scholarly journals Facies patterns and depositional processes in two Frasnian mixed siliciclastic-carbonate systems in the Cantabrian Mountains, northwest Spain

Geologos ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 1-23
Author(s):  
Gerard B.S. van Loevezijn ◽  
J.G.M. Raven
Keyword(s):  
Sea Level ◽  
Cantabrian Mountains ◽  
Third Order ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
Depositional Processes ◽  
Gravity Flows ◽  
Entry Points ◽  
Basin Geometry ◽  
Order Sequence

AbstractRelative sea level fluctuations during the Frasnian generated two shallow-marine, mixed siliciclastic-carbonate successions in the Devonian Asturo-Leonese Basin. Each system represents a third-order sequence-stratigraphical unit deposited in the same basin during comparable extreme greenhouse conditions without nearby fluvial entry points. Depositional control on the siliciclastic and carbonate distribution was driven by relative sea level fluctuations, basin geometry, availability of sand and the way sediment was distributed by shelf currents. Early Variscan flexural bending of the continental crust changed the basin shape from a shelf with a gradual profile and low dip (early Frasnian) towards a shelf with a steep depositional dip (late Frasnian). Shelf distribution changed from along-shelf transport (early Frasnian) towards offshore-directed gravity flows (late Frasnian). As a consequence, siliciclastic-carbonate distribution changed from a predominance of skeletal carbonate in the proximal shoreface – foreshore area and siliciclastic predominance distally (early Frasnian), to a distribution pattern with proximal shoreface skeletal carbonates, offshore muddy carbonates and a siliciclastic zone in between where gravity flows distributed the siliciclastic sediment down dip (late Frasnian).

Subsurface geological imaging of northeastern Tunisia during the middle to the upper Eocene: Insights from integrated geophysical interpretation

2021 ◽  
pp. 1-64
Author(s):  
Oussama Abidi ◽  
Kawthar Sebei ◽  
Adnen Amiri ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
...  
Keyword(s):  
Sea Level ◽  
Regional Scale ◽  
Upper Eocene ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Borehole Data ◽  
Third Order ◽  
Good Correspondence ◽  
Basin Inversion ◽  
Sea Level Fluctuations

The Middle to Upper Eocene series are characterized by multiple hiatuses related to erosion, non-deposition or condensed series in the Cap Bon and Gulf of Hammamet provinces. We performed an integrated study taking advantage from surface and subsurface geology, faunal content, borehole logs, electrical well logs, vertical seismic profiles and surface seismic sections. Calibrated seismic profiles together with borehole data analysis reveal unconformities with deep erosion, pinchouts, normal faulting and basin inversion which are dated Campanian, intra-Lutetian and Priabonian compressive phases; these events were also described at the regional scale in Tunisia. Tectonics, sea level fluctuations and climate changes closely controlled the depositional process during the Middle to Upper Eocene time. The depositional environment ranges from internal to outer platform separated by an inherited paleo-high. We determine eight third order sequences characterizing the interaction between tectonic pulsations, sea level changes and the developed accommodation space within the Middle to Upper Eocene interval. We correlate the obtained results of the Cap Bon-Gulf of Hammamet provinces with the published global charts of sea-level changes and we find a good correspondence across third order cycles. Model-based 3D inversion proved to be a solution to model the lateral and vertical lithological distribution of the Middle to Upper Eocene series.

Foraminiferal response to Albian relative sea-level changes in northwestern and central Alberta, Canada

1999 ◽  
Vol 36 (10) ◽  
pp. 1617-1643 ◽  
Author(s):  
Rebecca A Stritch ◽  
Claudia J Schröder-Adams
Keyword(s):  
Sea Level ◽  
Bottom Water ◽  
Gradual Increase ◽  
Western Canada ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
Faunal Assemblages ◽  
Water Oxygen ◽  
Southern Alberta

