Normal Marine Research Articles

Gobies (Gobioidei) of soft bottoms from Nha Trang and Van Phong bays (South China Sea, Vietnam)

Gobioid fishes collected in Nha Trang and Van Phong bays (Vietnam) represented by 44 species, including 30 species continuously associated with soft bottoms in the open parts of the bays with normal marine conditions are reviewed. A new species, Navigobius khanhoa sp. n., is described. This species differs from other species of the genus in much higher number of rays in the second dorsal fin (26), smaller size of the mouth, teeth on the jaws arranged in a single row, and other characters. Four species from the genera Acentrogobius, Eviota, Favonigobius, and Gnatholepis have not been identified to the species, and, most likely, some of them are new for science. Nine species are recorded in the fauna of Vietnam for the first time: Aulopareia unicolor, Bathygobius hongkongensis, Egglestonichthys bombylios, Glossogobius circumspectus, Oplopomops diacanthus, Oxyurichthys auchenolepis, Tomiyamichthys ex gr. russus, Tryssogobius porosus, and Valenciennea immaculata. An occurrence of Glossogobius olivaceus in the fauna of Vietnam is confirmed. Three species, G. olivaceus, Oligolepis acutipennis, and Periophthalmus kalolo, are recorded in the Cai River delta for the first time. A new synonymy is established: Eviota gurjanovae (Prokofiev, 2007) = E. prasina (Klunzinger, 1871). The current state of knowledge of Gobiidae fauna of Vietnam is discussed, and the updating of the species composition of Gobiodontini of Nha Trang Bay is presented in addition to the species list published earlier (Prokofiev, 2007).

Effects of microalgae on nutrient removal from mariculture wastewater in Can Gio District, Ho Chi Minh City, Vietnam


 
 
 Mariculture has currently brought greatly valuable products in many fields simultaneously released a large amount of wastewater contributing to water pollutions on account of its organic and inorganic constituents. Nowadays, with the development of environmental engineering, more and more approaches, especially friendly-environmental and highly effective wastewater biological methods, are being applied to tackle pollutions and minimize adverse effects of treatments to reach the sustainable development. This report focuses on the study of proliferation combined with elimination of polluting substances of marine algae species Tetraselmis suiscica, Tetraselmis sp., Platymonas sp. in aq- uaculture wastewater sampled from Can Gio District, Ho Chi Minh City, Vietnam with levels of concentration during 14 days under normal marine algae culture conditions, and compared to that in Daigo’s IMK media. The results shown that, the algae species all grew rapidly simultaneously gave high nutrients removal yields (COD, N, P) and created a considerable amount of biomass within a short period of culture. Particularly, Platomonas sp. and Tetraselmis suiscica could proliferate as well as give high treatment yields of organic substances (COD), PO43-, NO3-, NH4+ and Total Nitrogen in concentrated wastewater. To sum up, this study showed the potential of using microalgae to reduce COD, nitrogen and phosphorus in mariculture wastewater.
 Ngành nuôi trồng thủy hải sản trong những nằm gần đây đã mang lại nhiều sản phẩm có giá trị trong nhiều lĩnh vực đồng thời thải ra một lượng lớn nước thải gây ô nhiễm nguồn nước bởi các thành phần vô cơ và hữu cơ có trong nước thải. Ngày nay, với sự phát triển của kỹ thuật môi trường, ngày càng nhiều cách tiếp cận, đặc biệt là các phương pháp sinh học hiệu quả cao và thân thiện với môi trường đang được ứng dụng để xử lý ô nhiễm và giảm thiểu hậu quả bất lợi sau xử lý, nhằm hướng tới sự phát triển bền vững. Bài báo cáo tập trung nghiên cứu khả năng sinh trưởng và phát triển của ba loài vi tảo biển Tetraselmis suiscica, Tetraselmis sp., Platymonas sp. kết hợp với việc loại bỏ các hợp chất gây ô nhiễm có trong nước thải từ ao nuôi tôm của huyện Cần Giờ, Việt Nam và so sánh đối chiếu với môi trường dinh dưỡng Daigo’s IMK trong 14 ngày nuôi trồng. Kết quả cho thấy những vi tảo sinh trưởng rất nhanh nhờ vào việc sử dụng các chất ô nhiễm trong nước thải, đặc biệt hiệu suất xử lý COD, PO43-, NO3-, NH4+ và nitơ tổng của Platomonas sp. và Tetraselmis suiscica rất cao thậm chí trong môi trường nước thải đậm đặc. Do đó, chúng tôi kết luận, vi tảo có tiềm năng rất lớn trong việc giảm nồng độ chất hữu cơ, phốt pho và nitơ trong nước thải nuôi trồng thủy hải sản.
 
