Echinoderm Fragments Research Articles

Geochemical and mineralogical studies of the celestite bearing formations and associated sediments in Benghazi Formation, Ar Rajmah Group (Middle Miocene), Al Jabal Al Akhdar, NE Libya

The study area is located in the northeast of Libya, in the areas of Benghazi city and Ar Rajmah village. The purpose of this study is to find out geochemically and mineralogically the source of strontium element. Also the distribution of strontium in allochems, matrix and cement in the Benghazi Formation of the Ar Rajmah Group. Celestite grade 88.3 % (SrSO4) occurs only in the Benghazi Formation at Benghazi Cement Quarry as geodic nodules in the Middle Miocene rocks. Detailed mineralogical and chemical data have been collected on the celestite and associated sediments using XRF, XRD, EPMA, SEM and DSC techniques. Authigenic celestite and strontianite minerals occur both as a cement and as a replaced by other fracture filling minerals such as anhydrite. However, carbonate skeletal grains have quite high MgCO3 contents, reflecting sometimes the presence of dolomite and brucite minerals. The average Sr/Ca ratio of coralline algae is 0.65. Echinoderm fragments have the highest value 1.31 of Sr/Ca and containing 0.47 to 1.8 mole percent of MgCO3 in the Benghazi Formation. Echinoid spines contain higher strontium contents than other echinoderm fragments. Some bivalves are replaced totally by apatite and had a very high absolute concentration of strontium. The high strontium- low magnesium contents and vice versa are related to the diagenesis, mineralogical nature of the sediments and organic remains. Celestite occurs mainly in sedimentary beds of the Benghazi Formation, adjacent to the evaporitic environment (gypsum/anhydrite) and near sites of intense dolomitization

Juliana Lake: A Wetland in an Urban Environment1

Of all the remaining natural habitats of Benghazi’s urban area (NE Libya), perhaps the most threatened are its karst lakes and coastal salt marshes (locally known as Sebkha). Juliana Lake stands out as one example of a fragile ecosystem that is steadily shrinking and exposed to dredging, infilling and, consequently, possible damage to its aquatic organisms, and the inevitable loss of its renowned biodiversity. Several 19th & 20th–century traveller’s sketches and maps, soil maps, photographs and satellite images provide the bases for change in the size and magnitude of the lake and its adjacent areas over time. Assessment of the sediment composition and texture of material accumulating at the bottom of the lake reveals mixtures of Sebkha sediments such as salty clay, silt, and clayey sand, while sediments at the surface and around the lake are represented by quite soft whitish to yellowish and scattered patchy limestones of unknown affinity. Terra-rossa and Quaternary caliche are present also, but calcarenites cover considerable part of the studied area. The bio-micro components of these sediments are described and a number of small-sized benthic foraminifera have been identified. Macrofauna, which are primarily presented by recent benthic seashells belonging to phylum mollusca, have also been investigated and several species have been identified to the species level wherever possible. Other calcareous biotic components are predominantly shell fragments of molluscs, echinoderms and calcareous coralline red algae. It is concluded that the distribution, diversity and abundance of the total benthic organisms recovered in this survey reflect the habitat's richness in nutrients and consequently providing important food source for fish, birds, and mammals. It is argued that environmentally based planning strategies can preserve the fragile landscapes of Benghazi and, furthermore, ensure a more sustainable form of future urban development. In this context, urban planners should review routine urban planning practices affecting Juliana wetland and other natural landscapes of Benghazi, and adjust them to integrate nature into the urban scene of current and future development plans.

Dominance of Miocene echinoderms in the equatorial Neogene marine platform of Brazil and their insights into the paleoenvironment

