Ancient Turbidite Research Articles

Turbidity current initiation established using grain-size data: Insights from ancient turbidites

Turbidity current initiation established using grain-size data: Insights from ancient turbidites

Inverse modeling of turbidity currents using an artificial neural network approach: verification for field application

Abstract. Although in situ measurements in modern frequently occurring turbidity currents have been performed, the flow characteristics of turbidity currents that occur only once every 100 years and deposit turbidites over a large area have not yet been elucidated. In this study, we propose a method for estimating the paleo-hydraulic conditions of turbidity currents from ancient turbidites by using machine learning. In this method, we hypothesize that turbidity currents result from suspended sediment clouds that flow down a steep slope in a submarine canyon and into a gently sloping basin plain. Using inverse modeling, we reconstruct seven model input parameters including the initial flow depth, the sediment concentration, and the basin slope. A reasonable number (3500) of repetitions of numerical simulations using a one-dimensional layer-averaged model under various input parameters generates a dataset of the characteristic features of turbidites. This artificial dataset is then used for supervised training of a deep-learning neural network (NN) to produce an inverse model capable of estimating paleo-hydraulic conditions from data on the ancient turbidites. The performance of the inverse model is tested using independently generated datasets. Consequently, the NN successfully reconstructs the flow conditions of the test datasets. In addition, the proposed inverse model is quite robust to random errors in the input data. Judging from the results of subsampling tests, inversion of turbidity currents can be conducted if an individual turbidite can be correlated over 10 km at approximately 1 km intervals. These results suggest that the proposed method can sufficiently analyze field-scale turbidity currents.

Fidelity of turbidites as earthquake records

Turbidites record ground motion in the 2016 Kaikōura earthquake. Recent events are now revealing how turbidites record earthquakes, but turbidites are triggered in many ways, and testing if ancient turbidites are earthquake-triggered remains challenging.

Quantifying tabularity of turbidite beds and its relationship to the inferred degree of basin confinement

Abstract Tabular beds and sheet-like deposits in deep-water systems have been the subject of much research attention; they can form high quality hydrocarbon reservoirs, owing to their excellent lateral continuity and predictable geometry. Additionally, deposit tabularity is a piece of evidence used to infer flow confinement in ancient systems and thus to evaluate the suitability of outcrop datasets as reservoir analogues. However, the quantification of tabularity is rarely attempted and a consistent definition on how to describe it quantitatively is lacking. For this study, published data from eighteen well-constrained ancient turbidite systems in outcrop were analysed. A simple and novel methodology for the quantitative calculation of tabularity along a transect from log panels and photo panels was devised, based on: a) subdividing beds into two groups based on their thickness, b) calculating the percentage of beds continuous across a fixed window (500 m) and c) calculating the rate of thinning for the continuous beds within the same window. Calculations obtained from multiple locations within individual systems enable the investigation of proximal to distal, and axial to lateral changes in tabularity to be captured, and therefore permits the evaluation of tabularity in three-dimensions. A comparison between tabularity of the considered systems and their inferred degree of basin confinement shows that in the confined systems ≥90% of beds are continuous over 500 m compared to ≤40% for the two unconfined systems studied. In addition, different bed types were compared: hybrid event bed thinning rates are shown to be up to three times those of classical turbidites. This methodology provides a new tool to compare tabularity within and between systems quantitatively. It is hoped that the quantitative determination of tabularity will become a common workflow when describing ancient turbidite systems. It is suggested that this approach will enhance the value of outcrop data to inform models capturing the architecture of systems analogous to subsurface hydrocarbon reservoirs.

Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

Submarine fans and turbidite systems are important and sensitive features located offshore from river deltas that archive tectonic events, regional climate, sea level variations and erosional process. Very little is known about the sedimentary structure of the 1800 km long and 400 km wide Mozambique Fan, which is fed by the Zambezi and spreads out into the Mozambique Channel. New multichannel seismic profiles in the Mozambique Basin reveal multiple feeder systems of the upper fan that have been active concurrently or consecutively since Late Cretaceous. We identify two buried, ancient turbidite systems off Mozambique in addition to the previously known Zambezi-Channel system and another hypothesized active system. The oldest part of the upper fan, located north of the present-day mouth of the Zambezi, was active from Late Cretaceous to Eocene times. Regional uplift caused an increased sediment flux that continued until Eocene times, allowing the fan to migrate southwards under the influence of bottom currents. Following the mid-Oligocene marine regression, the Beira High Channel-levee complex fed the Mozambique Fan from the southwest until Miocene times, reworking sediments from the shelf and continental slope into the distal abyssal fan. Since the Miocene, sediments have bypassed the shelf and upper fan region through the Zambezi Valley system directly into the Zambezi Channel. The morphology of the turbidite system off Mozambique is strongly linked to onshore tectonic events and the variations in sea level and sediment flux.

