained marine water (saltwater) influence over seasonal and tidal timeframes, and parts that experience only freshwater or periodic saltwater influence. No attributes are reliable indicators of depositional position where saltwater incursion is short lived or where water is fresh. Where marine influence is sustained, Sr/Ba-HAc and Sr/Ba-NH4Ac are the most reliable positional indicators along the fluvial-to-marine transition. When compared strictly to salinity, Sr/Ba-HAc, Sr/Ba-NH4Ac, and δ13Corg all correlate predictably except in delta front and prodelta settings. Our data show that all six sediment attributes are heavily impacted by river-derived sedimentation, and it is not appropriate to compare values from strongly river-influenced settings (e.g., deltas) with those from weakly river-influenced settings (e.g., bays and estuaries).

Optical and geochemical assessment of petroleum source rock potential and palaeodepositional environments of Cretaceous mudstones, Koum Basin, North Cameroon

Limited organic matter (OM) characterisation studies on Cretaceous mudstone successions in the Koum Basin have resulted in a significant knowledge gap in the source rock potential; a petroleum system prerequisite. Field mapping and lithofacies analysis of outcrop sections point to fluvial channel and marginal to profundal lake deposits. Representative mudstone samples were evaluated using multiproxy organo-petrographic and bulk geochemical analyses to assess the kerogen type, thermal maturity, hydrocarbon generation potential, and deduce the paleodepositional environment. Results reveal that ∼90% of the samples are organic-lean and ∼10% organic-rich with TOC content of 2.81–6.91 wt%. Rock-Eval pyrolysis S2 yields of 14.50–54.18 mg HC/g rock and hydrogen index (HI) 784–846 mgHC/gTOC, suggest excellent potential for oil generation. High S1 values of 1.18–1.45 mg HC/g rock and low production indices (PI) of 0.02–0.03 indicate in situ generated free hydrocarbons. PI and Tmax of 438°C–443 °C, consistent with measured vitrinite reflectance (Ro% = 0.28–0.53%), Spore Colour Index (SCI = yellow to golden brown) and Thermal Alteration Index (TAI = 1.5 to 2.6) on the Chevron scale, portraying an immature to marginally mature OM. Oil-prone kerogen Type I-II dominates and to a lesser extent gas-prone Type III, derived from algal-terrestrial organic facies, typified by the predominance of amorphous OM 51.2%, liptinites 24.6%, vitrinite 16.4% and inertinite 7.8%. Based on lithofacies, and palynological evidence, a fluvio-lacustrine depositional setting with limited marine influence, under fluctuating warm humid to hot semi-arid paleoclimates, is inferred. A comparison with surrounding petroleum-producing basins further enhances the understanding of the Koum Basin's hydrocarbon potential within the West Central African rift system context.

Tropical peat fire emissions: 2019 field measurements in Sumatra and Borneo and synthesis with previous studies

