The Upper Cenomanian-Turonian (Upper Cretaceous) of the Saharan Atlas (Algeria)

2008 ◽  
Vol 179 (6) ◽  
pp. 593-603 ◽  
Author(s):  
Danièle Grosheny ◽  
Fettouma Chikhi-Aouimeur ◽  
Serge Ferry ◽  
Fatiha Benkherouf-Kechid ◽  
Mohamed Jati ◽  
...  
Keyword(s):  
Sea Level ◽  
Black Shale ◽  
Black Shales ◽  
Carbonate Platforms ◽  
Northern Tunisia ◽  
The North ◽  
Western Interior Basin ◽  
Platform Carbonates ◽  
Saharan Platform ◽  
Reference Section

Abstract A series of sections from the Ouled Nail, Hodna and Aurès massifs of Algeria have been studied to analyse the palaeogeographic evolution of the eastern part of the Saharan Atlas prior to and after the Cenomanian/Turonian (C/T) boundary event. Three periods are distinguished in the interval studied. During the middle to late Cenomanian, an overall ramp setting prevailed from the Saharan platform to the deeper environments of the Saharan Atlas. The latest Cenomanian and the earliest Turonian was marked by an episode of marked palaeogeographic change. Prior to the deposition of C/T boundary black shales, a rise in sea level occurred. Shallow-water carbonates were locally able to accommodate the sea-level rise. A “keep-up” response created a palaeogeography made up of isolated carbonate platforms separated by saddles, where a 1–20 m thick bed of deeper water mudstones was deposited as the lateral equivalent of the platform carbonates. At a larger scale, these saddles probably acted as corridors that allowed marine communication with the intra-Saharan basins (Tinrhert, Tademaït basins). Correlations show that the boundary black shales later filled up the saddles of the Saharan Atlas, and onlapped the carbonate platforms, before the deposition of lower Turonian open marine marls that everywhere blanket the successions. During the early to late Turonian, the palaeogeography again changed to restore a N-S oriented ramp setting, similar to that of the middle Cenomanian. Correlation with the deeper-water facies of nearby northern Tunisia, suggests that the uppermost Cenomanian mudstone immediately underlying the black shale facies in the Saharan Atlas is the lateral equivalent of the uppermost bed of the Fahdene Formation (the so-called “pre-Bahloul”) underlying the Bahloul black shale facies in the Tunisian Kalaat Senan reference section. Our platform-to-basin correlations show that the base of this bed is a regional transgressive surface, not a type II sequence boundary as suggested by previous authors. Finally, it is proposed that this mudstone bed correlates with Bed 63 of the Pueblo global reference section in the North American western Interior Basin, which also marks the beginning of the strong C/T boundary transgression.

Eustatic and palaeogeographic control of the western Aurès Upper Cretaceous sedimentation (Algeria)

2004 ◽  
Vol 175 (3) ◽  
pp. 273-288 ◽  
Author(s):  
Missoum Herkat
Keyword(s):  
Upper Cretaceous ◽  
Carbonate Platforms ◽  
The North ◽  
Basement Faults ◽  
Gradual Development ◽  
High Zone ◽  
Platform Carbonates ◽  
Bank System ◽  
Homoclinal Ramp ◽  
Saharan Platform

Abstract The Upper Cretaceous sedimentation in the Aurès Mountains occurred in a subsident basin delimited to the south by the Saharan platform and by the Preatlasic high zone to the north. In these series 4 transgressive-regressive megasequences are distinguished, the first one (I) in the late Albian-Cenomanian, the second one (II) in the Turonian, the third one (III) in the Coniacian - Santonian and the fourth one (IV) in the Campanian - Maastrichtian. Each megasequence is made up of three or four sequences, which correspond to third order cycles identified in the eustatic chart of Haq et al. [1987]. In late Albian and lower Turonian periods, during the deposition of basal sequences of the megasequences I and II, the reactivation of basement faults in the Aurès basin occurs consecutively to distension phases, resulting in the formation of rotated blocks. At the same time high eustatic levels are reached according to the global eustatic curve. These processes control the drowning of the carbonate platforms pre-existing to these sequences, and deep ramps progressively form on the tilted block tops. This sedimentary setting generates in the late Albian and lower Turonian series anoxic sequences made up of calcareous and shaly transgressive pelagic intervals. The succeeding sequences lack pelagic facies and are composed of alternate marls / carbonate beds deposited on a homoclinal ramp, indicating a gradual development of shallow open marine conditions, which became progressively restricted upwards. Toward the top of these megasequences, lagunal muds and isolated rudists mounds, surrounded by bioclastic and ooid / pellet banks occur. The Coniacian-Santonian and Campanian-Maastrichtian megasequences are characterized by a shallow ramp sedimentation, essentially marly during the Coniacian, Santonian and Campanian periods, interlayered with some bioclastic / ooid carbonate banks and upwards by sequences mostly homogeneous. The Maastrichtian platform carbonates are composed of bioclastic / ooid sands and were deposited in a ramp-barrier-bank system. Some sequences in the Campanian-Maastrichtian megasequence are condensed or absent due to the accommodation reduction related to a weak subsidence rate period.

