Stratigraphic Architecture of Deep - Water Leveed Channel Complexes of the Cerro Toro Formation, Upper Cretaceous, Southern Chile: ABSTRACT

Author(s):  
R. T. Beaubouef, R. M. Lindholm, P.
2010 ◽  
Vol 61 (1) ◽  
pp. 29-38
Author(s):  
Damir Bucković ◽  
Maja Martinuš ◽  
Duje Kukoč ◽  
Blanka Tešović ◽  
Ivan Gušić

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)The upper part of the Middle Coniacian/Santonian-Middle Campanian deep-water Dol Formation of the island of Brač is composed of countless fine-grained allodapic intercalations deposited in an intraplatform trough. Within the studied section 13 beds can be distinguished, each defined by its lower part built up of dark grey limestone with abundance of branched, horizontally to subhorizontally oriented burrows, and the upper part, in which the light grey to white limestone contains larger burrows, rarely branched, showing no preferential orientation. The lower, dark grey, intensively bioturbated levels are interpreted as intervals formed during high-frequency sea-level highstands, while the upper, light grey-to-white levels are interpreted as intervals formed during the high-frequency sea-level lowstands. Cyclic alternation of these two intervals within the fine-grained allodapic beds is interpreted as the interaction between the amount of carbonate production on the platform margin and the periodicity and intensity of shedding and deposition in the distal part of toe-of-slope environment, which is governed by Milankovitch-band high frequency sea-level changes.


2015 ◽  
Vol 59 ◽  
pp. 268-285 ◽  
Author(s):  
Amandine Prélat ◽  
David M. Hodgson ◽  
Mark Hall ◽  
Christopher A.-L. Jackson ◽  
Carol Baunack ◽  
...  
Keyword(s):  

Author(s):  
A. Yu. Guzhikov ◽  
G. N. Aleksandrova ◽  
E. Yu. Baraboshkin

In this article there are the results of sedimentological, palynological and paleomagnetic studies of upper Cretaceous in Alan-Kyr section (Central Crimea). The nomenclature of rocks was specified, and their deep-water genesis was justified. According to palynologic data, the age of sediments is estimated as late Campanian, in the lower part of the section palynomorphs were not found. In the lower part of the section there was established a reverse polarity magnetozone — probable analogue of C33r magnetic chron, which base should be desirable to use as a primary attribute to determine the lower border of Campanian stage in the section according to Wolfring’s recommendation [Wolfgring et al., 2018]. The received data found a significant divergence microfaunistic dating of the section, conducted before [Bragina et al., 2016].


2021 ◽  
Author(s):  
M. Stearman ◽  
B. Gergurich ◽  
T. Kent ◽  
A. Wickard ◽  
F. Laugier

2020 ◽  
pp. 1-17
Author(s):  
Mathia Sabino ◽  
Francesco Dela Pierre ◽  
Marcello Natalicchio ◽  
Daniel Birgel ◽  
Susanne Gier ◽  
...  

Abstract During Messinian time, the Mediterranean underwent hydrological modifications culminating 5.97 Ma ago with the Messinian salinity crisis (MSC). Evaporite deposition and alleged annihilation of most marine eukaryotes were taken as evidence of the establishment of basin-wide hypersalinity followed by desiccation. However, the palaeoenvironmental conditions during the MSC are still a matter of debate, chiefly because most of its sedimentary record is buried below the abyssal plains of the present-day Mediterranean Sea. To shed light on environmental change at the advent and during the early phase of the MSC, we investigated the Govone section from the Piedmont Basin (NW Italy) using a multidisciplinary approach (organic geochemical, petrographic, and carbon and oxygen stable isotope analyses). The Govone section archives the onset of the crisis in a succession of organic-rich shales and dolomite-rich marls. The MSC part of the succession represents the deep-water equivalent of sulphate evaporites deposited at the basin margins during the first phase of the crisis. Our study reveals that the onset of the MSC was marked by the intensification of water-column stratification, rather than the establishment of widespread hypersaline conditions. A chemocline divided the water column into an oxygen-depleted, denser and more saline bottom layer and an oxygenated, upper seawater layer influenced by freshwater inflow. Vertical oscillations of the chemocline controlled the stratigraphic architecture of the sediments pertaining to the first stage of the MSC. Accordingly, temporal and spatial changes of water masses with different redox chemistries must be considered when interpreting the MSC event.


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