Late Pleistocene Deep-Water Stratigraphy and Depositional Processes, Offshore Trinidad and Tobago

2000 ◽  
pp. 104-115 ◽  
Author(s):  
Tonya R. Brami ◽  
Carlos Pirmez ◽  
Curtis Archie ◽  
Sookdeo Heeralal ◽  
Kelly L. Holman
Keyword(s):  
Trinidad And Tobago ◽  
Late Pleistocene ◽  
Deep Water ◽  
Depositional Processes

Variability of fine-grained basin floor turbidites and evaluation of controls on their development: Late Pleistocene, Gulf of Corinth, Greece

2020 ◽  
Author(s):  
Natacha Fabregas ◽  
Robert Gawthorpe ◽  
Mary Ford ◽  
Martin Muravchik ◽  
Sofia Pechlivanidou ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Deep Water ◽  
Rift Basins ◽  
Fine Grained ◽  
Sea Level Fluctuations ◽  
Sediment Routing ◽  
Gulf Of Corinth ◽  
Depositional Processes ◽  
Energy Flows ◽  
Basin Floor

<p>The Gulf of Corinth is one of the World’s fastest extending continental rift basins. During the Late Pleistocene, it alternated between marine and lacustrine conditions due to climate-driven sea-level fluctuations connecting or isolating/semi-isolating it from the open ocean. Core from IODP Expedition 381 (Corinth Active Rift Development) provide a continuous record of depositional processes operating within this deep-water rift and the interaction of tectonic and climate drivers controlling deep-water deposition over the Middle to Late Pleistocene. Subaqueous sediment density flows affect the Gulf of Corinth and are classified either by physical flow properties and grain support mechanisms or by depositional processes. Existing classifications mainly describe deposits from decimetre to 10’s of meter scale with an emphasis on sandy beds. Thinner (millimetre to centimetre scale) and finer (muddy to sandy) subaqueous sedimentary density flows beds are understudied. Low energy flows and tail of flow processes need a better understanding and are the target of this work. The aim of this study is to characterise the variability of fine-grained subaqueous sedimentary gravity flow deposits and the controls on their development based on core data from Site M0079 (IODP Expedition 381).  This site is located in the deepest part of the Gulf of Corinth (857 m water depth), in the most distal part of the sediment routing system. Analyses were performed within a 100 m interval covering Marine Isotope Stages 6 and 7 (from ~130 to ~250 ka). Detailed, sub-centimetre visual logging recorded over 2 000 beds classified according to (1) the presence/absence of a coarse base, (2) the grain-size (silty or sandy) of the base (if any), (3) the presence/absence of laminations within the muddy intervals, (4) sedimentary structures. The bed types reflect the diversity of the sedimentary processes and the subaqueous sediment density flows are thus organised within the depositional model. Bed frequency analysis provides insight into the variability between marine and lacustrine conditions. Relative chemical composition obtained from high resolution (2 mm) X-ray fluorescence scanning is used: (1) to examine the interactions between tail of the flow and background sedimentation in the basin and (2) to assess the provenance of the sediments.</p>

An integrated high-resolution geophysical and geologic visualization of a Lake Bonneville shoreline deposit (Utah, USA)

2019 ◽  
Vol 7 (2) ◽  
pp. T265-T282 ◽  
Author(s):  
Katelynn M. Smith ◽  
John H. McBride ◽  
Stephen T. Nelson ◽  
R. William Keach ◽  
Samuel M. Hudson ◽  
...  
Keyword(s):  
High Resolution ◽  
Late Pleistocene ◽  
Depositional Environment ◽  
Three Dimensional ◽  
Sedimentary Facies ◽  
Basin And Range ◽  
Basin And Range Province ◽  
Lake Bonneville ◽  
Depositional Processes ◽  
Gravel Bar