Echinoderms are one of the most important invertebrates in the early to middle Miocene heterozoan carbonate deposits of the Pirabas Formation of the northern Brazil. The well-preserved echinoid tests were useful for accurate identification, whereas the sediment filling the tests provide significant information regarding the rock matrix. The dominance of disarticulated ophiuroid, crinoid, and asteroid plates, and damage on the echinoderm test provides a basis for taphonomic processes to elucidate a paleoenvironmental interpretation based on the echinoderm assemblages. Nineteen echinoderm taxa (ten valid species and nine species in open nomenclature) were recorded based on well-preserved and/or fragmented tests and/or spines, including Abertellidae †Abertella pirabensis (Santos, 1958), Placatenellidae †Placatenella complanata (Brito, 1981), Clypeasteridae †Clypeaster lamegoi Santos, 1958, †Clypeaster paraensis Brito, 1979, and †Clypeaster paulinoi Santos, 1958, Cassidulidae †Anisopetalus oliveirai (Santos, 1958) and †Rhyncholampas candidoi Fernandes and Morais, 1994, Echinolampadidae †Echinolampas paraense Santos, 1958, Schizasteridae †Agassizia eugeniae Brito and Ramires, 1974 and Schizaster sp., Cidaridae Cidaris sp., †Phyllacanthus priscus Brito and Ramires, 1974, and Prionocidaris sp. The smaller echinoderm fragments were dominated by disarticulated plates of Gorgonocephalidae ophiuroids, Comatulidae crinoid Sievertsella sp., Goniasteridae asteroids, as well as spines and tests fragments of Cidaridae echinoids. The echinoderm assemblages suggest an inshore and shallow water paleoenvironment over a soft sandy carbonate bottom. MicroCT analyses of sediments filling echinoid tests exhibited a microfossil assemblage, including foraminifera, sponges, ahermatypic corals, bryozoans, and mollusks. Broken and disarticulated tests and plates in chaotic orientations suggest high-energy paleoenvironment. Evidence of test damage indicates complex predator-prey interactions. Overall, the microCT analyses of echinoid tests proved to be a high accuracy non-destructive, analytical approach for investigating fossil echinoderms and their paleoenvironment.

Paleoenvironmental changes and biotic response to Aptian–Albian episodes of accelerated global change: Evidence from the western margin of the proto-North Atlantic (central-eastern Mexico)

The Aptian–Albian interval represents a time of distinctive atmospheric and oceanic changes. A major perturbation of the carbon cycle induced by intense volcanic activity produced episodes of environmental change affecting the abundance and evolution of marine plankton. Several studies based on pelagic and hemipelagic sections have used biostratigraphic events and carbon isotope stratigraphy tools to identify biotic responses to environmental perturbations. Few studies have included Aptian–Albian planktic microfossil communities and paleoenvironmental changes in Mexico, a region that was part of the western proto-North Atlantic margin. The aim of this study is to interpret paleoenvironmental and paleoceanographic conditions through a microfacies analysis of a carbonated succession of the Tamaulipas Formation from central-eastern Mexico (Tampico-Misantla Basin), within a temporal framework based on planktic foraminiferal and colomiellids biostratigraphy.The studied section, 92 m thick, consists of a continuous pelagic succession. Facies contain abundant planktic microfossils and span the stratigraphic interval between the Globigerinelloides blowi and Ticinella praeticinensis Zones. The Aptian/Albian Boundary in the studied section was established on the highest occurrence (HO) of planktic foraminifera such as Paraticinella rohri and the presence of Microhedbergella spp., followed by the lowest occurrence (LO) of colomiellids such as Colomiella recta.Detailed quantification of microfossil assemblages reveals variations in abundance of planktic foraminifera, radiolarians, praecolomiellids, colomiellids, dinocyst and echinoderm fragments. These variations related to fabric characterization and bioturbation indexes allow us to infer fluctuations in ancient trophic conditions in the water column, which might be associated with episodes of global environmental change such as Oceanic Anoxic Events.

Lithological characteristics and formation conditions of lower jurassic limestones occuring in the Patil mountain (south-western Crimea)

Background. In this article, we investigate an outcrop of the Lower Jurassic limestones of the Eskiorda suite located on the northern slope of the Bodrak River basin in the south-western Crimea.Aim. The outcrop under study is mentioned in the majority of monographs devoted to the geology of the Crimean Mountains. Although the palaeontology of this assemblage has been sufficiently studied, its lithological aspects require elucidation. We carried out a series of lithological studies to identify the composition, structure and formation conditions of this limestone assemblage.Materials and methods. A macroscopic study of the outcrop was conducted followed by a detailed lithological study of collected limestone samples using a polarising microscope.Results. The conducted microscopic analysis revealed three structural types: organogenic-detrital, detrital and oolitic-organogenic-detrital limestones. The dominant component in the composition was fragments of echinoderms, mainly crinoids. Among other components were — in descending order — brachiopods, gastropods, foraminifera, remains of green algae, sponges, ostracods, ammonites and radiolarians, whose total content did not exceed 10%. Cinoid fragments were round to a various degree. The limestone fragments (intraclasts) were characterised by organogenic-clastic and pelitomorphic structures with an organogenic sludge, occasionally containing fine-sandy and silty quartz admixtures. Oolitic-organogenic-detrital limestones were almost entirely composed of crinoid fragments, some of which represented oolith cores. A specific feature of the limestones under study is their significant hardness resulting from the cementation of the structural components predominantly with crustification cement of several generations.Conclusions. The obtained results allowed us to draw conclusions about the formation conditions of the studied rocks. The limestones were formed in shallow water under the action of waves on the sediment in zones of constant currents. The hydrodynamic action on the sediment led to the formation of intraclasts. The early lithification of the sediment contributed to the formation of a hard seabed, on which subsequent generations of echinoderms settled, lived and died, forming an accumulative carbonate body.