Turbidite systems of lacustrine rift basins: Examples from the Lake Kivu and Lake Albert rifts, East Africa

The Holocene turbidite systems of Lake Kivu and the Pliocene turbidite systems of Lake Albert in the East African Rift were examined using high-resolution 2-D and 3-D seismic reflection data and sediment core information. Based on investigations of seismic facies and lithofacies, several key turbidity-flow depositional elements were observed, including channels, overbank levees with sediment waves, and depositional lobes. Analyses of the sources of the recent and ancient turbidite systems in these two extensional basins suggest that flood-induced hyperpycnal flows are important triggers of turbidity currents in lacustrine rift basins. From source to sink, sediment dispersal, facies distribution, and depositional thickness of the turbidite systems are strongly influenced by rift topography. The Lake Kivu and Lake Albert rifts serve as excellent analogues for understanding the sedimentary patterns of lacustrine turbidites in extensional basins.

Re-created Early Oligocene seabed bathymetry and process-based simulations of the Peïra Cava turbidite system

Abstract: Sea-floor bathymetry is one of the principal controls on the routing of turbidity currents and the subsequent distribution of deposited sediments. Re-created sea-floor bathymetry is thus one of the main inputs for process-based numerical simulation of ancient turbidite systems. The sea floor underlying the Early Oligocene deposits of the Peïra Cava basin (Alpine foreland, southern France) has been re-created from an outcrop dataset by subjecting a surface-based 3D model to stepwise backstripping of overburden and removal of the post-depositional structural overprint. The surfaces that make up the 3D model were constructed based on field data including stratigraphic correlations, structural measurements and geological maps. Since deposition the Peïra Cava turbidites have been folded, faulted, tilted, uplifted and partly eroded, all of which was summarized and then accounted for during re-creation of the palaeo-sea floor. Uncertainties associated with the input parameters used for the re-creation include the lithological composition of the overburden and underburden, palaeo-water depth and structural restoration. The impact of these uncertainties was addressed by creating a range of scenarios within viable ranges for each of the separate parameters and then comparing the relief and geometry of re-created surfaces. Two mid-case palaeobathymetric surfaces were selected and used as input for process-based simulation of turbidity currents using commercially available software designed for modelling density flows. The simulation results were compared with the stratigraphic architecture observed at outcrop. The quality of the correlation was used as a test of how well the re-created palaeobathymetry mimics the true ancient sea floor.

Stratigraphic modelling of turbidite prospects to reduce exploration risk

This article presents an integrated workflow to model the evolution of ancient turbidity currents on a 3D structurally reconstructed palaeo-seafloor, allowing ancient turbidite sediment distributions to be estimated. Effective use of such approaches requires efficient model-inversion procedures so that model parameters (e.g. flow dimensions, densities etc.) can be estimated from any available data. It is shown that a directed Monte Carlo approach (i.e. a simple genetic search algorithm) is very effective. A case study of a Mesozoic prospect in the UK North Sea shows the power of these methods to discriminate between potentially attractive sediment-source locations. The main power of this approach lies in its ability to exclude many, otherwise attractive, sedimentation scenarios.

New insight into the evolution of large‐volume turbidity currents: comparison of turbidite shape and previous modelling results

