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Graphic correlation and sequence stratigraphy of Neogene rocks in the Gulf of Suez

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William N. Krebs at Independent Researcher
William N. Krebs
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William A. Wescott
William A. Wescott
D. Nummedahl
D. Nummedahl
D. Nummedahl
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I. Gaafar
I. Gaafar
I. Gaafar
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Abstract

Graphic correlation of paleontological data from wells and outcrops in the Gulf of Suez reveals that the Neogene section consists of at least eight biostratigraphic sequences (S10-S80) separated by graphic terraces (T00-T70) (geologic lacunae or hiatuses). Field analysis in the Sinai of terraces T00 to T30 and their associated fossil assemblages indicates that they represent widespread regressive or transgressive events. The number of true slratigraphic sequences (those bounded by regressive erosional surfaces) is therefore less than the number of paleontological sequences revealed by graphic correlation. Terraces T00 and T20 are sequence boundaries sensu Vail, and geophysical and well log evidence indicate that T40 is a condensed section and that T50 is an erosional unconformity or sequence boundary. Field observations of lacuna T10 al Wadi Thai in the Sinai region reveal that it consists of two ravinement surfaces and one condensed section in a narrow stratigraphic interval. Similarly, the T30 lacuna associated with the Markha Anhydrite at Wadi Feiran is composed of perhaps seven stacked flooding and regressive surfaces. These surfaces at both Wadi Thai and Wadi Feiran are probably associated with minor hiatuses. These minor hiatuses cannot be individually resolved by graphic correlation, particularly when the paleontological database is derived from well cuttings, but their sum total within a thin rock (hiatal) interval is detectable as a terrace. Despite this limitation, graphic correlation of paleontological data can recognize stratal surfaces and intervals that are critical to sequence stratigraphy. Fieldwork, rock core, well logs, and paleoenvironmental analysis are necessary for their interpretation and integration into sequence stratigraphy.
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... It then seeks to break its stratigraphic architecture into subsequences, which may be correlated to fourth-order, orbital-forcing eccentricity (405 Ky cycles of Laskar et al., 2004) here named stratons (Matthews and Frohlich, 2002;Al-Husseini and Matthews, 2008). Wescott et al. (1996) and Krebs et al. (1997) ...
... In subsequent literature (e.g. EGPC, 1996;Wescott et al., 1996;Dolson et al., 1996;Krebs et al., 1997), the Ayun Musa was raised to a formation and divided into the lower Lagia Member (or Markha Member) and upper Ras Budran Member (Figure 2). ...
... He considered the Lagia non-calcareous shale together with the overlying Rahmi Anhydrite 1 to represent a single regressive cycle. His interpretation is opposite to the one adopted here and by other authors , see their figure 9; Krebs et al., 1997). ...
Miocene Kareem Sequence, Gulf of Suez, Egypt
Article
  • Apr 2010
  • GEOARABIA
The Miocene Kareem Formation in the Egyptian Gulf of Suez, and its equivalent formations throughout the Red Sea (250–550 m thick), contain one of the most important petroleum reservoirs in these highly faulted rift basins. They present a difficult exploration target, particularly over the shelves of the sparsely explored Red Sea for several reasons: (1) water depth exceeds one kilometer, (2) they underlie thick evaporites (including salt exceeding one kilometer in thickness), (3) they are difficult to image by conventional seismic techniques, and (4) their lithology is laterally variable and difficult to predict (anhydrite, carbonate, sandstone, shale and marl). The target Red Sea formations are best controlled by boreholes in the Gulf of Suez, where the Kareem Formation and its members are characterized by various synonymous units. A review of representative data and interpretations shows that the formation and its members are better understood when considered as a third-order, transgressive-regressive (T-R) depositional sequence, named the Kareem Sequence in the Middle East Geologic Time Scale (ME GTS). The Sequence is bounded above by the Belayim Sequence Boundary (Sub-Belayim Unconformity) and below by the Kareem Sequence Boundary (Sub-Kareem Unconformity), both corresponding to major sea-level lowstands. It contains the Arabian Plate Langhian Maximum Flooding Surface Neogene 30 (MFS Ng30) at the top of the Kareem Maximum Flooding Interval (MFI). Its lower Rahmi Member forms the majority of the transgressive systems tract (TST). The Kareem MFI and