Supercritical-flow Deposits and Their Distribution in a Submarine Channel System, Middle Eocene, Ainsa Basin, Spanish Pyrenees

2019 ◽  
Vol 89 (6) ◽  
pp. 576-597 ◽  
Author(s):  
Pauline H. Cornard ◽  
Kevin T. Pickering
Keyword(s):  
Middle Eocene ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Small Scale ◽  
Supercritical Flow ◽  
Fine Grained ◽  
Facies Associations ◽  
Spanish Pyrenees ◽  
Basin Floor ◽  
Lower Slope

Abstract Studies of supercritical-flow deposits (SFDs) and their spatial distribution in ancient deep-water systems should provide an additional tool to improve the understanding of the flow dynamics during deposition and the architecture of sandbodies. Outcrop recognition of SFDs in ancient deep-marine environments remains poorly documented, although their study dates back to the 1970s. This paper focusses on the criteria for recognizing SFDs and their distribution in three selected depositional environments from an ancient mid-lower slope to a proximal-basin floor setting in the middle Eocene Ainsa Basin, Spanish Pyrenees. From field observations, six facies associations interpreted as related to supercritical flow are defined. These facies associations are grouped in two categories. The first group includes facies associations related to erosional coarse-grained supercritical-flow bedforms related to meter and centimeter-scale scours and backfilling structures interpreted as large-scale cyclic steps or small-scale cyclic steps, respectively. Erosional coarse-grained supercritical bedforms are observed mainly in relatively high-gradient slopes and relatively confined settings. The second group of facies associations are related to depositional fine-grained supercritical-flow bedforms associated with upflow-dipping sandstone lenses, upflow-stacked wavy bedforms, upflow-stacked sigmoidal bedforms, and plane beds, interpreted as unstable and stable antidunes and upper-flow-regime plane beds. Depositional fine-grained supercritical-flow bedforms are observed mainly in relatively unconfined settings such as lower-slope, break-of-slope and proximal basin-floor environments. Two main SFD trends were observed in the Ainsa Basin in: (i) an axial-lateral direction, showing a decrease in SFDs from channel axis to channel margin, and (ii) a longitudinal proximal–distal direction, showing an increase in SFDs from the Gerbe System (mid-slope environment), to the Banastón System (proximal basin-floor environment), to the Ainsa System (lower-slope environment). From this study, two parameters are recognized as likely playing an important role on whether a flow is under supercritical or subcritical conditions: (i) confinement of the sandbodies, and (ii) slope gradient.

Submarine topographic control on distribution of supercritical-flow deposits in lobe and related environments, middle Eocene, Jaca Basin, Spanish Pyrenees

2020 ◽  
Vol 90 (9) ◽  
pp. 1222-1243
Author(s):  
Pauline H. Cornard ◽  
Kevin T. Pickering
Keyword(s):  
Grain Size ◽  
Distal Part ◽  
Middle Eocene ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Seafloor Topography ◽  
Submarine Channels ◽  
Supercritical Flow ◽  
Spanish Pyrenees ◽  
Bed Thickness

ABSTRACT Submarine lobe and related deposits are amongst the largest discrete sandbodies on Earth, and can be significant hydrocarbon reservoirs. In outcrop and core-based studies, tools such as analysis of bed-thickness and grain-size distributions have been used to improve the understanding of the composition and architecture of such sandbodies. Analysis of sediment-gravity-flow (SGF) processes have also proved to be a useful tool in understanding the evolution of submarine lobes. In this paper, based on outcrop studies of submarine lobe and related deposits in the middle Eocene Jaca Basin, Spanish Pyrenees, a revised interpretation of the depositional environments of the lobe and related deposits and a new model for their architectural evolution is presented. This model is based on an analysis of bed-thickness, grain-size distribution, and a qualitative and quantitative study of the distribution of supercritical-flow deposits (SFDs) in these environments. The interpretation of lobe and related environments is mainly based on sandstone content and the distribution of sedimentary facies. The main supercritical-flow sedimentary structures recognized in the Jaca Basin, are unstable and stable antidunes, upper plane beds and backset-laminated beds. This study demonstrates that seafloor topography, strongly controlled by both syndepositional tectonics and the accumulation of mass-transport complexes, likely exerted a significant influence on lobe architecture and the distribution of SFDs. Local increase in bed thickness, together with a progressive decrease in grain size and little variation in the proportion of SFDs in proximal-to-distal and axial-to-lateral directions, can be explained by: i) an increase in basin confinement of the distal part of the Jaca Basin due to tectonically induced narrowing, ii) enhanced local lateral confinement due, at least in part, to “carbonate megaturbidites” present in the distal part of the Jaca Basin and creating topography. Thus, basin confinement is introduced as a new parameter playing a role on flow criticality. There is a decreasing proportion of SFDs between the submarine channels and canyons of the Ainsa Basin and the submarine lobes of the Jaca Basin, the last basin being the focus of this paper. This confirms previous studies showing that channel confinement and slope gradient likely played an important role in flow criticality.