AbstractThe Marnoso Arenacea Formation provides the most extensive correlation of individual flow deposits (beds) yet documented in an ancient turbidite system. These correlations provide unusually detailed constraints on bed shape, which is used to deduce flow evolution and assess the validity of numerical and laboratory models. Bed volumes have an approximately log‐normal frequency distribution; a small number of flows dominated sediment supply to this non‐channelized basin plain. Turbidite sandstone within small‐volume (<0·7 km3) beds thins downflow in an approximately exponential fashion. This shape is a property of spatially depletive flows, and has been reproduced by previous mathematical models and laboratory experiments. Sandstone intervals in larger‐volume (0·7–7 km3) beds have a broad thickness maximum in their proximal part. Grain‐size trends within this broad thickness maximum indicate spatially near‐uniform flow for distances of ∼30 km, although the flow was temporally unsteady. Previous mathematical models and laboratory experiments have not reproduced this type of deposit shape. This may be because models fail to simulate the way in which near bed sediment concentration tends towards a constant value (saturates) in powerful flows. Alternatively, the discrepancy may be the result of relatively high ratios of flow thickness and sediment settling velocity in submarine flows, together with very gradual changes in sea‐floor gradient. Intra‐bed erosion, temporally varying discharge, and reworking of suspension fallout as bedload could also help to explain the discrepancy in deposit shape. Most large‐volume beds contain an internal erosion surface underlain by inversely graded sandstone, recording waxing and waning flow. It has been inferred previously that these characteristics are diagnostic of turbidites generated by hyperpycnal flood discharge. These turbidites are too voluminous to have been formed by hyperpycnal flows, unless such flows are capable of eroding cubic kilometres of sea‐floor sediment. It is more likely that these flows originated from submarine slope failure. Two beds comprise multiple sandstone intervals separated only by turbidite mudstone. These features suggest that the submarine slope failures occurred as either a waxing and waning event, or in a number of stages.

Density- and viscosity-stratified gravity currents: Insight from laboratory experiments and implications for submarine flow deposits

Vertical stratification of particle concentration is a common if not ubiquitous feature of submarine particulate gravity flows. To investigate the control of stratification on current behaviour, analogue stratified flows were studied using laboratory experiments. Stratified density currents were generated by releasing two-layer glycerol solutions into a tank of water. Flows were sustained for periods of tens of seconds and their velocity and concentration measured. In a set of experiments the strength of the initial density and viscosity stratification was increased by progressively varying the lower-layer concentration, C L. Two types of current were observed indicating two regimes of behaviour. Currents with a faster-moving high-concentration basal region that outran the upper layer were produced if C L < 75%. Above this critical value of C L, currents were formed with a relatively slow, high-concentration base that lagged behind the flow front. The observed transition in behaviour is interpreted to indicate a change from inertia- to viscosity-dominated flow with increasing concentration. The reduction in lower-layer velocity at high concentrations is explained by enhanced drag at low Reynolds numbers. Results show that vertical stratification produces longitudinal stratification in the currents. Furthermore, different vertical and temporal velocity and concentration profiles characterise the observed flow types. Implications for the deposit character of particle-laden currents are discussed and illustrated using examples from ancient turbidite systems.

Beds comprising debrite sandwiched within co‐genetic turbidite: origin and widespread occurrence in distal depositional environments

AbstractCo‐genetic debrite–turbidite beds occur in a variety of modern and ancient turbidite systems. Their basic character is distinctive. An ungraded muddy sandstone interval is encased within mud‐poor graded sandstone, siltstone and mudstone. The muddy sandstone interval preserves evidence of en masse deposition and is thus termed a debrite. The mud‐poor sandstone, siltstone and mudstone show features indicating progressive layer‐by‐layer deposition and are thus called a turbidite. Palaeocurrent indicators, ubiquitous stratigraphic association and the position of hemipelagic intervals demonstrate that debrite and enclosing turbidite originate in the same event. Detailed field observations are presented for co‐genetic debrite–turbidite beds in three widespread sequences of variable age: the Miocene Marnoso Arenacea Formation in the Italian Apennines; the Silurian Aberystwyth Grits in Wales; and Quaternary deposits of the Agadir Basin, offshore Morocco. Deposition of these sequences occurred in similar unchannellized basin‐plain settings. Co‐genetic debrite–turbidite beds were deposited from longitudinally segregated flow events, comprising both debris flow and forerunning turbidity current. It is most likely that the debris flow was generated by relatively shallow (few tens of centimetres) erosion of mud‐rich sea‐floor sediment. Changes in the settling behaviour of sand grains from a muddy fluid as flows decelerated may also have contributed to debrite deposition. The association with distal settings results from the ubiquitous presence of muddy deposits in such locations, which may be eroded and disaggregated to form a cohesive debris flow. Debrite intervals may be extensive (&gt; 26 × 10 km in the Marnoso Arenacea Formation) and are not restricted to basin margins. Such long debris flow run‐out on low‐gradient sea floor (&lt; 0·1°) may simply be due to low yield strength (≪ 50 Pa) of the debris–water mixture. This study emphasizes that multiple flow types, and transformations between flow types, can occur within the distal parts of submarine flow events.