Reservoir quality of the Surmeh (Arab-D) reservoir in the context of sequence stratigraphy in Salman Field, Persian Gulf

The Upper Jurassic Surmeh reservoir in the northern Persian Gulf is a stratigraphic equivalent of Arab-D reservoir that is one of the best Jurassic reservoir rocks of the Arabian Peninsula. In this study, in the first step the palaeontology, sedimentary environment, sequence stratigraphy and reservoir quality of the Surmeh reservoir was investigated in a core-bearing well in Salman oil field. The palaeontological studies reveal a moderately diverse assemblage of benthic foraminifera. Dominated foraminifera include the agglutinated forms and miliolids and there are also fragments of alga, stromatoporoids, corals, bivalves, gastropods and echinoderms. These recorded fauna and flora resulted in distinction of three zones that characterize the age of undifferentiated Kimmeridgian-Tithonian. Based on petrographic observations, along with palaeontological materials, eight microfacies were identified that represent four sub-environments of a carbonate inner ramp including supratidal, intertidal, lagoon and shoal. These studies combined with well log responses resulted in identification of a 3rd order sequence and parts of an incomplete one that is composed of an incomplete HST. These 3rd order sequences comprise four 4th order subordinate sequences.In addition by integration of petrographic analyses, sub-environments energy regimes and petrophysical data, five reservoir zones were identified. Also, based on core porosity and permeability 6 Hydraulic Flow Unit (HFU) with poor to excellent reservoir quality in ascending trend were identified. The reservoir zone I, which belongs to the sabkha and littoral facies, represents the worst reservoir quality (includes HFU1 to HFU3), while the reservoir zone III with best reservoir quality (includes HFU4 and HFU5) comprises the back shoal grain-supported facies. The introduced sequences and reservoir zones in the studied well were propagated to three other wells throughout the Salman Field via using log responses. Also they were correlated with those introduced for Arab-D reservoir in the southern parts of the Persian Gulf providing a correlation framework. This pattern can be used in the next exploration wells which are going to be drilled especially in the northern parts of the Persian Gulf.

Paleogeographic and Age Findings on Planktonic Foraminiferal Assemblages of Yuksekova Complex in the Northeast of Elazig (Eastern Turkey)

The Yüksekova Complex is one of the parts of oceanic crust representing the Bitlis-Zagros suture zone in the eastern Turkey. The volcanosedimentary rocks of the unit, which is widely exposed around the Elaziğ (E-NE Turkey) province are located in the Seki-Hacihasan district (E Elazığ) and Asker Mountains (NE of Elazığ). In this area, the planktonic foraminifera bearing pink-red micritic limestones and related volcanogenic rocks were examined and aged. The volcanogenic rocks related to the micritic limestones are mainly spilitic and pillow shaped basalts. The volcanogenic rocks contain mainly of plagioclase ± pyroxene ± partly olivine set in amygdaloidal, intersertal, hyalo-microlitic porphyric textures. The sediments consist mainly of thin- to- medium-bedded muddy limestones. The pelagic red limestones are represented mostly by biomicrite and contain a large quantity of planktonic foraminifera and slight amount of thin shelled bivalve fragments, radiolaria, and echinoderm fragments. The planktonic foraminifera are composed mainly of Globotruncana arca, G. gagnebini, G. lapparenti, G. cf. falsostuarti, Globotruncanita stuarti, Gt. stuartiformis, Gt. conica, Globotruncanella citae and Rosita fornicata scattered into a micritic matrix. Small amounts of silt and sandsized quartz grains are also observed in some thin sections. Accordingly, based on planktonic foraminifera bearing micritic limestones, the age of the Yüksekova Complex is proposed Late Campanian-Late Maastrichtian. Thus, the Late Campanian-Late Maastrichtian aged red pelagic limestones of the Yüksekova Complex were deposited in the deeper parts of the Late Cretaceous Ocean, probably a deep shelf edge.

