scholarly journals A multi-proxy record of the Latest Danian Event at Gebel Qreiya, Eastern Desert, Egypt

2011 ◽  
Vol 30 (2) ◽  
pp. 167-182 ◽  
Author(s):  
J. Sprong ◽  
M. A. Youssef ◽  
A. Bornemann ◽  
P. Schulte ◽  
E. Steurbaut ◽  
...  
Keyword(s):  
Sea Level ◽  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Eastern Desert ◽  
Trace Element Geochemistry ◽  
Calcareous Nannofossils ◽  
Element Geochemistry ◽  
Sea Level Fluctuations ◽  
Sequence Of Events ◽  
Carbon Isotope Excursion

Abstract. The Latest Danian Event (LDE) is a proposed early Palaeogene transient warming event similar to the Paleocene–Eocene Thermal Maximum, albeit of smaller magnitude. The LDE can be correlated with a carbon isotope excursion (‘CIE-DS1’) at Zumaia, Spain, and the ‘top Chron C27n event’ defined recently from ocean drilling sites in the Atlantic and Pacific, supporting a global extent. Yet, records of environmental change during the LDE (e.g. warming and sea-level fluctuations) are still rare. In this study, we focus on the micropalaeontology (calcareous nannofossils and benthic foraminifera), mineralogy and trace element geochemistry of the LDE in the Qreiya 3 section from the southern Tethyan margin in Egypt. In this section, the LDE is characterized by the occurrence of anomalous beds intercalated within upper Danian shales and marls. The event beds of the LDE are situated above an unconformity on top of a shallowing-upwards sequence deposited in a well-oxygenated outer neritic to upper bathyal marine palaeoenvironment. The lower LDE bed is barren of benthic foraminifera, but contains pyrite and fish remains, and is interpreted as an anoxic level formed during rapid relative sea-level rise. Incursion of a Neoeponides duwi (Nakkady, 1950) benthic assemblage in LDE bed II is interpreted as repopulation of the seafloor after anoxia. The sea-level cycle associated with the LDE is estimated at about 50 m maximum in the Qreiya 3 section. The environmental changes at Qreiya 3 are of supra-regional extent, since a similar sequence of events has been observed at other southern Tethyan locations.

Stratigraphic and sedimentological aspects of the worldwide distribution of Apectodinium in Paleocene/Eocene Thermal Maximum deposits

2021 ◽  
pp. SP511-2020-46
Author(s):  
Christopher N. Denison
Keyword(s):  
Global Warming ◽  
Sea Level ◽  
Environmental Changes ◽  
Calcareous Nannofossil ◽  
Shallow Marine ◽  
Worldwide Distribution ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Taxonomic Changes ◽  
Data Gap

AbstractThe Paleocene/Eocene Thermal Maximum (PETM) is characterized by pronounced global warming and associated environmental changes. In the more-or-less two decades since prior regional syntheses of Apectodinium distribution at the PETM, extensive biological and geochemical datasets have elucidated the effect of rising world temperatures on climate and the biome. A Carbon Isotope Excursion (CIE) that marks the Paleocene/Eocene Boundary (PEB) is associated with an acme of marine dinocysts of the genus Apectodinium in many locations. Distinctive foraminiferal and calcareous nannofossil populations may also be present.For this up-dated, dinocyst-oriented view of the PETM, data from worldwide locations have been evaluated with an emphasis on stratigraphic and sedimentological context. What has emerged is that a change in lithology is common, often to a distinctive siltstone or claystone unit, which contrasts with underlying and overlying lithotypes. This change, present in shallow marine/coastal settings and in deepwater turbidite deposits, is attributed to radical modifications of precipitation and erosional processes. An abrupt boundary carries the implication that some time (of unknowable duration) is potentially missing, which then requires caution in the interpretation of the pacing of events in relation to that boundary. In most instances an ‘abrupt’ or ‘rapid’ CIE onset can be attributed to a data gap at a hiatus, particularly in shallow shelf settings where transgression resulted from sea-level rise associated with the PETM. Truly gradational lower boundaries of the PETM interval are quite unusual, and if present, are poorly known so far. Gradational upper boundaries are more common, but erosional upper boundaries have been reported.Taxonomic changes have been made to clarify identification issues that have adversely impacted some biostratigraphic interpretations. Apectodinium hyperacanthum has been retained in Wetzeliella, its original genus. The majority of specimens previously assigned to Apectodinium hyperacanthum or Wetzeliella (Apectodinium) hyperacanthum have been re-assigned to an informal species, Apectodinium sp. 1. Dracodinium astra has been retained in its original genus as Wetzeliella astra, and is emended.

