Chalky Limestone Research Articles

Multidiscipline Approach, Advanced LWD Boost Multistage Fracturing in Romania

Technology Update Since the start of production from the Lebada fields offshore Romania in 1987, operator Petrom tested various stimulation and completion measures to improve production from the fields’ low-permeability formations. However, by 2008, the company had not been able to achieve production of more than approximately 115 BOEPD per well. A new multidisciplinary approach to well design, combined with the implementation of advanced directional drilling, logging-while-drilling (LWD), and completion technologies, has now increased production per well to a peak of more than 1,000 BOEPD and to stabilized levels of up to 750 BOEPD. Petrom is the largest oil and gas producer in southeastern Europe. It was Romania’s national oil company until privatized in 2004, when it became a member of the OMV Group. Romania has been producing oil since 1856, mostly from onshore reservoirs. Petrom currently produces approximately 32,000 BOEPD from its five commercial offshore fields in the Black Sea, approximately 18% of the company’s annual 66 million BOE production in Romania (2009 figures). The Lebada Oil Fields Petrom’s Lebada Est (East) and Lebada Vest (West) fields are in block Histria XVIII in the Black Sea. Lebada Est was discovered in 1978 and represented Romania’s first offshore production when it came onstream in 1987. It produces oil from Upper Cretaceous carbonate shelf deposits—micritic, sandy and chalky limestones—overlain by overpressured Oligocene shales. Average porosity is 15% to 20% and average permeability is 0.8 md. Microfractures and intergranular porosity connect zones with good porosity in mainly calcareous reservoir forma-tions. Lebada Vest was discovered in 1985, with first production occurring in 1993. It is characterized by the same calcareous formations as Lebada Est in the top part and more clastic turbiditic fan deposits toward the bottom. A gas cap is often present. In 2008, Petrom reviewed technical proposals to increase production rates significantly, having achieved only very limited success until then with measures such as acid fracturing and hydraulic fracturing of older producers completed with cemented and perforated liners. It was concluded that high production would require long horizontal drain sections with good quality borehole to be drilled. Because the hydrocarbons lay within shelf deposits, horizontal continuation of reservoir properties could not be guaranteed. Thus, real-time petrophysical evaluation and well placement would be necessary. Synthetic oil-based mud (SOBM) would be beneficial to handle the Oligocene overpressured shale overburden, provide a better quality hole, and enable safe drilling, helping to ensure efficient, effective completions run along the reservoir section. However, this could limit the choice of formation evaluation logging tools. The low-permeability reservoir rock required hydraulic fracturing and fast, efficient, postdrilling reservoir characterization and natural open fracture detection to select the best locations for placing completion packers and ports.

SEQUENCE STRATIGRAPHY AND RESERVOIR CHARACTERISTICS OF THE TURONIAN‐CONIACIAN KHASIB FORMATION IN CENTRAL IRAQ

Bioturbated chalky limestones of the Khasib Formation (Upper Turonian – Lower Coniacian) form potential reservoir rocks at oilfields and structures in central Iraq. Core and cuttings samples and wire‐line logs from wells in the East Baghdad, Balad, Samarra and Tikrit fields (wells EB‐77, EB‐57, Ba‐1, Ba‐2, Sr‐1, Sr‐2, and Ti‐1) were used to investigate microfacies types and porosity evolution. Facies modelling was applied to predict the relationship between facies distribution and reservoir characteristics to construct a predictive geologic model which will assist future exploration in central Iraq.Microfacies analysis and electrofacies identification and correlations indicate that the limestones of the Khasib Formation were deposited in a ramp setting. The ramp developed over the distal margin of the Upper Cretaceous proforeland basin, adjacent to the evolved forebulge. Inner ramp facies are characterized by carbonate bank bioclastic packstones intercalated with lagoonal green shales. Middle ramp facies dominate the Khasib Formation and consist of bioturbated, chalky, dolomitic and bioclastic limestones. Bioclasts include benthic and planktonic foraminifera. Intense Thalassinoides and less common Palaeophycus bioturbation has enhanced the porosity of this facies. Outer ramp deposits consist of alternating mid‐ramp bioturbated bioclastic chalky limestones and argillaceous and marly limestones. The latter contain basinal bioclasts including planktonic foraminifera, oligosteginids, dwarf rotaliids, and sponge spicules.Sequence stratigraphic analyses of the Khasib Formation indicate that it represents a third‐order depositional cycle. At the base is a type 1 sequence boundary which separates it from the underlying LST deposits of the Kifl Formation. Shaly and argillaceous limestones in the lower part of the Khasib Formation represent the early TST. These are overlain by a thick, deepening‐upwards succession of outer ramp facies. The maximum flooding surface is represented by a thin and extensive horizon of Oligosteginal limestones with Palaeophycus bioturbation. HST deposits are represented by aggradational build‐ups of bioturbated chalky dolomitic limestones, followed by progradational late HST shales and limestones. The boundary with the overlying Tanuma Formation is a type 2 sequence boundary. Bioclastic packstones and intensively bioturbated (Thalassinoides) bioclastic limestones of the mid‐outer ramp are the primary source of fabric‐selective porosity which is greatly enhanced by diagenetic overprints. These two units constitute the prime target for future exploration in central Iraq.