scholarly journals Erratum to “A Perspective on Stratigraphic, Vertically-Upward “Displacements or Dislocations” of Conodont-Elements: An Example From the Upper Devonian, Pre-Lithified, Black Shales of the Chattanooga Shale Formation In Tennessee, USA” ...

2019 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Michael Iannicelli
Keyword(s):  
Black Shale ◽  
Environmental Chemistry ◽  
Black Shales ◽  
Photic Zone ◽  
Marine Organic Matter ◽  
Chattanooga Shale ◽  
Shale Formation ◽  
Organic Matter Biomarkers ◽  
Reference Section ◽  
Made In

Even though the author already incorporated the citation of Sinninghe-Damste & Schouten (2006) into the text of the paper, the author regrets having failed to include their full citation within the Reference Section of my above paper which is: Sinninghe-Damste, J. S. & Schouton, S. (2006). Biological markers for anoxia in the photic zone of the water column. In, Volkman, J. K. (ed.), Marine Organic Matter: Biomarkers, Isotopes and DNA, (pp. 127 – 163). The Handbook of Environmental Chemistry, vol. 2N. Springer: Berlin and Heidelberg. https://doi.org/10.1007/698_2_005 The author also needs to paraphrase a statement made in the last three lines of the 2nd paragraph on page 40 where it reads as: “Thus, we may conclude here that paleo-upfreezing of any conodont-element(s) originally buried in the pre-lithified, light-colored shale occurred in order to account for their presence in black shale”. Instead, in lieu of that statement, it should read as “At this point in time of the study, we may tentatively conclude here while completely concluding later in the study, that conodont-elements originally existing in the underlying, pre-lithified, light-colored shale, had to paleo-upfreeze vertically upward into pre-lithified, black shale sediment in order to account for their presence in lithified black shale”.

Revision of Tenticospirifer Tien, 1938, and similar spiriferid brachiopod genera from the Late Devonian (Frasnian) of Eurasia, North America, and Australia

2000 ◽  
Vol 74 (3) ◽  
pp. 444-463 ◽  
Author(s):  
Xueping Ma ◽  
Jed Day
Keyword(s):  
North America ◽  
Sea Level ◽  
South China ◽  
North American ◽  
Type Species ◽  
Western Europe ◽  
Late Devonian ◽  
Carbonate Platforms ◽  
The North ◽  
New Family

The cyrtospiriferid brachiopod genus Tenticospirifer Tien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears that Tenticospirifer evolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations of Tenticospirifer from eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American species Spirifera cyrtinaformis Hall and Whitfield, 1872, and related species identified as Tenticospirifer by North American workers, are reassigned to Conispirifer Lyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed with Conispirifer Lyashenko, 1985, selected as the type genus. The new family also includes the new genus Pyramidaspirifer with Platyrachella alta Fenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species of Pyramidaspirifer are restricted to late Frasnian deposits of central and western North America.

scholarly journals Abnormally high content of noble metals in wastes of the Fiagdon concentration plant: a possible new type of mineralization for the North Caucasus is gold-platinoid with base metals, localized in the Early-Middle Jurassic black shales

2021 ◽  
Author(s):  
А.Г. Гурбанов ◽  
А.Я. Докучаев ◽  
В.М. Газеев ◽  
О.А. Гурбанова
Keyword(s):  
Noble Metal ◽  
Black Shale ◽  
Middle Jurassic ◽  
Black Shales ◽  
North Caucasus ◽  
Concentration Plant ◽  
The North ◽  
Icp Ms ◽  
Polymetallic Mineralization ◽  
Gold Platinum