A high-resolution, multiproxy stratigraphic analysis of the Devonian–Carboniferous boundary sections in the Moravian Karst (Czech Republic) and a correlation with the Carnic Alps (Austria)

2013 ◽  
Vol 151 (2) ◽  
pp. 201-215 ◽  
Author(s):  
TOMÁŠ KUMPAN ◽  
ONDŘEJ BÁBEK ◽  
JIŘÍ KALVODA ◽  
JIŘÍ FRÝDA ◽  
TOMÁŠ MATYS GRYGAR
Keyword(s):  
Czech Republic ◽  
Gamma Ray ◽  
Sensu Stricto ◽  
Black Shales ◽  
Element Geochemistry ◽  
Carnic Alps ◽  
Sea Level Fluctuations ◽  
Stratigraphic Analysis ◽  
Carbon Isotope Excursion ◽  
Moravian Karst

AbstractA multidisciplinary correlation of the Devonian–Carboniferous (D–C) boundary sections from the Moravian Karst (Czech Republic) and the Carnic Alps (Austria), based on conodont and foraminifer biostratigraphy, microfacies analysis, field gamma-ray spectroscopy (GRS), carbon isotopes and element geochemistry, is presented in this paper. The study is focused on the interval from the MiddlePalmatolepis gracilis expansaZone (Late Famennian) to theSiphonodella sandbergiZone (Early Tournaisian). In Lesní lom (Moravian Karst), a positive δ13C excursion in theBisphatodus costatus–Protognathodus kockeliInterregnum from a distinct laminated carbonate horizon is correlated with a carbon isotope excursion from the Grüne Schneid section of the Carnic Alps and is interpreted as the equivalent of the Hangenberg black shales and a local expression of the global Hangenberg Eventsensu stricto. Higher up at both sections, a significant increase in the terrigenous input, which is inferred from the GRS signal and elevated concentrations of terrigenous elements (Si, Ti, Zr, Rb, Al, etc.), provides another correlation tieline and is interpreted as the equivalent of the Hangenberg sandstone. Both horizons are discussed in terms of relative sea-level fluctuations and palaeoceanographic changes. Recent studies show that conodont biostratigraphy is facing serious problems associated with the taxonomy of the first siphonodellids, their dependence on facies and discontinuous occurrences of protognathodids at the D–C boundary. Therefore, the correlative potential of geochemical and petrophysical signatures is high and offers an alternative for the refining of the problematic biostratigraphic division of the D–C boundary.

scholarly journals U–Pb geochronology, REE and trace element geochemistry of zircon from El Fereyid monzogranite, south Eastern Desert, Egypt

2021 ◽  
Vol 116 (4) ◽  
pp. 220-233
Author(s):  
Sergey G. SKUBLOV ◽  
Ahmed E. ABDEL GAWAD ◽  
Ekaterina V. LEVASHOVA ◽  
Mohamed M. GHONEIM
Keyword(s):  
Trace Element ◽  
Eastern Desert ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
South Eastern

Toarcian Ocean Anoxic Event (TOAE) recording in shallow environment : example from Central Atlas, Morocco

2020 ◽  
Author(s):  
Arnaud Ruchat ◽  
Thierry Adatte ◽  
Jorge Spangenberg
Keyword(s):  
Environmental Changes ◽  
Clay Mineralogy ◽  
Black Shales ◽  
Bulk Rock ◽  
Sea Level Fluctuations ◽  
Carbon Isotope Excursion ◽  
Sediment Records ◽  
Anoxic Event ◽  
Gondwana Margin ◽  
Dinosaur Tracks