Abstract. Peat fires in Southeast Asia are a major source of trace gases and particles to the regional-global atmosphere that influence atmospheric chemistry, climate, and air quality. During the November 2015 record-high Ocean Niño Index (ONI, 2.6) our mobile smoke sampling team made the first, or rare, field measurements of numerous trace gases, aerosol optical properties, and aerosol chemistry and mass emissions for fires burning only peat in the Indonesian province of Central Kalimantan (on the island of Borneo). The measurements used Fourier transform infrared spectroscopy (FTIR), whole air sampling (WAS), photoacoustic extinctiometers (PAX, 401 and 870 nm), and detailed off-line analyses of particulate matter (PM) collected on filters. In September–November 2019 we measured peat fire trace gas emissions again, using WAS only, under El Niño–Southern Oscillation (ENSO)-neutral conditions (ONI, 0.3) in more remote areas of Central Kalimantan and also the Indonesian provinces of Riau, Jambi, and South Sumatra, all on the island of Sumatra. The 2019 measurements significantly expanded the geographic range and climate conditions sampled. This paper presents the 2019 results and synthesizes them with the previous fieldwork to converge on more robust regional average emission factors (EFs; grams of compound per kilogram of biomass burned) for authentic peat fires. In addition, samples of peat imported from Indonesia were burned in US laboratories, and the EFs and optical properties were characterized in more detail than in the field by a larger suite of instrumentation. We use the improved knowledge of regional emissions based on the expanded field measurements to select the most representative lab data and compute a synthesized, more “chemically complete” set of EFs and aerosol optical properties for tropical peat fires. The modified combustion efficiency (MCE) values for the peat smoke sampled in 2019 were within the range of MCEs sampled in 2015, but with a lower average in 2019 (0.718±0.021, range 0.687–0.736) than 2015 (0.772±0.035, range 0.693–0.835). Averaging the new and older data together suggests an updated MCE for tropical peat fires of ∼0.76. Despite the difference in MCE, the study-average methane emission factors (EF CH4) were remarkably similar across the 2 years probing different regions: 9.42±2.51 g kg−1 in 2019 and 9.51±4.74 g kg−1 in 2015. When parsing the 2019 samples by province, the EFs for non-methane organic gases (NMOGs) were about 3 times higher in South Sumatra and Central Kalimantan than in Jambi and Riau, but the overall 2019 study average was only ∼15 % higher than the 2015 study average. South Sumatra peat fires emitted higher amounts of carbonyl and dimethyl sulfide, suggesting a volcanic or marine influence or effects of agricultural chemicals. The lab and fieldwork taken together provide EFs for 230 trace gases including CO2 (1544 g kg−1), CO (315 g kg−1), and CH4 (9.8 g kg−1). These are significant adjustments to IPCC-recommended EFs, −9 %, +50 %, and −53 %, respectively. We also report EFs for numerous NMOGs, 46 N-containing compounds, and 14 sulfur- or halogen-containing species. The use of high-resolution mass spectrometry in the lab allowed measurement of 82 % more NMOG mass than in the field. Gravimetrically measured EF PM2.5 in the field in 2015 (17.3±5.8 g kg−1) was ∼20 % lower than the average from lab studies (22.4±10.4 g kg−1), perhaps due to higher field temperatures. Taken together the lab and field data show that the single-scattering albedo (SSA) was largely independent of wavelength and MCE in the visible (∼0.998), but lower at low MCE at 401 and 405 nm with a value of 0.958 at the study-average MCE. The absorption Ångström exponent (AAE) at the average MCE was 5.7. By far the largest PM component was weakly absorbing insoluble organic carbon.

The Middle Triassic vertebrate deposits of Kupferzell (Germany): Palaeoenvironmental evolution of complex ecosystems

In 1977, within 3 months of excavation, a 500 m spanning road-cut near Kupferzell (southern Germany) produced a total of ~30,000 vertebrate remains from the Middle Triassic Lower Keuper. The bulk of the material stems from two temnospondyl amphibians, Gerrothorax pulcherrimus (~70%) and Mastodonsaurus giganteus (~30%), with the pseudosuchian archosaur Batrachotomus kupferzellensis ranging first among the other remains. Analyses of data collected during excavation, supplemented by new fieldwork, provide rich information on the sedimentary setting as well as the development of the fauna and their ecosystems. The sequence consists of: basal coaly mudstones (K1), massive siltstones (K2), green siliciclastic mudstones (K3), yellow to pale brown marlstones (K4), and yellow massive dolostones (K5). The deposits comprise a succession of similar water bodies that were emplaced on a lacustrine to floodplain setting in which carbonate muds dominated. Two main lake systems, with intermittent/periodical marine influence, as well as relatively stark periods of drought, harboured complex vertebrate ecosystems. These were dominated by a relatively high diversity of fishes and temnospondyl amphibians with a lesser, but notable, presence of archosaurs, forming the top predators of the trophic web. The sequence records alternating periods of flooding and desiccation, shaping a relatively complex environmental setting that was likely prone to the presence of life, eventually becoming an exceptional fossil lagerstätte. Kupferzell, together with nearby contemporaneous localities, represent relatively diverse and complex ecosystems (including several top predators) that allow understanding the evolution and palaeoecology of Middle Triassic vertebrate communities, including the groups that diversified during the Mesozoic era.

