Toward Standardization of Terminologies and Recognition of Chemostratigraphy as a Formal Stratigraphic Method

Ramkumar, Mu.

doi:10.1016/b978-0-12-419968-2.00001-7

Cited by 11 publications

(4 citation statements)

References 139 publications

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“…Chemostratigraphic units require consistent definition (i.e. Ramkumar, 2015). Zhu et al (2020, p. 1) claim TOCE is 'a welldocumented and clearly defined δ 13 C carb excursion, and that the term "HERB Event" was originally used informally, without definition or reference data, for a negative δ 13 C carb peak, a peak later shown to occur within the TOCE excursion'.'…”

Section: Discussionmentioning

confidence: 99%

Discussion of ‘Reply to “Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous”’

2021

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No basis for controversy exists in the naming of a global, strongly negative, uppermost Cambrian carbon isotope (δ13C) excursion. The HERB Event (HERB) has met the standards for chemostratigraphic units (i.e. consistent biostratigraphic brackets, content and concept) since 1992. By comparison, the TOCE excursion morphed through four temporally distinct δ13C events with spike-like nadirs that shifted temporally through the uppermost Cambrian until its synonymization with HERB (2006–12). In 2018, TOCE became a prolonged interval with very early onset and enveloped HERB – meaning five TOCE homonyms have been unambiguously defined and figured. HERB lies in the high-diversity ptychaspid biomere (trilobites) and below the ptychaspid extinction. But, data on it were used in TOCE’s 2006 proposal and in later iterations (2008, 2012) to show it (1) higher, both at and above the ptychaspid extinction; (2) at the level of HERB (2012, 2018); and (3) even extending well below HERB (2018). TOCE fails the recommendations for a formal chemostratigraphic unit. Its relationship to latest Cambrian biotic turnover includes equation with extinction and high-diversity intervals. One TOCE homonym is a synonym, albeit junior, of HERB.

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Section: Discussionmentioning

confidence: 99%

Discussion of ‘Reply to “Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous”’

2021

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“…Particular attention must be given to the methods of absolute dating and to the geological time scale. The chemostratigraphy (chemical stratigraphy) is based on the study of the chemical variations in the sedimentary successions with the aim to reconstruct the stratigraphic relationships [51][52][53][54][55]. It is based on the principle that the chemical signatures may be used as fossil groups or lithological groups in order to establish the stratigraphic relationships between the rocky layers.…”

Section: Chemostratigraphymentioning

confidence: 99%

“…In particular, the variability of the oxygen in the carbonate shells of foraminifera represents a proxy for the temperatures of the ocean during the geological past [56][57]. Recently, there were some attempts to formalize the chemostratigraphy as a standard method of stratigraphy [54][55], but this discipline is too young and many efforts need to be made again.…”

Section: Chemostratigraphymentioning

confidence: 99%

Introductory Chapter: An Introduction to the Stratigraphic Setting of Paleozoic to Miocene Deposits Based on Paleoecology, Facies Analysis, Chemostratigraphy, and Chronostratigraphy - Concepts and Meanings

Aiello¹

2019

New Insights Into the Stratigraphic Setting of Paleozoic to Miocene Deposits - Case Studies From the Persian Gulf, Peninsular M

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“…Chemostratigraphy involves the identification of the geological characteristics based on the spatial-temporal variation of the chemical elements in rocks or the various ratios between these elements (Ramkumar, 2015). Elemental chemostratigraphy can be used as an independent method or in conjunction with other information, such as lithological, geophysical, petrographical and biostratigraphical data.…”

Section: Introductionmentioning

confidence: 99%

Elemental geochemistry of the Upper Cretaceous reservoir and surrounding formations applied in geosteering of horizontal wells, Lebăda Field – Western Black Sea

Prundeanu

Chelariu

Perez³

2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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The precise landing and steering of horizontal wells using conventional mudlogging and Logging While Drilling (LWD) data is a particular challenge for the Lebăda Field, offshore Romania. The use of a new technique of elemental geochemistry analysis (or chemosteering) became an option for the identification of Cenomanian, Turonian–Coniacian–Santonian, Campanian and Eocene strata. This has enabled more accurate placement of the horizontal development wells within the desired reservoir target interval. Geochemical data enabled the identification of chemostratigraphic zones C1, C2, C3 and zone R that correspond to the reservoir section. The application is a result of the geochemical zonation performed using elements and ratios that are sensitive to depositional environment, sea level change, heavy mineral concentrations and siliciclastic input namely: Sr/Ca, Zr/Th, Si/Zr and Si/K. In ascending stratigraphic order, the ratio thresholds of zone C3 are Zr/Th > 11, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19, while zone R corresponds to 5.5 < Zr/Th < 11, Sr/Ca < 1.1, Si/Zr > 22 and Si/K > 19. C2 zone is defined by Zr/Th < 5.5, Sr/Ca > 1.1, Si/Zr < 22 and Si/K < 19 and C1 zone is characterized by Si/Zr > 22 and Si/K > 19. The selected geochemical ratios indicate a strong geochemical zonation. In the case of offset wells, 85.9% of the data confirmed the proposed classification and 89.4% for the real-time application case. The zone R shows a strong contrast with the surrounding formations facilitating critical decisions during well placement and geosteering, increasing the reservoir exposure by 28%. The quantitative approach delivered very valuable results, providing a solid foundation to define correlation and well landing intervals. Simultaneously, the cost of the method represents a fraction of the LWD cost and 0.15% of the total project cost, making it very cost effective and a standard approach for future projects.

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Toward Standardization of Terminologies and Recognition of Chemostratigraphy as a Formal Stratigraphic Method

Cited by 11 publications

References 139 publications

Discussion of ‘Reply to “Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous”’

Discussion of ‘Reply to “Uppermost Cambrian carbon chemostratigraphy: the HERB and undocumented TOCE events are not synonymous”’

Introductory Chapter: An Introduction to the Stratigraphic Setting of Paleozoic to Miocene Deposits Based on Paleoecology, Facies Analysis, Chemostratigraphy, and Chronostratigraphy - Concepts and Meanings

Elemental geochemistry of the Upper Cretaceous reservoir and surrounding formations applied in geosteering of horizontal wells, Lebăda Field – Western Black Sea

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