 

THE PERMIAN -TRIASSIC BOUNDARY, DEAD SEA, JORDAN: TRANSITIONAL ALLUVIAL TO MARINE DEPOSITIONAL SEQUENCES AND BIOSTRATIGRAPHY

The Permian to Triassic transition in Jordan is characterised by a sequence boundary underlain by red-bed, alluvial lithofacies deposited in a humid-tropical climate by low-sinuosity rivers, and overlain by shallow marine siliciclastics with thin carbonates. The low-gradient alluvial floodplain was repeatedly subjected to the development of ferralitic and pisolitic paleosols on the interfluves. In contrast, dysaerobic environments in the fluvial channels and abandoned lakes resulted in the preservation of a prolific flora of macro-plants and palynomorphs that indicate a probable range from Mid- to Late Permian age, though the abundant presence of the distinctive pollen Pretricolpipollenites bharadwajii indicates the youngest part of that range. Above the sequence boundary, reddened shallow-marine beds characterised by ripple cross-laminated, siltstones/sandstone with desiccation cracks and sparse surface burrows mark the initial Triassic marine transgression in the region (Arabian Plate Tr 10). These are followed by two thin limestone (packstone) beds with shallow scours and bivalve shell lags, that have yielded a low diversity assemblage of conodonts (e.g. Hadrodontina aequabilis ) and foraminifera (“ Cornuspira ” mahajeri ) that are interpreted as euryhaline taxa characterising the early Induan (Early Triassic). Thus the absence of body fossils and vertical infaunal burrows in the lowest marine beds may reflect low-diversity ecosystems following the Permian-Triassic extinction event, or be a result of stressed shallow marine environments. A gradational upward increase in grey, green and yellow siltstones beds accompanied by a concomitant increase in bioturbation (and infaunal vertical burrows) and thin-shelled bivalves about 15 m above the boundary indicates colonisation of the substrate under more normal shallow marine conditions perhaps indicating recovery phase following the extinction event.

Depositional System of the Carboniferous Huanglong Formation, Eastern Sichuan Basin: Constraints from Sedimentology and Geochemistry

AbstractUsing analyses of the lithology, sequences, paleoenvironment, and tectonic setting, the depositional system of the Carboniferous Huanglong Formation in the eastern Sichuan Basin was identified. The lithological characteristics of the Lower Member, Middle Member, and Upper Member were analyzed and classified. Before the use of carbon, oxygen, and strontium isotopes in the analysis, all of the geochemical data were tested for validity. On the basis of the Z values obtained from carbon and oxygen isotopes, the paleoenvironments of the three members were elucidated. Lower Member was dominantly an enclosed marine environment with intense evaporation and little freshwater input into the sea. Middle Member developed in a semi‐enclosed to normal marine environment with many rivers. Upper Member was formed in a normal marine environment. The east Sichuan Basin was enclosed by paleouplifts before the deposition of the Huanglong Formation, forming a relatively enclosed depositional setting. Paleogullies developed in the Silurian strata that underlie the Carboniferous rocks; these paleogullies can be identified. On the basis of a comprehensive analysis, we propose that the Huanglong Formation developed in a platform system. Four microfacies were identified: supratidal flat, dolostone flat, grain shoal, and shelf microfacies. The high‐permeability and high‐porosity characteristics of the grain shoal microfacies are favorable for hydrocarbon accumulation, while the supratidal flat and shelf microfacies developed very few high‐quality reservoirs. The paleogullies, in which increased amounts of grain shoal microfacies developed, controlled the distribution of high‐quality reservoirs.

Over half a century of Messinian salinity crisis

Did the Mediterranean ever become a desert during Messinian or was it a huge hyperhaline water body? According to Selli, the introduction of the concept and name of the Messinian Salinity Crisis in 1954, the second hypothesis was correct, but he did not succeed in preventing the rapid growth of popularity of the first hypothesis, triggered by the DSD Mediterranean campaign during the 1970s. The ensuing desiccation theory became popular enough to be included in elementary text books. The controversy has been revived in the new millennium and much former proof of the theory is now in doubt. The Mediterranean was not totally isolated, but often supplied with normal marine water. Instead of km-deep drawdown, shallower-to-absent level drop is favoured. Exposed canyons at the mouth of major Mediterranean rivers have turned into submarine channels filled by clastic sulphates. The mega-catastrophic potential of the desiccation theory has turned out to be less worrying. Perhaps the textbooks of our grandchildren should be updated. Within the frame of new evidence regarding normal water supply, even from the Indian Ocean, are discussed, based on two new palinspastic Messinian maps. However, reduced sharpness in the controversy and increasing consensus reached among specialists depend on ongoing inferred correlations between on-land and deep-marine Messinian evaporites. Only drilling across the whole, deep Mediterranean evaporite sequences can back-up the reliability of the correlation and validity of these new views.