Scaling analysis of deposition from turbidity currents

Many oil-bearing sedimentary deposits are formed by the settling of particles from turbidity currents. Modeling sedimentary processes that form these turbidites enables the calculation of properties such as extent, depth, porosity and permeability of hydrocarbon-bearing reservoirs. This paper estimates the extent and thickness of turbidites from the initial conditions of the turbidity flow. This is achieved by the application of scaling analysis of the partial differential equations that govern the dynamics of and deposition from turbidity currents. We apply the results of scaling analysis to five modern submarine fans. The predicted and actual values of the dimensions of the fan deposits match well. We then compare the derived results against tabulated sizes of ancient turbidites. The comparisons are good as long as we correctly identify the flow regimes in which the deposition took place. The good agreements observed in the two cases show that the estimates obtained using scaling analysis can provide useful first-guess values for the dimensions of the deposits.

Modelling subaqueous bipartite sediment gravity flows on the basis of outcrop constraints: first results

This paper presents the first attempt to provide a two-dimensional numerical model simulating processes and related deposits of individual subaqueous bipartite gravity flows. A new code for dense flows has been implemented and coupled with a code for turbulent flows. An integrated approach has been adopted: the numerical model is constrained by detailed facies tract analysis of outcropping ancient turbidites, and by grain-size analyses performed on the individual component facies. The results presented here illustrate the ability of the coupled model to simulate with good accuracy both the dense and turbulent flows and the related deposits. Particularly, the model can reproduce grain-size distributions comparable to those measured from the ancient turbidites.

Paleo-bathymetric controls on the stratigraphic architecture and reservoir development of confined fans in the Auger Basin: central Gulf of Mexico slope

With abundant well penetrations in proximal and distal settings and 3D seismic coverage, the Auger Basin is an ideal location to study the influence of basin setting and accommodation on the stratigraphic architecture of ancient turbidite systems. Pliocene-age turbidites at Macaroni Field were deposited in ponded accommodation in the distal portion of a salt-bounded intraslope basin, immediately inboard of a sediment spill point to the linked outboard basin. Deposits at Auger Field are contained within point-sourced submarine fans deposited in healed slope accommodation in the more proximal portion of the basin on the flank of a paleo-bathymetric ridge, immediately down depositional dip of a sediment spill point from an inboard basin. Both areas of the basin are distinct in terms of sediment dispersal patterns, rate of sediment fill, and preservation potential of reservoir/seal pairs, and while both fields contain sand-rich deposits and record vertical evolution from older sheet dominated- to younger channel dominated deposits over the Late Pliocene section, there are key differences in the nature in which the fill occurs. The ponded stratigraphic section at Macaroni Field records (1) an early mud-rich phase in which incoming flows are completely captured by confining topography, (2) a brief phase of diminished relief when high frequency fill/spill cycles occur, and ultimately (3) a phase of incision of the former basin sill and large-scale bypass to the outboard basin. Over the same period, the healed-slope section at Auger Field records a fill pattern consisting of alternating episodes of initial sand-rich sheet/lobe deposition followed by intervals of channelization. We acknowledge extra-basinal controls (eustacy, climate) on the timing, rate, and nature of sediment supply to the basin, but there is considerable evidence for paleo-bathymetric control on cyclical fill patterns observed at fourth and higher-order scales.

Outcrop‐scale acoustic facies analysis and latest Quaternary development of Hueneme and Dume submarine fans, offshore California

