Sea-level changes vs. organic productivity as controls on Early and Middle Devonian bioevents: Facies- and gamma-ray based sequence-stratigraphic correlation of the Prague Basin, Czech Republic

AbstractUpper Ordovician – lower Silurian sequences of the Bohemian Massif (in the Moldanubian Zone and Barrandian preserved in the Prague Basin; Rožmitál area; metamorphic ‘islets’ in the mantle of Central Bohemian Pluton; and in the Železné hory area), as well as along the northern margin of the Bohemian Massif in the Saxothuringian and Lugian (= West Sudetian) zones, show evidence of regressive–transgressive facies changes which can be related to glacio-eustatic sea-level fluctuations recognized elsewhere. Glacio-marine diamictites of late Ordovician (Hirnantian) age occur in the Prague Basin and Rožmitál area, and in north Bavaria and Thuringia. They provide evidence of temporary cooling of the region. Facies changes caused by synchronous sea-level changes allow stratigraphic correlation of even the faulted, weakly metamorphosed and biostratigraphically poorly dated sections in the Bohemian Massif. Correlation is based on sections in the Prague Basin in which the changes are best recorded and dated.

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Stratigraphic correlation potential of magnetic susceptibility and gamma-ray spectrometric variations in calciturbiditic facies (Silurian-Devonian boundary, Prague Synclinorium, Czech Republic)

Geologica Carpathica ◽

10.2478/v10096-010-0015-2 ◽

2010 ◽

Vol 61 (4) ◽

pp. 257-272 ◽

Cited By ~ 10

Author(s):

František Vacek ◽

Jindřich Hladil ◽

Petr Schnabl

Keyword(s):

Magnetic Susceptibility ◽

Czech Republic ◽

Deep Water ◽

Gamma Ray ◽

Sedimentary Environment ◽

Gamma Ray Spectrometry ◽

Stratigraphic Correlation ◽

Sea Level Changes ◽

Natural Gamma ◽

Correlation Potential

Stratigraphic correlation potential of magnetic susceptibility and gamma-ray spectrometric variations in calciturbiditic facies (Silurian-Devonian boundary, Prague Synclinorium, Czech Republic)Magnetic susceptibility (MS) and gamma-ray spectrometry (GRS) stratigraphy were used for correlation and characterization of eight Silurian-Devonian (S-D) sections in the Prague Synclinorium (Czech Republic). They represent two different facies developments: lower subtidal to upper slope deposits and slope-to-basin-floor distal calciturbidites. Sections from relatively shallow- and deep-water sections are easy to compare and correlate separately, although the detailed relationship between these two facies is still not entirely clear and correlations between the two settings are difficult. This may be due to sharp facies transitions and presence of stratigraphic gaps. The MS and GRS stratigraphic variations combined with sedimentologic data have been also used for reconstruction of the evolution of the sedimentary environment. The beds close above the S-D boundary show noticeably enhanced MS magnitudes but weak natural gamma-ray emissions. It may correspond to an increased amount of terrigenous magnetic material occurring with short-term shallowing (sedimentological evidence). In deep-water sections the uppermost Silurian is characterized by high MS and GRS values. It corresponds to a supply of recycled sediment to the lower wedge which occurred during the late Pridoli regression phase. The basal Devonian beds correspond to gradual deepening, but the overlying sequences reflect other shallowing episodes which are expressed in increasing MS and gamma ray activity of rocks. The MS and GRS fluctuations are interpreted as a result of local subsidence of the sea bottom along synsedimentary growth-faults and/or a biotic event rather than of eustatic sea-level changes.

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Aquifer-eustasy as the main driver of short-term sea-level fluctuations during Cretaceous hothouse climate phases

Geological Society London Special Publications ◽

10.1144/sp498-2019-105 ◽

2019 ◽

Vol 498 (1) ◽

pp. 9-38 ◽

Cited By ~ 9

Author(s):

Benjamin Sames ◽

M. Wagreich ◽

C. P. Conrad ◽

S. Iqbal

Keyword(s):