Trace elements and REE geochemistry of Middle Devonian carbonate mounds (Maïder Basin, Eastern Anti-Atlas, Morocco): Implications for early diagenetic processes

Trace and rare earth elements (REEs) have proven their utility as tools for assessing the genesis and early diagenesis of widespread geological bodies such as carbonate mounds, whose genetic processes are not yet fully understood. Carbonates from the Middle Devonian conical mud mounds of the Maïder Basin (eastern Anti-Atlas, Morocco) have been analysed for their REE and trace element distribution. Collectively, the carbonates from the Maïder Basin mud mounds appear to display coherent REE patterns. Three different geochemical patterns, possibly related with three different diagenetic events, include: i) dyke fills with a normal marine REE pattern probably precipitated in equilibrium with seawater, ii) mound micrite with a particular enrichment of overall REE contents and variable Ce anomaly probably related to variation of pH, increase of alkalinity or dissolution/remineralization of organic matter during early diagenesis, and iii) haematite-rich vein fills precipitated from venting fluids of probable hydrothermal origin.Our results reinforce the hypothesis that these mounds were probably affected by an early diagenesis induced by microbial activity and triggered by abundance of dispersed organic matter, whilst venting may have affected the mounds during a later diagenetic phase.

A diagnostic GDGT signature for the impact of hydrothermal activity on surface deposits at the Southwest Indian Ridge

The impact of hydrothermal activity on wider ocean geochemistry and microbial ecology remains a topic of much interest. To explore whether hydrothermal microbial signatures are exported to surrounding marine sediments or if such organisms serve as an important source of sedimentary organic matter, we determined the distributions of glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in surficial normal marine sediments, metalliferous sediments and low-temperature hydrothermal deposits at newly discovered hydrothermal fields and adjacent areas at the Southwest Indian Ridge (SWIR). The GDGTs in those samples varied significantly, evidently representing a variable influence of the hydrothermal activity. GDGT compositions of surficial background sediments in SWIR were similar to those commonly observed in marine sediments, dominated by GDGTs associated with marine planktonic archaea and especially GDGT−0 and crenarchaeol. In contrast, the GDGTs of metalliferous sediments strongly impacted by hydrothermal activity and low-temperature hydrothermal deposits were markedly different, characterized by high relative abundances of isoprenoid GDGTs (iGDGTs) bearing multiple rings (yielding a higher ring index), low relative abundances of crenarchaeol, and the presence of glycerol monoalkyl glycerol tetraether lipids (GMGTs; so called ‘H-tetraethers’) that were absent in the normal marine sediments. Sources for these hydrothermal-specific tetraether lipids likely include methanogens and anaerobic methanotrophic archaea (GDGT−0 and GDGT−1–3, respectively), Thermoprotei and Thermoplasmatales (elevated GDGT−3 and 4), and other thermophilic archaea including Methanobacteriales (GMGTs). Deposits influenced by low-temperature hydrothermal activity also contained higher abundances of branched GDGTs (brGDGTs) typically attributed to soil bacteria. The more distal metalliferous sediments influenced by the neutrally buoyant plume did not contain putative hydrothermal GDGTs, having the same GDGT distribution as the background sediments. This suggests that the neutrally buoyant plume has a limited potential to directly influence the organic matter inputs to surrounding sediments, due to a rapidly waning chemosynthetic microbial contribution relative to normal marine contributions as the plume dispersed and was diluted.

Foraminiferal and palynological organic matter records of the Upper Badenian (Middle Miocene) deposits at Anadoly (marginal part of the Ukrainian Carpathian Foredeep Basin)

