Effects of Bioturbation through the Late Eocene Impactoclastic Layer near Massignano, Italy
نویسندگان
چکیده
Effects of bioturbation through the Late 'Institute of Geochemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria, Eocene impactoclastic layer near (*christian,koeberl@univie,ac,at) 'Department of Geology, Auburn University, Auburn, AL 36849-5305, USA, Masignano, Italy. 'Osservatorio Geologico di Coldigioco, 1-62020 Frontale di Apiro (MC), Italy, r In: Geological and Biological Effects of Impact Events (ed. E. Buffetaut and C. Abstract. The purpose of this study was to investigate the variations in trace element composition resulting from bioturbation of a Late Eocene impactoclastic layer at Massignano, Italy, This layer has an age of 35.7 ± 0.4 Ma and is, Koeberl), "Impact Studies" Series, Springer Verlag, Heidelberg-Berlin, p. 197-216. therefore, coeval with both the North American tektite event (related to the Chesapeake Bay impact structure, USA) and the Popigai impact event (Siberia, Russia). The layer shows a distinct iridium anomaly of up to about 270 ppt. The i ~, stratigraphic leakage within Planolites and Zoophycos burrows was studied by using iridium coincidence spectrometry and conventional neutron activation analysis, on samples obtained by a micro drilling procedure. The iridium contents of the burrow fillings vary from 50 ppt about 20 cm below the impactoclastic layer
منابع مشابه
Late Eocene microkrystites and microtektites at Maud Rise (Ocean Drilling Project Hole 689B; Southern Ocean) suggest a global extension of the approximately 35.5 Ma Pacific impact ejecta strewn field
Late Eocene microtektites and microkrystites recovered from Ocean Drilling Project Hole 689B at Maud Rise (Southern Ocean) are stratigraphically and geochemically compared to spherules from the North American and Pacific strewn fields, and to devitrified spherules fiom the Eocene-Oligocene global stratotype section and point section in Massignano, Italy. The ODP 689B microkrystites compare well...
متن کاملEvidence for a second L chondrite impact in the Late Eocene: Preliminary results from the Wanapitei crater, Canada
Introduction: The Wanapitei impact structure (46°45 ́N; 80°45 ́W) is located 40 km NE of the city of Sudbury, Ontario, Canada. The 7 to 8 km in diameter crater is not exposed and lies completely within Lake Wanapitei [1]. The Wanapitei impact melt rocks contains about 1% of an extraterrestrial component and, based on Ni/Ir, Ni/Cr and Co/Cr ratios an L or LL chondrite projectile is advocated [2, 3...
متن کاملInteracting effects of Hydrobia ulvae bioturbation and microphytobenthos on the erodibility of mudflat sediments
Microphytobenthos-macrofauna sediment interactions and their effects on sediment erodability were examined in laboratory experiments. Sediment beds were manipulated in a tidal mesocosm to produce diatom mats in exponential or in stationary phases of development after 6, 8 or 11 d of culture. These sediment beds were used in flume experiments to investigate the influence of bioturbation by the g...
متن کاملRe-evaluating the Origin of an Upper Eocene Diamictite in the Coastal Plain of East-central Georgia: an Impactoclastic Layer?
Introduction: An Upper Eocene diamictite, unique in the Coastal Plain stratigraphy of east-central Georgia, has been described as an altered volcaniclastic deposit [1-4] resulting from widespread ashfall or pyroclastic flows [1,2]. While the breccia bed does appear strikingly similar to weathered silicic tuffs (Figure 1), previous authors have never speculated where the Late Eocene volcanic sou...
متن کاملSowing time and irrigation scheduling effects on seed yield and fatty acids profile of sunflower in semi-arid climate
A research was conducted in Southern Italy to study the changes in seed yield, oil content andfatty acids composition, in response to irrigation at different stages of growing season (at sowing,Dry; from sowing to beginning of flowering, S-BF; from visible bud to 75% flowering, VB-FF;from beginning of flowering to seed ripening, BF-M; from sowing to seed ripening, Full), in astandard sunflower ...
متن کامل