الأحافير الكلسية الدقيقة من الحجر الجيري الطباشيري لمتكون الأبدراز Abderaz العلوي والجزء السفلي لمتكون الأبتالخ Abtalkh، في منطقة كوبت – دوغ Kopet - Dogh شمال شرق إيران

For the first time, the calcareous nannofossils of the chalky limestone of upper Abderaz Formation and lower part of Abtalkh Formation have been studied. In this study, 83 nannoplanktonic species of 45 genera were identified and presented. A biostratigraphic study of calcareous nannofossils from this section has allowed the recognition of five calcareous nannofossil biozones of Sissingh (Geol Mijnbouw 56:37–65, 1977) CC17–CC21. On the obtained calcareous nannofossils, the age of this section is Late Santonian/Early Campanian–Early Late Campanian.

Lithostratigraphy and study of planktonic foraminifera of the Abderaz Formation at type section, Kopet-Dagh basin, IRAN

In order to study the fossil contents of the Abderaz Formation for biostratigraphical purposes the 300 meters thick section was sampled at type section. The sequence is mainly made up of grey shales and marls with two units of chalky limestone in upper part. The lower contact of the formation with Aitamir Formation is disconform while the upper contact with Abtalkh is continuous. There are huge amounts of inoceramids and ammonite. In the chalk limestone bonds of this formation which is belong to Santonian time planktonic, would exist some foraminifera with a less diversity because during the Santonian, the members of morphotype group three (M3) shows a regression in the above-mentioned section, with association of tegilla shapes decreases in the area and sea water. The study of the planktonic foraminifera in isolated form led to differentiate three morphotype groups. The first group is characterized by trochospiral tests usually indicate shallow waters, the second group contains forms with strong ornamentations and the primary keels representing mid waters and finally compact trochospiral tests with keels known as deep water indices are included in the third group. Studies on the morphotypes showed a regressive cycle for Abderaz Formation.

Lithostratigraphy and study of planktonic foraminifera of the Abderaz Formation at type section, Kopet-Dagh basin, IRAN

AbstractIn order to study the fossil contents of the Abderaz Formation for biostratigraphical purposes the 300 meters thick section was sampled at type section. The sequence is mainly made up of grey shales and marls with two units of chalky limestone in upper part. The lower contact of the formation with Aitamir Formation is disconform while the upper contact with Abtalkh is continuous. There are huge amounts of inoceramids and ammonite. In the chalk limestone bonds of this formation which is belong to Santonian time planktonic, would exist some foraminifera with a less diversity because during the Santonian, the members of morphotype group three (M3) shows a regression in the above-mentioned section, with association of tegilla shapes decreases in the area and sea water. The study of the planktonic foraminifera in isolated form led to differentiate three morphotype groups. The first group is characterized by trochospiral tests usually indicate shallow waters, the second group contains forms with strong ornamentations and the primary keels representing mid waters and finally compact trochospiral tests with keels known as deep water indices are included in the third group. Studies on the morphotypes showed a regressive cycle for Abderaz Formation.