The Badenian section of Anadoly near Kamyanets Podilskyy (Ukrainian Carpathian Foredeep Basin) consists of the Tyras Fm. (gypsum and Ratyn Limestone) and the Ternopil Mb. of the Kosiv Fm. The latter are 5.3 m thick and are composed of dark grey mudstones with limestone intercalations. This study indicates the occurrence of over 54 species of benthic foraminifers and 10 species of planktonics. Benthic foraminifera are represented mainly by calcareous forms; agglutinated tests are very rare. Planktonic foraminifera appear in the upper part of the succession studied. Five benthic foraminiferal assemblages are recognized: A ( Elphidium / Lobatula / Astrononion ) B (Hauerinidae), C ( Cibicidoides / Lobatula ), D ( Porosononion ) and E ( Uvigerina / Bulimina ). The foraminiferal record indicates deposition in a shallow subtidal environment (20 m depth) of normal marine salinity and temperate waters followed by gradual deepening of the basin to >50 m. Analysis of foraminiferal assemblages indicates that bottom waters were highly oxygenated during deposition of the lower and middle parts of the Anadoly sequence. During deposition of the upper part of the sequence the oxygenation of bottom water gradually decreased, as expressed by a large decrease in the proportion of oxic species and an increase in dysoxic ones. The same set of samples yielded low amounts of palynological organic matter represented by dominant black opaque phytoclasts; bisaccate pollen grains and dinoflagellate cysts are rare. Taxonomically impoverished assemblages of the latter consist of dominant Polysphaeridium and Cleistosphaeridium placacanthum associated with Lingulodinium machaerophorum and a few other taxa. The taxonomically richest assemblage was found in the topmost sample. These changes were interpreted as indicative for increased salinity in the surface water layer, with its maximum in the middle part of the section; the assemblage from the topmost part is characteristic for normal marine salinity.

Sedimentological and paleoenvironmental scenario before, during, and after the Messinian Salinity Crisis: The San Miguel de Salinas composite section (western Mediterranean)

A composite stratigraphic section ranging from the Messinian to the Pliocene, recording the most important phases of the Messinian Salinity Crisis, is represented in the San Miguel de Salinas area (Bajo Segura basin, SE Spain). Detailed magnetostratigraphic and facies analyses and foraminifer and nannoplankton assemblage studies were carried out. Integration of the results has allowed the characterization of the pre-evaporitic (synthem Messinian I), syn-evaporitic (synthem Messinian II), and post-evaporitic phases (synthem Pliocene) from a paleoenvironmental and chronostratigraphic standpoint. The pre-evaporitic phase is late Messinian and records a shallowing-upward trend. The syn-evaporitic phase took place in chron C3r and is characterized by laminated marls with intercalated selenitic gypsum beds and sandstones. Variations in foraminifer and nannoplankton assemblages together with episodic gypsum precipitation record major changes in water salinity in a stressed marine environment. The pre- and syn-evaporitic phases are separated by the intra-Messinian unconformity, represented by an erosional surface related with a sea-level fall. After the evaporitic phase, a sea-level fall generates the end-Messinian unconformity, whose strongly erosional nature is evidenced by the deeply carved paleovalley of San Miguel de Salinas. The post-evaporitic phase begins in the earliest Pliocene and records the re-establishment of normal marine conditions in the basin. Since the San Miguel de Salinas composite section can be considered as a benchmark for the study of the evolution of marginal Mediterranean basins during the Messinian Salinity Crisis, the detailed characterization of these different phases is of great importance in understanding this event.

Late Quaternary development of the Croatan Beach Ridge Complex, Bogue Sound, Bogue Banks, NC, USA and implications for coastal evolution

Foraminiferal, sedimentological, geophysical, and geochronologic data were utilized to elucidate the late Quaternary geologic development of the Croatan Beach Ridge Complex (CBRC), Bogue Sound, and Bogue Banks, North Carolina, USA. The CBRC is a relict beach ridge feature located on the mainland. It is separated from the modern barrier island, Bogue Banks, by Bogue Sound. Seventeen cores along shore-normal and shore-parallel transects provided material for sedimentologic and foraminiferal analysis and resulted in the recognition of seven depositional facies representing a variety of coastal depositional environments.Chronologic and depositional facies data suggest the CBRC was initiated during MIS 5a and rapid southward progradation produced a cape structure. Eolian reactivation of the upper sand of the CBRC occurred during the last glacial maximum (∼18 ka). The age of flood tide delta deposits in Bogue Sound suggests that the Holocene barrier island, Bogue Banks, had formed by ∼6 ka. Shoreface ravinement resulted in a shoreface landward of the present shoreline by ∼3.5 ka. Seaward and westward spit progradation of Bogue Banks began ∼1.7 ka and continued to ∼1.3 ka. Normal marine salinity conditions were present in Bogue Sound ∼1.1 ka, suggesting removal of at least the narrowest parts of the barrier island, coeval with a previously documented segmentation of the southern Outer Banks barrier islands. Previous work has linked this segmentation to climate warming and increased tropical storm activity during the Medieval Climate Anomaly.This study illustrates the complex response of this coastal system to Pleistocene and Holocene sea-level and climate change over two major sea-level cycles. In particular, the regional geomorphology during MIS5a and the Holocene sea-level highstand differ significantly and this, in large part, was controlled by the antecedent geologic framework, resulted in the contrasting more localized coastal geomorphic response.