Albian foraminiferal assemblages from three wells in northwestern (Imperial Spirit River No. 1, 12-20-78-6W6), central (AngloHome C&E Fort Augustus No. 1, 7-29-55-21W4), and southern Alberta (Amoco B1 Youngstown, 6-34-30-8W4) provide the basis to track a fluctuating sea-level history in western Canada. Two global second-order marine cycles (Kiowa - Skull Creek and Greenhorn) were punctuated by higher frequency relative sea-level cycles expressed during the time of the Moosebar-Clearwater, Hulcross, Joli Fou, and Mowry seas. A total of 34 genera and 93 subgeneric taxa are recognized in these Albian-age strata. Foraminiferal abundance and species diversity of the latest Albian Mowry Sea were higher than in the early to middle Albian Moosebar-Clearwater and Hulcross seas. The two earliest paleo-seas were shallow embayments of the Boreal Sea, and relative sea-level fluctuations caused variable marine to brackish conditions expressed in a variety of faunal assemblages. Towards the late Albian, relative sea level rose, deepening the basin and establishing increased marine conditions and more favourable habitats for foraminifera. In the deeper Joli Fou Seaway and Mowry Sea, however, reduced bottom water oxygen through stratification or stagnant circulation caused times of diminished benthic faunas. The Bluesky Formation in northwestern Alberta contains the initial transgression of the early Albian Moosebar-Clearwater Sea and is marked by a sudden faunal increase. In contrast, transgression by the late late Albian Mowry Sea was associated with a gradual increase of foraminiferal faunas. Numerous agglutinated species range throughout the entire Albian, absent only at times of basin shallowing. However, each major marine incursion throughout the Albian introduced new taxa.

Sea-level fluctuations in the late Middle Permian estimated from palaeosols of the Sichuan Basin, SW China

2020 ◽  
Vol 157 (8) ◽  
pp. 1333-1348
Author(s):  
Jun Li ◽  
Zhong Han ◽  
Xingyue Wen ◽  
Gregory J. Retallack ◽  
Chengmin Huang
Keyword(s):  
Sea Level ◽  
Sichuan Basin ◽  
Chemical Properties ◽  
Middle Permian ◽  
Sea Level Changes ◽  
Yangtze Craton ◽  
Relative Sea Level ◽  
Carbonate Microfacies ◽  
Additional Tool ◽  
Sea Level Fluctuations

AbstractTwo upper Middle Permian palaeosols, consisting of coal and pyrite intercalated with a 20 cm thick limestone, were found near Mount Emei in the SW Sichuan Basin, China. The macro- and micromorphology and physico-chemical properties, in conjunction with the mineralogical composition of the palaeosol horizons were investigated. This type of palaeosol is common within the Permian intertidal facies of the Upper Yangtze Craton. The section reflects fluctuations within the range of 0–25 m in relative sea-level, with the depositional environment changing from shallow-marine to littoral, followed by tidal-flat to littoral, and finally to continental volcanic rocks, based on a combination of palaeopedological and carbonate microfacies analyses. Such short-term relative sea-level fluctuations in late Middle Permian times in the SW Sichuan Basin of South China are consistent with the long-term falling trend on a global scale in late Middle Permian times, and may be related to regionally variable subsidence and global cooling. The combination of coastal palaeosol and carbonate microfacies analyses is proposed as an additional tool for estimating the amplitude of sea-level changes.

Onset of the Late Paleozoic Glacioeustatic Signal: A Stratigraphic Record from the Paleotropical, Oil-Shale-Bearing Big Snowy Trough of Central Montana, U.S.A.

2019 ◽  
Vol 89 (8) ◽  
pp. 761-783 ◽  
Author(s):  
Justin P. Ahern ◽  
Christopher R. Fielding
Keyword(s):  
Sea Level ◽  
Ice Age ◽  
Late Paleozoic ◽  
Time Interval ◽  
Relative Sea Level ◽  
Depositional Sequences ◽  
Sea Level Fluctuations ◽  
Shark Bay ◽  
Facies Associations ◽  
Central Montana