Agglutinated tubes as a feature of Early Ordovician ecosystems

Agglutinated tubes are produced by a variety of marine organisms. Such tubes will readily break down after the death of the producer, and hence are likely to be found only in deposits with rapid burial and/or exceptional preservation. Here we document agglutinated tubes from four localities of Early Ordovician age. The Lower Ordovician (upper Tremadocian) Afon Gam Biota of North Wales, UK, contains a diverse fossil assemblage including algae, worms, sponges, hyoliths, tergomyans, echinoderms, trilobites, and other arthropods. The biota also includes locally abundant agglutinated tubes composed largely of echinoderm fragments, in particular glyptocystitid (including Macrocystella) stem and brachiole ossicles. The tube producer appears to have preferentially selected echinoderms for use in tube building, with trilobites and tergomyans only rarely incorporated in the tubes. These tubes are named Echinokleptus anileis n. gen. n. sp. Similar tubes, although incorporating individual echinoderm ossicles rather than complete animals, occur in the Lower Ordovician (lower Floian) Tonggao Formation of South China. Possible additional agglutinated tubes are found in the Tremadocian–Floian Fezouata Shale of Morocco; these examples are composed of a range of bioclasts including echinoderm remains and hyolithids. Further possible tubes composed of mixed shelly material were observed in the Floian Landeyran Formation, Montagne Noire, France. The occurrence of morphologically similar agglutinated tubes on different continental blocks and at different palaeolatitudes indicates that the group responsible (inferred to be a polychaete annelid) was diversifying as part of the Great Ordovician Biodiversification Event, and similar interpretations should be considered for problematic bioclastic accumulations elsewhere.

Young colonization history of a widespread sand dollar (Echinodermata; Clypeasteroida) in western Taiwan

Arachnoides placenta is the most common sand dollar species in western Taiwan. Due to its lack of fossil record, the arrival of this species in Taiwan could not be estimated until now. Fragments of A. placenta was recovered sorting through a 1981- museum collection of sand dollars collected off Mailiao county, western Taiwan. Additional echinoderm specimens were recovered from Holocene sediments nearby, but no fragments of A. placenta were found, indicating a decline in the living population. A total of 11 echinoderm samples, including five specimens that were assigned to A. placenta with certainty, were sent for radiocarbon dating. Results showed that studied echinoderm fragments range from modern (after 1950) to as old as 2680 ± 55 a BP and the oldest date is from A. placenta. It is evident that Taiwan is an active migration front for A. placenta due to the relatively young arrival age for this pandemic species which is widespread in the Indo-West Pacific region. Additionally, the DNA sequence, including the cytochrome c oxidase subunit I (cox1) gene, of the species was obtained to conduct the first molecular phylogenetic study of sand dollars in Taiwan.

The Littoral Bottoms of Benidorm Island (Western Mediterranean Sea): Eco-Sedimentological Characterization Through Benthic Foraminifera

Benidorm Island is one of the most relevant protected marine areas in the Province of Alicante (south-eastern Iberian Peninsula). Its bathymetric gradient and the structural complexity of the seabed make it an ideal place to analyse foraminifer assemblages considering depth and sediment type (particle size distribution). For this purpose, seven sampling sites representing the variety of littoral/sublittoral bottoms present have been sampled. The seabed sediment is composed mainly of gravelly sand with a high bioclastic content, abundant echinoderm fragments, sponge spicules, and bivalve and gastropod shell debris. We have documented a highly diverse community of benthic foraminifera dominated by epiphytic species. This work also examines the relation between depth (or open marine influence) and the planktonic foraminifer ratio, discussing the implications in the geological marine record. The distribution of some benthic foraminifer key species has been evaluated in this regard. The scuba dives performed also reveal possible environmental deterioration due to increased marine recreational activities, mostly scuba diving and boating. Finally, the littoral bottoms surrounding Benidorm Island would be an excellent area for future research using foraminifera as bio-indicators for monitoring environmental impacts on coastal regions.

