Biostratigraphy and microfacies of the sedimentary sequences within volcano-sedimentary Maden Complex in Southeastern Turkey

<p>Maden Complex is a volcano-sedimantary unit, mainly composed of shallow and deep marine sedimentary rocks and associated volcanics. Deep marine units of Maden Complex, exposed between Çatak (Van) and Kozluk (Batman) regions have been studied with a combined sedimentological and paleontological approaches. The following species are recorded within the Melefan formation: <em>Morozovella aragonensis, Acarinina collactea, Acarinina cf. esnehensis, Acarinina soldadoensis, Acarinina boudreauxi, Acarinina bullbrooki, Acarinina mckanni, Acarinina pentacamerata, Acarinina</em> cf. <em>pseudosubsphaerica, Acarinina topilensis, Acarinina esnehensis, Chiloguembelina</em> sp., Globanomal<em>ina planoconica, Globanomalina australiformis</em>, <em>Globigerinatheka</em> sp., <em>Parasubbotina hagni, Pearsonites broedermanni, Pseudoglobigerinella bolivariana, <strong> </strong></em> <em>Planoglobanomalina pseudoalgerian</em>a<strong>, </strong><em>Pseudohastigerina wilcoxensis,  Subbotina roesnaensis, Subbotina yeguaensis.</em> Based on the defined planktonic foraminiferal species, the unit corresponds to the E7 zone and the depositional age of the formation is proposed as Early Eocene (Ypresian) to Middle Eocene (Lutetian). The deep marine sedimentary sequence mainly consists of pinkish to red colored micritic limestones including shale intercalations. The formation is represented by the pelloidal wackestone-packstone facies and comprises abundant planktonic foraminiferal assemblages.</p>

REE Characteristics of Lower Cretaceous Limestone Succession in Gümüşhane, NE Turkey: Implications for Ocean Paleoredox Conditions and Diagenetic Alteration

Trace and rare earth elements (REEs) are considered to be reliable indicators of chemical processes for the evolution of carbonate systems. One of the best examples of ancient carbonate successions (Berdiga Formation) is widely exposed in NE Turkey. The Lower Cretaceous limestone succession of Berdiga Formation may provide a case study that reveals the effect of ocean paleoredox conditions on diagenetic alteration. Measurement of major, trace and REEs was carried out on the Lower Cretaceous limestones of the Berdiga Formation, to reveal proxies for paleoredox conditions and early diagenetic controls on their geochemistry. Studied micritic limestone microfacies (MF-1 to MF-3) indicate deposition in the inner platform to a deep shelf or continental slope paleoenvironment during the Hauterivian-Albian. The studied limestone samples mainly exhibit low Mg-calcite characteristics with the general chemical formula of Ca98.35–99.34Mg0.66–1.65(CO3). They are mostly represented by a diagnostic REE seawater signature including (1) slight LREE depletion relative to the HREEs (ave. 0.72 of Nd/YbN and ave. 0.73 of Pr/YbN), (2) negative Ce anomalies (Ce/Ce* = 0.38–0.81; ave. 0.57), (3) positive La anomaly (La/La* = 0.21–3.02; ave. 1.75) and (4) superchondritic Y/Ho (ave. 46.26). Studied micritic limestones have predominantly low Hf (bdl to 0.5 µg/g), Sc (bdl to 2 µg/g) Th (bdl to 0.9 µg/g) contents suggesting negligible to minor shale contamination. These findings imply that micritic limestones faithfully record chemical signals of their parental and diagenetic fluids. The succession also exhibits high ratios of Eu/Eu* (1.01–1.65; ave. 1.29 corresponding to the positive Eu anomalies), Sm/Yb (1.26–2.74; ave. 1.68) and La/Yb ratios (0.68–1.35; ave. 0.9) compared to modern seawater and wide range of Y/Ho ratios (29.33–70.00; ave. 46.26) which are between seawater and hydrogenetic Fe-Mn crusts. Several lines of geochemical evidence suggest water-rock interaction between parental seawater and basaltic rocks at elevated temperatures triggered by hydrothermal activity associated with Early Cretaceous basaltic magma generation. The range of Ce/Ce* values is suggestive of mostly oxic to dysoxic paleoceanographic conditions, with a sudden change to dysoxic conditions (Ce/Ce* = 0.71–0.81), in the uppermost part of the MF-1. This is followed by an abrupt deepening paleoenvironment with a relative increase in the oxic state of the seawater and deposition of deeper water sediments (MF-2 and MF-3) above a sharp transition. The differences in microfacies characteristics and foraminifera assemblage between MF-1 and overlying facies (MF-2 and MF-3) may also confirm the change in paleoceanographic conditions. Therefore, REEs data obtained from studied limestones have the potential to contribute important information as to regional paleoceanographic conditions of Tethys during an important period in Earth history.

