Late Triassic Hexactinellid Sponges from the Pongo De Lorocache Limestones, Peru: New Evidence for Siliceous Sponge Dominance on Shallow Carbonate Platforms

Ameghiniana ◽  
2018 ◽  
Vol 55 (2) ◽  
pp. 215-222
Author(s):  
César Chacaltana ◽  
Marcelo G. Carrera
2015 ◽  
Vol 153 (2) ◽  
pp. 271-284 ◽  
Author(s):  
A. RUFFELL ◽  
M. J. SIMMS ◽  
P. B. WIGNALL

AbstractFrom 1989 to 1994 a series of papers outlined evidence for a brief episode of climate change from arid to humid, and then back to arid, during the Carnian Stage of the late Triassic Epoch. This time of climate change was compared to marine and terrestrial biotic changes, mainly extinction and then radiation of flora and fauna. Subsequently termed, albeit incorrectly, the Carnian Pluvial Event (CPE) by successive authors, interest in this episode of climatic change has increased steadily, with new evidence being published as well as several challenges to the theory. The exact nature of this humid episode, whether reflecting widespread precipitation or more local effects, as well as its ultimate cause, remains equivocal. Bed-by-bed sampling of the Carnian in the Southern Alps (Dolomites) shows the episode began with a negative carbon isotope excursion that lasted for only part of one ammonoid zone (A. austriacum). However, that the Carnian Humid Episode represents a significantly longer period, both environmentally and biotically, is irrefutable. The evidence is strongest in the European, Middle Eastern, Himalayan, North American and Japanese successions, but not always so clear in South America, Antarctica and Australia. The eruption of the Wrangellia Large Igneous Province and global warming (causing increased evaporation in the Tethyan and Panthalassic oceans) are suggested as causes for the humid episode.


1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.


2007 ◽  
Vol 40 (9) ◽  
pp. 36
Author(s):  
BRUCE JANCIN
Keyword(s):  

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