Depositional environments of Late Cretaceous Gongila and Fika formations, Chad (Bornu) Basin, Northeast Nigeria

Organic geochemical and palynofacies studies of 172 ditch cuttings samples of possible source rock shales from the Late Cretaceous Gongila and Fika formations in the Chad Basin of NE Nigeria were carried out to determine their paleoenvironments of deposition. Although dominated by amorphous organic matter, C/S ratios and molecular parameters suggest the mostly organic lean shales (TOC contents typically below 1.5%) were deposited in a normal marine environment. Levels of oxygenation influenced by water depth in the depositional environment appear to control organic richness and quality of the dark grey shales.The organic rich (TOC > 2.0%) upper part of the Fika Formation was deposited under anoxic conditions during the Late Cretaceous and could represent an Oceanic Anoxic Event. Mature intervals where such conditions prevailed would have generated liquid hydrocarbon, although none were sampled here.A trend of increasing organic richness towards the central part of the larger Chad Basin observed in this and other studies supports the development of organic rich marine shales (average TOC contents of 2–3%) of equivalent age in the Termit Basin where water depth would have been deeper and oxygen conditions at levels that permitted preservation of marine organic matter.

The Upper Ordovician black shales of southern Quebec (Canada) and their significance for naturally occurring hydrocarbons in shallow groundwater

Shale gas exploration in the St. Lawrence Platform of southern Quebec (eastern Canada) focussed on the Upper Ordovician Utica Shale from 2006 to 2010 during which 28 wells were drilled, 18 of which were fracked. The St. Lawrence Platform is thus considered as a pristine geological domain where potential environmental effects of fracking can be evaluated relative to the natural baseline conditions of the shallow aquifers. In the Saint-Édouard area southwest of Quebec City, it has been shown that groundwater carries variable and locally high levels of naturally occurring dissolved hydrocarbons in which thermogenic ethane and propane can be found. Fifteen shallow (30–147m) wells were drilled into bedrock and sampled (cores and cuttings) with the purpose of characterizing the shallow bedrock in a shale gas pre-development context.The shallow bedrock geology is made of three Upper Ordovician clastic formations. The Lotbinière and Les Fonds formations are time- and facies-correlative with the Utica Shale present at a depth of 1.5 to 2km in this area. They are dominated by calcareous black shales with minor siltstone and micrite beds. The Nicolet Formation is the youngest unit of the area and consists of gray to dark gray shales with locally abundant thick siltstone and fine-grained sandstone beds.The organic matter in the Lotbinière and Les Fonds formations is represented by solid bitumen with subordinate liptinite algae, graptolites and chitinozoans representing normal marine Type II kerogen. Both formations are at the post-peak hydrocarbon generation as indicated by the equivalent random vitrinite reflectance of 0.94 to 1.04%. Rock Eval data support the Type II nature of the kerogen and the late oil window maturation level.Hydrocarbon extracts from the three formations have yielded high to low concentrations of C1 to C6. For all units, an upward decrease in total volatiles (C1+C2+C3) together with an increase in the gas dryness ratio (C1/C2+C3) is recorded, the transitions occurring at depths shallower than 50m where the shales are more fractured. The upward increase in the gas dryness ratio results from the more significant reduction of ethane and propane concentrations compared to that of methane. Consistent with the dryness ratio trend, the δ13CVPDB values of methane change from thermogenic values (≈−50‰) for deeper samples, to more biogenic (negative) values (<−60‰) at shallow depths. A similar δ2HVSMOW trend of more negative values at shallower depths is noted. The δ13CVPDB and δ2HVSMOW values of rock-hosted methane indicate that samples at shallow depth recorded a microbial influence. It is proposed that diffusion and some microbial degradation of hydrocarbons are responsible for the decrease of rock volatiles and the in situ generation of biogenic methane in the shales at shallow depths to mix with the in situ thermogenic methane.The Utica Shale is a very good source rock with high generation potential. However, thermogenic volatiles can also originate from shallower units with much shorter migration pathways. The mixed thermogenic and biogenic methane in the groundwater results from fracture-enhanced diffusion and biodegradation of volatiles at shallow depths.