Late Pleistocene Geomorphic Evolution of Cephalonia Island, Western Greece, Inferred from Uplifted Marine Terraces

Combined with eustatic sea-level changes, uplifted Quaternary marine terraces provide insight into the tectonics of coastal areas. Cephalonia Island lies 35 km off the western coast of mainland Greece and 15 km northeast of the Hellenic subduction zone. Late Pleistocene eustatic sea-level oscillations and the long-term tectonic movements are imprinted on the landscape of the southern part of the island, in the form of seven uplifted marine terraces. In the present study we aim to identify and map in detail these terraces, applying Digital Elevation Model analysis, utilizing Geographic Information Systems techniques and extensive fieldwork. The GIS-based analysis combined with field geomorphological observations revealed a sequence of seven marine terraces at the southern part of the main island ranging in elevation between 4 m and 176 m asl. Microscope, petrological and microgeomorphological analyses on two caprock samples suggest strong marine influence during the deposition of the sediments covering the marine terraces. The age of the formation of the 32 m marine terrace was assigned to the MIS 3e, based on OSL dating of a caprock sample, and an average uplift rate of 1.4 ± 0.35 mm a−1 was calculated for the last 61 ± 5.5 ka. Assuming a uniform uplift rate for the Late Pleistocene allowed us to correlate the marine terrace with the sea-level highstands and constrain their ages.

Surfing the tide: Homeward migration of sea trout (Salmo trutta) in a Patagonian river

This study evaluates the influence of marine and freshwater conditions on the timing of river entry and upstream migration of sea trout (Salmo trutta) in the Grande River of Tierra del Fuego, Patagonia. We analysed the in-river catch-and-release records from a group of fishing lodges that dominate the Grande River fishery during January-April 2008 (n=5029 fish) as a function of environmental variables: tidal amplitude, stage in the lunar cycle, river discharge, and river water temperature along the homeward migration season. We discuss the value of the daily catch rate as an abundance index in the Grande river, then analyse the temporal structure of the tidal cycle in the Grande River estuary, a macro-tidal environment with a mean tidal amplitude of 5.7m, and analyse the fit of a generalized additive model to trout catches on a daily basis in four sections along the river to identify the environmental variables that may affect trout abundance throughout the homeward migration. Fish catches in each section of the river were differentially affected by specific environmental variables: tidal amplitude had a positive and significant effect on catches in the lower river sections, whereas water temperature and river discharge significantly affected catches in upper sections (positive effect of temperature; negative effect of discharge). Catches in the lower section clearly reflect the river entry stage of the homeward migration, with a bi-modal shape significantly correlated with the tidal cycle. The first peak was composed mainly of larger multi-sea-winter trout that move upstream, whereas the second one had a wider range of fish lengths, including a large proportion of small and maybe nonreproductive trout that overwinter in the lower river. Based on our results, we conclude that the large tides in the Grande River estuary strongly affect the river entry timing of sea trout. The underlying mechanisms of this effect may be a combination of increased olfactory recognition and increased tidal transport modulated by the seasonal tidal cycle, which operates on trout during coastal migration to produce the pulses observed in the Grande River sea trout run. In the middle and upper sections of the river, where the tidal effect at river entry was dissipated as upstream migration progressed, trout catches increased with water temperature and decreased with river discharge, which may operate through their influence on in-river migration rate and abundance, but also through changes in catchability.

Mineralogy and Geochemistry of beach sediments associated with the Precambrian crystalline rocks (Vijayan Complex) of Sri Lanka; perspective for heavy minerals