Contribution of geophysical methods to explaining water flow in a carbonate medium Favray site (Nièvre, France)

Question Thegeologic formations of the study area, limestone and chalky limestone belong to upper Oxfordian and lower Kimeridgian. Two springs; Fontbout (70 l/s) and Favray (300 l/s) are situated in this area. Those two springs are witness to the existence of a water reservoir of important volume. The similarity of the results of their hydro-chemical analysis shows that they belong to the same aquifer. The direction of water flow in the studied area is NW–SE, the springs are located in the s...

Configuration of the limestone aquifers in the central part of Egypt using electrical measurements

The Western Desert of Egypt is an area of natural expansion for agricultural, industrial, and civil activities. This expansion has led to a great demand for groundwater. In the central part of Egypt, on the western limestone plateau, vertical electrical sounding and borehole geophysical logging were conducted to delineate aquifer boundaries. The measurements were interpreted using the lithological information from the drilled wells as a constraining factor. Fractured chalky limestone sediments represent the main aquifer, which is covered by sand and gravel deposits and which rests directly on partially saturated and highly resistive massive limestone. Discontinuous clay layers, which overlie the aquifer unit, were detected in the southern part of the study area as well as a relatively thin marly limestone layer in the northern part. The integrated analyses carried out represent a significant and cost-effective method for delineating the main aquifer in this area. In turn, future well locations can be placed with more confidence than before, in accordance with the evaluation of the potentiality of the groundwater aquifers in the area. Although the groundwater is normally brackish, it can serve the acute demands for water, especially for agricultural purposes.

REPLACEMENT OF Ti02 PIGMENT BY CaC03 FROM CEFALONIA IN EMULSION PAINTS

The purpose of this work is to show that calcium carbonate from the chalky limestone deposits of Minies in Kefalonia, exploited by IONIAN KALK S.A., is a suitable raw material for paint industry and especially in emulsion (water based) paints. The deposit is characterized by a high calcium carbonate content (>99 %), high whiteness and low yellowness, by negligible content of heavy metals and low contents of MgO (<0.15 %), Si02 (<0.05 %) andFe203 (<0.01 %). This research was based on determination of the optical and mechanical properties of the emulsion white water based paints, which included calcium carbonate from the Kefalonia limestone deposits. The calcium carbonate replaced Ti02 pigment in various proportions. It is concluded that this product can be utilized not only as inert filler and extender but may have more functional application acting simultaneously as pigment. Replacement of TiO2 pigment by calcium carbonate may reach 50% without deteriorating the optical and mechanical properties significantly. Hence calcium carbonate from this deposit offers excellent optical properties to paints, reduces sufficiently their production cost and replaces a great part of the proportion of titanium dioxide, which is currently used as white pigment.

Development and compartmentalization of chalky carbonate reservoirs: The Urgonian Jura-Bas Dauphiné platform model (Génissiat, southeastern France)

The chalky limestones of the upper Barremian-middle Aptian Urgonian Limestone Formation of the Jura-Bas Dauphiné platform (southeastern France) are characterised by a total porosity between 17.9 and 24.5%, a threshold radius between 1.04 and 2.13 μm, a trapped porosity between 51.4 and 68.3% and a gas permeability between 161 and 410 mD. They were formed in response to the diagenetic evolution of dominantly micritic sediments deposited during a “calcite sea” interval. Their present-day reservoir qualities and transport properties are controlled by the intercrystalline microporosity of microcrystalline areas (peloids or matrix). This intercrystalline microporosity is the product of a meteoric porewater input (installation of a shallow-burial phreatic environment characterised by a short residence time of porewaters) which promoted an aggrading neomorphism (Ostwald ripening process). The impact of the burial diagenesis on the reservoir qualities and the transport properties of these chalky limestones is limited. The chalky units are presently compartmentalized by horizontal layers of compact limestones characterised by a total porosity between 2.9 and 4.5%, a threshold radius between 0.04 and 0.09 μm, a trapped porosity of 92.4–92.8% and a gas permeability of 2 mD. Like the chalky limestones, the present-day reservoir qualities and transport properties of compact limestones are controlled by the intercrystalline microporosity of microcrystalline areas. The petrophysical differences between the chalky and compact limestones result from differences in the pore network of microcrystalline areas due to an increase in the average size of particles and a modification of crystal–crystal contacts. These petrographical differences reflect an evolution of micritic areas of original sediments during submarine lithifications (precipitation of microcrystalline cements within the pore space and/or an increase in solid–solid contacts by crystal growth) which preceded the aggrading neomorphism induced by the meteoric porewater input.