Diagenetic evolution of Tortonian temperate carbonates close to evaporites in the Granada Basin (SE Spain)

The Granada Basin (SE Spain) is a small basin located in the central part of the Betic Cordillera, structured as such in the late Tortonian and initially connected to the Atlantic Ocean and to the Mediterranean Sea. During the late Tortonian, normal marine conditions prevailed, leading to the deposition of skeletal carbonate sediments on platforms around structural highs. The marine connections were later interrupted, first to the Atlantic Ocean and then to the Mediterranean Sea, and a thick evaporite sequence, marking the transition from marine to continental conditions, was deposited during the latest Tortonian. In this work, the diagenetic evolution of the Tortonian temperate carbonates (TTC), underlying and close to the evaporite bodies, is revealed and discussed. The diagenetic study includes petrographic analyses (conventional petrography, cathodoluminescence, and fluorescence), geochemical analyses (major, minor and trace elements, and δ13C and δ18O stable isotopes), and microthermometry of fluid inclusions. In the TTC, marine diagenetic processes such as micritization and fibrous calcite-cement precipitation and mechanical compaction took place during or just after deposition (Eogenesis). An initial burial event (Mesogenesis 1) is characterized by: 1) stabilization of the temperate-water carbonates by freshwater, and 2) porosity occlusion via precipitation of low-Mg bladed and syntaxial/mosaic calcite cements. The TTC were then subaerially exposed (or got close to the surface) during evaporite deposition and underwent pedogenesis, Mg-smectite infiltration, and pyrite formation (Telogenesis 1). Subsequent brine-related diagenetic alterations, such as dolomitization and silica, halite, and sylvite replacements of carbonate grains occurred during a second burial episode (Mesogenesis 2) concomitant with the Messinian lacustrine deposition, this being followed by chemical compaction (stylolite formation). Finally, the area was uplifted and the TTC exhumed. Microstalactitic (dripstone) and fibre/whisker calcite cement precipitation and extensive dissolution relate to this Pliocene–Quaternary late event (Telogenesis 2). In the study case diagenetic history is closely linked to basin evolution, as diagenetic pathways of carbonate rocks were related to major geodynamic events, including basin restriction leading to evaporite deposition, and several episodes of subsidence and uplift. Up to now, only very few diagenetic studies have attempted to demonstrate this correlation between diagenetic history and basin evolution.

Sepia from the Miocene of the Central Paratethys: new taxa and notes on late Cenozoic cuttlefish diversity

A new and locally abundant species of Sepia, S. juliebarborarum sp. nov., and single records of S. aff. loerentheyi and S. aff. sanctacrucensis from the upper Badenian of Slovakia and Austria, S. mikuzi sp. nov., S. aff. mikuzi sp. nov. and Sepia sp. from the middle Badenian of Slovenia, document a greater Miocene sepiid diversity in the Central Paratethys than previously recorded. In the present study, Miocene sepiids from the Central Paratethys are systematically revised and, in part, compared to other coeval taxa from elsewhere. Middle Miocene diversity in the Central Paratethys amounts to nine species, inclusive of four taxa retained in open nomenclature. Here we use the morphology of the dorsal shield and septal suture lines as key features for systematic assignment at the species level. Usage of the generic name Sepia for these Miocene sepiids is corroborated by uniquely preserved material of S. vindobonensis from the middle Badenian of Austria. This reveals only minor morphological differences during ontogeny from the Recent type species of Sepia, S. officinalis. The stratigraphical range of sepiids in the Central Paratethys is reinterpreted and shown to be early to late Badenian. Miocene Sepia diversity in the Central Paratethys is greater than previously supposed, which supports normal marine conditions and an open connection with the Mediterranean.http://zoobank.org/urn:lsid:zoobank.org:pub:3B32BA47-EB28-4A75-95FE-6349C08BB5EA.

Use of Mussel Casts from Archaeological Sites as Paleoecological Indicators: An Example from CA-MRN-254, Marin County, Alta California

Archaeological investigations at prehistoric site CA-MRN-254 at the Dominican University of California in Marin County, California, revealed evidence of Native American occupation spanning the past 1,800 years. A dominant source of food for the inhabitants in the San Francisco Bay area was the intertidal, quiet-water dwelling blue mussel (Mytilus trossulus), although rare occurrences of the open coast-dwelling California mussel (Mytilus californianus) suggest that this species was also utilized sporadically. On rare occasions, cultural horizons at this site contain abundant sediment-filled casts of the smaller mussel Modiolus sp. These casts were formed soon after death when the shells filled with sediment and were roasted along with living bivalve shellfish for consumption. Thin sections of these mussel casts display sedimentological and microbiological constituents that shed light on the paleoenvironmental conditions when they were alive. Fine-grained sediment and pelletal muds comprising these casts suggest that the mussels were collected in a low energy, inner bay environment. The rare presence of the diatoms Triceratium dubium and Thalassionema nitzschioides indicate more normal marine (35 psu) and possibly warmer conditions than presently exist in San Francisco Bay. Radiocarbon dating of charcoal associated with the mussel casts containing these diatoms correlates with a 600-year period of warming from ca. A.D. 700–1300, known as the Medieval Climatic Anomaly. Results of this mussel cast study demonstrate that they have great potential for providing paleoenvironmental information at this and other archaeological sites.

