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E F Letnikova - One of the best experts on this subject based on the ideXlab platform.
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Chemostratigraphy of the vendian cambrian carbonate sedimentary cover of the tuva mongolian microcontinent
Russian Geology and Geophysics, 2013Co-Authors: I A Vishnevskaya, E F LetnikovaAbstract:Abstract The carbonate sediments from the Vendian–Cambrian shelf of the Tuva-Mongolian microcontinent were dated by Sr and C isotope Chemostratigraphy. Analysis of the Sr-isotopic characteristics (0.70725–0.70873) and δ 13 C variations (+ 10.5 to –3.5‰), as well as their comparison with the data on the key sections of Siberia, Africa, Central Asia, Australia, South America, and Spitsbergen, showed that the carbonate sedimentary cover of the Tuva-Mongolian microcontinent accumulated at 600–520 Ma and the carbonate sediments of the Muren Formation and the basal beds of the Bokson Group near the Ukha-Gol River are the oldest. Their sedimentation followed the Marinoan global glaciation.
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Chemostratigraphy of the Vendian–Cambrian carbonate sedimentary cover of the Tuva-Mongolian microcontinent
Russian Geology and Geophysics, 2013Co-Authors: I A Vishnevskaya, E F LetnikovaAbstract:Abstract The carbonate sediments from the Vendian–Cambrian shelf of the Tuva-Mongolian microcontinent were dated by Sr and C isotope Chemostratigraphy. Analysis of the Sr-isotopic characteristics (0.70725–0.70873) and δ13C variations (+ 10.5 to –3.5‰), as well as their comparison with the data on the key sections of Siberia, Africa, Central Asia, Australia, South America, and Spitsbergen, showed that the carbonate sedimentary cover of the Tuva-Mongolian microcontinent accumulated at 600–520 Ma and the carbonate sediments of the Muren Formation and the basal beds of the Bokson Group near the Ukha-Gol River are the oldest. Their sedimentation followed the Marinoan global glaciation.
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U-Pb age and Sr-Chemostratigraphy of limestone from the Sorna Formation, Azyr-Tal Range, Kuznetsk Alatau
Doklady Earth Sciences, 2011Co-Authors: G. V. Ovchinnikova, A B Kuznetsov, E F Letnikova, Igor M. Gorokhov, O. K. Kaurova, B. M. GorokhovskiiAbstract:The U-Pb(Pb-Pb) age was determined for limestone from member III of the Sorna Formation out- cropped on the Azyr-Tal Range, Kuznetsk Alatau. The weighted average value from three calculated values is 523 ± 5 Ma (MSWD = 0.02, 2σ). This age coincides with the Early Cambrian age interval determined with Sr isotopic Chemostratigraphy (87Sr/86Sr ratio is 0.70850–0.70852). The low value of μ2 = 238U/204Pb for limestone is due to the evolution of diagenetic fluid containing lead from the mantle reservoir into the Sorna sediments.
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sr Chemostratigraphy of carbonate sedimentary cover of the tuva mongolian microcontinent
Doklady Earth Sciences, 2010Co-Authors: A B Kuznetsov, E F Letnikova, I A Vishnevskaya, G V Konstantinova, E P Kutyavin, N K GeletiiAbstract:This study uses Sr isotope Chemostratigraphy to place constraints on the depositional age of carbonate rocks from the Tuva-Mongolian microcontinent. The age of carbonate rocks of the Irkut Formation (87Sr/86Sr initial ratio equal to 0.70480–0.70485) is determined to be older than 1250 Ma, whereas carbonates of the Zabit (0.70706–0.70727 and 0.70828–0.70848) and Agarin Gol (0.70725–0.70743) formations were deposited in the interval 630–560 Ma.
D K Wright - One of the best experts on this subject based on the ideXlab platform.
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Chemostratigraphy of the upper carboniferous schooner formation southern north sea
2005Co-Authors: T J Pearce, Ken Ratcliffe, David Wray, D K Wright, Andrea MoscarielloAbstract:Summary The virtually barren, mainly redbed sequences of the Schooner Formation (Upper Carboniferous) of the southern North Sea are an important gas reservoir, although well placement and reservoir development are hampered by the lack of a reliable stratigraphical framework. Chemostratigraphy has enabled the Schooner Formation encountered in well 44/21-3 to be divided into three chemostratigraphical units (S1, S2 and S3) and eleven sub-units (S1a–f, S2a–b and S3a–c), based on variations in mudstone and sandstone geochemical data acquired from core samples and cuttings. The geochemical characteristics of the units can be related to variations in mineralogy, depositional environment, climate and provenance. The units are correlated subregionally and the correlation is used to corroborate seismic correlations. A high-resolution chemostratigraphical zonation and correlation based on sub-units redefines models of reservoir architecture and enhances reservoir development in the nearby Schooner field.