Southeastern landmass of Sri Lanka is laid on the Vijayan Complex (VC) rocks, a Precambrian basement characterized with specific geological features since the mineralized contact zone of the Highland–Vijayan boundary is nearby. However, the coastal sedimentation of such a basement is rarely interpreted. Hence, the mineralogy and geochemistry of surface sediments exposed along 45 km long southeast (SE) coast were studied to find the compositions and to interpret the terrestrial compart. Studied beach faces expose as sandy siliciclastic sediments with scatter depositions of black and red coloured heavy sediments, as 10–15 cm beds, within 1–3 km from deltaic environments. X-ray diffraction analysis of such heavy placers indicate the presence of predominant ilmenite, almandine garnet, zircon, monazite and ferrihydride. The sediments from other areas are rich in lighter minerals of quartz, albite and magnesium-calcite representing the average beach sediment mineralogy of SE coast. Upper continental crust normalized X-ray fluorescence data show an enriched tendency of Zr (9.8) > V > Nb > Th > TiO2 (6.2) > Cr (2.5) > MnO > Fe2O3 > As > Y > Zn and depleted tendency of Pb (0.8) > CaO >P2O5 > Sr > Sc > Cu (0.1) indicating the leachability of depleted elements and strong recycling processes of High Field Strength Elements (HFSE). Hierarchical cluster analysis and Pearson correlation matrixes indicate the presence of four geochemically related sample clusters. These analyses further showed that the cluster 1 relates to heavy sediments deposits with higher terrigenous influences while cluster 4 relates to siliciclastic sediments with higher marine influences. Hence, geochemical anomalies of cluster 1 to 4 show decreasing abundances for HFSE and opposite tendencies for CaO, Sr, I, Br, and F confirming the mineralogical results. Higher terrigenous influenced sediment samples evident for the presence of solid phases of titanium carriers (As–V–TiO2), phosphorus–HFSE carriers (Pb–Th–P2O5–Y–Cl–Nb–Zr), authigenic carbonates (Sr–Br–CaO) and Fe–Mn coatings (Zn–Cr–MnO–Fe2O3–Cu). Compatibility variable ratios of Th/Sc, Zr/Sc, TiO2/Zr, Cr/Th and V/Th respectively show 15.16, 364.38, 20.85, 2.95 and 9.73 values for these coastal sediments. Based on the published international and VC average lithological data, the present study concluded that the primary sources for the sedimentation have felsic signatures showing relations to granitic gneisses and granitic intrusive rocks of the VC. Apart from the terrestrial provenances, the coastal area has been affected by lower secondary influences of anthropogenic, marine inorganic and organic matters.

Fuzzy Logic approach to detect the influence of marine vs. continental (anthropic) elements in the geochemistry of the Asturian coastline sediments

This work was done in 35 beaches along 400km of the of Asturias coast (north-west of Spain).In a first approximation, by means of graphical treatment, positive and negative anomalies were found what led to the hypotheses formulation regarding the sedimentation processes formation. These hypotheses were then contrasted with Data Mining and Fuzzy Logic with the implementation of PreFurGe tool on the same database used for classical statistical treatment.With PreFuRGe tools it was possible to validate some of the previous conclusions obtained with multivariate classical statistical tests as well as to better understand the qualitative behavior of marine vs continental elements, according to the evolution of a specific variable designated as consequent. For this study, marine, Na, S, Sr as well as mining/industrial, As, Cu, Fe were highlighted as consequents.The different origins of the materials of Cantabrian coast were revealed; (1) those of typical marine origin; and (2) those of continental origin, which were grouped by fuzzy clusters, in two different groups: (2.1) a non-anthropic continental one linked to the lithologies present in the main river watershed that flow into the study area; and (2.2) the other, also continental, but linked to mining and/or industrial activity, transported by rivers to the beaches.In this study, the stratigraphic sequence of materials of the coast could be easily associated with their origin based on the fuzzy rules with greater approximation than using classical statistics.

Linking Bacterial Communities to Optical-Derived Properties of Porewater DOM in Sediments in the Coastal East China Sea

Bacterial communities and porewater dissolved organic matter (DOM) pool are intimately interactive in sedimentary environments. Estuarine coastal regions are an interactive area between terrestrial and marine influences in terms of DOM origins and freshness. Yet, we know little about the relationships between the bacterial communities and DOM in those regions. In this study, porewater DOM samples were collected from 42 sites in the coastal East China Sea. The porewater DOM optical properties were determined by fluorescence and absorption spectra, while the corresponding bacterial community compositions of those sediments were examined by 16S rRNA gene high-throughput sequencing. The results showed that bacterial species richness was positively correlated with multiple terrestrial indicators based on the optical properties of DOM, which implied that heterogeneous DOM from terrestrial origins might harbor a wider spectrum of bacterial taxa in marine sediments. The analysis of the co-occurrence network of the bacterial communities showed that the edges and density for samples with low DOM freshness were 3.4 times and 3 times those for the samples with high DOM freshness, respectively. This suggested that the connection among the bacterial taxa under the lower DOM freshness condition were enhanced and that reduced freshness of DOM may encourage more complimentary utilization of resources. The findings provide a new insight into such interactive processes of heterogeneous organic matter utilization meditated by microorganisms in coastal sediments.

