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Document Type:Latin Dissertation
Language of Document:English
Record Number:55594
Doc. No:TL25548
Call number:‭3237348‬
Main Entry:Jessica Hope Whiteside
Title & Author:Catastrophic, climatic, and biotic modulation of ecosystem evolutionJessica Hope Whiteside
College:Columbia University
Date:2006
Degree:Ph.D.
student score:2006
Page No:316
Abstract:I examine links between catastrophic events, climate variability, and biotic modulation on evolution at the ecosystem-level of orbitally-paced Early Mesozoic Pangean great lakes. One of the largest controls on the diversity of taxa within ecosystems is mass extinction. High-resolution bulk organic, wood, and compound-specific (n-alkane) carbon isotopic data from North American rift sequences demonstrate the timing and duration of carbon cycle disruptions at the Triassic-Jurassic mass-extinction relative to Earth's most extensive flood basalt event, the Central Atlantic magmatic province (CAMP). N-alkane data allow correlation with marine strata: a transient 100-360 ky pre-magmatic shift begins at the extinction interval and a post-magmatic shift lasts more than 1.6 m.y. challenging models of physical maintenance and relation to CAMP eruptions, and suggesting catastrophically-triggered functional reorganization of the biosphere that plays out over evolutionary time. Timing of carbon cycle disruption provides a direct test of recent claims of CAMP synchrony with the palynological turnover events for Moroccan sections. Newly discovered zones of reverse polarity within CAMP flow sequences of Morocco have been hypothesized (Marzoli et al., 2004; Knight et al., 2004) as correlates of the uppermost Triassic reverse chron in the Newark basin, thus suggesting that much of the Moroccan CAMP was synchronous with or predates the Triassic-Jurassic boundary. Here, however, we explain these reverse polarity zones as correlatives of poorly sampled basalt flow sequences and overlying strata in eastern North America and reverse polarity sequences recognized in the Paris basin (Yang et al. 1996). Revised Milankovitch cyclostratigraphy constrains the duration of eastern North America basaltic flows to ∼610 ky after the palynologically identified Triassic-Jurassic boundary. Palynological data indicate correlation of the initial carbon isotopic excursion (Hesselbo et al., 2001) at St. Audrie's Bay to the palynological and vertebrate extinction level in eastern North America, suggesting a revised magnetostratigraphic correlation and robust tests of the Marzoli-Knight hypothesis. We conclude that as yet there are no compelling data showing that any of the CAMP predated or was synchronous with the Triassic-Jurassic extinction event. Cyclicity is a general feature of lacustrine strata because lake level is sensitive to climate change. The structure of ecosystems is thought to be an evolution of complex interactions through a continuum of environments and lineages. The extent to which the specific history of a lake is shared is unknown. (Abstract shortened by UMI.)
Subject:Earth sciences; Biotic; Catastrophic; Climatic; Ecosystem; Paleontology; Biogeochemistry; 0425:Biogeochemistry; 0418:Paleontology
Added Entry:P. Olsen
Added Entry:Columbia University