Abstract In the Big Snowy Mountains of central Montana, USA, late Visean to Bashkirian strata preserve a nearly complete, but poorly documented, paleotropical stratigraphic succession that straddles the range of current estimates of the onset of the Late Paleozoic Ice Age (LPIA). Sedimentologic and stratigraphic investigation of the Otter (late Visean to Serpukhovian) and Heath (Serpukhovian) formations, with secondary focus on the overlying Tyler (late Serpukhovian to Bashkirian) and Alaska Bench (Bashkirian) formations, facilitated an appraisal of paleotropical environmental change preserved in this succession. Three facies associations reminiscent of environments currently forming in Shark Bay, Australia, were identified in the Otter Formation: shallow semi-restricted littoral platform, intertidal platform, and supratidal plain. Five facies associations broadly comparable to modern environments present in the Sunda Shelf and southern coast of the Persian Gulf were identified in the Heath Formation: offshore outer ramp, mid- to outer ramp, inner ramp, coastal plain, and sabkha. Facies associations preserved in the Heath Formation are here explained in the context of a protected, homoclinal carbonate ramp situated in a partially silled epicontinental embayment. A shift from low-magnitude relative sea-level oscillations preserved in the Otter Formation to a cyclothemic stratigraphic pattern entailing ≥ 6 fourth-order, high-frequency and high-magnitude relative sea-level fluctuations in the Heath Formation is here interpreted to record the main eustatic signal of the LPIA in central Montana. Current published biostratigraphic constraints for the observed stratigraphy estimate the main eustatic signal of the LPIA to have occurred approximately between 331 (base Serpukhovian) and 327 Ma in central Montana. A distinct upward transition from coal and paleosol-bearing depositional sequences in the lower Heath to evaporite and limestone-bearing depositional sequences in the upper Heath preserves a broad humid to arid paleoclimate shift during deposition of this unit, which influenced hydrographic circulation patterns and the resultant distribution of anoxic environments in the Big Snowy Trough during this time interval. Improved depositional and sequence stratigraphic models of the Heath Formation proposed in this study permit new insight into the theoretical distribution of, and water depth necessary to preserve, black, organic-rich claystone and shale in partially silled intracratonic basins, in addition to new temporal constraints on LPIA onset in paleotropical western Laurentia.

Smithian shoreline migrations and depositional settings in Timpoweap Canyon (Early Triassic, Utah, USA)

2014 ◽  
Vol 151 (5) ◽  
pp. 938-955 ◽  
Author(s):  
NICOLAS OLIVIER ◽  
ARNAUD BRAYARD ◽  
EMMANUEL FARA ◽  
KEVIN G. BYLUND ◽  
JAMES F. JENKS ◽  
...  
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Depositional Environments ◽  
Small Scale ◽  
Early Triassic ◽  
Relative Sea Level ◽  
Depositional Sequence ◽  
Sea Level Fluctuations ◽  
Stacking Pattern ◽  
Shallow Subtidal

AbstractIn Timpoweap Canyon near Hurricane (Utah, USA), spectacular outcrop conditions of Early Triassic rocks document the geometric relationships between a massive Smithian fenestral-microbial unit and underlying, lateral and overlying sedimentary units. This allows us to reconstruct the evolution of depositional environments and high-frequency relative sea-level fluctuations in the studied area. Depositional environments evolved from a coastal plain with continental deposits to peritidal settings with fenestral-microbial limestones, which are overlain by intertidal to shallow subtidal marine bioclastic limestones. This transgressive trend of a large-scale depositional sequence marks a long-term sea-level rise that is identified worldwide after the Permian–Triassic boundary. The fenestral-microbial sediments were deposited at the transition between continental settings (with terrigenous deposits) and shallow subtidal marine environments (with bioturbated and bioclastic limestones). Such a lateral zonation questions the interpretation of microbial deposits as anachronistic and disaster facies in the western USA basin. The depositional setting may have triggered the distribution of microbial deposits and contemporaneous marine biota. The fenestral-microbial unit is truncated by an erosional surface reflecting a drop in relative sea level at the scale of a medium depositional sequence. The local inherited topography allowed the recording of small-scale sequences characterized by clinoforms and short-distance lateral facies changes. Stratal stacking pattern and surface geometries allow the reconstruction of relative sea-level fluctuations and tracking of shoreline migrations. The stacking pattern of these small-scale sequences and the amplitude of corresponding high-frequency sea-level fluctuations are consistent with climatic control. Large- and medium-scale sequences suggest a regional tectonic control.

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

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–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–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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