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Chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian stephanian sequences west midlands u k
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of Chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
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Chemostratigraphy: a method to improve interwell correlation in barren sequences — a case study using onshore Duckmantian/Stephanian sequences (West Midlands, U.K.)
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of Chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
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Chemostratigraphy: A New Tool for the Correlation of Ancient Sequences
AAPG Bulletin, 1993Co-Authors: T J Pearce, D K Wright, S. Cope, R.t.j. MoodyAbstract:Chemostratigraphy involves the application of major and trace-element geochemistry to the characterization and correlation of strata in petroleum basins, particularly where biostratigraphic control is poor. The geochemistry of sediments is highly variable and sensitive to subtle changes in composition and uniform succession may show primary differences in the chemistry of their constituent minerals or in the proportions of accessory phases. Geochemical data are acquired by analysis using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). These techniques enable the rapid acquisition of high-quality data on approximately 30 elements for a large number of samples. Data are used to characterize a geochemical [open quotes]fingerprint[close quotes] both for individual beds and sedimentary units and to recognize long-term geochemical trends. Chemostratigraphic correlations between wells are established on the identification of similar geochemical characteristics. Geochemical data can differentiate between successions of sedimentary units having repetitious lithological and E-Log characteristics. Core-based chemostratigraphies have the potential for high-resolution fingerprinting and correlation of individual beds and small-scale sedimentary units. Cuttings-based chemostratigraphies can be used to differentiate between thick sedimentary units and to identify long-term geochemical trends. Geochemical data can define marker horizons which can be utilized as a basis for E-Log correlations. Othermore » applications can determine changes in sediment provenance, which is important in modeling depositional system and reservoir geometry, fingerprint and predict the extent of claystone permeability barriers in reservoirs, investigate the geochemical controls responsible for E-log signatures, aiding research into interpretation of the responses of downhole geochemical tools, and investigate diagenetic histories.« less
A B Kuznetsov - One of the best experts on this subject based on the ideXlab platform.
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Sr isotopic Chemostratigraphy of Precambrian carbonate rocks in the Amderma Rise, Pai-Khoi Ridge
Doklady Earth Sciences, 2016Co-Authors: A B Kuznetsov, E. V. Starikova, A. V. Maslov, G V KonstantinovaAbstract:The Sr and C isotopic compositions of Precambrian carbonate rocks are determined for Amderma Rise, in the northeastern margin of Pai-Khoi Ridge. Based on the Sr isotopic Chemostratigraphy, it is established for the first time that the Amderma Formation is referred to the Early Vendian, while the Morozovsk Formation is Late Riphean in age. This conclusion along with detailed mapping proves that the Precambrian “section” of the Amderma Rise is a series of tectonic plates combined in a nonchronostratigraphic order. Volcanic and sedimentary rocks of the Morozovsk and Sokolninsk formations make up the allochthon proper, while carbonate rocks of the Amderma Formation make up the para-autochthon. The high values of δ^13С (up to +9.5‰) identified in limestones of both formations suggest a considerable distance of the Pai-Khoi paleobasin from the passive margin of the Baltic Region upon facies similarity to the Laurentia active margins.
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U-Pb age and Sr-Chemostratigraphy of limestone from the Sorna Formation, Azyr-Tal Range, Kuznetsk Alatau
Doklady Earth Sciences, 2011Co-Authors: G. V. Ovchinnikova, A B Kuznetsov, E F Letnikova, Igor M. Gorokhov, O. K. Kaurova, B. M. GorokhovskiiAbstract:The U-Pb(Pb-Pb) age was determined for limestone from member III of the Sorna Formation out- cropped on the Azyr-Tal Range, Kuznetsk Alatau. The weighted average value from three calculated values is 523 ± 5 Ma (MSWD = 0.02, 2σ). This age coincides with the Early Cambrian age interval determined with Sr isotopic Chemostratigraphy (87Sr/86Sr ratio is 0.70850–0.70852). The low value of μ2 = 238U/204Pb for limestone is due to the evolution of diagenetic fluid containing lead from the mantle reservoir into the Sorna sediments.