<p>The Toarcian Ocean Anoxic Event (TOAE) took place in the early Jurassic (­ ∼183 My) and is characterised by the widespread deposition of organic matter-rich black shales in deep basins, and by a negative carbon isotope excursion reflecting profound environmental changes. This event is well documented in the sedimentary record of deeper marine settings, in which the TOAE is marked by the presence of organic-rich shales. However, the recording of the TOAE in shallower environments is less common, due to incomplete sediment records, to sea-level fluctuations and the lack of good biostratigraphy markers.</p><p>Here we present data gathered from a new extremely shallow section in Morocco (Dadès Gorges, Central Atlas), which was located along the northern Gondwana margin. This section consists of alternating dolomitic limestones and paleosols, associated with the presence of several dinosaur tracks and other sedimentary features such as stromatolites, ripple marks, mud cracks and fossil roots. This section shows a significant increase in mercury (Hg) located just below a negative excursion in <sup>13</sup>C <sub>carbonate</sub> isotopes (-3 ) that we attributed to the TOAE NCIE, which coincides with several cyclical episodes of emersion. Bulk rock and clay mineralogy indicate an increase in weathering intensity in the upper part of the section marked by higher phyllosilicates quartz and kaolinite contents.</p><p>The upper part of the section shows a gradual decrease in the number of carbonate banks coinciding with an increase of clay-rich intervals. The carbonate banks interbedded with the clay levels are almost entirely composed of an accumulation of stromatolites reflecting even more extreme conditions, which coincide with the TOA-NCIE.</p><p>These results confirm the presence of the TOAE-NCIE even in the most shallow environments of the Tethys. The observed Hg anomalies have been globally recorded and are probably linked with the volcanic activity from the Karoo Ferrar province. This marker combined with stable isotopes is therefore a very promising correlative tool.</p>

scholarly journals Carbon isotope (δ13Ccarb) and facies variability at the Wenlock–Ludlow boundary (Silurian) of the Midland Platform, UK

2016 ◽  
Vol 53 (7) ◽  
pp. 725-730 ◽  
Author(s):  
John A. Blain ◽  
David C. Ray ◽  
James R. Wheeley
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Carbonate Platform ◽  
Temporal Variations ◽  
Spatial Variations ◽  
Sea Level Fluctuations ◽  
Depositional Settings ◽  
Carbon Isotope Excursion

The Wenlock–Ludlow series boundary (Silurian) has been recognized as a time of pronounced sea-level rise and the end of a globally recognized Late Homerian Stage (Mulde) positive carbon isotope excursion (CIE). However, the precise timing and synchronicity of the end of the excursion with respect to the Wenlock–Ludlow boundary is debated. Within the type Wenlock and Ludlow areas (UK), high-resolution δ13Ccarb isotope data are presented across the Wenlock–Ludlow boundary, and within a range of carbonate platform settings. Correlation between sections and depositional settings has been based upon the characteristics of high-order sea-level fluctuations (parasequences). Comparisons between parasequence-bounded δ13Ccarb values reveal clear spatial variations, with lighter values recorded from more distal settings and heavier values from shallower settings. Temporal variations in the δ13Ccarb values are also documented and appear to reflect local variations in carbonate provenance and productivity in response to sea-level rise. While δ13Ccarb values converge in all sections towards the Wenlock–Ludlow boundary, the apparent end of the Mulde CIE appears diachronous and is progressively older within more distal settings.

Insolation-paced sea level during the Early Pleistocene, Taiwan

2021 ◽  
Author(s):  
Romain Vaucher ◽  
Shahin E. Dashtgard ◽  
Chorng-Shern Horng ◽  
Christian Zeeden ◽  
Antoine Dillinger ◽  
...  
Keyword(s):  
Sea Level ◽  
Benthic Foraminifera ◽  
Sediment Accumulation ◽  
Sediment Flux ◽  
Early Pleistocene ◽  
Glacial Cycles ◽  
Shallow Marine ◽  
Sea Level Fluctuations ◽  
Summer Insolation ◽  
O Isotope