Pilot Valley, located in the eastern Basin and Range, Western Utah, USA, contains numerous shorelines and depositional remnants of Late Pleistocene Lake Bonneville. These remnants present excellent ground-penetrating radar (GPR) targets due to their coherent stratification, low-clay, low-salinity, and low moisture content. Three-dimensional GPR imaging can resolve fine-scale stratigraphy of these deposits down to a few centimeters, and when combined with detailed outcrop characterization, it provides an in-depth look at the architecture of these deposits. On the western side of Pilot Valley, a well-preserved late Pleistocene gravel bar records shoreline depositional processes associated with the Provo (or just post-Provo) shoreline period. GPR data, measured stratigraphic sections, cores, paleontological sampling for paleoecology and radiocarbon dating, and mineralogical analysis permit a detailed reconstruction of the depositional environment of this well-exposed prograding gravel bar. Contrary to other described Bonneville shoreline deposits, calibrated radiocarbon ages ranging from 16.5 to 14.3 (ka, BP) indicate that the bar was stable and active during an overall regressive stage of the lake, as it dropped from the Provo shoreline (or just post-Provo level). Our study provides a model for an ancient pluvial lakeshore depositional environment in the Basin and Range province and suggests that stable, progradational bedforms common to the various stages of Lake Bonneville are likely not all associated with periods of shoreline stability, as is commonly assumed. The high-resolution GPR visualization demonstrates the high degree of compartmentalization possible for a potential subsurface reservoir target based on ancient shoreline sedimentary facies.

scholarly journals Markov chains and entropy tests in genetic-based lithofacies analysis of deep-water clastic depositional systems

2016 ◽  
Vol 8 (1) ◽  
pp. 45-51
Author(s):  
Szabolcs Borka
Keyword(s):  
Markov Chains ◽  
Deep Water ◽  
Pannonian Basin ◽  
Depositional Environments ◽  
Structural Elements ◽  
Chi Square ◽  
Fine Grained ◽  
Hydrocarbon Reservoir ◽  
Depositional Processes ◽  
Chi Square Test

AbstractThe aim of this study was to examine the relationship between structural elements and the so-called genetic lithofacies in a clastic deep-water depositional system. Process-sedimentology has recently been gaining importance in the characterization of these systems. This way the recognized facies attributes can be associated with the depositional processes establishing the genetic lithofacies. In this paper this approach was presented through a case study of a Tertiary deep-water sequence of the Pannonian-basin.Of course it was necessary to interpret the stratigraphy of the sequences in terms of “general” sedimentology, focusing on the structural elements. For this purpose, well-logs and standard deep-water models were applied.The cyclicity of sedimentary sequences can be easily revealed by using Markov chains. Though Markov chain analysis has broad application in mainly fluvial depositional environments, its utilization is uncommon in deep-water systems. In this context genetic lithofacies was determined and analysed by embedded Markov chains. The randomness in the presence of a lithofacies within a cycle was estimated by entropy tests (entropy after depositional, before depositional, for the whole system). Subsequently the relationships between lithofacies were revealed and a depositional model (i.e. modal cycle) was produced with 90% confidence level of stationarity. The non-randomness of the latter was tested by chi-square test.The consequences coming from the comparison of “general” sequences (composed of architectural elements), the genetic-based sequences (showing the distributions of the genetic lithofacies) and the lithofacies relationships were discussed in details. This way main depositional channel has the best, channelized lobes have good potential hydrocarbon reservoir attributes, with symmetric alternation of persistent fine-grained sandstone (Facies D) and muddy fine-grained sandstone with traction structures (Facies F)

scholarly journals Fringe or background: Characterizing deep-water mudstones beyond the basin-floor fan sandstone pinchout

2020 ◽  
Vol 90 (12) ◽  
pp. 1678-1705
Author(s):  
Kévin Boulesteix ◽  
Miquel Poyatos-Moré ◽  
David M. Hodgson ◽  
Stephen S. Flint ◽  
Kevin G. Taylor
Keyword(s):  
Deep Water ◽  
Turbidity Currents ◽  
Stratigraphic Correlation ◽  
Low Density ◽  
Karoo Basin ◽  
Depositional Processes ◽  
Stratigraphic Architecture ◽  
Sand Supply ◽  
Stacking Pattern ◽  
Basin Floor