Early Permian (Cisuralian) ostracods from Japan: characteristic ostracod assemblage from a seamount of the Panthalassic Ocean

Silicified ostracods were recovered from Cisuralian micritic limestones of the Ryozensan Limestone Formation from the southwestern part of Ryozensan Mountain, Taga City located in Shiga Prefecture, Central Japan. Twenty-seven species belonging to 19 genera were obtained, of which six species are new and are described here: Bairdia tagaensis Tanaka sp. nov., Bairdiacypris ikeyanoriyukii Tanaka sp. nov., Kellettina noriyukii Tanaka sp. nov., Microcheilinella shigensis Tanaka sp. nov., Oliganisus ryozensannensis Tanaka sp. nov., and Pustulobairdia ohmiensis Tanaka sp. nov. Some Palaeozoic limestone localities in Japan cap greenstones and are surrounded by younger cherts (such as Mino Terrane of this study). They represent a characteristic reef and reef-slope environment around a seamount surrounded by deep sea ocean floor. This result is concordant with the ostracod assemblage. After this report, a Panthalassan ostracod fauna could be defined for the Cisuralian.

A NEW CONSIDERATION ABOUT THE ALMOPIA-PAIKON BOUNDARY BASED ON THE GEOLOGICAL MAPPING IN THE AREA OF NEROSTOMA-LAKKA (CENTRAL MACEDONIA, GREECE)

Geological mapping along the boundary of Almopia and Paikon zone in the 'Nerostoma' region, NNW of Lakka village defines mafic volcanogenic rocL·, meta-pelites and radiolarites, thick-bedded to massive micritic limestones and flysch meta-sediments that dip mainly towards SW. Middle-Late Cretaceous fossiliferous limestones overlie unconformably the flysch meta-sediments and are characterised only by a primary foliation SO that dips at shallow angles to the NNW-N. Secondary foliations SI (sub-parallel to SO) and S2 are observed in the meta-clastic rocks. A Dl event caused Fl and progressively F2 folds to which S2 is the axial plane schistosity dipping to SW. This event which has not affected the fossiliferous limestones is related to an oblique convergence or inclined transpression during the Late Jurassic-Early Cretaceous. A D2 event dated in Early Tertiary caused an intense NE-thrusting and S-C cataclastic fabric defining top-to-the NE sense-of-shear. At many parts, the unconformity contact between the fossiliferous limestones and the underlying flysch is obliterated by this thrusting event. As a result, the boundary between Almopia and Paikon zones as paleo-geographically defined in this area seems to be meaningless for the Jurassic-Cretaceous times.

Stratigraphy of the White Limestone of Jamaica

The lithostratigraphy of the White Limestone Group (Eocene-Miocene) of Jamaica is revised based on geological mapping across the northern part of the Clarendon block. Eight shallow-water formations are recognised which are from base to top: Healthy Hill Formation (new name): predominantly white grainstones; Troy Formation: recrystallized and dolomitized limestones; Swanswick Formation: white grainstones; Claremont Formation: pale micritic limestones (locally recrystallized and dolomitized); Somerset Formation: pink grainstones and packstones with large white globular foraminifers; Walderston Formation: pink grainstones; Browns Town Formation: white packstones and wackestones with abundant large lens shaped foraminifers and abundant corals; and Newport Formation: pale wakestones and carbonate mudstones. The facies and their foraminifer assemblages are interpreted in terms of sequence stratigraphy.