Bacteria Halotolerant from Karst Sinkholes as a Source of Biosurfactants and Bioemulsifiers.

Halotolerant bacteria with biosurfactant (BS) and bioemulsifiers (BE) activity can coexist in Karstic sinkholes with marine influence. Two sinkholes in the Yucatan peninsula were selected to isolate bacteria with BE and BS activity stable in NaCl. The optimal time, the effect of nitrogen and carbon source in the medium, and the conditions (agitation, pH and salinity) for the production of BS and BE compounds in planktonic and sessile (stimulate the formation of biofilms in cell roller) culture were determined. Eighty strains showed the highest emulsification activity (EI24 ≥ 50%) and drop-collapse ≥ 4 mm. 87% of the strains are moderately halotolerant, and 21% bordered the limit of extreme halotolerance. Twenty-four strains maintained or improved their BS and BE activity under salinity conditions at 5% and 10%, being the most active genera Bacillus, Paenibacillus and Lysinibacillus, identified by sequencing of the 16S rRNA gene. The results show that the nitrogen source positively affects the BS and BE activity, regardless of the type of culture. The sessile culture markedly stimulated BS activity with significant differences. However, we did not find a greater influence on the culture conditions. The results suggest that halotolerant bacteria from sinkholes could be implemented in bioremediation and other biotechnological applications.

Holocene foraminifera from the outer zone of the Bahía Blanca Estuary, Argentina (South America)

In this study, Holocene paleoenvironmental changes were interpreted based on benthic foraminifers from a core (39°20′S-61°27′W) extracted from the Argentine Continental Shelf close to the Bahia Blanca Estuary, in the south of Buenos Aires Province. Foraminiferal fauna was determined, and found to include 44 species of 22 genera. From micropaleontological and sedimentological analysis, paleoenvironmental changes during the middle-late Holocene were recognized. Two stages were determined: from 8319–8045 to 7836-7623 Cal. yrs BP, the sediments reflected a shallow environment with estuarine conditions and low energy, enabling determination of a coastal depositional environment. As from ca. 7836–7623 up to ca. 651-557 Cal. yrs BP, the sediments indicated a passage towards to a shallow shelf environment with great marine influence, displaying a high degree of energy and oxygenation, which may have been related to a rise in sea level ca. 7836 -7623 Cal. yrs BP. The detailed study of the benthic foraminiferal fauna presented herein and the sedimentological and chronological analysis performed on the continental shelf next to the Bahía Blanca Estuary provide further proof of the relative location of the mean sea level during the middle Holocene transgressive hemicycle in Argentina.

Tracing marine conditions in the Ipubi Black Shales, Araripe Basin, NE Brazil: An approach by chemical elements contents

The aim of this study was to test the hypothesis of a marine influence during the Ipubi Formation deposition (late Barremian-early Aptian age) in the Araripe Basin northeast, Brazil. For this, it was utilized a representative section in the southernmost part of the basin. The section is composed of mudstone, shale-marl laminae, and black shale rocks. The organic matter in the samples is 3.27 and 18.28%; whereas the CaCO3 present values in order of 23.42–66.46%. The geochemical proxies, such as V/Ni, Ni/V (V/(V + Ni) Fe/Al suggest depositional condition from sub-oxic to anoxic. The Sr/Ba and Rb/Sr data range from brackisch to hypersaline waters. The ingression of a seawater in the Araripe Basin triggered the organic matter accumulation, as well as the trace metals mobility in the bottom surface. Our data suggests that the Ipubi Formation represents the boundary of transitional to marine conditions in the Araripe Basin, and the basin owned as a silled basin when the increase of relative sea level made it possible the water inlet in the basin.

New Early Cretaceous species of Zonocypris G. W. Mller, 1898 (Crustacea: Ostracoda) from the Crato Formation, Brazil.