Petrographic and chemical traits of Cenomanian platform carbonates (central Lebanon): implications for depositional environments

This paper provides new data on the Cenomanian (Late Cretaceous) carbonates in Lebanon, which, due to their location and considerable thickness, represent an important segment of the broader Eastern Mediterranean platform. Detailed field and microfacies investigations have shown that the Late Albian–Cenomanian succession (i.e., the Sannine Formation in Lebanon) consists of a number of lithologically distinct strata. These are: micritic limestone, silicified micrite, bioclastic limestone, chalky limestone (foraminifera-wackestone), marl and marly limestone, dolostone and dolomitic limestone. The laminated micritic limestones are typically associated with chert nodules and bands, and are interpreted to have been deposited in deep marine environments. The bioclastic limestones have abundant skeletal fragments suggesting deposition in relatively shallow marine settings, an interpretation that is further supported by the presence of local palaeo-channels within the limestones. Geochemically, the formation includes five distinct chemical groups, each characterized by certain chemical traits reflecting the lithological nature of the various facies. The micritic limestones have relatively low concentrations of most major and trace elements (Mg, Sr, Si, Al, K, P, Ti and Rb). In sharp contrast, the marly limestone samples have the highest concentrations of most of these elements. The silicified micrites have a wide range of Si and Sr contents, but abundances of most elements are intermediate between those of the micritic limestones and the marly limestones. The chalky limestones have relatively low Si and Al, but relatively high P contents. The dolomitic limestones have the lowest Rb and Sr concentrations. The normalized REE patterns of representative samples of most of these rocks are parallel to subparallel and nearly flat. Based on facies analysis and chemical traits, we have constructed a carbonate platform ramp model for this succession, in which the dolostones and marly limestones were deposited in back ramp to subtidal environments, the bioclastic limestones accumulated in shallow, wave-dominated to deep ramp environment, and the micritic limestones and silicified micrites formed in a deep ramp environment. This ramp was influenced by sea-level fluctuations and tectonic activities. The proposed model has wider implications for the geodynamic evolution of the eastern Mediterranean region during the Cretaceous Period, and is consistent with interpretations of some other tectonically active margins worldwide.

Thermal conductivity of limestone from Gaziantep (Turkey)

In this study, thermal conductivity (TC) of limestone from Gaziantep, Turkey, was investigated. The limestone samples were collected from different parts of the city representing Gaziantep and Fırat formation which are clay and chalky limestone. TC of the samples was measured for saturated, partially saturated and dried conditions. Water absorption, dry unit weight and apparent porosity of the samples were also measured to correlate with TC. Measurements showed that TC was increased with increasing the water content of samples. The TC of the samples decreased while the porosity increased. Relationships between TC and both dry unit weight and porosity were driven. There was a very good exponential relationship between TC and saturation degrees of sample, porosity and density. Moisture content increased TC up to 113%.

Modeling and interpretation of Q logs in carbonate rock using a double porosity model and well logs

Attenuation data extracted from full waveform sonic logs is sensitive to vuggy and matrix porosities in a carbonate aquifer. This is consistent with the synthetic attenuation (1 / Q) as a function of depth at the borehole-sonic source-peak frequency of 10 kHz. We use velocity and densities versus porosity relationships based on core and well log data to determine the matrix, secondary, and effective bulk moduli. The attenuation model requires the bulk modulus of the primary and secondary porosities. We use a double porosity model that allows us to investigate attenuation at the mesoscopic scale. Thus, the secondary and primary porosities in the aquifer should respond with different changes in fluid pressure. The results show a high permeability region with a Q that varies from 25 to 50 and correlates with the stiffer part of the carbonate formation. This pore structure permits water to flow between the interconnected vugs and the matrix. In this region the double porosity model predicts a decrease in the attenuation at lower frequencies that is associated with fluid flowing from the more compliant high-pressure regions (interconnected vug space) to the relatively stiff, low-pressure regions (matrix). The chalky limestone with a low Q of 17 is formed by a muddy porous matrix with soft pores. This low permeability region correlates with the low matrix bulk modulus. A low Q of 18 characterizes the soft sandy carbonate rock above the vuggy carbonate. This paper demonstrates the use of attenuation logs for discriminating between lithology and provides information on the pore structure when integrated with cores and other well logs. In addition, the paper demonstrates the practical application of a new double porosity model to interpret the attenuation at sonic frequencies by achieving a good match between measured and modeled attenuation.

