Late Ordovician (Hirnantian) depositional pattern and sea-level change in shallow marine to shoreface cycles in central Sweden

2004 ◽  
Vol 141 (5) ◽  
pp. 605-616 ◽  
Author(s):  
PETER DAHLQVIST
Keyword(s):  
Foreland Basin ◽  
Late Ordovician ◽  
Fair Weather ◽  
Upper Ordovician ◽  
Sedimentary Structures ◽  
Accommodation Space ◽  
Facies Associations ◽  
Storm Wave ◽  
Marine Facies ◽  
Abundant Supply

The Upper Ordovician Kyrkås Quartzite Formation at the Nifsåsen Quarry (Jämtland, Sweden) exhibits c. 90 m of siliciclastic sedimentary rocks deposited on a shallow shelf at the craton-attached part of the Caledonian foreland basin. Five lithologies are distinguished, including claystone, mudstone, siltstone, subarkose and sublitharenite. Based on these five lithologies, sedimentary structures and biota, three marine facies associations are defined: the Mudstone association (FA1) deposited close to storm wave base, the Sandstone/mudstone association (FA2) formed between storm and fair-weather wave bases, and the Sandstone association (FA3) accumulated above fair-weather wave base. The facies associations are arranged in two sequences, c. 50 and 40 m thick, separated by a transgressive surface, indicating repeated shoreline progradation. Both sequences commence with marine heterolithic shales and siltstones, with upwardly increasing frequency of tempestites. Continued shoaling is indicated by a dominance of hummocky and trough (locally tabular) cross-stratified sandstone beds in the upper part of each sequence. Sand beds are increasingly amalgamated up-sequence, reflecting progressively diminishing accommodation space. The depositional style and sedimentary structures indicate that the study area was storm-dominated with an abundant supply of siliciclastic material. Biostratigraphic data tie the depositional changes to the globally recognized Late Ordovician (Hirnantian) glacial interval. These data suggest that the first sequence was formed during the initial phase of regression in the earliest Hirnantian. The lowermost part of the overlying sequence contains elements of a typical Hirnantia fauna followed by beds yielding Normalograptus persculptus, suggesting a second regressive cycle in the Jämtland basin during the early N. persculptus Biozone.

scholarly journals TECTONOSEDIMENTARY SIGNIFICANCE OF THE MESSINIA CONGLOMERATES (SW PELOPONNESE, GREECE)

2017 ◽  
Vol 43 (2) ◽  
pp. 715
Author(s):  
A. Pavlopoulos ◽  
E. Kamperis ◽  
S. Sotiropoulos ◽  
M. Triantaphyllou
Keyword(s):  
Flow Direction ◽  
Foreland Basin ◽  
Sediment Supply ◽  
Accommodation Space ◽  
Gravity Flows ◽  
Facies Associations ◽  
Rapid Changes ◽  
Gravity Driven ◽  
Main Flow Direction ◽  
Lateral Variations

The marine fill of the Gavrovo-Tripolis foreland basin in the Messinia area (SW Peloponnese), includes facies and facies associations, deposited by sediment gravity flows in slope and inner fan settings. The above-mentioned gravity-driven sedimentary processes, resulted in the formation of thinning-upward sequences and fining fan facies associations, composed of impressive sheet-conglomerates at the base (Agia Mavra, Agia Varvara and Mali units), presenting mainly normal internal structure, while clay and sand-clay members predominate at the top. These conglomerates advocate a significant sediment supply and extended accommodation space, during periods of dramatic tectonic uplift, associated with the westward propagation of Pindos thrust front. In the prograding fan system, dominate paleo-currents with main flow direction to southwest. The finer fan facies associations show rapid lateral variations, both in lithology and thickness, indicating rapid changes in the inner, incised, part of the foredeep. Nannofossil analyses suggest that the sedimentation took place during Oligocene (NP22 to NP24 biozones). Three NNW-SSE trending thrust fault zones bound the above-mentioned units and they caused an important structural thickening of the fan facies associations. Biostratigraphic analyses date the end of the thrust activity in GavrovoTripolis zone in Late Oligocene (biozone NP24).