Two new species of Zonocypris G. W. Mller, 1898 are described from the late Aptian of the Araripe Basin, Northeast Brazil: Zonocypris berthoui sp. nov. and Zonocypris dorsoconvexa sp. nov. Species of this genus occur from the Early Cretaceous to the Holocene and are characterized by a small globular carapace, often ornamented over the whole surface by concentric ridges with simple normal pore canals, showing a remarkable morphological stability during the evolution of the genus. The first records of the genus point to an Atlantic origin. In Aptian deposits, species of Zonocypris are rare, occurring in brackish/freshwater assemblages, with marine influence.

Mineralogical and Geochemical Compositions of Ammonian Illite-Enriched High-Rank Coals of the Xingying Mine, Northeastern Chongqing, China.

Ammonian illite (NH4-illite)-rich late Permian coals of high rank were discovered in southwestern China. This research reports new mineralogical and geochemical data of 11 bench samples from the adjacent Xingying mine, northeastern Chongqing Coalfield, southwestern China, with an emphasis on the modes of occurrence and origin of NH4-illite. The Xingying coals, with low ash yields and medium sulfur, have a high rank (semianthrite, Ro,ran = 3.67%), owing to the plutonic metamorphism. Minerals in the coal consist of NH4-illite and pyrite and, to a lesser extent, jarosite, albite, and anatase, with traces of chamosite, quartz, bassanite, apatite, fluorapatite, florencite, and rhabdophane. Compared with world hard coals, vanadium is significantly enriched with a concentration coefficient (CC) higher than 10; Mo and Pb are enriched (5 < CC < 10); F, Co, Ni, Cu, Ge, Se, Y, Zr, Nb, Ag, Cd, In, Sn, Cs, Sm, Eu, Tb, Dy, Er, Yb, Hf, Bi, and U are slightly enriched (2 < CC < 5) in the Xingying coals. Fluorine in host rocks, including roof, floor, and parting, is significantly enriched. Fluorine concentration in the coal may be increased greatly if the coal is mixed with host rocks during mining activity. Hence, the Xingying coals should be subjected to beneficiation before utilization for the environment and human health. The Al2O3/TiO2 and Eu anomalies demonstrated that the terrigenous materials come from the mafic basalts of the Kangdian Upland. NH4-illite is formed by interaction of pre-existing kaolinite or K-illite with NH4+ released from organic matter under high temperatures during the process of hydrothermal alteration. The authigenic chamosite, albite, quartz, anatase, apatite, fluorapatite, and rhabdophane are also deposited from the hydrothermal solutions. In addition, the Xingying coals are subjected to marine influences. Based on the preliminary evaluation, the Xingying coals cannot be a potential source for critical elements such as rare earth elements and yttrium. This indicates that not all the late Permian coals in southwestern China have economic significance for critical elements.

Terrestrial and marine influence on atmospheric bacterial diversity over the north Atlantic and Pacific Oceans

The diversity of microbes and their transmission between ocean and atmosphere are poorly understood despite the implications for microbial global dispersion and biogeochemical processes. Here, we survey the genetic diversity of airborne and surface ocean bacterial communities sampled during springtime transects across the northwest Pacific and subtropical north Atlantic as part of the Tara Pacific Expedition. We find that microbial community composition is more variable in the atmosphere than in the surface ocean. Bacterial communities were more similar between the two surface oceans than between the ocean and the overlying atmosphere. Likewise, Pacific and Atlantic atmospheric microbial communities were more similar to each other than to those in the ocean beneath. Atmospheric community composition over the Atlantic was dominated by terrestrial and specifically, dust-associated bacteria, whereas over the Pacific there was a higher prevalence and differential abundance of marine bacteria. Our findings highlight regional differences in long-range microbial exchange and dispersal between land, ocean, and atmosphere.