ABSTRACT Mud dominates volumetrically the fraction of sediment delivered and deposited in deep-water environments, and mudstone is a major component of basin-floor successions. However, studies of basin-floor deposits have mainly focused on their proximal sandstone-prone part. A consequent bias therefore remains in the understanding of depositional processes and stratigraphic architecture in mudstone-prone distal settings beyond the sandstone pinchouts of basin-floor fans. This study uses macroscopic and microscopic descriptions of over 500 m of continuous cores from research boreholes from the Permian Skoorsteenberg Formation of the Karoo Basin, South Africa, to document the sedimentology, stratigraphy, and ichnology of a distal mudstone-prone basin-floor succession. Very thin- to thin-bedded mudstones, deposited by low-density turbidity currents, stack to form bedsets bounded by thin packages (< 0.7 m thick) of background mudstones. Genetically related bedsets stack to form bedset packages, which are bounded by thicker (> 0.7 m thick) background mudstones. Stratigraphic correlation between cores suggests that bedsets represent the distal fringes of submarine fan lobe elements and/or lobes, and bedset packages represent the distal fringes of lobe complexes and/or lobe complex sets. The internal stacking pattern of bedsets and bedset packages is highly variable vertically and laterally, which records dominantly autogenic processes (e.g., compensational stacking, avulsion of feeder channels). The background mudstones are characterized by remnant tractional structures and outsize particles, and are interpreted as deposited from low-density turbidity currents and debris flows before intense biogenic reworking. These observations challenge the idea that mud accumulates only from hemipelagic suspension fallout in distal basin-floor environments. Thin background mudstones separating bedsets (< 0.7 m thick) are interpreted to mainly represent autogenically driven lobe abandonment due to up-dip channel avulsion. The thicker background mudstones separating bedset packages (> 0.7 m thick) are interpreted to dominantly mark allogenically driven regional decrease of sand supply to the basin floor. The recognition of sandstone-prone basin-floor fans passing into genetically linked distal fringe mudstones suggests that submarine lobes are at least ∼ 20 km longer than previously estimated. This study provides sedimentological, stratigraphic, and ichnological criteria to differentiate mudstones deposited in different sub-environments in distal deep-water basin-floor settings, with implications for the accurate characterization of basin-floor fan architecture, and their use as archives of paleoenvironmental change.

Options for Monetising Deep Water Gas in Trinidad and Tobago

2014 ◽  
Author(s):  
N. A. Alleyne ◽  
V.. Stoute
Keyword(s):  
Natural Gas ◽  
Trinidad And Tobago ◽  
Deep Water ◽  
Fossil Fuels ◽  
Critical Path ◽  
Petroleum Exploration ◽  
Financial Outcomes ◽  
Associated Gas ◽  
Gas To Liquids ◽  
Water Gas

Abstract Notwithstanding the global thrust to develop renewable sources of energy, fossil fuels, coal, crude oil and natural gas are expected to play a significant role in meeting the world's energy needs for decades to come. Natural gas with the highest hydrogen concentration among the fossil fuels is the preferred fossil fuel from an environmental impact standpoint. Trinidad and Tobago, like the rest of the world, is taking its petroleum exploration activities into deep water, its onshore and continental shelf provinces being fully explored. The development of petroleum reservoirs in deep water has many challenges. This paper explores the unique challenges posed by developing deep water gas fields with a focus on the options available for monetising the natural gas produced from these fields. The options for getting gas to market are well known and include pipelines, liquefied natural gas (LNG), compressed natural gas (CNG), gas to solid petrochemicals (GTS), gas to liquids (GTL) and gas to wire (GTW). Most of these options are operating in Trinidad and Tobago. The paper evaluates the financial outcomes from applying the pipeline, LNG and CNG options, either offshore or onshore, for gas extracted from deep water fields across a range of reserve levels and well productivities. It aims to establish criteria for deciding which means of monetisation is preferred. The reserve and productivity ranges reflect typical values encountered in the deep water provinces in Latin America, North America and Africa. These provinces account for 85% of all the deep water fields and 74 % the deep water reserves which have been discovered worldwide. Because the paper focuses on the monetisation of natural gas, its findings will be applicable to any successful deep water exploration in Trinidad and Tobago because all situations, even the discovery of oil, will require that the associated gas be handled. The handling of gas has the potential of being on the critical path in deciding on the development of deep water fields in Trinidad and Tobago.

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