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Current Issue   2020 Vol.  9 No.  1 Published: 2020-01-20 1 A new early Visean coral assemblage from Azrou-Khenifra Basin, central Morocco and palaeobiogeographic implications Sergio Rodríguez, Ian D. Somerville, Pedro Cózar, Javier Sanz-López, Ismael Coronado, Felipe González, Ismail Said, Mohamed El Houicha A new early Visean coral assemblage has been recorded from turbidite facies in the southern part of the Azrou-Khenifra Basin, northwest of Khenifra, central Morocco. The newly discovered Ba Moussa West (BMW) coral fauna includes Siphonophyllia khenifrense sp. nov., Sychnoelasma urbanowitschi, Cravenia lamellata, Cravenia tela, Cravenia rhytoides, Turnacipora megastoma and Pleurosiphonella crustosa. The early Visean age of the coral assemblage is supported by foraminiferal and conodont data, with the recognition of the basal Visean MFZ9 Zone. This confirms that the first transgression in the Azrou-Khenifra Basin was during the earliest Visean. The allochthonous coral assemblage was recovered from coarse-grained proximal limestone debris flow and turbidite beds within a fault-bounded unit, lying to the west of a thrust syncline containing upper Visean limestones. No evidence exists of the former early Visean shallow-water platform from which the corals were derived. All other in situ platform carbonate rocks around the southern margin of the Azrou-Khenifra Basin are probably of late Visean (Asbian-Brigantian) age. The early Visean Ba Moussa West coral fauna can be compared with that at Tafilalt in eastern Morocco, as well as in other Saharian basins of Algeria. Many of the genera and species in the Ba Moussa West assemblage are identical to those in NW Europe, with which it must have had marine connections. The new rugose species described, Siphonophyllia khenifrense, is probably endemic to North Africa. Its ecological niche in NW Europe was occupied by S. cylindrica or S. aff. garwoodi. 2020 Vol. 9 (1): 1-20 [Abstract] ( 99 ) [HTML 1KB] PDF (10329 KB)   ( 28 ) 21 Benthic foraminiferal assemblages from the Safranbolu Formation (Cuisian, Eocene), Northwest Anatolia, Turkey Kubra Okur, Hatice Kutluk Twenty-one outcrop samples collected from a 28-m-thick section from the Safranbolu Formation of the southwestern part of the Safranbolu Basin, Anatolia, Turkey yielded well-preserved benthic foraminifera belonging mainly to the genera Alveolina, Nummulites, Assilina, Rotalia, Disclocyclina and Orbitolites. Alveolina is the most diversified genus that is represented by sixteen species: Alveolina archiaci, A. axiampla, A. barattoloi, A. carantana, A. colatiensis, A. cuspidata, A. distefanoi, A. histrica, A. lehneri, A. oblonga, A. polatliensis, A. rakoveci gueroli, A. ruetimeyeri, A. rugosa, A. safranboluensis and A. sirelii. Alveolina safranboluensis and A. sirelii are described new. Comparison of the fossil assemblage with those assemblages previously reported from both Turkey and other Tethyan sub-basins revealed that the deposition occurred during the Cuisian (Eocene) and corresponded to Shallow Benthic Foraminiferal Zones (SBFZ) 10-12. The abundance and diversity of the larger benthic foraminifera indicated that the Safranbolu Formation was deposited under transgressive conditions. 2020 Vol. 9 (1): 21-41 [Abstract] ( 100 ) [HTML 1KB] PDF (13610 KB)   ( 24 ) 42 The sedimentary dynamics of Sabellaria alveolata bioconstructions (Ostia, Tyrrhenian Sea, central Italy) Stefania Nunzia Lisco, Pasquale Acquafredda, Salvatore Gallicchio, Luisa Sabato, Andrea Bonifazi, Frine Cardone, Giuseppe Corriero, Maria Flavia Gravina, Cataldo Pierri, Massimo Moretti Sabellaria alveolata (Linnaeus 1767) is a polychaete able to build bioconstructions of different thickness, size and patchiness, in intertidal and subtidal environments. Its biological features have been the object of numerous studies worldwide. The worm reefs are formed by millions of tubes built by sand and shells (whole or in fragments) bonded together with a strong glue produced by the worm itself. Hence, Sabellaria alveolata represents a sedimentological asset for the coastal protection, since it contributes to create natural barriers against storm waves and erosion, and supplies the beach with new sandy deposits. This work shows a multidisciplinary approach to studying a bioconstruction of Sabellaria alveolata along the Latium coast (Ostia, Tyrrhenian Sea, central Italy), proposing image analysis as a novel technique to investigate worm reefs, along with classical sedimentological/ecological tools. The Sabellaria bioconstructions have been analysed at different scales of observation, suggesting the more appropriate strategies to develop a reliable model illustrating the different growth steps of these bioconstructions. 