На Северном Кавказе благороднометалльное (золото, серебро, платина, элементы платиновой группы) оруденение черносланцевого типа локализовано в тоар-ааленских флишоидных углеродсодержащих терригенных отложениях, приуроченных к региональной Самуро-Белореченской металлогенической зоне (СБМЗ) – от Дагестана до Адыгеи и Краснодарского края. Вовлечение в поисково-разведочные работы этого стратегического минерального типа оруденения дает возможность расширить минерально-сырьевую базу Южного федерального округа России. Цель исследований – выявление содержаний благородных металлов и элементов платиновой группы (ЭПГ) в промышленных отходах Фиагдонской обогатительной фабрики (ФОФ) и в рудовмещающих тоар-ааленских черносланцевых толщах. ФОФ, в частности, перерабатывала руды полиметаллических месторождений Кадат и Какадур, локализованных в тоар-ааленских флишоидных углеродсодержащих терригенных отложениях Авсандур-Ламардонского рудного поля (АЛРП). Проведена оценка АЛРП на возможность выявления здесь промышленно значимого золото-платиноидного с полиметаллами оруденения в черносланцевой толще. Методы исследования. ICP-MS анализом проанализированы 5 проб в Центре «ИГЕМ-Аналитика» на масс-спектрометре X-Series IIи 13 проб – в Лаборатории физико-химических и химических методов анализа ИМГРЭ на приборе Elan 6100 DRC. Результаты работы. Установленные в 18 пробах (в керне скважин) Фиагдонского хвостохранилища (ФХ) повышенные содержания благородных металлов можно объяснить наличием как в рудах АЛРП, так и во вмещающей их нижне-среднеюрской углеродсодержащей песчано-глинистой флишоидной толще нового для Северного Кавказа нижне-среднеюрского золото-платиноидного cполиметаллами оруденения в черносланцевой толще (2,5-3,2 мас. % УГВ). Предложена модель образования золото-платинового оруденения черносланцевого типа за счет конвекции вадозных вод в высоко металлоносных (Au, Ag, Pt, Pd) ранне-среднеюрских флишоидных толщах алевролито-аргиллитового состава. При поисковых работах на золото-кварцевый, золото-сульфидный и колчеданно-полиметаллический с золотом типы оруденения в Горной Осетии и в восточной части Горного Дагестана был выявлен ряд перспективных на золото объектов.В пределах СБМЗ может быть выявлен ряд промышленно значимых объектов с золото-платиноидным с полиметаллами оруденением в черносланцевых толщах тоар-ааленского возраста. Предложен комплекс мероприятий с минимальными временными, материальными и финансовыми затратами. In the North Caucasus noble-metal (gold, silver, platinum, elements of the platinum group (PGE)) mineralization of the black-shale type is localized in Toar-Aalenian flysch-like organic matter rich, terrigenous sediments in the regional (from Dagestan to Adygea and Krasnodar Territory) Samuro-Belorechenskaya metallogenic zone (SBMZ). Involvement in prospecting and exploration of this strategic type of mineralization provides the opportunity to expand the mineral resource base of the Southern Federal District of Russia. The Aim of the research is to identify the content of platinum and PGE in the industrial wastes of the Fiagdon concentration plant (FCP) and in the ore-bearing Toar-Aalenian black shale strata. In particular, processed ores of the Kadat and Kakadur polymetallic deposits, localized in Avsandur-Lamardon ore field (ALOF). The ALRP was prospected for economic gold-platinum with polymetallic deposit in the black-shales series. Methods. ICP-MS analysis - 5 samples were analyzed by ICP-MS in IGEM-Analytics Center on an X-Series II mass spectrometer and 13 samples - in the Laboratory of Physical-Chemical and Chemical Methods of Analysis of the IMGRE on the Elan 6100 DRC instrument. Results. The elevated noble metal concentrations established in 18 samples (borehole core samples) from the Fiagdon tailings dump could be explained by the presence of both the ALRP ores and the gold-platinum with polymetallic mineralization in the host Toar- Aalenian black-shales series (2.5-3.2 wt. % of carbonaceous matter). The model of formation of gold-platinum mineralization at the expense of vadose water convection in highly metalliferous (Au, Ag, Pt, Pd) Early-Middle Jurassic flysch-like strata of siltstone-argillite composition is proposed. During prospecting works for gold-quartz, gold-sulfide and colliery-polymetallic with gold types of mineralization in the Mountain Ossetia and in the eastern part of Mountain Dagestan a number of promising objects for gold were revealed. A number of economic significant objects with gold-platinum with polymetallic mineralization in black-shale series of Toar-Aalenian age can be identified within the SBMZ. A complex of prospecting with minimal time, material and financial expenses is proposed

scholarly journals Ultrabasites and the sources of noble metals (Au, Pt, Pd) in the North Caucasus