regressive systems tract (RST or HST) occur within the upper Shagar Member. The paleontology of the Formation is characterized by Planktonic Foraminiferal Zone N9 and in recent papers also N8, and Calcareous Nannofossil Biozone NN5, but the Formation’s assignment to Miocene stages (Burdigalian, Langhian and Serravallian) is unresolved in the literature. In this paper, the Kareem Sequence is interpreted in terms of Kareem subsequences 1 to 6. At semi-regional scales (10s of km), the older three are each represented by an anhydrite bed (Rahmi Anhydrite 1 to 3, each c. 10 m thick) overlain by deep-marine deposits (shale, marl and carbonate, 10s of meters thick). Subsequences 4 to 6 are represented in El Morgan field (Kareem A to C units), and in representative boreholes, by three deep-marine shale/marl units, each of which is overlain by a regressive shallow-marine sandstone unit. The Kareem Sequence is correlated to third-order orbital sequence DS3 1.1 with a depositional period of ca. 2.43 million years between ca. 16.1 and 13.7 million years before present (Ma), or numerically the latest Burdigalian, Langhian and earliest Serravallian (Langhian: 15.97–13.65 Ma in GTS 2004; 15.97–13.82 Ma in GTS 2009). The six subsequences are correlated to the orbital 405,000 year eccentricity cycle (referred to as Stratons 40–35 or DS4 1.1.1 to 1.1.6). The older three subsequences form the transgressive systems tract; the fourth contains the maximum flooding interval MFI (ca. 14.9–14.7 Ma) in its lower part. The regressive systems tract starts in the upper part of the fourth subsequence and encompasses subsequences 5 and 6. The orbital architecture of the Sequence provides a simplified framework for predicting lithology and reservoir development. The six Kareem subsequences carry the orbital-forcing glacio-eustatic signal. During low eccentricity, Antarctic ice-making and global sea-level drops, the northernmost Gulf of Suez and Bab Al Mandeb Strait restricted marine circulation in the Gulf and Red Sea rift basins. The resulting evaporitic setting was associated with the deposition of the Rahmi Anhydrite 1 to 3 beds and exposure over paleohighs. The deeper-marine deposits above the three Rahmi Anhydrite beds, and those of subsequences 4 to 6 reflect high eccentricity, Antarctic ice-melting, global sea-level rises, pluvial conditions at low latitudes (10–30oN), and open-marine circulation in the Red Sea. During pluvial periods, fluvio-deltaic systems prevailed over the mountainous rift shoulders and coastal plains and carried massive clastics into the Gulf and Red Sea Basins.
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... Among the publications concerned with biostratigraphic analysis either in surface sections or subsurface boreholes of the Gulf of Suez (eg: El-Heiny and Martini, 1981;Haggag et al. 1990;El-Azabi, 2004;Abul-Nasr et al. 2009;Al-Husseini, 2012;El-Atfy et al. 2013;Hewaidy et al. 2016;Ied et al. 2019 andShahin andElBaz, 2021;Ayyad et al. 2023). The sequence stratigraphical studies include that of (Hughes et al. 1991;Krebs et al. 1997;Bosworth and McClay 2001;Catuneanu et al. 2011 andGowthrope et al. 2003). Additionally, there are many Geophysical studies to determine the hydrocarbon prospects using well logging and seismic data interpretation (eg: Dolson et al. 2001;Radwan et al. 2021a-c;Sarhan 2020& 2021. ...
... The Syn-rift deposits overlie the Pre-rift ones through a large unconformity. The two lower syn-rift rock units (Abu Zenima and Nukhul formations) are locally disconnected by an angular unconformity and correlatable transgressive surface (Krebs et al. 1997). ...
Biostratigraphy of the Lower Miocene Nukhul Formation, Gulf of Suez, Egypt
Article
Full-text available
  • Apr 2024
Lower Miocene Nukhul Formation of two onshore wells (ARS-6 and SIDRI-20) situated in the Eastern side Gulf of Suez was investigated for their planktonic foraminiferal content to define its geologic age. The identified planktonic foraminifera contain 20 species belonging to 9 genera. The allocation of the planktonic foraminifera proposes two planktonic biozone of ARS-6 well. The Nukhul Formation is the oldest syn-rift deposits in the Gulf of Suez rift system in Egypt and it is an important exploration target and oil-producing reservoir in the Gulf of Suez. It is the primary hydrocarbon producer for fifteen fields in the region. However, local tectonics affect the reservoir quality and determining the exact age of the Syn-rift Nukhul Formation. This research aims to determine the age of the first Syn-rift rock unit in the Abu Rudeis-Sidri field using planktonic foraminifera. The age of Nukhul Formation is a controverse and previous work on them show the differences in their ages. The biostratigraphic analyses indicate that the Nukhul Formation reveals Burdigalian age.