Oxfordian neptunian dykes with brachiopods from the southern part of the Kraków-Częstochowa Upland (southern Poland) and their links to hydrothermal vents

Neptunian dykes with abundant brachiopods, cf. Lacunosella sp. and fragments of echinoderms, occur in Oxfordian limestones in the southern part of the Krakow-Czestochowa Upland. The dykes fill fissures that have opened in the massive limestones due to local extension of the sedimentary basin located along the northern, passive margin of the Tethys Ocean. These fissures transmitted warm hydrothermal solutions that controlled the mass growth of free-living bacteria and microbial mats feeding the fauna, mostly brachiopods and echinoderms, settling the seafloor around the fissures. For some time, the fissures remained empty and their vertical walls were settled by stromatolites. Infilling of the fissures was an abrupt event related to faulting in the Oxfordian and to the rejuvenation of dislocations cutting through the Paleozoic basement. Then, in the Cretaceous, and primarily in the Cenozoic, tectonic discontinuities filled with neptunian dykes were penetrated by karst waters and by hydrothermal solutions, which partly silicified the carbonate material infilling the dykes. The formation of dykes is genetically related to the Late Jurassic, Pan-European stress-field reorganization caused by the opening of the Northern Atlantic and Tethys Oceans.

Planktonic Foraminiferal Biostratigraphy, Microfacies Analysis, Sequence Stratigraphy, and Sea-Level Changes Across the Cretaceous-Paleogene Boundary In the Haymana Basin, Central Anatolia, Turkey

Abstract The Cretaceous–Paleogene (K/Pg) boundary in the Haymana Basin, Central Anatolia, Turkey, was delineated using planktonic foraminiferal biostratigraphy, microfacies analysis, and sequence stratigraphy. An ∼ 29 m outcrop consisting of limestone and marl was measured, and four planktonic foraminiferal biozones were identified spanning the boundary. Planktonic foraminiferal extinction across the K/Pg boundary was catastrophic and abrupt. The extinction level is overlain by a unit (Zone P0) showing an increase in echinoid fecal pellets and authigenic clay minerals such as glauconite, suggesting low sedimentation rates in the early Danian. Ten microfacies types were identified indicating inner-ramp to basinal paleoenvironments based on the sedimentological characteristics and microfossil and macrofossil assemblages. Maastrichtian carbonates contain large benthic foraminifera, calcareous red algae, bryozoans, fragments of echinoderms and mollusks, and planktonic foraminifera. Overlying Maastrichtian–Danian silty marls and silty limestones have common planktonic and benthic foraminifera. Progradation of carbonates into the basin took place during the highstand systems tract, and deposition of a silty marl succession occurred during the transgressive systems tract. The K/Pg boundary is in the upper part of the transgressive systems tract, below a maximum flooding surface. Sequence stratigraphic analysis of a second section, Campo Pit, New Jersey, USA, showed that the K/Pg boundary occurs within a transgressive systems tract in New Jersey as well, suggesting a global sea-level rise across the K/Pg boundary.

Reconstructing Upper Cretaceous (Cenomanian) paleoenvironments in Armenia based on Radiolaria and benthic Foraminifera; implications for the geodynamic evolution of the Tethyan realm in the Lesser Caucasus

Radiolarians extracted from the sedimentary cover member of the Amasia ophiolite (NW Armenia), Foraminifera, and microfacies observed in the pre-obduction carbonate platform sequence of the South-Armenian Block (Vedi, SE of Yerevan) provide important time constraints for the geodynamic evolution of the Tethyan realm in the Lesser Caucasus.The radiolarian faunal assemblage extracted from radiolarites overlying basaltic lavas (Amasia) is characterized by the presence of Pseudodictyomitra tiara (Holmes), pointing to a Cenomanian age; it establishes the youngest submarine volcanic event of the Tethyan realm preserved in the Lesser Caucasus.The Vedi area allows the detailed study of the obduction of ophiolites onto the South-Armenian Block (SAB), the carbonate sequence of which is overlain conformably by a siliciclastic flysch-type sequence. The last 160m of the SAB carbonate sequence has been studied during this study; they consist of alternating packstones and grainstones with fragments of echinoderms, gastropods, dasycladale algae and frequent clasts of rudists. The presence of benthic Foraminifera such as Cuneolina gr. pavonia, Daxia cenomana and Pseudocyclammina rugosa argues for a Cenomanian age. The analyzed microfacies and the foraminiferal assemblage suggest a back reef depositional environment.Results from these two distinct geological and paleogeographic areas (the Tethyan oceanic realm preserved in NE Armenia/Amasia and the top of the carbonate sequence of the South-Armenian Block that crops out at Vedi/SE of Yerevan) point to a major geodynamic change that took place during the Cenomanian, involving both the late stage of submarine oceanic magmatic activity and the obduction of ophiolites onto the South-Armenian Block.