Sea Level ◽

Phase Relationship ◽

Sea Level Changes ◽

Short Term ◽

Groundwater Levels ◽

Sequence Stratigraphic ◽

Sea Level Fluctuations ◽

Minimum Estimate ◽

Underlying Mechanisms ◽

Continental Ice Sheets

AbstractA review of short-term (<3 myr: c. 100 kyr to 2.4 myr) Cretaceous sea-level fluctuations of several tens of metres indicates recent fundamental progress in understanding the underlying mechanisms for eustasy, both in timing and in correlation. Cretaceous third- and fourth-order hothouse sea-level changes, the sequence-stratigraphic framework, are linked to Milankovitch-type climate cycles, especially the longer-period sequence-building bands of 405 kyr and 1.2 myr. In the absence of continental ice sheets during Cretaceous hothouse phases (e.g. Cenomanian–Turonian), growing evidence indicates groundwater-related sea-level cycles: (1) the existence of Milankovitch-type humid-arid climate oscillations, proven via intense humid weathering records during times of regression and sea-level lowstands; (2) missing or inverse relationships of sea-level and the marine δ18O archives, i.e. the lack of a pronounced positive excursion, cooling signal during sea-level lowstands; and (3) the anti-phase relationship of sea and lake levels, attesting to high groundwater levels and charged continental aquifers during sea-level lowstands. This substantiates the aquifer-eustasy hypothesis. Rates of aquifer-eustatic sea-level change remain hard to decipher; however, reconstructions range from a very conservative minimum estimate of 0.04 mm a−1 (longer time intervals) to 0.7 mm a−1 (shorter, probably asymmetric cycles). Remarkably, aquifer-eustasy is recognized as a significant component for the Anthropocene sea-level budget.

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Sedimentological and sequence stratigraphic analysis of Carboniferous deposits in western Libya: Recording the sedimentary response of the northern Gondwana margin to climate and sea-level changes

Journal of African Earth Sciences ◽

10.1016/j.jafrearsci.2009.09.007 ◽

2010 ◽

Vol 57 (4) ◽

pp. 279-296 ◽

Cited By ~ 16

Author(s):

Sebastian Fröhlich ◽

Laurent Petitpierre ◽

Jonathan Redfern ◽

Paul Grech ◽

Stéphane Bodin ◽

...

Keyword(s):

Sea Level ◽

Sea Level Changes ◽

Sequence Stratigraphic ◽

Stratigraphic Analysis ◽

Gondwana Margin ◽

And Sea Level

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Latest Pliensbachian–Toarcian eustatic calibration using shallow-marine sedimentological record coupled with basinal geochemical analyzes

10.5194/egusphere-egu2020-8499 ◽

2020 ◽

Author(s):

François-Nicolas Krencker ◽

Alicia Fantasia ◽

Mohamed El Ouali ◽

Lahcen Kabiri ◽

Stéphane Bodin

Keyword(s):

Sea Level ◽

Special Focus ◽

Level Fluctuation ◽

Sea Level Changes ◽

Relative Sea Level ◽

Sequence Stratigraphic ◽

Sea Level Fluctuations ◽

Anoxic Events ◽

Chemical Index Of Alteration ◽

Sea Level Fluctuation

<p><span>Sea-level fluctuation is an important parameter controlling the sedimentation in deep-marine environments and influenced also the expansion of oxygen-depleted conditions in neritic settings during oceanic anoxic events (OAEs). Despite this fundamental role, sea-level fluctuation remains on a short timescale (<1 Myr) one of the least constrained parameters for numerous OAEs. Here we refine the sequence stratigraphic framework for the uppermost Pliensbachian&#8211;Toarcian with a special focus on the Toarcian OAE interval. This study is based on sedimentological and total organic carbon isotope data used to correlate 16 sections located in the central High Atlas (Morocco). Palinspastically, those sections formed a 50-kilometer proximal&#8211;distal transect along the northern Gondwana continental shelf, which allow reconstructing the shoreline migration through time and space. Our sequence stratigraphic interpretation is then compared to the geochemical signals (e.g. detrital index, chemical index of alteration) measured on samples collected in deep-environment settings from numerous basins distributed worldwide. Our study shows that the relative sea-level changes recorded in Morocco can be correlated over large distances across those basins, indicating that the relative sea-level changes were driven by eustatic fluctuations. This study gives insights into the relationship between relative sea-level fluctuations and the geochemical record.</span></p>

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Late Triassic – Jurassic development of the Danish Basin and the Fennoscandian Border Zone, southern Scandinavia

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v1.4681 ◽

2003 ◽

Vol 1 ◽

pp. 459-526 ◽

Cited By ~ 34

Author(s):

Lars H. Nielsen

Keyword(s):