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sr Chemostratigraphy of carbonate sedimentary cover of the tuva mongolian microcontinent
Doklady Earth Sciences, 2010Co-Authors: A B Kuznetsov, E F Letnikova, I A Vishnevskaya, G V Konstantinova, E P Kutyavin, N K GeletiiAbstract:This study uses Sr isotope Chemostratigraphy to place constraints on the depositional age of carbonate rocks from the Tuva-Mongolian microcontinent. The age of carbonate rocks of the Irkut Formation (87Sr/86Sr initial ratio equal to 0.70480–0.70485) is determined to be older than 1250 Ma, whereas carbonates of the Zabit (0.70706–0.70727 and 0.70828–0.70848) and Agarin Gol (0.70725–0.70743) formations were deposited in the interval 630–560 Ma.
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Chemostratigraphy of neoproterozoic carbonates implications for blind dating
Terra Nova, 2001Co-Authors: Victor A Melezhik, A B Kuznetsov, I M Gorokhov, A E FallickAbstract:The δ13Ccarb and 87Sr/86Sr secular variations in Neoproteozoic seawater have been used for the purpose of ‘isotope stratigraphy’ but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for ‘blind dating’. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local δ13Ccarb fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative δ13Ccarb excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and ‘blind dating’. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590–544 Myr interval, and two age-groups at 660–610 and 740–690 Myr can be resolved.
Michael M Joachimski - One of the best experts on this subject based on the ideXlab platform.
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darriwilian middle ordovician Chemostratigraphy linked to graptolite conodont and trilobite biostratigraphy in the fagelsang 3 drill core scania sweden
Gff, 2018Co-Authors: Stig M. Bergström, Per Ahlberg, Jorg Maletz, Frans Lundberg, Michael M JoachimskiAbstract:A recent core drilling in the geologically classical Fagelsang area resulted in a 58.70-m-long drill core through the lowermost Sandbian Sularp Shale, the Darriwilian Almelund Shale and Komstad Limestone, and part of the late Tremadocian to earliest Darriwilian Toyen Shale. The shales contain zone index graptolites that are used for an update of the standard Darriwilian graptolite zone succession in Baltoscandia in which six zones are now recognized. The Komstad Limestone interval and lowermost part of the Almelund Shale have beensubdivided into four conodont zones. The δ13Corg Chemostratigraphy, which has been established through the entire drill core based on 120 closely spaced samples, shows a somewhat subdued development of the middle Darriwilian Isotope Carbon Excursion (MDICE), which is dated in terms of graptolite biostratigraphy. The Fagelsang isotope curve is correlated with a closely similar δ13Ccarb curve from a coeval, apparently stratigraphically essentially continuous, succession at Kargarde in south-central Sweden, which previously has been subdivided into 13 conodont zones and subzones. For the first time, these conodont zonal units can be calibrated with Fagelsang graptolite zones using δ13Corg Chemostratigraphy. The several new results of this study are expected to be useful for assessing biostratigraphic relations between units in shale and carbonate facies in Baltoscandia and elsewhere in the world. (Less)
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darriwilian middle ordovician Chemostratigraphy linked to graptolite conodont and trilobite biostratigraphy in the fagelsang 3 drill core scania sweden
Gff, 2018Co-Authors: Stig M. Bergström, Per Ahlberg, Jorg Maletz, Frans Lundberg, Michael M JoachimskiAbstract:AbstractA recent core drilling in the geologically classical Fagelsang area resulted in a 58.70-m-long drill core through the lowermost Sandbian Sularp Shale, the Darriwilian Almelund Shale and Komstad Limestone, and part of the late Tremadocian to earliest Darriwilian Toyen Shale. The shales contain zone index graptolites that are used for an update of the standard Darriwilian graptolite zone succession in Baltoscandia in which six zones are now recognized. The Komstad Limestone interval and lowermost part of the Almelund Shale have been subdivided into four conodont zones. The δ13Corg Chemostratigraphy, which has been established through the entire drill core based on 120 closely spaced samples, shows a somewhat subdued development of the middle Darriwilian Isotope Carbon Excursion (MDICE), which is dated in terms of graptolite biostratigraphy. The Fagelsang isotope curve is correlated with a closely similar δ13Ccarb curve from a coeval, apparently stratigraphically essentially continuous, succession at...