Thrust dissection control of deep-water clastic dispersal patterns in the Klematia–Paramythia foreland basin, western Greece

2000 ◽  
Vol 137 (6) ◽  
pp. 667-685 ◽  
Author(s):  
PAVLOS AVRAMIDIS ◽  
ABRAHAM ZELILIDIS ◽  
NIKOLAOS KONTOPOULOS
Keyword(s):  
Middle Eocene ◽  
Foreland Basin ◽  
Field Studies ◽  
Depositional Environments ◽  
Dispersal Patterns ◽  
Submarine Fans ◽  
Fine Grained ◽  
Thrust Front ◽  
Facies Associations ◽  
Western Greece

The Klematia–Paramythia basin is an internal part of the middle Ionian zone of the Hellenide orogen in western Greece. It consists of Middle Eocene to Late Miocene turbidites, up to 3300 m thick, which were deposited in a series of submarine fans. Field studies suggest that the configuration and the depositional environments of the basin were affected by two tectonic phases. During the first tectonic phase, in Middle Eocene to Late Oligocene times, a foreland basin was formed west of the Pindos Thrust front. During the second tectonic phase, in the Early Miocene, the Ionian zone (a part of the foreland basin) was subdivided by internal thrusting into three sub-basins (internal, middle and external) and changed to a complex type foreland basin. Comparison of the type and facies associations of the turbidite deposits that accumulated within the basin suggests that these two tectonic phases had a significant effect on sedimentary dispersal patterns. During the first tectonic phase in the Klematia–Paramythia basin (when it was part of the foreland basin), fine-grained turbidites, up to 1050 m thick, accumulated on the distal part of a submarine fan. The lower part (900 m thick) of these deposits consists of thin to thick interbedded sandstone/mudstone beds which are interpreted as lobes and lobe-fringe (outer-fan) deposits. The upper parts (150 m thick) of these deposits are composed of very thin to thin siltstone/mudstone beds, representing a basin plain environment. During the second tectonic phase, sediments up to 2260 m thick were deposited in the Klematia–Paramythia basin. These deposits are interpreted as lobes and lobe-fringe (outer-fan) fine-grained turbidites in the central part of the basin, channel and interchannel deposits (inner-fan) in some areas of the periphery of the basin, and shelf deposits in the northern and southern terminations of the basin.

scholarly journals Chasing the 400 kyr pacing of deep-marine sandy submarine fans: Middle Eocene Aínsa Basin, Spanish Pyrenees

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2019-173 ◽  
Author(s):  
Blanca Cantalejo ◽  
Kevin T. Pickering ◽  
Ken G. Miller ◽  
Conall Mac Niocaill
Keyword(s):  
Gamma Ray ◽  
Middle Eocene ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Marine Environments ◽  
Submarine Fans ◽  
Fine Grained ◽  
Spanish Pyrenees ◽  
Tectonically Active ◽  
Anchor Points