Late Ordovician microbial reefs in the Lianglitag Formation (Bachu, Tarim, NW China)

Reefs in the Late Ordovician are usually built up by metazoans, whereas in the Early and Middle Ordovician microbial reefs are dominating. In the Late Ordovician (Katian) Lianglitag Formation, at Bachu, Tarim, NW China, however, three distinct stages of thrombolithic microbial reefs are exposed. The lower and upper reef intervals are characterized by widespread microbial carbonates with almost constant thicknesses (biostromes). The middle reef interval exposes dome-like mounds, and shows a higher diversity of reef-building and reef-dwelling organisms. Calcareous algae such as Vermiporella are abundant, but also other components such as fragments of Halysis, brachiopods, molluscs, echinoderms, bryozoans, and trilobites have been found in the microbial reef units. The purpose of this study is to describe for the first time the composition and microfacies of the reefs in this remote area. Especially the question of whether or not these Late Ordovician reefs represent remnants of the Early/Middle Ordovician microbial-dominated reef type just lacking Calathium and lithistid sponge is addressed. The results indicate that the local conditions on the leeward side of the carbonate platform, where waters are less well agitated and thus less well oxygenated, and probably also characterized by temporarily elevated water temperatures hampering the growth of metazoan reefs, were responsible for the proliferation of the Late Ordovician microbial reefs in the Bachu area.

STRATIGRAPHY OF THE CARNIAN - NORIAN CALCARI CON SELCE FORMATION IN THE LAGONEGRO BASIN, SOUTHERN APENNINES

The Upper Triassic Calcari con Selce Formation, cropping out in the southern Apennines (S Italy), consists of 400 m of micritic limestones, often nodular, with chert beds and nodules, organized in dm to m beds intercalated with mm (rarely centimetric) marly horizons. Three intervals characterized by higher siliciclastic content have been recognized within this formation, and stratigraphically ordered after an accurate conodont biostratigraphical investigation: 1) the green clay-radiolaritic horizon, previously named in literature with the informal expression of “livello argilloso ad Halobia superba”, Tuvalian (upper Carnian); 2) an interval of some tens of meters of limestones and shales with abundant chert beds, here informally termed the brown member, Tuvalian/Lacian (upper Carnian/lower Norian; 3) the ca. 3 m thick red shale horizon, Sevatian (upper Norian) in age. All these intervals are characterized by micritic limestones or marly limestones with bivalves, radiolarians and conodonts alternating with shales (green, or red) having thicknesses of 50 cm or more. These intervals are also associated to an increase of calciturbidites, consisting of echinoderm fragments, isolated thin-shelled bivalves and reworked, partially lithified intraclasts of the Calcari con Selce Fm. The Carnian green clay-radiolaritic horizon and the Sevatian red siliciclastic interval are useful lithostratigraphic markers recognizable throughout the Lagonegro Basin and have been used as guide horizons to evaluate the lateral continuity of contiguous limestone beds. The green clay-radiolaritic horizon has been logged in 4 sections (Pignola 2, Mt. Armizzone, Pezza la Quagliara, San Michele). The sections are presently at approximately 50 km distance - but Tertiary thrusts occur between the sections, suggesting a larger separation at the time of the deposition of the Formation. Above the green clay-radiolaritic horizon, single carbonate beds or banks with the same stratigraphic position and common characteristics are recognizable in all sections. The thickness of these limestone beds may vary, but the shale interlayers and cherty beds are identical, thus, the carbonate beds have been correlated. The stratigraphic interval comprising the Sevatian red shale horizon has been acquired in two sections separated by 7 km, Monte Buccaglione (i.e lower portion of the Sasso di Castalda section) and Monte Cugnone, with a Terrestrial Laser Scanner (TLS). TLSs produce high resolution and high accuracy 3D representations of outcrops, stored as point-clouds. A regular sequence of limestone beds and shale interlayers, distinguished because of their different reflectance, has been recorded below the red shale horizon, and the thickness of single carbonate banks resulted identical within the instrumental resolution. Calcareous beds or banks thus can be correlated at the basinal scale. This implies that the Lagonegro Basin is characterized by laterally continuous carbonate sedimentation, most probably controlled by allocyclic factors, providing potential for cyclostratigraphic investigations. Original papers

USING MULTIPLE ENVIRONMENTAL PROXIES TO DETERMINE DEGREE OF MARINE INFLUENCE AND PALEOGEOGRAPHICAL POSITION OF THE JOGGINS FOSSIL CLIFFS, UNESCO WORLD HERITAGE SITE