Diachronism in the sedimentary cover around the Troodos ophiolitic massif (Cyprus)

Abstract The detailed micropaleontologic study of the sedimentary series overlying the youngest ophiolitic basalts of the Troodos massif (Cyprus), confirms the late Campanian age of the top of the oldest terrigenous cover (Kannaviou Formation) topping these ophiolites themselves assigned to Cenomanian-Turonian. It also demonstrates for the first time the strong diachronism of the Lefkara Formation chalky limestones, unconformably overlying either the Kannaviou Fm. sandstones and clays, or the oceanic basalts. This diachronism over short distances and the on-lap of the Lefkara Fm. are revealed by varying stratigraphic gaps within the Paleocene-Miocene interval and are indicated by new age datings of the transgressive basal part of the Lefkara Fm. along six principal sections: late Thanetian (Zone P5) at the Pano Lefkara typelocality; early Ypresian (Sub-zone P6a) at Agia Anna; earliest Bartonian (Zone P13) at Kannaviou and Analiontas; early-middle Lutetian (Zones P10 to P11) at Kofinou; Langhian (Zone N8) at Choulou. Maastrichtian deposits are missing and Maastrichtian Globotruncanidae/Heterohelicidae only observed as individual reworked specimens within well-dated Tertiary levels. Finally, we discuss the influence of the Tertiary extensional brittle tectonics on this diachronism, the on-lap processes and the differential subsidences occurring after the late Cretaceous/? early-middle Paleocene folding (Laramian compression).

Facies analysis, cyclic sedimentation and paleoenvironment of the Middle Eocene Rus Formation in Qatar and Adjoining areas

The Middle Eocene Rus Formation in Qatar and adjacent area consists of evaporite-carbonate sequences. The Rus Formation extends over a large area in the Middle East and can be correlated with confidence throughout the eastern Arabian Peninsula. In this study, the Rus Formation in Qatar is redescribed and subdivided into two new members from bottom to top: the gypsiferous dolomitic limestone Traina Member and the chalky limestone Al-Khor Member. These units were deposited in two different depositional settings ranging from supratidal to subtidal environments. Seven lithofacies are recognized from studied surface and subsurface sections throughout the Rus Formation. These are limestone, chalky limestone, dolomitic limestone, cherty limestone, marl, claystone and gypsum. These facies show a cyclic sedimentation in southern Qatar.

Salinity sources of Kefar Uriya wells in the Judea Group aquifer of Israel. Part 1—conceptual hydrogeological model

In the Yarkon–Taninim groundwater basin, the karstic Judea Group aquifer contains groundwater of high quality. However, in the western wells of the Kefar Uriya area located in the foothills of the Judea Mountains, brackish groundwater was locally encountered. The salinity of this water is caused presumably by two end members designated as the ‘Hazerim’ and ‘Lakhish’ water types. The Hazerim type represents surface water percolating through a highly fractured thin chalky limestone formation overlying the Judea Group aquifer. The salinity of the water derives conjointly from several sources such as leachates from rendzina and grumosols, dissolution of caliche crusts which contain evaporites and of rock debris from the surrounding formations. This surface water percolates downwards into the aquifer through a funnel- or chimney-like mechanism. This local salinization mechanism supercedes another regional process caused by the Lakhish waters. These are essentially diluted brines originating from deep formations in the western parts of the Coastal Plain. The study results show that salinization is not caused by the thick chalky beds of the Senonian Mt Scopus Group overlying the Judea Group aquifer, as traditionally considered but prevalently by aqueous leachates from soils and rock debris. The conceptual qualitative hydrogeological model of the salinization as demonstrated in this study, is supported by a quantitative hydrological model presented in another paper in this volume.