2021 ◽  
Author(s):  
И.А. Богуш ◽  
Г.В. Рябов ◽  
В.И. Черкашин ◽  
Н.А. Исаева
Keyword(s):  
Black Shale ◽  
Noble Metals ◽  
Genetic Relationships ◽  
Practical Importance ◽  
Historical Review ◽  
Black Shales ◽  
North Caucasus ◽  
The Caucasus ◽  
Lower Paleozoic ◽  
The North

Ультрабазиты Северного Кавказа являются древнейшими магматическими породами, возраст которых определяется как нижнепалеозойский (ордовик-силур). Эти породы играют ключевую роль в металлогении благородных металлов Кавказа. С ультрабазитами связаны гигантские запасы металлов в региональной углеродсодержащей девонской черносланцевой толще Северного Кавказа. Практическое значение имеют пермскские пропилиты (Чучкурское месторождение) и металлоносные юрские коры выветривания ультрабазитовых массивов. До настоящего времени не оценены благородные металлы лиственитов Северного Кавказа, сопровождающих ультрабазиты. Цель работы. Показать, что ультраосновные породы являются донорами благородных металлов (Au, Pt, Pd) для Северного Кавказа на протяжении всего фанерозоя. Подтвердить пространственно-временную связь ультрабазитов с благороднометалльным оруденением в черных сланцах Кавказа. Доказать на примере Беденского массива ультрабазитов наличие рудоносной коры выветривания, залегающей на размытой поверхности серпентинитов. Методы исследований. Сделан краткий исторический обзор исследований ультрабазитов с ориентацией на генетические связи благородных металлов (Au, Pt, Pd) с ультрабазитовой магмой. Проведен анализ геологических материалов по наиболее крупным на Северном Кавказе Беденскому и Малкинскому ультрабазитовым массивам - их составу, геохимическим особенностям и потенциальной рудоносности. Результаты работы. По химическому составу ультрабазиты Северного Кавказа отнесены к альпинотипному формационному типу. Установлена рудообразующая роль альпинотипных ультрабазитов для благородных металлов в осадочных и метаморфических толщах фанерозоя региона. Благородные металлы активно проявляются в металлогении фанерозойских геотектонических эпох: каледонской, герцинской, киммерийской и альпийской, имея единый первичный ультрабазитовый источник. Свежие, неизмененные серпентиниты в настоящее время не обнаруживают аномальные содержания благородных металлов, представляющих промышленный интерес. Насыщение серпентинитов благородными металлами проявляется при их экзогенной переработке в обогащенных продуктах их разрушения. Потенциально промышленными осадочными комплексами, состоящими из обогащенных продуктов разрушения серпентинитов, являются коры выветривания серпентинитов и осадочные черносланцевые толщи Северного Кавказа. Ультрабазитовая магма на Северном Кавказе послужила первичным глубинным источником благородных металлов в осадочных и метаморфогенных фанерозойских толщах Кавказа The ultrabasites of the North Caucasus are the oldest igneous rocks, whose age is defined as the Lower Paleozoic (Ordovician-Silurian). These rocks play a key role in the metallogeny of the noble metals of the Caucasus. Huge reserves of metals in the regional carbonaceous Devonian black shale stratum of the North Caucasus are associated with ultrabasites. Permian propylites (Chuchkurskoye deposit) and metal-bearing Jurassic crusts of weathering of ultrabasic massifs are of practical importance. To date, the noble metals of the listvenites of the North Caucasus accompanying ultrabasites have not been evaluated. Aim. Show that ultrabasic rocks are donors of noble metals (Au, Pt, Pd) for the North Caucasus throughout the entire Phanerozoic. Confirm the spatio-temporal relationship of ultrabasic rocks with noble metal mineralization in the black shales of the Caucasus. Prove the presence of an ore-bearing weathering crust on the eroded surface of serpentinites using the example of the Bedensky ultrabasic massif. Methods. A brief historical review of ultrabasite studies with a focus on the genetic relationships of noble metals (Au, Pt, Pd) with ultrabasite magma is made. The analysis of geological materials on the Bedene and Malkin ultrabasite massifs, the largest in the North Caucasus, is carried out - their composition, geochemical features and potential ore content. Results. According to the chemical composition, the ultrabasites of the North Caucasus are attributed to the alpinotype formation type. The ore-forming role of alpinotype ultrabasites for noble metals in sedimentary and metamorphic strata of the Phanerozoic region has been established. Noble metals are actively manifested in the metallogeny of the Phanerozoic Geotectonic epochs: Caledonian, Hercynian, Cimmerian and Alpine, having a single primary ultrabasic source. Fresh, unaltered serpentinites do not currently show anomalous contents of noble metals of industrial interest. The saturation of serpentinite with noble metals is manifested during their exogenous processing in the enriched products of their destruction. Potentially industrial sedimentary complexes consisting of enriched products of destruction of serpentinites are the weathering crusts of serpentinites and sedimentary black-shale strata of the North Caucasus. Ultrabasic magma in the North Caucasus served as the primary deep-seated source of precious metals in sedimentary and metamorphogenic Phanerozoic strata of the Caucasus