Biostratigraphical and palaeoecological significance of graptolites, trilobites and conodonts in the Middle-Upper Ordovician Andersö Shale: an unusual ‘mixed facies’ deposit in Jämtland, central Sweden

2002 ◽  
Vol 93 (1) ◽  
pp. 35-57 ◽  
Author(s):  
Christian Pålsson ◽  
Kristina Månsson ◽  
Stig M. Bergström
Keyword(s):  
Foreland Basin ◽  
Distribution Patterns ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Geographical Position ◽  
Global Classification ◽  
Early Late ◽  
Basin Margin ◽  
Upper Slope

ABSTRACTAlthough only about 20m thick, the Andersö Shale contains one of the most diverse, if not the most diverse, late Middle-early Late Ordovician faunas known in Baltoscandia. It includes more than 20 trilobite species, more than 20 species of other shelly fossils, about 10 graptolite species, and about 20 conodont species. Based on its lithology, its geographical position near the foreland basin margin, and the presence of trilobites of the raphiophorid association and conodonts of the Periodon-Pygodus biofacies, this formation is interpreted to represent an outer shelf-upper slope (ramp) deposit laid down in moderately deep water. The co-occurrence of some widespread and biostratigraphically diagnostic conodonts, graptolites and trilobites makes it possible directly to compare distribution patterns of these fossils, establish ties between graptolite and conodont zones, and correlate the formation with units elsewhere in Europe, North America and China. Stratigraphically and faunally, the Andersö Shale is of particular interest in straddling the Middle-Upper Ordovician Series boundary as this boundary is recognised in the new global classification of the Ordovician System.

Refinement of the stratigraphic framework for the Regional C depositional unit of the McMurray Formation and implications for the early transgression of the Alberta Foreland Basin, Canada

2020 ◽  
Vol 90 (10) ◽  
pp. 1322-1345 ◽  
Author(s):  
Chloé C.F. Château ◽  
Shahin E. Dashtgard ◽  
James A. MacEachern
Keyword(s):  
Foreland Basin ◽  
Channel System ◽  
Mcmurray Formation ◽  
Accommodation Space ◽  
Stratigraphic Framework ◽  
Clearwater Formation ◽  
History Of ◽  
Marine Facies ◽  
Depositional Units ◽  
Stratigraphic Evolution

ABSTRACT The Lower Cretaceous McMurray Formation in Alberta and Saskatchewan, Canada, comprises a series of depositional units (DUs) consisting of stacked parasequences bounded by flooding surfaces and incised by fluvio-estuarine channel belts. The fluvio-estuarine channel belts of the McMurray Fm have been the focus of numerous studies whereas the regional DUs have received substantially less attention. Of the regional DUs, Regional C (equivalent to the middle McMurray) is the most understudied, yet this interval records the history of the McMurray Formation between deposition of fluvial strata in the lower McMurray and marine facies in the upper McMurray and overlying Clearwater Formation. Determining the history of the Regional C DU is fundamental for accurately reconstructing the stratigraphic evolution of the McMurray Fm and, by extension, the early evolution of the Alberta Foreland Basin. The Regional C is divided into two DUs separated by a regionally mappable flooding surface. This surface occurs 11 to 15 m below the top of the Regional C and is traceable over a 2,550 km2 area. This flooding surface divides the thick interval of undifferentiated Regional C into a lower C2 DU and an upper C1 DU, each with a maximum thickness of < 15 m. The thickness of the C2 and C1 DUs indicates that deposition at this time also occurred in a setting of low to moderate accommodation creation, which is consistent with the rest of the McMurray Formation. The limited available accommodation space was easily surpassed by sediment supplied by the paleo-distributive channel system, leading to a basinward progradation of the shoreline. The C2 and C1 DUs are retrogradationally stacked, with the maximum regressive paleo-shoreline of C1 lying landward of that of C2. This stacking arrangement indicates that the shoreline backstepped during the early stages of transgression of the Boreal Sea. The backstepping of the paleo-shoreline from C2 to C1 time is consistent with previous studies that show continued and stepwise retrogradation and/or transgression of the paleo-shoreline from the onset of deposition in the lower McMurray Formation through to maximum transgression in the Clearwater Formation. Together, these studies demonstrate that the early drowning of the Alberta Foreland Basin was persistent and slow.

Blackriveran (lower Mohawkian, Upper Ordovician) lithostratigraphy, rhythmicity, and paleogeography: Ottawa Embayment, eastern Ontario, Canada

1999 ◽  
Vol 36 (12) ◽  
pp. 2033-2050 ◽  
Author(s):  
O Salad Hersi ◽  
G R Dix
Keyword(s):  
New York ◽  
Carbonate Platform ◽  
Progressive Increase ◽  
Intertidal Mudflat ◽  
Rhythmic Pattern ◽  
Upper Ordovician ◽  
Depositional Facies ◽  
Accommodation Space ◽  
Regional Correlation ◽  
Facies Associations