In an attempt to understand the relative importance of climate and tectonics in modulating coarse-grained sediment flux to a tectonically active basin during what many researchers believe to be a greenhouse period, we have studied the Middle Eocene deep-marine Aínsa Basin, Spanish Pyrenees. We use orbital tuning of many spectral gamma-ray-logged fine-grained siliciclastic sections, already shown to contain Milankovitch frequencies, in conjunction with a new high-resolution palaeomagnetic study through the basin sediments, to identify polarity reversals in the basin as anchor points to allow the conversion of a depth-stratigraphy to a chronostratigraphy. We use these data, in conjunction with a new age model incorporating new biostratigraphic data, to pace the development of the deep-marine sandy submarine fans over c. 8 million years. Timing for the sandy submarine fans shows that, unlike for the fine-grained interfan sediments, coarse-grained delivery to the basin was more complex. Approximately 72% of the sandy fans are potentially coincident with the long-eccentricity (400 kyr) minima and, therefore, potentially recording changing climate. The stratigraphic position of some sandy fans is at variance with this, specifically those that likely coincide with a period of known increased tectonic activity within the Aínsa Basin, which we propose represents the time when the basin was converted into a thrust-top basin (Gavarnie thrust sheet), presumably associated with rapid uplift and redeposition of coarse clastics into deep-marine environments. We also identify sub-Milankovitch climate signals such as the c. 41.5 Ma Late Lutetian Thermal Maximum. This study demonstrates the complex nature of drivers on deep-marine sandy fans in a tectonically active basin over c. 8 Myr. Findings of this study suggest that, even during greenhouse periods, sandy submarine fans are more likely linked with times of eccentricity minima and climate change, broadly consistent with the concept of lowstand fans. However, hysteresis effects in orogenic processes of mountain uplift, erosion and delivery of coarse siliciclastics via fluvial systems to coastal (deltaic) and shallow-marine environments likely contributed to the complex signals that we recognize, including the 2–3 Myr time gap between the onset of deep-marine fine-grained sediments in the early development of the Aínsa Basin and the arrival of the first sandy fans.Supplementary Materials: Filtered records for each of the analysed gamma-ray logged sections. Anchor points, SARs tables and graphs and alternative tuning sections are available at: https://doi.org/10.6084/m9.figshare.c.5132975

The late Miocene eolian record at the eastern margin of the Puna Plateau, NW Argentina: Evidence of upper-tropospheric paleocirculation

2022 ◽  
Vol 92 (1) ◽  
pp. 32-49
Author(s):  
Jonathan Ledesma ◽  
Cecilia E. Del Papa ◽  
Patricio Payrola
Keyword(s):  
Atmospheric Circulation ◽  
Late Miocene ◽  
Amazon Basin ◽  
Coarse Grained ◽  
Small Scale ◽  
Provenance Analysis ◽  
Humid Climate ◽  
Upper Troposphere ◽  
Facies Associations ◽  
Puna Plateau

Abstract The Puna–Altiplano Plateau of the Central Andes is the second-highest plateau in the world (after Tibet), with a mean elevation of 4000 m.a.s.l. and an arid to hyperarid climate. Uplift of the Puna–Altiplano Plateau has affected lower-level atmospheric circulation, acting as a barrier to humid easterly winds from the Amazon basin and favoring an across-strike precipitation gradient resulting in a humid climate towards the east of the plateau and an arid to hyperarid climate in the orogen's interior. In the modern climate, the Bolivian High anticyclone regulates upper troposphere circulation, but little is known about the high-altitude tropospheric circulation of the past. This work focuses on the eolian record of the San Antonio de los Cobres basin along the eastern border of the Puna Plateau, NW Argentina, with the aim of analyzing its origin and thus elucidating the late Miocene winds. The eolian deposits are constrained by 7.8 Ma (K/Ar and U/Pb) and 6.4 Ma (U/Pb) ignimbrites at the nearly basal and upper contacts, respectively. Based on stratigraphic, sedimentological, and provenance analysis of the eolian units, we have identified three main facies associations (FAs): FA1) cross-stratified sandstones with large- to small-scale tabular, planar cross-bedding and with trough cross-stratification; FA2) sandstones with planar to low-angle stratification associated with thinly laminated ripple sandstone strata; FA3) medium- to coarse-grained massive sandstones associated with pebbly to bouldery, matrix-supported conglomerates and clast-supported conglomerates. The lateral and vertical facies assemblages indicate a dune field confined to topographic depressions dominated by transverse dunes with straight and sinuous crestlines that laterally grade into sandsheets associated with ephemeral streams. Paleoflows, lithotypes, and grain-size determinations indicate a persistent north-northwest provenance and wind velocities of 24–38 km/h (with maximum velocities of 55–75 km/h). The results of our analysis coupled with data from previous studies indicates that, for at least the last ca. 8 Myr, the winds have been blowing constantly from the north-northwest with an intensity similar to the present. This implies that the paleo-atmospheric circulation had a similar pattern to the present-day one. Therefore, we conclude that the upper-troposphere circulation in the Puna Plateau of NW Argentina was already regulated by the Bolivian High anticyclone during the Miocene, generating constant north-northwesterly winds.