Geochemistry of Aegean Sea sediments: implications for surface- and bottom-water conditions during sapropel deposition since MIS 5

Piston cores collected from the Aegean Sea provide a record of sapropel sequence S1, S3-S5. Primary productivity calculations using the equations of Muller and Suess suggest surface paleoproductivities ranged from 180 to 995 g C m-2 year-1 for sapropels and from 40 to 180 g C m-2 year-1 for nonsapropel sediments with corresponding total organic carbon values of 9%-12% and 1%-3%, respectively. The higher paleoproductivities exceed those in the most fertile modern upwelling zones, so are probably overestimated. Instead, enhanced preservation, particularly for S4 and S5, likely resulted from poor bottom-water ventilation beneath a salinity-stratified water column. If the preservation factor in the equations of Howell and Thunell is increased to account for such conditions, more realistic paleoproductivity estimates ensue. The interpreted presence of a deep chlorophyll maximum layer for S3-S5 within the lower part of the photic zone may account for high marine organic carbon and increased export production. A deep chlorophyll maximum layer is not advocated for S1 because of the presence of N. Pachyderma (d) immediately below S1. The organic geochemical data show that both marine and terrestrial organic matter contributed equally to sapropels S3, S4, and S5. Sapropels S3-S5 were deposited under normal marine conditions with very limited and temporary establishment of near-euxinic bottom-water conditions. Highly depleted and somewhat uniform Δ34S values together with the absence of fully euxinic conditions during sapropel intervals suggest that bacterially mediated sulfate reduction took place consistently below the sediment-water interface. It is believed that climbing levels of primary productivity triggered the onset of sapropel deposition, but that other contemporaneous factors extended and enhanced the conditions necessary for sapropel deposition, including increased nutrient supply from riverine inflow, water column stratification and reduced oxygenation of bottom waters, and buffering of low bottom-water oxygen levels by accumulating terrestrial organic carbon.

DIE HYDROIDEN DER CIÉNAGA GRANDE DE SANTA MARTA (KOLUMBIEN) UND EINIGES ZU IHRER OKOLOGIE

Two brackish water hydroids exist in the Ciénaga Grande de Santa Marta: Calyptospadix cerula Clarke, 1882 and Cordylopbora caspia Pallas, 1771. C. caspia, found so far only in the canal of Los Cocos, is completely developed in a salinity range of 0-10 %o. C. cerula is euryhaline. It is found in a salinity range from 3 %o up to normal marine conditions. Below 3 %o it changes into the menontphase. The change in activity of both species depends on salinity and probably on temperature. C. caspia is fertile during the fresh water period, whereas for C. cerula gonosome have been found from the beginning of June to the end of September. At a salinity of more than about 20 %o other marine hydroids like Laomedea bicuspidata Clarke, 1875 and Laomedea tottoni Leloup 1935 also enter the Ciénaga. For these two species no gonothecae have been observed so far.

Buried or brined? Eurypterids and evaporites in the Silurian Appalachian basin

Eurypterid-bearing deposits from the late Silurian Appalachian basin are often interpreted as having been deposited under hypersaline conditions. These interpretations are based on the close association of abundant eurypterid remains with evaporite deposits and structures such as salt hoppers in the Salina and Bertie groups. To determine whether this association reflects life habitat, or is the result of taphonomic or diagenetic processes, the co-occurrence of eurypterids and salt hoppers in the upper Silurian Appalachian basin was examined at several stratigraphic scales. A survey of eurypterid remains from the prolific Ellicott Creek Breccia Member of the Fiddler's Green Formation (Bertie Group) found that 2% of the 479 specimens surveyed are crosscut by salt hoppers or incipient halite structures. In a regional survey, displacive salt hoppers occurred in the same bed as eurypterid remains in 37% (19:51) of all eurypterid-bearing units. In these units, salt hoppers were typically the only structures found intimately associated with eurypterids, sometimes crosscutting them. The disruptive nature of the hoppers in the Ellicott Creek Breccia, for example, suggests that they formed within the sediment rather than at the air-water interface, and that organic remains might have acted as nucleation points for developing halite crystals. To explain these associations, we present a depositional model in which displacive salt hoppers formed within NaCl-saturated groundwater as a result of surface evaporation in the vadose zone during regressive phases, and only after eurypterid remains were buried. In this scenario, the intimate association of eurypterids and salt hoppers in these deposits reflects early-stage diagenetic overprinting rather than conditions during life. Our model largely refutes the hypothesis that eurypterids were halotolerant organisms based on their co-occurrence with salt hoppers. We conclude that eurypterids preserved in upper Silurian carbonate ramp deposits were primarily denizens of more normal marine or hyposaline subtidal settings.