The Ottawa Embayment contains erosional remnants of a shallow-water carbonate platform (St. Lawrence Platform) of Late Ordovician (Caradocian) age. Stratigraphy of three Blackriveran formations - in ascending order, Pamelia, Lowville, and Chaumont - documents regional changes in continuity and types of depositional facies. The Pamelia Formation contains two members, each containing basin-wide basal siliciclastic units overlain by interbedded limestone, dolostone, and shale. An alternate division recognizes six shallowing-upward units; regionally extensive, intertidal to supratidal, dolomitic sandstone and (or) sandy dolostone define their tops. Sedimentary structures and isotope (C, O) geochemistry support a syngenetic origin of this stratigraphic (bedded) dolomite. The Lowville Formation contains two facies associations: subtidal to lower intertidal bioclastic and oolitic packstone - grainstone followed by lagoonal to intertidal mudflat facies. Lateral facies continuity is reduced compared to the Pamelia Formation. The Chaumont Formation contains thick beds of burrowed, bioclastic, peloidal mudstone to packstone, and minor shale. No rhythmic pattern is recognized in these subtidal facies. Upsection decrease of rhythmic sedimentation, with a decrease in lateral facies continuity of the studied strata reflects a progressive increase in net accommodation space related to Taconic transgression. Higher order rhythmicity of dolostone and sandstones of the Pamelia Formation can be traced into adjacent regions (New York and Kingston, Ont.). Dolomitic units may identify basin-wide chronostratigraphic markers, potentially useful for future sequence analysis. Regional correlation reveals a good oceanographic linkage between the Ottawa Embayment and the Appalachian Basin during Pamelia time and a restricted access across a paleohigh in the Montréal region. By the time of Lowville deposition, Taconic transgression had breached this restriction.

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

scholarly journals High resolution stratigraphy of initial stages of rifting, Sergipe-Alagoas Basin, Brazil

2017 ◽  
Vol 47 (4) ◽  
pp. 657-671 ◽  
Author(s):  
Carrel Kifumbi ◽  
Claiton Marlon dos Santos Scherer ◽  
Fábio Herbert Jones ◽  
Juliano Kuchle
Keyword(s):  
Radical Change ◽  
High Rate ◽  
Tectonic Activity ◽  
Accommodation Space ◽  
Facies Associations ◽  
Half Graben ◽  
Lateral Connection ◽  
Depositional Units ◽  
Two Parameters ◽  
Channel Deposits

ABSTRACT: The present work aims to characterize the Neo-Jurassic to Neocomian succession of the Sergipe-Alagoas Basin, located in northeast region of Brazil, in order to discover the influence of tectonics on sedimentation in detailed scale and thus separating this sedimentary succession in tectono-stratigraphic units. Fieldwork observations and stratigraphic sections analysis allowed subdividing this rift succession into three depositional units that indicate different paleogeographic contexts. Unit I, equivalent to the top of Serraria Formation, is characterized by braided fluvial channel deposits, with paleocurrent direction to SE; unit II, corresponding to the base of Feliz Deserto Formation, is composed of anastomosed fluvial channel and floodplain facies associations; and unit III, equivalent to the major part of Feliz Deserto Formation, is characterized by delta deposits with polymodal paleocurrent pattern. The changes of depositional system, as well as paleocurrent direction, suggest that the previously described units were deposited in different evolutionary stages of rifting. Units I and II represent the record of a wide and shallow basin associated with the first stage of rifting. Unit I is characterized by incipient extensional stress generating a wide synclinal depression, associated to the low rate of accommodation and low tectonic activity. These two parameters progressively increase in unit II. The paleocurrent direction of unit I indicates that the depocenter of this wide basin was located at SE of the studied area. No conclusion could be done on paleocurrent from unit II because of the low amount of measurements. Unit III suggests a second stage marked by a deeper basin context, with a high rate of accommodation space associated with the lateral connection of faults and individualization of the half-graben. The scattering in the paleocurrent direction in this unit indicates sedimentary influx coming from several sectors of the half-graben. The boundary between these two stages is marked by a flooding surface that indicates an extremely fast transition and suggests a radical change in geometric characteristics of the basin due to the increase of tectonic activity.

scholarly journals Effect of Hydrothermal Activity on Organic Matter Enrichment of Shale: A Case Study of the Upper Ordovician and the Lower Silurian in the Lower Yangtze, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 495 ◽  
Author(s):  
Yizhou Huang ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Isotope ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Hydrothermal Activity ◽  
Late Ordovician ◽  
Sedimentary Organic Matter ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Activity Intensity