<p>The Pleistocene was a phase of global cooling of the Earth through which glacial-interglacial cycles occurred, and the growth and decay of the ice-sheets resulted in quasi-cyclic sea-level fluctuations driven by orbital forcing. Despite that summer insolation is mostly controlled by precession, the records of the glacial cycles showcase a significant periodicity of ~41 kyrs during the Early Pleistocene forced by Earth’s obliquity (tilt) that varies the latitudinal distribution of insolation especially in high latitudes. The dominance of obliquity over precession in marine archives is commonly attributed to the in-phase effect of obliquity-related insolation versus the opposite-phased influence of precession, which may cancel out the summer insolation signal received by the southern and northern hemispheres.</p><p>Here, we present a clastic shallow marine record from the Cholan Formation (Early Pleistocene; Taiwan). Facies analysis indicates that quasi-cyclic deposition occurred in shoreface to offshore environments in the paleo-Taiwan Strait. The magnetobiostratigraphic framework indicates that the studied section occurs in the lower part of the Matuyama subchron (1.925 - 2.595 Ma) close to the lower limit of the Olduvai (1.925 Ma) normal polarity subchron. Comparison of the stratigraphy to a d<sup>18</sup>O isotope record of benthic foraminifera and orbital curves of precession and obliquity at the time of sediment accumulation reveals a good correlation between depositional cycles and the Northern Hemisphere summer insolation, demonstrating precession dominated sea-level fluctuations during the Early Pleistocene. These results underpin recent findings suggesting that d<sup>18</sup>O isotope records of benthic foraminifera have a more significant precession signal than previously described. This study also demonstrates that shallow-marine stratigraphic successions in high-accommodation and high-sedimentation basins can be outstanding climate archives, possibly even preserving sediment flux responding to half-precession cycles.</p>

Optimum microfossil sequences and cyclic sediment patterns in Early Cretaceous pelagic strata

1993 ◽  
Vol 30 (2) ◽  
pp. 391-411 ◽  
Author(s):  
Felix M. Gradstein ◽  
Zehui Huang ◽  
Inger L. Kristiansen ◽  
James G. Ogg
Keyword(s):  
Spectral Analysis ◽  
Atlantic Ocean ◽  
Sea Level ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Planktonic Foraminifera ◽  
Power Spectra ◽  
Calcareous Nannofossils ◽  
Data Set ◽  
Sea Level Fluctuations

Three sequencing methods were used to calculate the most likely biozonation and the periodicity of sedimentary cycles in Lower Cretaceous pelagic strata of the Atlantic and Indian oceans.A database was built of 378 first and last stratigraphic occurrences of calcareous nannofossils, dinocysts, foraminifers, and geomagnetic reversals in highest Jurassic through Lower Cretaceous deep marine strata at 10 Atlantic Ocean and 3 Indian Ocean drilling sites. There are 135 different events in total, about one third of which are unique to either ocean. Using the complete data set, the quantitative stratigraphy methods STRATCOR and RASC calculated closely comparable optimum sequences of average first- and last-occurrence positions. The preferred zonal solution, based on the STRATCOR method, includes 56 events, each of which occurs at three or more sites. The events comprise 6 geomagnetic reversals, 25 nannofossils, 5 planktonic foraminifera, 8 benthic foraminifera, and 12 dinocysts occurrences. Nine assemblage zones have been recognized of Tithonian through Albian age. All but 2 of 18 nannofossil events in the Atlantic Ocean optimum sequence were reported in the same stratigraphic order in a standard Mesozoic nannofossil zonation.Our quantitative examination, using Walsh spectral analysis, of the Lower Cretaceous cyclic sequences at three Deep Sea Drilling Project (DSDP) sites in the Atlantic Ocean generally supports the hypothesis that they are the product of cyclic climatic changes controlled by the Milankovitch orbital cycles. The peaks in the power spectra usually can be related to obliquity and precession cycles; some peaks seem to correspond to the eccentricity cycle. Obliquity seems to be the most important and persistent orbital element responsible for cyclic sedimentation in the Early Cretaceous Atlantic Ocean.The actual pelagic sedimentation rates were calculated for some cores using the results of spectral analysis. The correlation of the actual pelagic sedimentation rate with cyclic patterns and the occurrence of calcareous turbidites indicate that the changes in cycle pattern are the reflection of changes in the oceanographic setting. The changes in oceanographic setting are related to relative-sea-level fluctuations. The intervals dominated by laminated limestone were deposited during higher sea-level periods.

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