scholarly journals Geochemical features of metalliferous black shale of North Caucasus

2019 ◽  
Author(s):  
И.А. Богуш ◽  
Г.В. Рябов ◽  
В.И. Черкашин ◽  
Н.А. Исаева
Keyword(s):  
Black Shale ◽  
Noble Metals ◽  
Chemical Weathering ◽  
Precious Metals ◽  
Primary Source ◽  
Black Shales ◽  
North Caucasus ◽  
Weathering Processes ◽  
The North ◽  
Starting Point

Объектами исследования являются терригенные породы, входящие в состав Тоханского комплекса (Тоханский покров), расположенные в пределах Передового хребта Северного Кавказа и прослеженные на протяжении более 200 километров. Тоханский комплекс сложен пелитоморфными углеродсодержащими отложениями (черными сланцами) с подчиненными проявлениями вулканогенных, глинистокремнистых, глинистокарбонатных и псаммитовых пород, испытал зеленокаменный метаморфизм. Целью работы был анализ геохимических особенностей углеродсодержащей черносланцевой герцинской толщи Северного Кавказа. Специфическим для черных сланцев является комплекс элементов, типоморфных для ультрамафитовых пород: хром, кобальт, никель, титан, марганец, ванадий, фосфор. Халькофильные элементы гидротермалитов в черных сланцах, такие как медь, цинк, свинец, содержатся обычно в небольших количествах, но локально, в флюидоактивных зонах тектонических нарушений, их содержание резко возрастает. Группа элементов, типоморфных спутников золота мышьяк, висмут, сурьма, в неизмененных сланцах проявлена слабо, концентрируясь в участках наложенной гидротермальной проработки. Установлена значительная возмущающая роль магния в сланцах. Все это говорит о своеобразии черносланцевых отложений и значительном влиянии ультраосновного материала на их петрохимические особенности. Петрохимические модули указывают на установленную невысокую проявленность процессов механической дифференциации, низкую степень вклада процессов химического выветривания и низкий уровень показателя зрелости материала пород области сноса при формировании основной массы отложений. Площадное и точечное опробование черных сланцев на благородные металлы показало повсеместное присутствие золота, платины и палладия в аномальном количестве в сумме трех металлов не менее 1 г/т. Изложенный материал впервые однозначно указывает на ультрабазиты в качестве единого первичного источника благородных металлов в черносланцевом комплексе. Показано, что благородные металлы (Au, Pt, Pd) сингенетичны вмещающим осадочным терригенным толщам и отлагаются в процессе седиментогенеза. Анализ рудоносности черных сланцев Кавказа и установление древнейшего источника благородных металлов стали отправным пунктом для создания авторами металлометрической геологогенетической модели благородных металлов Северного Кавказа, охватывающей весь фанерозойский этап его развития. Черносланцевая зона Северного Кавказа может рассматриваться как новая перспективная провинция благородных металлов Au, Pt, Pd. The objects of the study are terrigenous rocks that are part of the Tokhan complex (Tokhan cover), located within the Advanced ridge of the North Caucasus and traced for more than 200 kilometers. The Tokhan complex is composed of pelitomorphic carbonaceous sediments (black shales) with subordinate manifestations of volcanogenic, claysiliceous, claycarbonate and psammitic rocks, has experienced greenstone metamorphism. The aim of the work was to analyze the geochemical features of the carbonaceous black shale Hercynian strata of the North Caucasus. Specific for black shale is a complex of elements typomorphic to ultramafic rocks: chromium, cobalt, nickel, titanium, manganese, vanadium, phosphorus. Chalcophilic elements of hydrothermalites in black shales, such as copper, zinc, lead, are usually contained in small quantities, but locally, in fluidactive zones of tectonic disturbances, their content increases sharply. A group of elements, typomorphic satellites of gold arsenic, bismuth, antimony, in unmodified shales is weakly manifested, concentrating in the areas of superimposed hydrothermal development. A significant perturbing role of magnesium in shale has been established. All this indicates the originality of black shale deposits and the significant influence of ultrabasic material on their petrochemical characteristics. Petrochemical modules indicate the established low manifestation of mechanical differentiation processes, a low degree of contribution of chemical weathering processes and a low level of maturity of the material in the drift area during the formation of the bulk of the deposits. Areal and point testing of black shale for noble metals showed the ubiquitous presence of gold, platinum and palladium in abnormal amounts in the sum of three metalsnot less than 1 g / t.The presented material for the first time clearly indicates ultrabasites as a single primary source of precious metals in the black shale complex. It is shown that noble metals (Au, Pt, Pd) are syngenetic to the host sedimentary terrigenous strata and are deposited during sedimentogenesis. Analysis of the orebearing black shales of the Caucasus and the establishment of the oldest source of precious metals became the starting point for the creation of the authors metallogenically geologicalgenetic models of noble metals in the North Caucasus spanning the entire Phanerozoic stage of its development. The black shale zone of the North Caucasus can be considered as a new promising province of precious metalsAu, Pt, Pd.