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lower middle ordovician δ13c Chemostratigraphy of western baltica jamtland sweden
Palaeoworld, 2015Co-Authors: Rongchang Wu, Mikael Calner, Oliver Lehnert, Olof Peterffy, Michael M JoachimskiAbstract:The province of Jamtland, central Sweden, records a well-preserved but very thin suite of the Lower-Middle Ordovician cool-water carbonates. In this study we present the first carbon isotope profile for these strata on the basis of whole-rock samples from the Brunflo 2 core. The studied succession is 41.55 m thick and includes, in ascending order, the Bjorkasholmen Formation, Latorp Limestone, Toyen Shale, and the Lanna, Holen, and Segerstad limestones. We identify two distinct positive delta C-13 excursions that can be used for intra-as well as inter-continental correlations. A positive excursion in the Toyen Shale probably correlates to the mid-late Floian and the Oepikodus evae Zone in Baltica and Precordillera, and the Reutterodus andinus Zone in North America. A continuous increase in delta C-13 values through the upper Holen Limestone and the preserved part of the overlying Segerstad Limestone is interpreted as the rising limb of the Middle Darriwilian Isotope Carbon Excursion (MDICE), an important tie-point for the global correlation of the Jamtland strata. Negative delta C-13 values associated with the Latorp Limestone may correlate with similar low values in the late Tremadocian and early Floian of the Argentine Precordillera and the Shingle Pass and Ibex sections in North America. (C) 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved. (Less)
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a new upper middle ordovician lower silurian drillcore standard succession from borenshult in ostergotland southern sweden 2 significance of delta c 13 Chemostratigraphy
Gff, 2012Co-Authors: Stig M. Bergström, Oliver Lehnert, Mikael Calner, Michael M JoachimskiAbstract:A total of 239 isotope samples are used for establishing the δ13C Chemostratigraphy in the upper Middle Ordovician to Lower Silurian succession in the approximately 70 m long Borenshult drillcore. The study interval starts in the upper Darriwilian Furudal Limestone and ends in the Rhuddanian Motala Formation. Four named δ13C excursions are recognized in 3–4 formations, namely the Guttenberg isotope carbon excursion (GICE) in the lower-middle Freberga Formation, the Kope (Rakvere) excursion in the uppermost Freberga Formation and possibly the Slandrom Formation, the Whitewater (Moe) excursion in the Lower Member of the Jonstorp Formation and the Hirnantian isotope carbon excursion (HICE) in the Loka Formation. The Middle Darriwilian isotope carbon excursion (MDICE) is missing in the drillcore and it is suggested that the study succession starts just above the interval of this excursion, which is in agreement with the range of MDICE in other Baltoscandic successions. The widespread Waynesville (Saunja) excu...
T J Pearce - One of the best experts on this subject based on the ideXlab platform.
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Elemental Chemostratigraphy of the Late Neoproterozoic & Early Cambrian Sediments in Oman
Seventh Arabian Plate Geology Workshop: Pre-Cambrian to Paleozoic Petroleum Systems in the Arabian Plate, 2018Co-Authors: R. Mccabe, T J Pearce, I. Gomez-perez, H. Rawahi, K. Bergmann, J-m. Dawans, B. BaloushiAbstract:Elemental Chemostratigraphy is employed on outcrop and well sections in order to produce a regional surface to subsurface correlation framework of the late Neoproterozoic and early Cambrian sediments in Oman. Samples have been analysed using ICP techniques, with high-resolution data acquired for 48 elements. The key elements employed to produce the chemostratigraphic framework are Si, Al, Ca, Mg, Ti, Zr, Y, Th, the rare earth elements, Cr, Mo and U. The relative abundance of these elements are interpreted be influenced by changes in lithology, detrital heavy minerals and redox-sensitive authigenic minerals that themselves are interpreted to reflect temporal variations in environment, weathering and sediment provenance. Based on marked variations in the key elements and derived element ratios, the study interval is divided into six chemostratigraphic sequences and six higher-resolution chemostratigraphic packages. The chemostratigraphic zones can be correlated with confidence from the outcrop to subsurface and, in conjunction with other disciplines, is being employed to refine the lithostratigraphy of the Nafun and Ara Groups in the subsurface of south Oman.