Oceanographic controls on shallow‐water temperate carbonate sedimentation: Spencer Gulf, South Australia

AbstractSpencer Gulf is a large (ca22 000 km2), shallow (&lt;60 m water depth) embayment with active heterozoan carbonate sedimentation. Gulf waters are metahaline (salinities 39 to 47‰) and warm‐temperate (ca12 to −28°C) with inverse estuarine circulation. The integrated approach of facies analysis paired with high‐resolution, monthly oceanographic data sets is used to pinpoint controls on sedimentation patterns with more confidence than heretofore possible for temperate systems. Biofragments – mainly bivalves, benthic foraminifera, bryozoans, coralline algae and echinoids – accumulate in five benthic environments: luxuriant seagrass meadows, patchy seagrass sand flats, rhodolith pavements, open gravel/sand plains and muddy seafloors. The biotic diversity of Spencer Gulf is remarkably high, considering the elevated seawater salinities. Echinoids and coralline algae (traditionally considered stenohaline organisms) are ubiquitous. Euphotic zone depth is interpreted as the primary control on environmental distribution, whereas seawater salinity, temperature, hydrodynamics and nutrient availability are viewed as secondary controls. Luxuriant seagrass meadows with carbonate muddy sands dominate brightly lit seafloors where waters have relatively low nutrient concentrations (ca0 to 1 mg Chl‐a m−3). Low‐diversity bivalve‐dominated deposits occur in meadows with highest seawater salinities and temperatures (43 to 47‰, up to 28°C). Patchy seagrass sand flats cover less‐illuminated seafloors. Open gravel/sand plains contain coarse bivalve–bryozoan sediments, interpreted as subphotic deposits, in waters with near normal marine salinities and moderate trophic resources (0·5 to 1·6 mg Chl‐a m−3) to support diverse suspension feeders. Rhodolith pavements (coralline algal gravels) form where seagrass growth is arrested, either because of decreased water clarity due to elevated nutrients and associated phytoplankton growth (0·6 to 2 mg Chl‐a m−3), or bottom waters that are too energetic for seagrasses (currents up to 2 m sec−1). Muddy seafloors occur in low‐energy areas below the euphotic zone. The relationships between oceanographic influences and depositional patterns outlined in Spencer Gulf are valuable for environmental interpretations of other recent and ancient (particularly Neogene) high‐salinity and temperate carbonate systems worldwide.

A sequence stratigraphic model of benthic foraminiferal facies trends with Triassic and Jurassic examples

Abstract Foraminiferal facies trends are outlined in a new sequence stratigraphic model embracing depositional conditions from alluvial plain to offshore shelf settings. The biofacies proxies include distribution of benthic species, faunal diversities and frequency of normal marine (contra restricted) taxa. In the transgressive–regressive framework, biofacies trends are portrayed as assemblage expansion and reduction separated by trend changes. Assemblage expansion means upward increase in diversity and frequency of normal marine taxa, while assemblage reduction means upward decrease of the same proxies. The model is based on two modern bathymetric profiles and five Mesozoic sections, the latter documenting three settings in a transgressive–regressive sequence: 1) A deeper basinal setting, with hypoxia at maximum flooding, shows a trend change from assemblage expansion to reduction in the transgressive systems tract, marking a shift from the restricting effect of shallow water to that of hypoxia. The maximum flooding reveals a change from assemblage reduction to expansion. 2) An intermediate basinal setting with normal shelf conditions at maximum flooding is typified by continuous assemblage expansion in the transgressive systems tract, while the maximum flooding shows a change from expansion to reduction. 3) At a basin marginal position the maximum transgression is marked by extremely low diversities and relatively homogeneous assemblages. The study demonstrates that changing foraminiferal facies trends signify depositional conditions reflecting arrangement of sequence components such as flooding events, systems tracts and boundaries. Assemblage trend changes are discrete stratigraphic horizons signalling shifts in the effect of environmental factors (water depth, salinity, oxygenation) in the sequence architecture.