Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 9 of 9 for “"Toarcian"”.
-
Microfaunal investigation of the Early Toarcian (Lower Jurassic) extinction event in N.W. Europe
… Sea-level rise across the Pliensbachian - Toarcian boundary culminated in the falciferum Zone of the Toarcian and is one of the best authenticated eustatic events in the Jurassic. This major transgressive pulse was marked by deepw ater marine sequencesa nd was associatedw ith the deposition …
-
Palaeoenvironmental change from the Hettangian to Toarcian in Moyeni (Quthing District), southwestern Lesotho
… ripple marks. These suggest that by the Toarcian the land surface was again covered by temporary lakes and streams into which the lavas outpoured during the early stages of the Karoo volcanism. The study area is structurally deformed by ~ESE-WNW trending normal faults, some of which …
-
Towards an understanding of the carbon isotopic changes across the Toarcian oceanic anoxic event
… tenuicostatum and lower falciferum zones of the Toarcian (early Jurassic, 183 Ma) ocean anoxic event (OAE). In this study, we reveal that apparent negative isotopic excursions in bulk organic and carbonate carbon were the result of compositional changes of organic matter and diagenesis, …
-
Biogeochemical Cycling and Paleoenvironmental Reconstructions of the Toarcian Oceanic Anoxic Event from Western North America
The Toarcian Oceanic Anoxic Event (T-OAE; ~183 million years ago) represents an interval during the Mesozoic when the emplacement of the Karoo-Ferrar Large Igneous Province (LIP) is thought to have resulted in significant environmental change. Associated with this interval was the widespread …
-
The impact of global environmental changes on exceptional preservation, extinction, and recovery in the early Jurassic (late Pliensbachian-Toarcian)
… Of particular importance are the Pliensbachian/Toarcian boundary event (~184.2 million years ago) and the Toarcian Oceanic Anoxic Event (TOAE, ~183 million years ago); these events represent two of the most severe environmental perturbations of the Early Jurassic Epoch, leading to marine …
-
Evaluating redox cycling across the Toarcian Oceanic Anoxic Event with implications for paleo-environmental reconstructions and organic matter sulfurization
… environmental change during the Early Jurassic Toarcian Oceanic Anoxic Event or T-OAE (~183 Ma). The first chapter of this dissertation investigates the record of marine anoxia across the Pliensbachian to Toarcian transition. Specifically, I investigate the temporal and geographic development of …
-
Triassic-Jurassic biochronology of the eastern Iskut River map area, northwestern British Columbia
… (Kunae and Carlottense Zones), Lower Toarcian (Assemblage Zones 2-3 of Jakobs), Upper Toarcian (Assemblage Zone 6 of Jakobs), Aalenian (Erycitoides howelli assemblage zone), Lower Bajocian, Upper Bathonian, and Lower Callovian. In the eastern Iskut River map area: i) the Stuhini Group …
-
The middle Jurassic of New Zealand : a study of the lithostratigraphy and biostratigraphy of the Ururoan, Temaikan and Lower Heterian Stages (?Pliensbachian to ?Kimmeridgian)
… Ururoan is equivalent to the ?Sinemurian to Late Toarcian, Temaikan to the ?latest Toarcian to Early Callovian and the Early Heterian to the Middle Callovian to latest Middle to Late Oxfordian. Early Ururoan is correlated with the ?Sinemurian to Pliensbachian based on the presence of the ammonite …
-
The evolution and palaeobiogeography of mesozoic planktonic foraminifera
… that the first planktonic taxa appeared in the Toarcian. This origination in the centre of Western Tethys was followed by a rapid expansion of planktonic foraminifera throughout Peri-Tethys. This expansion is dominated by the genera Conoglobigerina and Globuligerina and while some believe that …