Abstract The Joggins Fossil Cliffs site was selected as a UNESCO World Heritage site because of its unparalleled preservation of Pennsylvanian terrestrial organisms in their environmental context. Despite an abundance of research over the past 150 years, significant questions remain regarding the Joggins paleoenvironment, including the degree of marine influence and whether the gymnospermous Cordaites trees may represent the earliest mangroves. Sedimentologic and paleontologic data from interbedded limestone beds indicate open marine conditions in the oldest part of the section, with a waning marine influence up section. Limestone beds, which occur primarily at the base of cycles interbedded with coal and floodplain deposits, are 15–100 cm thick and contain ostracodes, bivalves, and echinoderm fragments. Independent lines of evidence to support a diminishing marine influence in fluvial and coastal deposits with time include: (1) the presence of punctate brachiopods, echinoderm fragments, and ostracodes in...

Carbonate diagenesis of the Late Pleistocene limestone of the Faaa M0020A core: IODP Expedition 310, Tahiti Sea Level Change

The diagenetic history of the pre-LGM (Last Glacial Maximum) limestone from the core by IODP Expedition 310 was investigated texturally and geochemically. The limestone is mostly deposited in reef front and fore-reef settings and mostly composed of corals, coralline algae, and microbialites with a minor contribution of green algae, mollusks, and echinoderm fragments. Relatively high abundance of microbialites is the quite distinctive feature, compared to other reefal sediments described elsewhere. Texturally, shallow marine cements are characterized by acicular and botryoidal aragonite and druse HMC, and equant LMC cements of meteoric origin are relatively rare. Presence of LMC equant cements appears to be facies-controlled, thus is dependant upon the nature of substrates. It appears that the limestone was mostly subjected to vadose meteoric diagenesis during the last glacial period. The fibrous HMC cements in vuggy pores together with their oxygen isotopic compositions and textural evidence suggest that the limestone was subaerially exposed during the last glacial period and resubmerged during deglaciation. Stable isotopic and trace elemental analyses were carried out for microbialites that were originally composed of HMC. Oxygen isotopic compositions and Fe and Sr contents of pre-LGM microbialites are clearly distinguished from those of post-LGM limestone. This suggests that the limestone had undergone meteoric diagenesis in the different diagenetic system, depending upon the magnitude of the partition coefficients of trace elements. No clear difference between unaltered (post-LGM) and altered (pre-LGM) limestone was observed for Mn, Mg, and carbon isotope, indicating a closed diagenetic system. However, the diagenetic system was semi-open with respect to Sr and oxygen isotope. In addition, enriched carbon isotopic compositions of the pre-LGM limestone may imply that vegetation cover was negligible for the formation of paleosol layers. This is also supported by poorly preserved unconformity surface with an absence of paleosol layers within the core.

Carbonates within a Pleistocene glaciomarine succession, Yakataga Formation, Middleton Island, Alaska

AbstractUplifted during the 1964 Alaskan earthquake, extensive intertidal flats around Middleton Island expose 1300 m of late Cenozoic (Early Pleistocene) Yakataga Formation glaciomarine sediments. These outcrops provide a unique window into outer shelf and upper slope strata that are otherwise buried within the south‐east Alaska continental shelf prism. The rocks consist of five principal facies in descending order of thickness: (i) extensive pebbly mudstone diamictite containing sparse marine fossils; (ii) proglacial submarine channel conglomerates; (iii) burrowed mudstones with discrete dropstone layers; (iv) boulder pavements whose upper surfaces are truncated, faceted and striated by ice; and (v) carbonates rich in molluscs, bryozoans and brachiopods. The carbonates are decimetre scale in thickness, typically channellized conglomeratic event beds interpreted as resedimented deposits on the palaeoshelf edge and upper slope. Biogenic components originated in a moderately shallow (ca 80 m), relatively sediment‐free, mesotrophic, sub‐photic setting. These components are a mixture of parautochthonous large pectenids or smaller brachiopods with locally important serpulid worm tubes and robust gastropods augmented by sand‐size bryozoan and echinoderm fragments. Ice‐rafted debris is present throughout these cold‐water carbonates that are thought to have formed during glacial periods of lowered sea‐level that allowed coastal ice margins to advance near to the shelf edge. Such carbonates were then stranded during subsequent sea‐level rise. Productivity was enabled by attenuation of terrigenous mud deposition during these cold periods via reduced sedimentation together with active wave and tidal‐current winnowing near the ice front. Redeposition was the result of intense storms and possibly tsunamis. These sub‐arctic mixed siliciclastic‐carbonate sediments are an end‐member of the Phanerozoic global carbonate depositional realm whose skeletal attributes first appeared during late Palaeozoic southern hemisphere deglaciation.