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... Three hiatuses (unconformities) are inferred within this interval: (1) Intra-lower Rudeis I within CNM5 Zone, indicated by sharp, erosional based calcarenite and conglomerate beds, and the disappearance of S. belemnos, S. disbelemnos (Figs. 9, 10, 15); (2) Intra-lower Rudeis II (with a duration of ~ 0.6 Myr) inferred between the S. heteromorphus FCO and the FO of Gs. subquadratus as these events occurred very close to each other just above a calcarenite layer (Figs. 9, 10, 15); and (3) Mid-Rudeis (with a minimum duration of 1 Myr) within CNM5 Zone at the end of Burdigalian between S. heteromorphus FCO and T. sicanus FO (Fig. 15). The Mid-Rudeis unconformity is also recorded in the basinal area of the Gulf of Suez, and referred to by some authors as the mid-Clysmic tectonic event (Patton et al., 1994;Krebs et al., 1997). ...
Biostratigraphically constrained age assessment and paleoenvironments of the early Miocene syn-rift deposits of the Gulf of Suez eastern margin, Egypt
Article
  • Apr 2024
  • J ASIAN EARTH SCI
The absence or rarity of some global marker taxa in the semi-restricted Suez rift basin has led to uncertainty with respect to the age of the early syn-rift deposits. To tackle this issue, high-resolution foraminiferal and calcareous nannofossil biostratigraphy was undertaken on sections in the Wadi Baba area at the eastern basin margin. Two planktic foraminiferal bioevents of early Miocene age are recognized: First Occurrences (FOs) of Globigerinoides subquadratus and Trilobatus sicanus. These bioevents define three zones/subzones: MMi2b, MMi2c-MMi3 and MMi4. Calcareous nannofossil analysis provided the basis for the definition of three zones: CNM4 to CNM6 based on FOs of Helicosphaera ampliaperta and Sphenolithus belemnos, and the first common occurrence of S. heteromorphus. Our results assign a new age estimate of late Aquitanian to early Burdigalian (<19.01 Ma) for the Nukhul Formation, and Burdigalian to early Langhian for the Rudeis Formation, with three possible hiatuses. Integration of benthic foraminiferal biofacies, lithofacies and nannofossil paleoecological markers reveals a broad range of paleoenvironments, from shoreface to upper bathyal. The Nukhul Formation was deposited in nearshore, nutrient-rich, well-oxygenated conditions. Deeper water environments of neritic to upper bathyal prevailed during the Rudeis Formation. Comparison with coeval deposits in the offshore area of the basin reveals significant paleoenvironmental variability during the Burdigalian associated with episodic subsidence along basinal faults. Climate-sensitive taxa and oxygen isotope data indicate a prevalence of warm paleoclimatic conditions. Our results suggest the development of a seaway connecting the Gulf of Suez with the Mediterranean during the early Miocene rather than Chattian.
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... The Eocene-Oligocene transition is marked by large-scale extinction of organisms, and floral and faunal turnover and changes (Frederiksen, 1988;Haasl and Hansen, 1996; Oboh settings such as continental, coastal and marginal marine (Rull, 2002). Graphic correlation is a fundamental method that offers improved stratigraphic resolution and enhanced accuracy and precision end results (Mann and Lane, 1995;Krebs et al., 1997;Krebs, 2011). ...