The uppermost Quaternary deposits of the Hueneme and Dume submarine fans in the Santa Monica Basin have been investigated using a closed‐spaced grid of boomer seismic‐reflection profiles, which give vertical resolution of a few tens of centimetres with acoustic penetration to 50 m. Acoustic facies integrated with geometry define six architectural elements, some with discrete subelements that are of a scale that can be recognized in outcrops of ancient turbidite systems. In the Santa Monica Basin, the relationship of these elements to fan morphology, stratigraphy and sediment source is precisely known.The width of upper Hueneme fan valley has been reduced from 5 km since the last glacial maximum to 1 km at present by construction of laterally confined sandy levees within the main valley. The middle fan comprises three main subelements: thick sand deposits at the termination of the fan valley, low‐gradient sandy lobes typically 5 km long and &lt; 10 m thick, and scoured lobes formed of alternating sand and mud beds with many erosional depressions. The site of thickest lobe sediment accumulation shifts through time, with each sand bed deposited in a previous bathymetric low (i.e. compensation cycles). The lower fan and basin plain consists of sheet‐like alternations of sand and mud with shallow channels and lenses.Variations in the rate of late Quaternary sea level rise initiated changes in sediment facies distribution. At lowstand, and during the approximately 11 ka stillstand in sea level, the Hueneme Fan was fed largely by hyperpycnal flow from the Santa Clara River delta, depositing high sediment waves on the right hand levee and thick sandy lobes on the middle fan. At highstand of sea level, most turbidity currents were generated by failure of silty prodelta muds. In contrast, the smaller Dume Fan was apparently always fed from littoral drift of sand through a single‐canyon point source.

Abstract: Comparing Modern and Ancient Turbidite Channels and Channel-like Elements: Insight for a First Principle Approach to Exploration and Exploitation of Deep-Water Reservoirs&amp;nbsp;

Abstract: Comparing Modern and Ancient Turbidite Channels and Channel-like Elements: Insight for a First Principle Approach to Exploration and Exploitation of Deep-Water Reservoirs&amp;nbsp;

Numerical simulation of turbidity current flow and sedimentation: II. Results and geological applications

ABSTRACTA process‐based, forward computer model of turbidity current flow and sedimentation, termed the TCFS model, has been developed to trace the downslope evolution of individual turbidity flows. Details of the model itself have been presented in a preceding paper. We here outline a series of tests of the TGFS model.The sensitivity tests of the TCFS model to general geological controls reveal the quantitative relationship between these controls and the behaviour of turbidity flows and the geometry and textural features of the resulting turbidites. Experimental turbidity currents on relatively steep slopes accelerate more rapidly and reach higher velocities than those on gentle slopes. Flows with larger initial volumes have higher initial velocities, travel further downslope, and form beds of greater thickness and downslope extent than smaller flows. Experimental high‐concentration flows with suspended‐sediment concentrations of 25% accelerate more rapidly and reach higher downslope velocities than dilute flows with 5% suspended sediment. The higher velocities and enhanced hindered‐settling effects of the high‐concentration flows lead to much greater transport distances and reduced vertical and lateral sediment size grading in the resulting turbidites. Beds formed by experimental high‐concentration flows are massive or show coarse‐tail grading whereas beds formed by low‐concentration flows show distribution‐grading. Experimental flows fed by coarse sediment sources tend to deposit the bulk of their suspended sediment loads on the proximal slope, resulting in more rapid flow deceleration and sedimentation than flows fed by silt‐rich, fine‐grained sediment sources. Turbidites formed by coarse‐sediment flows tend to have a wedge‐shaped geometry, with low downslope extent and high surface relief, whereas turbidites formed by fine‐sediment flows tend to have a tabular geometry, with greater downslope extent and lower surface relief.A specific geological test of the TCFS model is based on studies of modern turbidity currents in Bute Inlet, British Columbia, Canada. With the input initial and boundary conditions estimated from Bute Inlet, the model predicts the downslope velocity evolution of turbidity currents comparable to those of modern and ancient turbidity flows measured in Bute Inlet. Model‐calculated vertical and downslope grain‐size properties of turbidites are similar to those exhibited by surface and cored Bute Inlet turbidites. Model flows tend to decelerate more rapidly than some stronger turbidity currents in the Bute Inlet system, and model beds tend to decrease in grain‐size downslope more rapidly than observed bottom sediments. This is probably because the TCFS model flows lacked clay, which is abundant in Bute Inlet; they do not fully simulate turbulent mixing of suspended sediments; and they better represent the unsteady, depositional stage of turbidity‐currents than the preceding stage of more‐or‐less steady‐flow conditions.These tests demonstrate that the TCFS model provides a semi‐quantitative method to study the growth patterns of submarine turbidite systems. It can serve as a predictive tool for analysing the facies architecture of ancient turbidite systems through simulating multi‐depositional events by improving its erosion function, and the compatibility between its numerical components.