2020 Vol. 9 (1): 42-59 [Abstract] ( 92 ) [HTML 1KB] PDF (9113 KB)   ( 22 ) 60 Age of the earliest transgressive event in the Krishna-Godavari Basin, India: Evidence from dinoflagellate cysts and planktonic foraminifera biostratigraphy Ashish Kumar Mishra, Nallamuthu Malarkodi, Arun Deo Singh, Dinesh Babu, Vandana Prasad A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on early Cretaceous subsurface well cutting sediments from well A (DNG) (2800-2746 m depth) from the Krishna-Godavari Basin, India. The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework. The study shows dominance of early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna, Cribroperidinium perforans, Hystrichodinium voigtii, Kleithriasphaeridium eoinodes, and planktonic foraminifera Hedbergella aptiana, Hedbergella mitra, Hedbergella praelippa, Hedbergella tardita, Microhedbergella miniglobularis and Hedbergella mitra species. In addition to this, the dinoflagellate cyst data was compared with the dinoflagellate biozones of Austral and Tethyan provinces. Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study, a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin. The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of East coast from north to south. 2020 Vol. 9 (1): 60-70 [Abstract] ( 193 ) [HTML 1KB] PDF (7004 KB)   ( 23 ) 71 First steps in reconstructing Early Jurassic sea water temperatures in the Andean Basin of northern Chile based on stable isotope analyses of oyster and brachiopod shells Matthias Alberti, Franz T. Fürsich, Nils Andersen The stable isotope (δ13C, δ18O) composition of a collection of Lower Jurassic brachiopods and oysters from the Andean Basin of northern Chile was analyzed. The results allow the first reconstruction of absolute water temperatures for several ammonite zones in the Lower Jurassic of South America. The temperature record starts with comparatively high values in the Late Sinemurian (average: 27.0 ℃; Raricostatum Zone). Just before the Sinemurian-Pliensbachian transition, temperatures dropped to an average of 24.3 ℃. The lowest temperature value in the dataset was recorded for a brachiopod shell of the latest Pliensbachian Spinatum Zone (19.6 ℃). No data are available for the Early Toarcian, but results for the late Toarcian show again comparatively warm conditions (average: 24.4 ℃; Thouarsense-Levesquei zones). Even though more material and analyses are necessary to corroborate the recorded temperatures, the present dataset seems to indicate the global nature of the Late Pliensbachian Cooling Event. In contrast, the global warming during the Toarcian Oceanic Anoxic Event has not been recorded due to a lack of Early Toarcian material. The δ13C record of brachiopods and oysters documents a gradual increase in values representing background conditions. Oyster shells were used for high-resolution stable isotope analyses and show seasonal temperature fluctuations over a period of around three years in the life time of the bivalves. If explained only by temperatures, the δ18O values point to a minimum estimate for the seasonality in the late Toarcian of slightly more than 3 ℃. 2020 Vol. 9 (1): 71-87 [Abstract] ( 101 ) [HTML 1KB] PDF (4670 KB)   ( 26 ) 88 Ooidal ironstones in the Meso-Cenozoic sequences in western Siberia: Assessment of formation processes and relationship with regional and global Earth processes Maxim Rudmin, Santanu Banerjee, Elshan Abdullayev, Aleksey Ruban, Ekaterina Filimonenko, Elena Lyapina, Roman Kashapov, Aleksey Mazurov This study investigates the process of formation of ooidal ironstones in the Upper Cretaceous-Paleogene succession in western Siberia. The Formation of such carbonate-based ironstones is a continuing problem in sedimentary geology, and in this study, we use a variety of data and proxies