Graphic correlation and paleoenvironmental investigation of the upper Eocene-lower Oligocene sediments in the Dahomey Basin, southwestern Nigeria: insights from palynomorphs
Article
Full-text available
  • Dec 2022
This study presents the results of a comprehensive qualitative and quantitative palynological analysis of four shallow boreholes (Epe-1, Olokonla-1, Ikoyi-1 and Badore-1) in the lower Eocene–upper Oligocene periods of the Dahomey Basin, southwestern Nigeria. The lithostratigraphic analysis revealed three lithologies (sandy-shales, shaly-sands and sandstones). Two most important palynological zones, the Verrucatosporites usmensis , as well as the Magnastriatites howardi Pan-tropical zones, are delineated. First Appearance Datum (FAD) of Achomosphaera alcicornu marked the late Eocene–early Oligocene boundaries (E/O) within the four boreholes, while FAD of Adnatosphaeridium multispinosum defined the late Eocene–early Oligocene boundary (E/O) in Ikoy-1. Two informal palynological assemblage zones were revealed in the four boreholes. Common occurrences of palms, mangrove, fresh water and brackish water pollen, and pteridophyte spores with spots records of marine elements and algae species during marine invasion suggested fluctuation from fluvio-deltaic/nearshore to marginal marine paleoenvironments. Graphic correlation discloses that for every meter of sedimentary rock accretion within Epe-1, equally amounted to merely 0.31 m, 0.56 m, as well as 0.47 m of sediments, which were put down in Olokonla-1, Ikoyi-1, as well as Badore-1, respectively. These comparative rates of sedimentary rock accretion show with the purpose of either there is fewer attrition occurrence and/or extra accommodation gap within Epe-1 than Olokonla-1, Ikoyi-1, as well as Badore-1. The assessment of the slopes, intercept and correlation equations through graphic correlation procedures enable the identification of four biostratigraphic events in Epe-1, Olokonla-1, Ikoyi-1, as well as Badore-1. The findings in this investigation are necessary for depositional succession and paleoenvironmental understandings, as well as basin investigation, and above all, to show a relationship of broadly separated boreholes.
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... The eFFT spectrograms of tuned data (Fig. 7c, e) reflect the presence of variable sedimentary cycles at ca. 14-14.7 Ma, which match the g4-g3 orbital resonance between Mars and Earth. The present study revealed the presence of an unconformity surface T40 between the Shagar and Rhami Members, which agrees with Wescott et al. (1996), Krebs et al. (1997), Al-Husseini et al. (2010), and Youssef (2011) with the continuous sedimentation of the Rhami and Mreir Members. ...
Cyclostratigraphy and eccentricity tunning of the middle Miocene succession, Gulf of Suez, Egypt: Astronomical age dating and undetected hiatus
Article
  • May 2022
  • MAR PETROL GEOL
The middle Miocene Kareem Formation is a major hydrocarbon reservoir in the Gulf of Suez rift basin. However, the controversies over the age of the Kareem Formation have remained a subject of debate due to the absence of marker species and the presence of barren intervals, especially in evaporite seals or sand reservoirs. Moreover, the absolute age and duration of a well-known established hiatus in this formation (T40) has not been estimated until now. The present study introduces for the first time an integrated stratigraphic chart of Middle Miocene foraminiferal and calcareous nannofossil bioevents in Egypt, together with an astronomically tuned timescale (ATS) established on gamma-ray variations of two wells, Gs197-2 in the October Basin and J58-81 in the July Basin. This integrated time scale helps us refine the age assignments and estimate the duration of the gaps. According to the new ATS and integrated biostratigraphic age models, the Kareem Formation spans 13.25 to 15.15 Ma, and the major T40 hiatus is found to occur in both wells at the Shagar/Rahmi Members boundary, with a duration of ca. 0.242 Myr and 0.195 Myr in Gs197–2 and J58-81, respectively. These two wells represent the most complete Middle Miocene of the Kareem Formation, recording six calcareous nannofossils, four planktonic, and one benthic foraminiferal biohorizons, and enabling us to define the Langhian-Serravalian boundary. The middle Miocene Kareem succession exhibits prominent decameter-to meter-scale sedimentary cycles, interpreted herein as an imprint of the short eccentricity and obliquity.
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... The eFFT spectrograms of tuned data (Fig. 7c, e) reflect the presence of variable sedimentary cycles at ca. 14-14.7 Ma, which match the g4-g3 orbital resonance between Mars and Earth. The present study revealed the presence of an unconformity surface T40 between the Shagar and Rhami Members, which agrees with Wescott et al. (1996), Krebs et al. (1997), Al-Husseini et al. (2010), and Youssef (2011) with the continuous sedimentation of the Rhami and Mreir Members. ...