Salpingoporella? popgrigorei, a new species of Dasycladales (calcareous algae) from the Lower Aptian deposits of Pădurea Craiului (northern Apuseni Mountains, Romania)

A new dasycladalean alga Salpingoporella? popgrigorei n. sp. was identified in Pădurea Craiului Mountains (northern Apuseni, Romania) in the Lower Aptian limestone of the Valea Bobdei Member. The new alga was found within the external platform coarse bioclastic facies with fragments of corals, sclerosponges, bivalves (including rudists), gastropods, echinoderms, brachiopods, and bryozoans. The micropaleontological assemblage consists of foraminifera, calcareous algae, rare rivulariacean-type cyanobacteria, and some problematic microfossils. The deposits are Early Bedoulian in age, as clearly indicated by the orbitolinid foraminifera Orbitolinopsis pygmaea, Paracoskinolina sunnilandensis and Palorbitolina lenticularis. Salpingoporella? popgrigorei n. sp. is a medium-sized dasycladalean alga showing funnel-like laterals with an euspondyl arrangement. The laterals consist of two distinctive parts. The proximal part is narrow and flattened. The distal part widens relatively suddenly, and then narrows slightly before the final widening towards the exterior, in the place where the laterals most probably formed an assimilatory cortex. The distinctive features of the new species are represented by the shape of the laterals. The new Salpingoporella best resembles the Upper Hauterivian–Lower Barremian p.p. Salpingoporella genevensis (Conrad), especially due to the quadrangular aspect of the laterals in middle-deep tangential section. However, differences refer to the laterals’ general shape, and to the typical features of the laterals in deep tangential section of Salpingoporella? popgrigorei n. sp.

Oxfordian ramp system (La Manga Formation) in the Bardas Blancas area (Mendoza Province) Neuquén Basin, Argentina: Facies and depositional sequences

The outcrops of the Oxfordian La Manga Formation at Bardas Blancas, Neuquén Basin, west-central Argentina, allow the recognition of six different depositional facies (A to F) on the basis of sedimentological analysis, taphonomic attributes and microfacies studies. These depositional facies correspond to outer ramp (A), middle ramp (B), inner ramp— oolitic shoal (C), inner ramp margin (patch reef) (D), lagoon deposits (E), and a paleokarst surface (F). Outer ramp deposits which are not completely represented, consist of greyish carbonate beds, where the fabric of the shell beds (gryphaeids) reflects the action of waves and currents. Middle ramp deposits consist of a packstone–grainstone lithofacies indicating the importance of storm processes and is dominated by ooids, intraclasts, pelecypods, echinoderms and gastropods which accumulated on a middle-ramp storm-dominated shoreface. Trace fossils belong to the Skolithos and Cruziana Ichnofacies characterizing the upper, lower and middle shoreface setting respectively. The inner ramp deposits consist of oolitic grainstones and subordinate packstones shoal with a small sponge bioherm at the base. Different types of ooids, peloids and coated grains are abundant, as well as skeletal fragments of molluscs, echinoderms and corals. Lithofacies and microfacies studies suggest a high energy and shallow-water depositional setting. The inner ramp margin deposits consist of reef core facies, fore and back reef facies characterized by a scleractinian community of relatively low generic diversity. The rich associated fauna consists of bivalves, echinoids, serpulids, bryozoans, dasycladacean algae and cyanophytes, as well as foraminifers and ostracods. The growth forms of the corals are indicative of shallow well illuminated water. Both the back and fore reef deposits suggest intensive reworking by storm waves or currents. The lagoon deposits consist of bioclastic and peloidal wackestones as well as bioclastic–intraclastic packstones which accumulated on a lagoon under intermittently agitated water in a shallow subtidal to intertidal settings. A stratiform breccia with both matrix and clasts supported fabrics is interpreted as paleokarst. The clasts are derived from the rocks of oolitic shoal and inner ramp margin (patch reef). The six depositional facies are included into a major organizational framework of three third-order depositional sequences (DS-1, DS-2, DS-3) mainly represented by transgressive and highstand systems tracts stages with sequence boundaries of regional importance. The general depositional evolution is here related to the slow subsidence experienced during the Oxfordian–earliest Kimmeridgian time related to tectonic inversion in the Neuquén Basin. A four step (architectural and sedimentary) schematic model of the response of the platform to sea-level changes is proposed.