Search results for "water"

Middle Triassic sharks from the Catalan Coastal ranges (NE Spain) and faunal colonization patterns during the westward transgression of Tethys

2020

Abstract Palaeogeographic changes that occurred during the Middle Triassic in the westernmost Tethyan domain were governed by a westward marine transgression of the Tethys Ocean. The transgression flooded wide areas of the eastern part of Iberia, forming new epicontinental shallow-marine environments, which were subsequently colonized by diverse faunas, including chondrichthyans. The transgression is recorded by two successive transgressive–regressive cycles: (1) middle–late Anisian and (2) late Anisian–early Carnian. Here, we describe the chondrichthyan fauna recovered from several Middle Triassic stratigraphic sections (Pelsonian-Longobardian) located at the Catalan Coastal Basin (western…

Palynofacies and calcareous nannofossils in the Upper Kimmeridgian, southeastern Paris basin (France)

2005

AbstractThe Upper Kimmeridgian Members “Calcaires blancs supérieurs” and the “Marnes à exogyres supérieures” of the southeastern Paris basin were investigated for their palynofacies and calcareous nannofossils. These members display alternating limestone-marl lithotypes and represent shallow marine palaeoenvironments. The lower carbonate member is interpreted as a proximal palaeoenvironment (palaeobathymetry = 5 to 10 m), where storm and swell deposits were prevalent and the salinity was occasionally weak. The relative richness of brown phytoclasts in this part is favoured by good preservation related to restricted conditions. These conditions would explain the dominance of the nannofoss…

First report of Gogia (Eocrinoidea, Echinodermata) from the Early-Middle Cambrian of Sonora (Mexico), with biostratigraphical and palaeoecological co…

2009

10 pages; International audience; The blastozoan echinoderm genus Gogia is reported for the first time in the Early and the Middle Cambrian of Mexico. Reports in different members of the section of San José de Gracia (Sonora State, northwestern Mexico) extend the palaeogeographical range of the genus to the South Laurentia, and the stratigraphic range of Gogia granulosa to the whole first half of middle Middle Cambrian. Isolated plates occur in rocks deposited in detrital inner platform and complete specimens, in carbonate outer platform, confirming their ability to live in diverse environments. Their presence in these different environments through the Early-Middle Cambrian on Laurentia ag…

Pseudoskirroceras, a remarkable but poorly known Early Pliensbachian Tethyan ammonite genus: New data from the High Atlas (Morocco).

2007

13 pages; International audience; The discovery of new Early Pliensbachian ammonite faunas in Central High Atlas (Morocco) allows the re-examination of the taxonomic, stratigraphical and palaeogeographical framework of the genus Pseudoskirroceras, an intriguing but until now poorly known Tethyan taxon. For the first time, several specimens of Pseudoskirroceras mastodon (Fucini, 1935) the type species of the genus, have been collected in a well-known stratigraphical context. This material allows the evaluation of intra-specific variability and consequently the assessment of the taxonomical relevance of various geometrical and ornamental features. The best diagnostic features are the clearly …

Vegetation dynamics of Kisima Ngeda freshwater spring reflect hydrological changes in northern Tanzania over the past 1200 years: implications for pa…

2021

13 pages; International audience; Kisima Ngeda (KN), a spring on the northern margin of saline Lake Eyasi, Tanzania, sustains an Acacia-Hyphaene palm woodland and Typha swamps, while the surrounding vegetation is semi-desert. To study the vegetation changes associated with this spring, which represents a plausible modern analog for the fossil springs documented in the nearby paleoanthropological and archaeological sites of Olduvai Gorge, we analyzed the pollen content of a 43 cm-long sediment core that documents vegetation changes since the last ~1200 years (from cal yrs. C.E. 841 to 2011). Our results show that (1) Hyphaene palms, which require meso-halophytic soil conditions were most abu…

COMMENT TO LEHRMANN ET AL. NEW SECTIONS AND OBSERVATIONS FROM THE NANPANJIANG BASIN, SOUTH CHINA

2016

In the study of Earth-surface environmental processes during the events associated with the Permian–Triassic boundary, a key issue is the nature of the latest Permian pre-extinction surface in shallow marine limestones in numerous sites, principally within the Tethyan realm. Sediments below this surface pre-date the extinction event, so that the limestones comprising these latest Permian facies contain diverse fossil remains of organisms that lived just before the extinction. At all reported sites, this surface is disconformably overlain by post-extinction sediments, which contain microbialites in many places, particularly in Tethys. The nature of the youngest pre-extinction surface remains…

Using growth and geochemical composition of Clathromorphum compactum to track multiscale North Atlantic hydro-climate variability

2020

International audience; Records of ocean/atmosphere dynamics over the past centuries are essential to understand processes driving climate variability. This is particularly true for the Northwest Atlantic which is a key region with an essential role in global climate regulation. Over the past two decades, coralline red algae have been increasingly used as environmental and climatic archives for the marine realm and hold the potential to extend long-term instrumental measurements. Here, we investigate the possibility to extract climate and environmental information from annual growth patterns and geochemical composition of the coralline red algae, Clathromorphum compactum, from Saint-Pierre …

2020

Skeletal remains in archaeological strata are often assumed to be of similar ages. Here we show that combined Sr and O isotope analyses can serve as a powerful tool for assessing fish provenance and even for identifying fossil fish teeth in archaeological contexts. For this purpose, we established a reference Sr and O isotope dataset of extant fish teeth from major water bodies in the Southern Levant. Fossil shark teeth were identified within Iron Age cultural layers dating to 8–9th century BCE in the City of David, Jerusalem, although the reason for their presence remains unclear. Their enameloid 87Sr/86Sr and δ18OPO4 values [0.7075 ± 0.0001 (1 SD, n = 7) and 19.6 ± 0.9‰ (1 SD, n = 6), res…

Ammonite paleobiogeography during the Pliensbachian-Toarcian crisis (Early Jurassic) reflecting paleoclimate, eustasy, and extinctions.

2011

14 pages; International audience; The Pliensbachian-Toarcian crisis (Early Jurassic) is one of the major Mesozoic paleoecological disturbances when ca. 20% of marine and continental families went extinct. Contemporaneously, profound paleobiogeographical changes occurred in most oceanic domains including a disruption of ammonite provincialism during the Early Toarcian. Here, we quantitatively reappraise the structure and evolution of paleobiogeographical patterns displayed by ammonite faunas before, during, and after the biological crisis, over a time-interval including 13 biochronozones. The high-resolution study presented here involves the use of hierarchical Cluster Analyses, non-metric M…

Depositional environments and iron ooid formation in condensed sections (Callovian Oxfordian, South-eastern part of the Paris basin, France)

2005

Carbonate platforms across Western Europe were superseded at the Middle–Upper Jurassic (Callovian–Oxfordian) boundary either by alternating marl–limestone and widespread marl deposits or by condensed sections containing iron ooids. The characteristics of marine condensed sections in the south-eastern part of the Paris Basin (France) and their distribution pattern are examined here, and a model of iron ooid formation is developed. Iron ooids are found from the shoreface to the offshore zone. They are most abundant in the median-to-distal offshore transition zone, where they originally formed. They also occur commonly, albeit often as reworked grains, in the proximal offshore zone, to which t…