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... The Gulf of Suez Rift (GOSR) is one of the most intensively investigated structural elements in North Africa, mainly due to its importance as a significant hydrocarbon territory (Alsharhan and Salah, 1994;Alsharhan, 2003). Much is known about the late syn-rift sediments in the GOSR due to their commercial interest in the subsurface and comparatively widespread exposure in the field (e.g., Wescott et al., 1996;Krebs et al., 1996;Sharp et al., 2000;Young et al., 2000Young et al., , 2003and Leppard and Gawthorpe, 2006). Conversely, relatively little is known about the earliest syn-rift units within the GOSR due to their local preservation at outcrop and lack of penetration by wells in the subsurface. ...
Sedimentary cover determination and structural architecture from gravity data: East of Suez Area, Sinai, Egypt
Article
  • Jan 2022
Potential field data have many applications in structural mapping, mineral exploration, sedimentary cover determination, and searching for groundwater and hydrocarbons in areas like Sinai, Egypt. Consequently, gravity data of the area of study were interpreted to map the basement surface and to detect the geologic structures controlling the area of study. In this study, gravity data were separated into its components (regional and residual). The deep and shallow structures affecting the East of Suez area were detected and statistically analyzed using rose diagram. The thickness of the sediments and basement surface were detected from Analytical Signal (AS) technique. The WNW (Najd fault system), NW (Gulf of Suez trend), and NNE (Gulf of Aqaba trend) were the predominant and oldest structural regimes affecting the East of Suez area. Comparing our results with the previous studies shows that favored flow pathways for groundwater are along the NW and NNE directions. The thickness of the sediment varied from 233 to 5389 m. The central parts of the study area were of suitable thickness for the accumulation of groundwater and hydrocarbons. The results of our study reflect that the gravity data can be used as an initial stage in detecting potential areas for hydrocarbons and groundwater.
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TECTONOSTRATIGRAPHIC RESPONSE TO FAULTING IN RED BED ENVIRONMENT USING LIDAR DATA: THE ABU ZENIMA FORMATION SINAI
Article
  • Jun 2024
This study investigates the tectono-stratigraphic response of the continental red beds of Abu Zenima Formation, Sinai using digital outcrop modelling to the evolution of the intra-block Nukhul fault zone during the Oligo-Miocene initial rifting phase in the Suez Rift, Egypt. Nukhul fault zone is one of the several intra-block fault zones from a 500 Km2 area of the Hammam Faraun fault block and is interpreted to have evolved from two isolated fault segments trending NW-SE. Abu Zenima Formation represents the early fluvio-lacustrine syn-rift stratigraphy and documents an early phase of basin fill in the hanging-wall of Nukhul fault zone. The stratal geometries are characterised by considerable along-strike variability in thickness and onlap relationship. The thickest stratigraphy developed towards the centre of the fault segments. This shows variation in displacement along the strike from maxima at fault centre to minima at fault tip produced as a result of temporal and spatial evolution of normal fault growth. Fault-propagation folds that form due to the growth of extensional faults, in particular fault-parallel syncline and fault-perpendicular anticline control the structural style of the early syn-rift basin. The observed onlap relationship of the lower stratal geometries and the subsequent pronounced thinning of the upper stratal geometries towards the fault-perpendicular anticline from the two NW-SE segments, indicates that the two fault segments interacted at an early age during the initial rifting and were subsequently linked as a normal fault zone. The implication of this study could be related to hydrocarbon exploration of early syn-rift play in many rift basin within the passive (Atlantic type) continental margins. Such basin contains excellent fluvial reservoirs with thickness variation, truncation and onlap relationship across the basin. Thus, understanding the tectonic control and other synorogenic sedimentation and resultant depositional geometries of syn-rift sedimentary rocks will substantially reduces hydrocarbon exploration risk.
