The Palynological Response to the Toarcian Oceanic Anoxic Event (Early Jurassic) at Peniche, Lusitanian Basin, Western Portugal PDF Download
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Author: V.F. Correia
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: V.F. Correia
Publisher:
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Category :
Languages : en
Pages : 0
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Author: M. Reolid
Publisher: Geological Society of London
ISBN: 1786205467
Category : Science
Languages : en
Pages : 418
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Book Description
The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred during the early Toarcian (c. 183 Ma; Early Jurassic) and resulted in numerous collateral effects including global warming, enhanced weathering, sea-level change, carbonate crisis, marine anoxia–dysoxia, and a second-order mass extinction. This volume presents the last advances for understanding early Toarcian environmental changes through different disciplines: biostratigraphy, micropalaeontology, palaeontology, ichnology, palaeoecology, sedimentology, integrated stratigraphy, inorganic, organic and isotopic geochemistry, and cyclostratigraphy. The study of this abrupt climate change is critical for predicting future global changes, and for understanding the complex biogeochemical interactions through time between geosphere, atmosphere, hydrosphere and biosphere.
Author: Matías Reolid
Publisher: Springer
ISBN: 3319672118
Category : Science
Languages : en
Pages : 127
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This book presents the first overview of the Toarcian Oceanic Anoxic Event in the southern Iberian paleomargin, in the western Tethys. The study of catastrophic events that affected the ecosystems in the past is of great interest, because it offers the possibility of establishing models that can be applied to current and future environmental changes. The book provides comprehensive information on the changes in marine ecosystems in connection with a global massive extinction, the Early Toarcian, and with the deposition of black shales, global warming and a disruption of the carbon cycle. In addition, the book describes the incidence of this event in this part of the Tethys close to the connection with the Protoatlantic, the Hispanic Corridor. Special attention is paid to sedimentological and ichnological aspects, fossil content (macroscopic and microscopic), and geochemistry. It also presents the facies changes related to fragmentation of the shelf and the evolution to hemipel agic troughs and swells in this paleomargin. Lastly, it characterizes this anoxic event in under-researched outcrops from southern Spain and compares the findings with those in well-known sections from northern and central Europe. This book offers a unique resource for all researchers interested in the Toarcian Oceanic Anoxic Event, but also in oceanic anoxic events that occurred during the Mesozoic in general, because of their similarity to recent climatic changes.
Author: Jorge Ferreira
Publisher:
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Category :
Languages : en
Pages : 0
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At ~183 Ma when large amounts of organic matter was dumped onto the ocean beds (known as the Toarcian Oceanic Anoxic Event, T-OAE), the Early Toarcian marine biota experienced one of the most important biological crises in Earth history. Calcareous nannoplankton was deeply affected and started only to recover from the end of the Early Toarcian. After the T-OAE, as phytoplankton communities dwelling the oceans photic layer recover from the previous disturbing conditions, the ecological niches once occupied by calcareous nannoplankton are again replenished. Located in the westernmost part of the Tethyan ocean, the Lusitanian Basin acted as a seaway between the NW Tethys and the Mediterranean Tethys provinces, therefore been actively influenced by these two different water masses. Hence such a region stands as the perfect spot to study the calcareous nannoplankton community, as its fossil remains bears species typical of both provinces. In order to appraise the nannoplankton demise and subsequent recovery, absolute and relative abundances of nannofossils were determined from pelagic marl-limestone couplets from three sections of the Lusitanian Basin. Also brachiopods shells were investigated for stable carbon and oxygen isotopes analysis. In order to independently assess the morphologic evolution of Lotharingius coccoliths, a Toarcian section from south France was studied. Different statistic methodologies were used throughout this work, in order to screen for robust and significant information from the numerous datasets that were built.
Author: Veronica Piazza
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Alexandra Kunert
Publisher:
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Category :
Languages : en
Pages :
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The Toarcian Oceanic Anoxic Event (T-OAE) of the Early Jurassic is one of several Mesozoic instances of expanded ocean anoxia, coupled with feedbacks and perturbations in Earth's systems. The drivers for these feedbacks are debated, but the general consensus is that the event is initially rooted in the emplacement of the Karoo-Ferrar large igneous province. The T-OAE is also linked to a second-order mass extinction in the marine and terrestrial realms. Study of the T-OAE aims to provide insight into the causes and consequences of the environmental changes, which may be applicable at present given that some of the characteristics of the T-OAE (e.g. carbon inputs leading to global warming) are reflected in the modern environment. The purpose of this study, which focused on an Early Jurassic section containing the T-OAE in northeastern British Columbia, was to provide extensive insight into the local depositional environment, as well as a glimpse at the global ocean paleoredox conditions across the duration of the event. In northeastern British Columbia, the Early Jurassic is divided into the Gordondale Member and Poker Chip Shale of the lower Fernie Formation. The studied drill core contains both members; the Gordondale is the basal member composed of organic-rich, calcareous mudstone, whereas the overlying Poker Chip shale is a siliceous mudstone to siltstone unit. To provide context for the T-OAE in the study core, organic carbon isotope compositions were profiled in search of a telltale negative carbon isotope excursion (N-CIE) which signals the event zenith. The event was identified by an N-CIE in the uppermost 7 meters of the Gordondale Member below the contact with the Poker Chip Shale. Local paleoenvironmental reconstruction was accomplished using elemental redox sensitive trace metal geochemistry to determine the redox regimes (oxic, suboxic, anoxic or euxinic) and hydrography (open versus restricted) of the depositional basin. The Gordondale Member was characterised as anoxic to euxinic. Elevated Mo and V (up to 370 μg/g and 2757 μg/g, respectively) suggested some intervals were deposited in an euxinic environment. The U and Re concentrations are also elevated in the euxinic intervals (up to 36 μg/g and 878 ng/g, respectively). Intervals with lower Mo and V concentrations ( 53 μg/g and 289 μg/g, respectively) but elevated U and Re content (up to 33 μg/g and 287 ng/g, respectively) indicated anoxic (non-sulfidic) conditions. The Poker Chip Shale was characterised by suboxic conditions (moderate Mo, V, U, and Re concentrations; 21 μg/g, 248 μg/g,
Author: Alice Eileen Kennedy
Publisher:
ISBN:
Category : Anoxic zones
Languages : en
Pages : 308
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Author: Vanessa Phan
Publisher:
ISBN:
Category :
Languages : en
Pages : 69
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Author: Alexander Hudson
Publisher:
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Category :
Languages : en
Pages : 57
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Author: Gerta Keller
Publisher: Geological Society of America
ISBN: 0813725054
Category : Science
Languages : en
Pages : 468
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Book Description
"Comprises articles stemming from the March 2013 international conference at London's Natural History Museum. Researchers across geological, geophysical, and biological disciplines present key results from research concerning the causes of mass extinction events"--