scholarly journals Black shale deposition during Toarcian super-greenhouse driven by sea level

2013 ◽  
Vol 9 (6) ◽  
pp. 2703-2712 ◽  
Author(s):  
M. Hermoso ◽  
F. Minoletti ◽  
P. Pellenard
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Sea Level ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Black Shale ◽  
Black Shales ◽  
Positive Trend ◽  
Sea Level Changes ◽  
Organic Carbon Burial

Abstract. One of the most elusive aspects of the Toarcian oceanic anoxic event (T-OAE) is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the end of the overarching positive trend in the carbon isotopes that characterises the T-OAE. In the present study, we have attempted to establish a sequence stratigraphic framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance) and geochemical (Si, Zr, Ti and Al) measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo), the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE (defined by the positive carbon isotope trend) due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by >10% Total Organic Carbon (TOC) content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE), likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the atmosphere–ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales during the serpentinum and bifrons Zones were restricted to epicontinental seas (higher Mo to TOC ratios) during a period of relative high sea level, and carbon isotopes returning to pre-T-OAE values. Comparing palaeoredox proxies with the inferred sequence stratigraphy for Sancerre suggests that episodes of short-term organic carbon enrichment were primarily driven by third-order sea level changes. These black shales exhibit remarkably well-expressed higher-frequency cyclicities in the oxygen availability in the water column whose nature has still to be determined through cyclostratigraphic analysis.

scholarly journals Erratum to “A Perspective on Stratigraphic, Vertically-Upward “Displacements or Dislocations” of Conodont-Elements: An Example From the Upper Devonian, Pre-Lithified, Black Shales of the Chattanooga Shale Formation In Tennessee, USA” ...

2019 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Michael Iannicelli
Keyword(s):  
Black Shale ◽  
Environmental Chemistry ◽  
Black Shales ◽  
Photic Zone ◽  
Marine Organic Matter ◽  
Chattanooga Shale ◽  
Shale Formation ◽  
Organic Matter Biomarkers ◽  
Reference Section ◽  
Made In

Even though the author already incorporated the citation of Sinninghe-Damste & Schouten (2006) into the text of the paper, the author regrets having failed to include their full citation within the Reference Section of my above paper which is: Sinninghe-Damste, J. S. & Schouton, S. (2006). Biological markers for anoxia in the photic zone of the water column. In, Volkman, J. K. (ed.), Marine Organic Matter: Biomarkers, Isotopes and DNA, (pp. 127 – 163). The Handbook of Environmental Chemistry, vol. 2N. Springer: Berlin and Heidelberg. https://doi.org/10.1007/698_2_005 The author also needs to paraphrase a statement made in the last three lines of the 2nd paragraph on page 40 where it reads as: “Thus, we may conclude here that paleo-upfreezing of any conodont-element(s) originally buried in the pre-lithified, light-colored shale occurred in order to account for their presence in black shale”. Instead, in lieu of that statement, it should read as “At this point in time of the study, we may tentatively conclude here while completely concluding later in the study, that conodont-elements originally existing in the underlying, pre-lithified, light-colored shale, had to paleo-upfreeze vertically upward into pre-lithified, black shale sediment in order to account for their presence in lithified black shale”.