Hydrochemical Characteristics of the Major Springs in the Maqarin Dam Site on the Yarmouk River (Northern Jordan)

Most water development schemes in Jordan have paid limited attention to the chemistry of water and its implication on water origin, movement, and evolution. Various aspects of water quality have also been ignored in recent projects. Chemical characteristics of groundwater in a major catchment area adjacent to the Maqarin dam in northern Jordan have been investigated. Because water from this area is an intended major source of water for Jordan, it is vital to understand the nature of the chemistry of the springs in the area, as well as the potential water-rock interaction. The study area is underlain by sedimentary rocks of Upper Cretaceous age. This study evaluates the water quality of 12 springs from aquifers within the bituminous marl formation and chalky limestone formation (aquifers B-3 and B-4, respectively) situated in the surrounding area of the Maqarin dam site on the Yarmouk river. Analyses show that the water of the springs are characterized as alkaline earth-biocarbonate chemical type, consistent with the calcareous lithology of the aquifers. Constituents contained in all water from springs sampled are within or below World Health Organization (WHO) standards set for domestic purposes.

Lower Miocene stratigraphy of the Gebel Shabrawet area, north Eastern desert Egypt

The Lower Miocene carbonate/siliciclastic sequence of the Shabrawet area, comprises a complex alternation of autochthonous and allogenic sediments. The sequence can be subdivided into two lithostratigraphic units. The lower unit (unit I) is equivalent to the Gharra Formation. It is mainly clastic and composed of sandstones, siltstones and shales with minor limestone intercalations. These sediments are rich in Clypeaster spp., Scutella spp., Miogypsina intermedia, Operculina complanata, and smaller foraminifera. The upper unit (unit II) was considered by previous workers as being equivalent to the Marmarica Formation. It consists mainly of non-clastic rocks, dominated by sandy and chalky limestones rich in larger foraminifera (miogypsinids and nummulitids). This unit is topped by a highly fossiliferous ( Heterostegina, Operculina and Planostegina) sandy limestone. The present study places both units in the Gharra Formation and reports for the first time M. intermedia from the Miocene sequence of the Shabrawet area.

Joint development during fluctuation of the regional stress field in southern Israel

Four trends of joint sets (WNW–ESE, NW–SE, NNW–SSE and NE–SW) are found in upper Turonian carbonate rocks within the Neqarot syncline of south-central Israel. The two most predominant sets strike parallel to the trend of maximum compressive stress directions ( S H) associated with the plate-related Syrian Arc stress field (SAS; WNW–ESE) active during the Cretaceous to present and the perturbed regional stress field (NNW–SSE) related to stress accumulation on the Dead Sea Transform during the Miocene to the present. Eighty-two percent of the beds in this study contain joints parallel with the latter trend, whereas 42% contain joints parallel to the former trend. All beds with layer thickness to spacing ratio (FSR)>1.5 have NNW–SSE joint sets compatible with the Dead Sea Transform stress field (DSS), whereas all joints sets that are not compatible with the DSS stress field fall beneath this value for FSR. Considering lithology, joints in five of six chalky limestone beds and all marly limestone beds are compatible with the DSS, whereas joints compatible with the SAS do not develop in these marly and chalky limestone beds. In the study area, the joint sets lack a consistent formation sequence where more than one set is found in a single bed. We use these observations to conclude that all studied joints are Miocene or younger, that the regional stress field from the Miocene to the present fluctuated , between DSS and SAS states, and that the higher FSRs correspond to a greater amount of joint-normal strain in response to the DSS.

Sequence development of Late Cenomanian–Turonian carbonate ramps, platforms and basins in Israel