The effect of organic matter on hydrocarbon potential, storage space, and gas content of shale is well-known. Additionally, present-day content of sedimentary organic matter in shale is controlled by depositional and preservation processes. Therefore, a study of the enrichment mechanisms of sedimentary organic matter provides a scientific basis for the determination of favorable areas of shale gas. In this study the Upper Ordovician Xinkailing Fm. and the first member of the Lower Silurian Lishuwo Fm. were examined. Stratigraphic sequences were identified through conventional logs and elemental capture spectrum data. Oxygen isotope analysis was applied to recover paleotemperature of seawater in the study area. The excess silicon content was calculated and the origin of the silica was determined by the Fe-Al-Mn ternary plot. The enrichment mechanism of organic matter was analyzed by two aspects: redox conditions and paleoproductivity. As a result, the stratigraphic interval was divided into two 3rd-order sequences. Through oxygen isotope, the paleotemperature of seawater was 62.7–79.2 °C, providing evidence of the development of hydrothermal activity. Analysis of excess siliceous minerals identified two siliceous mineral origins: terrigenous and hydrothermal. It also revealed an upwards decreasing tendency in hydrothermal activity intensity. Strong hydrothermal activity during the Late Ordovician, recognized as TST1, formed a weak-oxidizing to poor-oxygen environment with high paleoproductivity, which promoted organic matter enrichment. During the Late Ordovician to the Early Silurian, identified as RST1, TST2, and RST2, weakening hydrothermal activity caused the decline of paleoproductivity and increased oxidation of bottom waters, leading to a relative decrease of organic matter content in the shale. Therefore, favorable areas of shale gas accumulation in the Upper Ordovician and Lower Silurian are determined stratigraphically as the TST1, with a high total organic carbonate content. Geographically, the hydrothermally-active area near the plate connection of the Yangtze and the Cathaysian is most favorable.

scholarly journals Depositional, diagenetic and stratigraphic aspects of Macaé Group carbonates (Albian): example from an oilfield from Campos Basin

2015 ◽  
Vol 45 (2) ◽  
pp. 243-258 ◽  
Author(s):  
Juliana Okubo ◽  
Ricardo Lykawka ◽  
Lucas Veríssimo Warren ◽  
Julia Favoreto ◽  
Dimas Dias-Brito
Keyword(s):  
Deep Water ◽  
Carbonate Rocks ◽  
Facies Analysis ◽  
Sedimentary Facies ◽  
Fair Weather ◽  
Thin Sections ◽  
Carbonate Sedimentation ◽  
Diagenetic Processes ◽  
Campos Basin ◽  
Facies Associations

<p>Carbonate rocks from the Macaé Group (Albian) represent an example of carbonate sedimentation related to the drift phase in Campos Basin. This study presents depositional features, integrating them with diagenetic and stratigraphic aspects of the Macaé Group carbonates including the upper part of the Quissamã Formation and the lower part of the Outeiro Formation. Macroscopic analyses in cores and microscopic ones in thin sections allowed the recognition of eleven sedimentary facies - nine of them corresponding to the Quissamã Formation and two of them representing the Outeiro Formation. These facies were grouped into five facies associations. Oolitic grainstones and oncolitic grainstones are interpreted to be deposited in shallow depth probably in shoals above the fair weather wave base. The interbanks between shoals were formed in less agitated waters and characterized by deposition of peloidal bioclastic packstones and wackestones representative of sedimentation in calm waters. Bioclastic packstones and oolitic packstones/wackestones represent allochthonous deposits related to the beginning of the regional drowning that occur in upper Quissamã Formation. Pithonellids wackestones and bioclastic wackestones with glauconite are related to deep water deposits, characteristics of the Outeiro Formation. Post-depositional features revealed the action of diagenetic processes as, micritization, cimentation, dissolution, compaction, dolomitization and recrystallization occurred during the eo- and mesodiagenesis phases. Vertical facies analysis suggests shallowing upward cycles stacked in a sequence progressively deeper towards the top (from the Quissamã Formation to the Outeiro Formation).</p>

scholarly journals The specificity of paleocoenosis and a trophic structure of the Upper Ordovician Bol’shaya Kos’yu reef (Northern Urals)

2020 ◽  
Author(s):  
L. A. Shmeleva ◽  
Keyword(s):  
Trophic Structure ◽  
Active Participation ◽  
Late Ordovician ◽  
Close Connection ◽  
Upper Ordovician ◽  
Northern Urals ◽  
Leading Role ◽  
Microbial Organisms

The study of the spatial-temporal and paleoecological structures of the paleocenoses of the Bolshaya Kosyu reef showed that the sphinctozoic sponges Amblysiphonelloides reticulata Rigby & Potter, 1986 and Corymbospongia sp. starting from the late Ordovician could settle in sublittoral environments with active hydrodynamics in close connection with cyanobacteria, which played a leading role in the functioning of the trophic structure of this ecosystem. Fossilized biofilms and glycocalyx, tubular and worm-like bacteriomorphs found on the surface of sponges are evidence of active participation of microbial organisms in the life of sphinctozoal sponges.

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