scholarly journals The Cenomanian-Turonian boundary problem in NW-Germany with comments on the north-south correlation to the Regensburg Area

1984 ◽  
Vol 33 ◽  
pp. 103-113
Author(s):  
G. Ernst ◽  
C. J. Wood
Keyword(s):  
Boundary Problem ◽  
Black Shale ◽  
Black Shales ◽  
Lower Saxony ◽  
Nw Germany ◽  
Shale Formations ◽  
The North ◽  
Facies Change ◽  
Marly Limestone ◽  
Water Facies

The lithostratigraphical successions across the Cenomanian-Turonian boundary are described. Two dif­ferent facies can be distinguished: A shallow water red marly limestone facies ('Rotpliiner') characterised by evidence of condensation and stratigraphical hiati; and a more complete deeper water facies with alternating marly limestones and black shales ('Black Shales' or 'SchwarzweiBe Wechselfolge'). A se­quence of litho- and ecoevents permits subdivision and correlation of the two facies. The base of both facies is apparently isochronous and rests on white coccolith limestones, the so-called 'Arme rhotoma­gense Schichten' of the Upper Cenomanian Calycoceras naviculare Zone. The stage boundary was traditionally drawn at the facies change, but biostratigraphical evidence places the boundary within the Rotpliiner/Black Shale formations. In Lower Saxony the extinction datum of Rotalipora cushmani agrees with records from other areas, i.e. within the Upper Cenomanian Metoicoceras ges/inianum Zone below the entry of Actinocamax plenus. From the Teutoburger Wald (Miinsterland) and Regensburg area (Bavaria) an apparent di­achroneity of this datum is indicated. The uppermost Cenomanian Neocardioceras juddii Zone of the international scheme has been identified only in the Black Shale facies. The diagnostic ammonites and inocaramid (Mytiloides aff. duplicostatus) of the basal Turonian Pseudaspidoceras f/exuosum Zone have not been recorded in either facies. For practical purposes the base of the Turonian is taken at the entry of Myti/oides, as is usual in Central Erope. Below this level there is a 'zone of uncertainty' with poorly preserved inoceramids of questionable generic identity. Above the entry of recognizable Mytiloides, an interregional fades-independent Myti/oides mytiloides ecoevent is traceable across W.-Germany to east­ern England. Critical species concepts within Mytiloides are reviewed in the context of possible facies dependence. Of importance for the North-South correlation is the recognition of Mytiloides sp. at the base of the Praeglobotruncana helvetica Zone in the Regensburg area.

scholarly journals Black shale deposition during Toarcian super-greenhouse driven by sea level

2013 ◽  
Vol 9 (4) ◽  
pp. 4365-4384 ◽  
Author(s):  
M. Hermoso ◽  
F. Minoletti ◽  
P. Pellenard
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Sea Level ◽  
Sequence Stratigraphy ◽  
Carbon Isotopes ◽  
Black Shale ◽  
Black Shales ◽  
Positive Trend ◽  
Sea Level Changes ◽  
Organic Carbon Burial

Abstract. One of the most elusive aspects of the Toarcian Oceanic Anoxic Event (T-OAE) is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the T-OAE (defined by the overarching positive trend in the carbon isotopes). In the present studied, we have attempted to establish a sequence stratigraphy framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance) and geochemical (Si, Zr, Ti and Al) measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo), the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by > 10% Total Organic Carbon (TOC) content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE), likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the Atmosphere–Ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales were restricted to epicontinental seas (higher Mo to TOC ratios) during a period of relative high sea level, and carbon isotopes returning to pre-T-OAE values. Comparing palaeoredox proxies with the inferred sequence stratigraphy for Sancerre suggests that episodes of short-term organic carbon enrichment were primarily driven by third-order sea level changes. These black shales exhibit remarkably well-expressed higher-frequency cyclicities in the concentration of redox-sensitive elements such as iron or vanadium whose nature has still to be determined through cyclostratigraphic analysis.

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