assembled from core samples to develop a model to explain how the ooidal ironstones formed. Research on pyrite framboids and geochemical redox proxies reveals three intervals of oceanic hypoxia during the deposition of marine ooidal ironstones in the Late Cretaceous to the Early Paleogene Bakchar ironstone deposit in western Siberia; the absence of pyrite indicates oxic conditions for the remaining sequence. While goethite formed in oxic depositional condition, chamosite, pyrite and siderite represented hypoxic seawater. Euhedral pyrite crystals form through a series of transition originating from massive aggregate followed by normal and polygonal framboid. Sediments associated with goethite-chamosite ironstones, encompassing hypoxic intervals exhibit positive cerium, negative europium, and negative yttrium anomalies. Mercury anomalies, associated with the initial stages of hypoxia, correlate with global volcanic events. Redox sensitive proxies and ore mineral assemblages of deposits reflect hydrothermal activation. Rifting and global volcanism possibly induced hydrothermal convection in the sedimentary cover of western Siberia, and released iron-rich fluid and methane in coastal and shallow marine environments. This investigation, therefore, reveals a potential geological connection between Large Igneous Provinces (LIPs), marine hypoxia, rifting and the formation of ooidal ironstones in ancient West Siberian Sea. 2020 Vol. 9 (1): 88-108 [Abstract] ( 111 ) [HTML 1KB] PDF (9068 KB)   ( 26 ) 109 Liquefaction structures induced by the M5.7 earthquake on May 28, 2018 in Songyuan, Jilin Province, NE China and research implication Zhu-Fu Shao, Jian-Hua Zhong, John Howell, Bing Hao, Xi-Wu Luan, Ze-Xuan Liu, Wei-Min Ran, Yun-Feng Zhang, Hong-Qi Yuan, Jing-Jing Liu, Liang-Tian Ni, Guan-Xian Song, Jin-Lin Liu, Wen-Xin Zhang, Bing Zhao An earthquake of magnitude M5.7 occurred in Yamutu village, Songyuan City, Jilin Province, NE China (45°16'12"N/124°42'35"E) on May 28, 2018, with a focal depth of 13 km. The epicenter is located at the intersection of the Fuyu/Songyuan-Zhaodong Fault, Second Songhua River Fault and Fuyu North Fault which lies northwest of Tancheng-Lujiang Fault (Tan-Lu Fault). The earthquake-induced widespread liquefaction structures and ground surface fissures within 3 km from the epicenter, caused serious disasters to the local surroundings. The visible liquefied structures include sand volcanoes, liquefied sand mounds, sand dikes and sand sills. Sand volcanoes can be divided into sand volcano with a crater, sand volcano without a crater and water volcano (no sand). Other soft-sediment deformation structures (SSDS) induced by the earthquake include deformation lamination, load and flame structures, deformation folds, dish structures, convolute bedding and water-escape structures. The formation process of the sand volcanoes comprises three stages: (1) building up excess pore-fluid pressure in the liquefied layer, (2) cracking of the low-permeable overlying layer, and (3) mixture of sand-water venting out of the ground surface. During the upward movement, the liquefied sand is injected into the low-permeable layer to form sand veins, sand sills and various types of deformation structures. Vertical distribution of seismic liquefaction structure can be divided into four zones: the thoroughly liquefied zone, the lower liquefied zone with SSDS, the upper liquefied zone with SSDS, and the ground surface liquefied zone. The liquefaction occurred at a burial depth of 2-5 m, and the thickness of liquefied sand is 2 m. NE-SW (35°-215°) trending compressive stress is possibly the seismogenic trigger of the Songyuan M5.7 earthquake that caused the fault (Fuyu/Songyuan-Zhaodong Fault) to reactivate. The study of the Songyuan seismic liquefaction structures gives insight into the prediction of modern earthquakes and disaster-prone areas. Meanwhile it provides abundant basic material for studying earthquake-induced SSDS in both ancient and modern sediments. The research is obviously of great significance to reveal that the northern Tan-Lu Fault has entered a stage of active seismic activity since the 21st century. 2020 Vol. 9 (1): 109-127 [Abstract] ( 120 ) [HTML 1KB] PDF (11906 KB)   ( 28 )

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