APPROACHES TO PALAEOGEOGRAPHIC RECONSTRUCTIONS OF THE LATROBE GROUP, GIPPSLAND BASIN, SOUTHEASTERN AUSTRALIA

2005 ◽  
Vol 45 (1) ◽  
pp. 581 ◽  
Author(s):  
T. Bernecker ◽  
A.D. Partridge
Keyword(s):  
Co2 Storage ◽  
Depositional Environments ◽  
Petroleum Systems ◽  
Fine Grained ◽  
Southeastern Australia ◽  
Depositional System ◽  
Facies Associations ◽  
Marine Fossils ◽  
Coal Accumulation ◽  
Gippsland Basin

In the Gippsland Basin, the seaward extent of paralic coal occurrences can be mapped in successive time slices through the Paleocene and Eocene to provide a series of straight to gently arcuate surrogate palaeoshorelines within the petroliferous Latrobe Group. Palaeogeographic reconstructions that incorporate this information provide a unique perspective on the changes affecting a siliciclastic depositional system on a passive continental margin where basin development has been primarily controlled by thermal sag. In contrast, the absence of calcareous marine fossils and lack of extensive, widespread and thick fine-grained sediments on the marine shelf and continental slope, beyond the seaward limits of coal accumulation, have contributed to the false impression that the Latrobe Group accumulated in a largely non-marine basin. Based on the proposed model for palaeoshoreline delineation, seismic data, sequence analysis, petrography and palynology can be integrated to subdivide the main depositional environments into distinct facies associations that can be used to predict the distribution of petroleum systems elements in the basin. The application of such palaeogeographic models to the older section of the Latrobe Group can improve the identification of these petroleum systems elements in as yet unexplored parts of the Gippsland Basin. Given the recent attention paid to the basin as a CO2 storage province, palaeogeographic interpretations may be able to assist with the selection of appropriate injection sites.

Environmental control on granular clinoforms of ancient carbonate shelves

2006 ◽  
Vol 143 (3) ◽  
pp. 343-365 ◽  
Author(s):  
A. QUIQUEREZ ◽  
G. DROMART
Keyword(s):  
Environmental Control ◽  
Depositional Environments ◽  
Angle Of Repose ◽  
Coarse Grained ◽  
Carbonate Platforms ◽  
Carbonate Sediment ◽  
Sediment Grain Size ◽  
Sedimentary Structures ◽  
Lower Slope ◽  
Sediment Fabric

The purpose of this paper is to document the influence of depositional environments on shallow-water, low-relief clinoforms from the description of five ancient carbonate platforms: the Neoproterozoic (Namibia), Middle Jurassic (France), Lower Cretaceous (France), Upper Cretaceous (Oman) and Miocene (Turkey). These examples have been investigated on the basis of field observations. The clinoforms are described with reference to geometric and compositional attributes: declivity, shape, height, sedimentary structures, sediment fabric and components. The results show great variability in stratal geometry, declivity and facies distribution: (1) depositional profiles vary from exponential, to sigmoidal, to oblique; (2) maximal slope angles range from 3 to 25°, most of them being grouped between 10 and 18°; (3) facies differentiation identified from lateral facies successions along beds, and vertical facies successions through beds, is pronounced to subtle. This study documents linkages between depositional environments and clinoform attributes. Proximal/shallow clinoforms display round-edged exponential profiles. Sediment deposition has resulted from unidirectional currents in the upper convex section, and storm-generated oscillatory currents in the lower concave part. The sediment fabric changes gradually along this type of clinoform. There is little vertical facies differentiation through these clinobeds which have formed from a continuous amalgamation of deposits. By contrast, distal clinoforms (shelf break, distally steepened ramp settings) yield a much broader spectrum of profiles and are generally shorter and steeper. Sedimentary structures in gravel-sized deposits of the upper slope indicate pure traction by unidirectional currents. Conversely, marks of oscillatory flows (undular, wavy top bounding surfaces of clinobeds) are common in the lower slope. Intercalation of massive, fine-grained deposits suggests offshore transport of carbonate mud by suspension. Each distal clinobed represents a single flow event. Accordingly, facies differentiation is weak laterally but may be pronounced through the clinobeds. Our study suggests that low-relief forms of proximal/shallow environments, which contain coarse-grained and photo-independently produced debris, record hydrodynamic equilibrium profiles, whereas the higher-relief forms of this setting rather reflect a high differential production rate of carbonate sediment with water depth. The carbonate sediment of the distal clinobeds mainly derives from skeletal production by oligophotic and photo-independent biota of the middle shelf/ramp and upper portion of the clinoforms. The contribution by in situ skeletal biota only becomes significant on the lower slope, indicating that the distal, submerged slopes of carbonate platforms are not organically but hydrodynamically generated. Our compilation shows that the slope angles of shallow marine, low-relief clinoforms do not simply correlate to the sediment grain size and fabric, in contrast to what has been documented for the high, linear slope profiles. This difference stems from the depositional settings, namely the involved transport mechanisms. Low-relief clinoform accretion seems to be dominantly influenced by wave-induced sediment transport, in contrast to linear flanks of high-relief clinoforms that build to the angle of repose, and for which gravity is the primary transport process.