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Chemostratigraphy of the upper carboniferous schooner formation southern north sea
2005Co-Authors: T J Pearce, Ken Ratcliffe, David Wray, D K Wright, Andrea MoscarielloAbstract:Summary The virtually barren, mainly redbed sequences of the Schooner Formation (Upper Carboniferous) of the southern North Sea are an important gas reservoir, although well placement and reservoir development are hampered by the lack of a reliable stratigraphical framework. Chemostratigraphy has enabled the Schooner Formation encountered in well 44/21-3 to be divided into three chemostratigraphical units (S1, S2 and S3) and eleven sub-units (S1a–f, S2a–b and S3a–c), based on variations in mudstone and sandstone geochemical data acquired from core samples and cuttings. The geochemical characteristics of the units can be related to variations in mineralogy, depositional environment, climate and provenance. The units are correlated subregionally and the correlation is used to corroborate seismic correlations. A high-resolution chemostratigraphical zonation and correlation based on sub-units redefines models of reservoir architecture and enhances reservoir development in the nearby Schooner field.
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Chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian stephanian sequences west midlands u k
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of Chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
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Chemostratigraphy: a method to improve interwell correlation in barren sequences — a case study using onshore Duckmantian/Stephanian sequences (West Midlands, U.K.)
Sedimentary Geology, 1999Co-Authors: T J Pearce, B M Besly, David Wray, D K WrightAbstract:Abstract Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.). These successions represent the onshore equivalents of the `Barren Red Measures' which are important hydrocarbon-bearing sequences in the Southern North Sea. Much is known about the onshore successions in terms of sedimentology, mineralogy and provenance and thus they provide the ideal test for the validity of Chemostratigraphy as a stratigraphic tool. Reliable inorganic geochemical data have been acquired from geochemical analyses of core, sidewall core and cuttings samples, with 19 elements being determined. Stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data. The established lithostratigraphic units of the Duckmantian/Stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further. This results in an independent chemostratigraphic correlation being established for the two boreholes, which has been assessed statistically by discriminant function analysis. From the geochemical and mineralogical data, distinct changes in provenance are identified within the Upper Carboniferous successions. The sediments of the Coal Measures were derived from a north westerly and westerly source (?Caledonian), whereas the Etruria Formation sediments came from the Wales Brabant Massif, the sediments having mixed Caledonian and Cadomian characteristics. Eventually these sediments were replaced by sediments from a southern Hercynian source (Halesowen and Salop Formations).
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Chemostratigraphy: A New Tool for the Correlation of Ancient Sequences
AAPG Bulletin, 1993Co-Authors: T J Pearce, D K Wright, S. Cope, R.t.j. MoodyAbstract:Chemostratigraphy involves the application of major and trace-element geochemistry to the characterization and correlation of strata in petroleum basins, particularly where biostratigraphic control is poor. The geochemistry of sediments is highly variable and sensitive to subtle changes in composition and uniform succession may show primary differences in the chemistry of their constituent minerals or in the proportions of accessory phases. Geochemical data are acquired by analysis using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). These techniques enable the rapid acquisition of high-quality data on approximately 30 elements for a large number of samples. Data are used to characterize a geochemical [open quotes]fingerprint[close quotes] both for individual beds and sedimentary units and to recognize long-term geochemical trends. Chemostratigraphic correlations between wells are established on the identification of similar geochemical characteristics. Geochemical data can differentiate between successions of sedimentary units having repetitious lithological and E-Log characteristics. Core-based chemostratigraphies have the potential for high-resolution fingerprinting and correlation of individual beds and small-scale sedimentary units. Cuttings-based chemostratigraphies can be used to differentiate between thick sedimentary units and to identify long-term geochemical trends. Geochemical data can define marker horizons which can be utilized as a basis for E-Log correlations. Othermore » applications can determine changes in sediment provenance, which is important in modeling depositional system and reservoir geometry, fingerprint and predict the extent of claystone permeability barriers in reservoirs, investigate the geochemical controls responsible for E-log signatures, aiding research into interpretation of the responses of downhole geochemical tools, and investigate diagenetic histories.« less