Sea Level ◽

Large Scale ◽

Upper Triassic ◽

Border Zone ◽

Late Triassic ◽

Sea Level Changes ◽

Sequence Stratigraphic ◽

The North ◽

Layer Cake ◽

Thermal Cooling

The continental to marine Upper Triassic – Jurassic succession of the Danish Basin and the Fennoscandian Border Zone is interpreted within a sequence stratigraphic framework, and the evolution of the depositional basin is discussed. The intracratonic Permian–Cenozoic Danish Basin was formed by Late Carboniferous – Early Permian crustal extension followed by subsidence governed primarily by thermal cooling and local faulting. The basin is separated from the stable Precambrian Baltic Shield by the Fennoscandian Border Zone, and is bounded by basement blocks of the Ringkøbing–Fyn High towards the south. In Late Triassic – Jurassic times, the basin was part of the epeiric shallow sea that covered most of northern Europe. The Upper Triassic – Jurassic basin-fill is subdivided into two tectono-stratigraphic units by a basinwide intra-Aalenian unconformity. The Norian – Lower Aalenian succession was formed under relative tectonic tranquillity and shows an overall layer-cake geometry, except for areas with local faults and salt movements. Deposition was initiated by a Norian transgression that led to shallow marine deposition and was accompanied by a gradual climatic change to more humid conditions. Extensive sheets of shoreface sand and associated paralic sediments were deposited during short-lived forced regressions in Rhaetian time. A stepwise deepening and development of fully marine conditions followed in the Hettangian – Early Sinemurian. Thick uniform basinwide mud blankets were deposited on an open storm-influenced shelf, while sand was trapped at the basin margins. This depositional pattern continued until Late Toarcian – Early Aalenian times when the basin became restricted due to renewed uplift of the Ringkøbing–Fyn High. In Middle Aalenian – Bathonian times, the former basin area was subjected to deep erosion, and deposition became restricted to the fault-bounded Sorgenfrei–Tornquist Zone. Eventually the fault margins were overstepped, and paralic–marine deposition gradually resumed in most of the basin in Late Jurassic time. Thus, the facies architecture of the Norian – Lower Aalenian succession reflects eustatic or large-scale regional sea-level changes, whereas the Middle Aalenian – Volgian succession reflects a strong tectonic control that gradually gave way to more widespread and sea-level controlled sedimentation. The uplift of the Ringkøbing–Fyn High and most of the Danish Basin occurred concurrently with the uplift of the North Sea and a wide irregular uplifted area was formed, which differs significantly from the postulated domal pattern.

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The Bakken Formation - understanding the sequence stratigraphic record of low-gradient sedimentary systems, shale depositional environments, and sea-level changes in an icehouse world

The Sedimentary Record ◽

10.2110/sedred.2020.4.4 ◽

2020 ◽

Vol 18 (4) ◽

pp. 4-9

Author(s):

Sven O Egenhoff ◽

Neil S Fishman

Keyword(s):

Sea Level ◽

High Amplitude ◽

Depositional Environments ◽

Ice Age ◽

Bakken Formation ◽

Sea Level Changes ◽

Sequence Stratigraphic ◽

Sea Level Fluctuations ◽

Layer Cake ◽

Low Amplitude

The Bakken Formation is a major petroleum producer in the continental US. However, its deposition in an intracratonic, low-gradient setting has often been mistakenly described as “layer-cake”. This contribution is designed to highlight the time-transgressive nature of its main petroleum-producer, the middle Bakken member. Correlation of individual parasequences reveal the subtle nature of otherwise invisible low-angle stratigraphic geometries. Sequence stratigraphically-relevant surfaces occur throughout the unit and subdivide the entire Bakken into 5 third-order sequences; one of them is a hidden sequence at the base of the petroleum-producing middle Bakken indicating both a lowstand and a subsequent transgression. The organic-rich shales above and below the middle Bakken were deposited in an oxygen-deficient environment and show several burrow/fecal string types and indications of active currents during deposition. The Bakken records high amplitude sea-level changes during sequences compared to relative low amplitude sea-level changes of parasequences. This, coupled with a likely mismatch in timing of Bakken deposition relative to world-wide ice-age-induced cyclicity makes it unlikely that the Bakken sea-level fluctuations were dominated by glaciation.

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The late Silurian–Middle Devonian long-term eustatic cycle as a possible control on the global generic diversity dynamics of bivalves and gastropods

Geologos ◽

10.2478/logos-2013-0012 ◽

2013 ◽

Vol 19 (3) ◽

pp. 193-200

Author(s):

Dmitry A. Ruban

Keyword(s):

Sea Level ◽

Middle Devonian ◽

Marine Biodiversity ◽

Time Interval ◽

Sea Level Changes ◽

Regional Tectonic ◽

Stratigraphic Ranges ◽

Global Sea Level ◽

Diversity Dynamics

Abstract A long-term eustatic cycle (fall and subsequent rise of the global sea level) embraced the late Silurian-Middle Devonian time interval. Potentially, these sea-level changes could drive global biodiversity. The stratigraphic ranges of 204 bivalve genera and 279 gastropod genera included into the famous Sepkoski database allow reconstructing changes in the total diversity and the number of originations and extinctions of these important groups of marine benthic macro- -invertebrates during this interval. None of the recorded parameters coincided with the long-term global sea-level cycle. It cannot be not excluded, however, that the global sea-level changes did not affect the regions favourable for bivalve and gastropod radiation because of regional tectonic mechanisms; neither can it be excluded that the eustatic control persisted together with many other extrinsic and intrinsic controls. Interestingly, the generic diversity of gastropods increased together with a cooling trend, and vice versa. Additionally, the Ludlow, Eifelian, and Givetian biotic crises affected, probably, both fossil groups under study. There was also a coincidence of the relatively high bivalve generic diversity, initial radiation of gastropods and the entire biota, and the diversification of brachiopods with the Early Devonian global sea-level lowstand, and this may be interpreted as evidence of a certain eustatic control on the marine biodiversity.

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