Origins and engineering hazards of Swedish glaciomarine and marine clays

1991 ◽  
Vol 7 (1) ◽  
pp. 257-264 ◽  
Author(s):  
R. L. Stevens ◽  
M. S. Rosenbaum ◽  
L. G. Hellgren
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Three Dimensional ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Land Uplift ◽  
Fine Grained ◽  
Depositional Settings ◽  
Late Weichselian ◽  
Three Dimensional Models

AbstractThis paper relates the Engineering features of fine-grained clays in the Göteborg area to their glacial sources, depositional settings and postdepositional changes. These deposits occupy valley and coastal areas where urban expansion has been concentrated, despite the considerable problems with settlement and quick-clay behaviour. Both mineralogical and permeability trends are largely determined by the textural characteristics of the deposits. The depositional environments, which have largely controlled the textural trends, are known to have evolved during late Weichselian times due to glacial retreat, isostatic land uplift and climatic changes. A generalized lithostratigraphical model has been produced and this is used here to help understand and predict the variability of the geotechnical properties. The stratigraphical trends in texture, mineralogy and structure are considered within four broad genetic categories: 1) coarse-grained glacial deposits, 2) glaciomarine deposits, 3) very distal glaciomarine deposits, and 4) shallow-marine deposits. These divisions can often be recognized within the logs of geotechnical reports, which suggested that they could provide the basis for development of three-dimensional models which have both geological and geotechnical predictive power within the vicinity of Göteborg. They could also act as a guide for the development of similar models in urban areas elsewhere.

scholarly journals Paleogene extension in the Northern Aegean: Colluvial/debris flow deposits of the Early-Middle Eocene in NW Thrace Basin, Turkey

2021 ◽  
Vol 72 (3) ◽  
Author(s):  
Serdar Akgündüz ◽  
Hayrettin Koral
Keyword(s):  
Debris Flow ◽  
Fault Zone ◽  
Middle Eocene ◽  
Late Eocene ◽  
Coarse Grained ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Early Oligocene ◽  
Thrace Basin ◽  
Nw Turkey

The Thrace Basin consists of Paleogene–Neogene deposits that lie in the lowland south of the Strandja highlands in NW Turkey, where metagranitic and metasedimentary rocks occur. The Akalan Formation consisting of colluvial fan/debris flow deposits represents the base of the sequence in the northern Thrace basin where it is bounded by a right lateral strike-slip oblique fault called “The Western Strandja Fault Zone”. This formation exhibits a coarse-grained, angular and grain-supported character close to the fault zone which has releasing-bends. Fine-grained, rounded, and matrix-supported sediments occur away from the contact. During this study, the Akalan Formation is described for the first time as having larger benthic foraminifera (LBF) of Coskinolina sp of Ypresian–Lutetian, Nummulites obesus of early Lutetian, Dictyoconus egyptiensis of Lutetian, Orbitolites sp. of Ypresian–Bartonian, Miliola sp of early–middle Eocene, Idalina grelaudae of early Lutetian–Priabonian, Ammobaculites agglutinans, Amphimorphina crassa, Dentalina sp., Nodosaria sp., Operculina sp., Lenticulina sp., Quinqueloculina sp. and Amphistegina sp. of Eocene. This unit passes upward with a conformity into reefal limestones of the middle/late Eocene–early Oligocene Soğucak Formation. At times, the limestone overlies the conformity, there is an indication of a prograding sedimentary sequence. The new stratigraphic, paleontological, sedimentological and structural findings related to the NW Thrace Basin suggest a strong transtensional/extensional tectonic control for the initial Paleogene sedimentary deposition during the Ypresian–Lutetian period as shown by fossil content of the Akalan Formation. Right lateral-slip extensional tectonics appears to have had activity during the middle–late Eocene transgressive deposition of the Soğucak Formation when the basin became deepened and enlarged.

Sign in / Sign up

Export Citation Format

Share Document