The Cenomanian–Turonian carbonate-dominated lithofacies of Israel reflect a complex interplay between tectonics, sea-level change, and palaeoecology. Improved correlation based on revision of the bio- and chronostratigraphic framework has enabled the establishment of a sequence-stratigraphic model comprising five sequences delineated by four sequence boundaries, in the Late Cenomanian–Early Coniacian interval. The Late Cenomanian–Turonian succession begins with prograding, highstand, carbonate-platform deposits of the first sequence. Interruption of progradation and drowning of this platform took place within the Late Cenomanian guerangeri Zone (=the vibrayeanus Zone in Israel), resulting in a drowning unconformity which is regarded as a Type 3 sequence boundary (labelled CeUp). The drowning is attributed in part to extinctions in the rudist-dominated biofacies (e.g., Caprinidae), which led to reduced carbonate production and enhanced the impact of the sea-level rise. Similar drowning of Tethyan platforms around the C/T boundary has been linked to the establishment of coastal upwelling and consequent eutrophication. Outer ramp hemipelagic facies (Derorim and the Lower Ora formations) replaced the platform carbonates, thickening substantially southwards in the Eshet-Zenifim Basin of southern Israel. Along the ancient continental slope (Mediterranean coastal plain) evidence of this drowning is obscured by submarine erosion, while in central and northern Israel the drowned section is represented by condensation or a hiatus, reflecting an elevated, sediment-starved sea-floor. A carbonate platform dominated by rudistid shoals (‘Meleke’ Member; Shivta Formation) was re-established in the Judean hills and northern Negev during the middle part of the Turonian coloradoense Zone (local zone T4). Later, during kallesi Zone times (T7), the platform facies prograded southwards towards the Eshet-Zenifim intra-shelf basin. The drowning succession and overlying resurrected carbonate platform are topped in central and southern Israel by a pronounced Type 1 sequence boundary (Tu1) between the kallesi (T7) and ornatissimum (T8) zones (Middle Turonian). In central Israel and northern Negev the sequence boundary is overlain by lowstand deposits of the ‘Clastic Unit’ and by the transgressive and highstand inner to mid-ramp deposits of the Nezer and Upper Bina formations. In the southern Negev the sequence boundary is overlain by lowstand and transgressive systems tracts of mixed carbonates, siliciclastics, and localized evaporites (Upper Ora Formation), and then by mid to inner ramp carbonates of the Gerofit Formation. The latter represents a very high rate of accumulation, indicating rapid, continued subsidence balanced by platform growth. The Tu2 sequence boundary of the Late Turonian is expressed in the southern Negev by a shift from inner ramp carbonates of the Gerofit Formation to outer ramp chalky limestones of the Zihor Formation, indicating localized drowning. The succeeding Co1 sequence boundary again indicates localized drowning of the prograding highstand deposits of the Zihor Formation (‘Transition Zone’) overlain by Lower Coniacian transgressive deposits of the upper part of the Zihor Formation. All of these third-order sequences are expressed in southern Israel, where the rate of subsidence was in balance with sea-level fluctuations. In contrast, the Judean Hills and eastern Galilee areas have a more incomplete succession, characterized by hiatuses and condensation, because of reduced subsidence. More distal areas of continuous deep-water deposition in western Galilee and the coastal plain failed to record the Middle Turonian lowstand, while a longer term, second-order sequence spanning the entire Late Cenomanian–Early Coniacian interval, is present in the Carmel and Yirka Basin areas.

00/02347 Estimation of reservoir parameter using a hybrid neural network

A new open-air Mousterian site was found in karst depression on hilly limestone terrain of central Israel at Nesher Ramla. The paper highlights the complex history of depositional, post-depositional and pedogenic processes that took place at the later phases of Mousterian site formation during the OSL age interval between ∼80 and ∼115 ka. The Upper sequence is divided into Unit I and Unit II, both comprising rather uniform calcareous, gravel-rich, silty clay deposits. Gravel largely consists of calcrete (Nari) and possibly some chalky limestone. Unit I is darker, partially decarbonated, magnetically enhanced, and shows microscopic features of shrink–swell process analogous to Vertisols. Mousterian artifacts, chunks of ochre and animal bones are scarce in this unit. Unit II has increased gravel, magnetic susceptibility values drop, and humus and carbonate content both increase. Mousterian artifact density significantly increases in the middle part of Unit II. Lithologic characteristics, thin sections and SEM/EDS all indicate that the Upper sequence originated from periodic erosion of loess-derived soils developed upon chalky hillslopes intermittent with more stable periods when hominins occupied the site. The proposed model relates the Upper sequence to heterogeneous anthropogenic pedosediments with high proportions of eroded soil materials and signs of in situ pedogenesis. Apart from singular mm-sized pyrogenic features, remnants of bedded combustion features in the Upper sequence are lacking, probably because of pedogenic and diagenetic alterations on the site.