Late precambrian outer-fan turbidites from Namibia - vertical and lateral characteristics

Little is known about the lateral dimensions of distal (outer-fan to fan-fringe) ancient turbidites because of outcrop limitations. The Zebrapüts and Brak River Formations of the Zerrissene turbidite system, well exposed in hyper-arid Namib Desert of south-western Africa, provide a good opportunity of examining facies types, facies associations, vertical sequences and lateral continuity of distal turbidites. The two formations are characterised by sequences of Mutti and Ricci Lucchi facies B 1, C 2, D 1, D 2, F, G and a glacial facies. Facies F represents small scale slumps related to the glacial facies, and not slumping from shelf areas. Four facies associations have been recognised (designated 1 to 4) and these represent lobe sandstone, fan-fringe, glacial-marine/turbidite and basin plain facies. No large scale thinning- or thickening-upward sequences are present, but minor (compensation) cycles have been recognized. In only one instance are these statistically significant. Individual units are laterally continuous for at least several kilometres. One shallow channel has been identified in the lobe sandstones.

Turbidite systems: State of the art and future directions

The study of turbidite systems covering a wide range of physical scales has led to confusion regarding the use of certain key terms and hence a breakdown in communication between workers involved in turbidite research. There are three fundamentally different scales and types of observations derived from the study of outcrop data (ancient systems), high‐resolution seismic reflection and side scan sonar data (modern systems), and multichannel seismic reflection data (modern and older buried systems). Despite the variability of scale the same terms are used to describe features that may have little in common. Consequently, turbidite system terminology has become imprecise and even misleading in some cases, thus providing impediments to developing useful predictive models for processes, depositional environments, and lateral and vertical distribution of sand bodies within turbidite systems. To address this concern, we review the principal elements critical to deepwater systems: slump scars, submarine canyons, channels, channel fill deposits, overbank deposits, and lobes and discuss some of their recognition criteria with each different type of data base. Local and regional tectonic setting, relative sea level variations, and bottom current activity are probably the main factors that control size, external geometry, internal stratal configuration, and facies characteristics of both modern and ancient turbidite systems. These factors ultimately control the timing and bounding characteristics between stages of growth of deepwater systems. If comparison of elements from different turbidite deposits using various data types is carried out at similar physical and temporal scales, predictive models eventually may be improved.

Astronomically induced paleoclimatic oscillations reflected in Pliocene turbidite deposits on Corfu (Greece): Implications for the interpretation of higher order cyclicity in ancient turbidite systems

Research Article| April 01, 1993 Astronomically induced paleoclimatic oscillations reflected in Pliocene turbidite deposits on Corfu (Greece): Implications for the interpretation of higher order cyclicity in ancient turbidite systems GertJan Weltje; GertJan Weltje 1Comparative Sedimentology Division, Institute of Earth Sciences, P.O. Box 80.021, NL 3508 TA Utrecht, Netherlands Search for other works by this author on: GSW Google Scholar Poppe L. de Boer Poppe L. de Boer 1Comparative Sedimentology Division, Institute of Earth Sciences, P.O. Box 80.021, NL 3508 TA Utrecht, Netherlands Search for other works by this author on: GSW Google Scholar Geology (1993) 21 (4): 307–310. https://doi.org/10.1130/0091-7613(1993)021<0307:AIPORI>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation GertJan Weltje, Poppe L. de Boer; Astronomically induced paleoclimatic oscillations reflected in Pliocene turbidite deposits on Corfu (Greece): Implications for the interpretation of higher order cyclicity in ancient turbidite systems. Geology 1993;; 21 (4): 307–310. doi: https://doi.org/10.1130/0091-7613(1993)021<0307:AIPORI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The growth pattern of fan lobes in the early Pliocene Corfu turbidite system (Greece) demonstrates that regional climatic fluctuations in the land-locked Mediterranean completely concealed global glacioeustatic effects. The temporal evolution of the fan lobes studied closely matches the astronomical precession cycle in this time interval (∼23 ka), strongly suggesting that regular waxing and waning of the sediment supply to the delta-fed turbidite system were directly driven by changes of precipitation and continental runoff. The common lack of high-resolution time control in ancient turbidite systems may lead to mistaken interpretations of higher order cyclicity in ancient turbidite sequences produced by precession-induced variations of sediment supply at low paleolatitudes. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.