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Sedimentology and sequence stratigraphy of shallow and deeper marine Miocene deposits: A case study from the St. Paul and Gebel El‐Zeit blocks, Gulf of Suez, Egypt
Article
  • Dec 2023
Marginal and deeper marine facies typify the Miocene exposures along the western margin of the Gulf of Suez rift basin. The stratigraphic setting of these facies is a subject of debate and confusing at best. Integrative sedimentological and sequence stratigraphic study of successions exposed in the St. Paul and El‐Zeit blocks provides insight into the lateral relationships between the two facies and their evolution, a topic that is not fully understood. The St. Paul block, located at the basin margin, has thin shallow marine facies, while the succession of El‐Zeit block, situated near the basin axis, consists of basal conglomerates, thin shallow marine carbonates, thick deeper marine shale and marginal evaporites. The facies architecture of these successions is interpreted as belonging to two different depositional models: a fan‐delta/lagoon system followed upwards by an alluvial fans/sabkha‐tidal flat system in the St. Paul hangingwall basin, and carbonate–siliciclastic–evaporite systems on the hangingwall dip‐slope ramp of El‐Zeit block. These models may help understanding the sedimentary history of other similar blocks in the rift basin. The studied facies show many striking features such as deposition during tilting of fault block, abrupt facies and thickness variations, coarse clastic shedding, erosion channel filling, onlapping of high standing blocks and evaporite accumulation. These features are the result of major tectonic events that triggered the formation of unconformities at different hierarchical levels during the late early to middle Miocene. These unconformities subdivide the Miocene facies into five depositional sequences separated by basin‐wide erosional boundaries. This division greatly improves the age control of marginal marine facies. It affords new insight into the evolution of marginal marine facies along the western margin of the basin in relation to deeper facies in the basin centre. Facies and thickness changes in these tectonically induced sequences indicate that basin floor irregularities, subsidence rates, climatic changes, variable sediment influx, sea‐level/brine‐level changes and basin isolation/connection to the Mediterranean Sea are also important factors responsible for their evolution.
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A composite standard approach to biostratigraphic evaluation of the North Sea Palaeogene
Article
Full-text available
  • Dec 1995
This composite standard establishes a scaled biostratigraphic sequence that incorporates all the fossil occurrences usually reported in paleontological studies of the North Sea Paleogene. All relevant taxonomic groups are represented, including benthic and planktic foraminifera, siliceous microfossils (diatoms and radiolarians), calcareous nannoplankton and palynomorphs (dinoflagellate cysts and sporomorphs). The North Sea Composite Standard was initiated in graphic correlation to a general Cenozoic composite standard with essentially complete representation of the geological record on a worldwide basis. Following this initial chronostratigraphic calibration, additional graphic correlations of area wells were done to develop a separate North Sea Composite Standard which precisely catalogues the relatively limited ranges and overall endemism of the intrabasinal biostratigraphy. The resulting database has extensive well control in the Central and South Viking grabens and provides definitive stratigraphic coverage, in that wells formally designated as lithostratigraphic types and references are included. In application, the composite standard provides a basis for consistent stratigraphic evaluations unencumbered by the incongruities of the many consultant-specific zonal schemes. The graphic correlation results clearly indicate that the Paleogene sediments accumulated in a punctuated series of regional pulses. Major time-stratigraphic breaks are defined by data terraces in relation to the composite standard scale. The length of each horizontal terrace spans an interval of composite standard units (time) that is not represented by a significant rock record in the comparison well. Geologically, horizontal terraces are related to missing section (i.e., faults and/or unconformities) or periods of sediment starvation. In the Paleogene of the North Sea, most of the terraces appear to represent periods of widespread sediment starvation because: they usually occur within a shale unit that is time-correlative throughout the North Sea; deep-marine (bathyal) conditions are indicated by associated benthic foraminifera assemblages in the sediments above and below; most are marked by a distinctive fossil assemblage (e.g., unusually high abundances of radiolarians, planktic foraminifera and calcareous nannofossils); they are confirmed by appropriate seismic stratal geometries. The terraces occur in a time-succession, each correlating in terms of composite standard units from well to well throughout the study area. Considered in the broader context of related geological and seismic data, the graphic correlation terraces appear to be marking major hiatuses resulting from widespread sediment starvation. Therefore, the stratigraphie subdivision afforded by the graphic correlation terraces may be used to define major depositional sequences within the Paleocene-Eocene. In general, the hiatuses are situated between rapidly deposited sections (i.e., steep lines of correlation) that contain major subsea fan sandstones (lowstand systems tract). The nomenclature introduced in this study for these depositional sequences emphasizes the relationship to established lithostratigraphic units based on analysis of the type and reference wells. However, the past regional application of lithostratigraphic terms does not always respect the boundaries between the biostratigraphically defined depositional sequences. Based on electric log criteria alone, genetic packages are difficult to resolve regionally due to the repetitive lithological character of the Paleogene deposits and the pronounced lenticularity of sandstone units. Consequently, the Paleogene Composite Standard has an essential role to play in guiding sequence stratigraphie interpretations.
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