Back-barrier evolution and along-strike variations in infilling of the Kosi Bay lake system, South Africa

This study examines both the inlet dynamics, recorded in the back-barrier stratigraphy of Kosi Bay, and the competing effects of waterbody segmentation on along-strike changes in the character and nature of an incised valley fill at Kosi Bay, South Africa. The Kosi Bay system comprises four interconnected lakes (Lake Makhawulani, Lake Mpungwini, Lake Nhlange and Lake Amanzimnyama) subject to varying degrees of marine influence. Formerly, the system's only connection to the ocean was through the Bhanga Nek palaeo-inlet. The location of this system behind a continuous coastal barrier predisposes it to excellent archives of environmental change related to changing sea-level and sediment supply. In this context, two cores were extracted from the system (KB2 and KB4), together with over 150 km of seismic reflection profiling, as well as AMS radiocarbon analyses and legacy data in order to present a new stratigraphic evolution model for this back-barrier system. A total of 5 seismic units were imaged (Units A-E). A major unconformity surface (SB), characterised by broad u-shaped incised valleys, incises the underlying unconsolidated sandy acoustic basement (Unit A). Unit B forms as thickly developed central basin deposits, partially infilling the incised valleys. Two forms of prograding spits are evident -Unit C1 progrades from the palaeo-highs of the valley interfluves into the nearest available accommodation space and Unit C2 progrades from the margins of the system into the basin. These are separated by an erosional surface (T-RS) formed by migrating tidal channels as sea-level rose and marine waters entered the system during the Holocene. Unit C2 spits are in turn associated with slump deposits formed on the steepest part of the margins (Unit D) that were dated to 2900 ± 165 cal. BP. The unusual depth of Surface T-RS is attributed to (1) limited sediment supply during sea-level rise, (2) the presence of easily erodible fine sediments in which this surface erodes and (3) a larger tidal prism when the Bhanga Nek inlet was still open and system segmentation by Units C2 and D had not yet occurred. Unit E caps the stratigraphy and is interpreted as lacustrine fines with a thin layer of acoustically transparent material (gyttja) on top. The deposition of Unit E signifies the closure of the system to the ocean and the overall shift from an estuarine/lagoon environment to a lacustrine one. Recalibrated AMS dates place the system closure to between 3160 and 2900 cal. BP, coeval with the formation of the prograding marginal spits and waterbody segmentation (Unit C2). Along-strike variation in the timing of the basin infilling, attributed to changes to the inlet functioning coupled to the segmentation of the waterbody, is characteristic of this area. At 1450 cal. BP, a new tidal inlet formed to the north of Lake Makhawulani, where impounded waters were diverted via a low point in the back-barrier coastal dune cordon. The formation of this inlet suggests a prolonged period of back-barrier flooding until a low point in the barrier was breached during the Holocene sea-level highstand of 1.5 m. Such inlet development and along-strike back flooding of incised valleys is an unusual attribute of coastal waterbodies of South Africa.

A multidisciplinary approach to characterise the Early-Middle Holocene palaeoenvironmental evolution of the Sado Valley of Portugal: Implications for late Mesolithic human communities

In this paper we present the results of a multidisciplinary study performed in the Carrasqueira valley, a tributary of the River Sado (SW Portugal), aimed at characterising the Holocene environmental conditions during the late Mesolithic occupation of this valley. Our findings are based on a 13.5 m long sediment core (Arez3) collected on the alluvial plain close to a late Mesolithic shell midden, the Arapouco site. The results of the multiproxy analyses (texture, magnetic susceptibility, organic composition and chemistry, n-alkanes and palynology) point to a greater marine influence between ca. 8850 cal yrs. B.P. (at the core base) and ca. 7450 cal yrs. B.P. (at 750 cm below mean sea level (MSL)) and the existence of an environment similar to the present-day central estuarine basin. At this point in time, sedimentation rates were lower than the rate of sea-level rise, resulting in the formation of a drowned area with intertidal environments developing on the less incised margins. After 7040 cal yrs. B.P. the contribution of organic matter from terrestrial plants and freshwater phytoplankton to the sediment increased, reflecting a change in the sedimentary pattern, with the estuarine environments progressively giving way to freshwater environments. After the Middle Holocene (ca. 6530 cal yrs. B.P.), negative shifts of δ15N to values ~0‰ point to hyper-eutrophication and cyanobacteria bloom episodes under backswamp conditions. According to these results, the estuarine environment prevailed in the area until 7040 cal yrs. B.P. (5090 cal yrs. B.C.; 390 cm below MSL), i.e., during the Mesolithic occupation of the valley, allowing for the occurrence and for the exploitation of marine shellfish and fish by these hunter-gatherer communities at the proximity of the downstream occupation areas.