Carbon-isotope stratigraphy of the Middle–Upper Cambrian in eastern Laurentia: implications for global correlation

2021 ◽  
pp. 105052
Author(s):  
N.O.E.L. SHEMBILU ◽  
K.A.R.E.M. AZMY
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Stratigraphy ◽  
Upper Cambrian ◽  
Global Correlation ◽  
Isotope Stratigraphy

Oxygen and carbon isotope stratigraphy of early Cambrian carbonates in southeastern Newfoundland and England

1992 ◽  
Vol 129 (3) ◽  
pp. 265-279 ◽  
Author(s):  
M. D. Brasier ◽  
M. M. Anderson ◽  
R. M. Corfield
Keyword(s):  
Carbon Isotope ◽  
Carbonate Rocks ◽  
Thermal Alteration ◽  
Carbon Isotope Stratigraphy ◽  
Oxygen And Carbon Isotope ◽  
Global Correlation ◽  
Granitic Intrusion ◽  
Isotope Stratigraphy ◽  
Siliciclastic Sediments ◽  
Reference Section

AbstractCarbonate rocks have been sampled through predominantly siliciclastic sediments above the Precambrian-Cambrian global stratotype level in southeastern Newfoundland to assess their potential for oxygen and carbon isotope stratigraphy. Comparable successions were sampled at Nuneaton and Comley in England. Greatly depleted δ18O signals are attributed to widespread thermal alteration during deep burial and granitic intrusion, including within the stratotype region. Carbon isotope ratios appear to have been less affected and these are described from nine sections. A provisional, composite δ13C curve is based on non-ferroan, pink nodular and bedded micrites. Several δ13C excursions occur in the fossiliferous Bonavista Group and allow the position of the Tommotian-Atdabanian boundary to be identified. Chemostratigraphic correlation of the new Precambrian-Cambrian boundary stratotype may, however, prove difficult because of the lack of suitable, well-preserved carbonates. The search must begin for a comparable reference section allowing global correlation of the boundary level using chemostratigraphy as well as biostratigraphy.

Carbon-isotope stratigraphy of the SPICE event (Upper Cambrian) in eastern Laurentia: implications for global correlation and a potential reference section

2018 ◽  
Vol 156 (08) ◽  
pp. 1311-1322 ◽  
Author(s):  
Karem Azmy
Keyword(s):  
Carbon Isotope ◽  
Head Group ◽  
Upper Cambrian ◽  
Green Point ◽  
Global Correlation ◽  
Isotope Profile ◽  
Isotope Stratigraphy ◽  
Lowermost Part ◽  
Spice Event ◽  
Shallow Bay

AbstractThe δ13C profile from the lower interval of the Martin Point section in western Newfoundland (Canada) spans the Upper Cambrian (uppermost Franconian – lowermost Trempealeauan). The investigated interval (∼110 m) is a part of the Green Point Formation of the Cow Head Group and consists of the upper part of the Tucker Cove Member (topmost part of the Shallow Bay Formation) and the lowermost part of the Martin Point Member (bottom of the Green Point Formation). It is formed of rhythmites of marine carbonates alternating with shales and minor conglomeratic interbeds. Multiscreening petrographic and geochemical techniques have been utilized to evaluate the preservation of the investigated lime mudstones. The δ13C and δ18O values of the sampled micrites (−4.8 ‰ to +1.0 ‰ VPDB and −8.2 ‰ to −5.3 ‰ VPDB, respectively) have insignificant correlation (R2= 0.01), as similarly do the δ13C values with their Sr counterparts (R2= 0.07), which supports the preservation of at least near-primary δ13C signatures that can be utilized to construct a reliable high-resolution carbon-isotope profile for global correlations. The δ13C profile exhibits two main negative excursions: a lower excursion (∼4 ‰) that reaches its maximum at the bottom of the section and an upper narrow excursion (∼6 ‰) immediately above the boundary of the Tucker Cove/Martin Point members (Shallow Bay Formation – Green Point Formation boundary). The lower excursion may be correlated with the global SPICE event, whereas the upper excursion may match with a post-SPICE event that has been also recognized in profiles of equivalent sections on different palaeocontinents.

scholarly journals A chemostratigraphic framework for the type-Maastrichtian

2020 ◽  
Author(s):  
Johan Vellekoop ◽  
Pim Kaskes ◽  
Sinnesael Matthias ◽  
John W. M. Jagt ◽  
Robert P. Speijer ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Border Region ◽  
Time Interval ◽  
Stratigraphic Correlation ◽  
Stable Carbon ◽  
Carbon Isotope Stratigraphy ◽  
Global Correlation ◽  
Isotope Stratigraphy

<p>The youngest time interval of the Cretaceous Period is known as the Maastrichtian, a reference to the marine strata exposed in the area surrounding the city of Maastricht, in the Netherlands-Belgium border region. The stratigraphic succession at the original type-locality of the Maastrichtian (ENCI quarry, NL) only covers the upper part of the Maastrichtian Stage as it is nowadays defined. However, in combination with similar rock sequences in several other quarries (e.g. Hallembaye, Curfs) in the region, a substantial part of the Maastrichtian Stage is represented.</p><p>While the type-Maastrichtian strata have provided a wealth of paleontological data, comparatively little geochemical work has been carried out on this succession. So far, the age assessment of, and stratigraphic correlation with, the type-Maastrichtian has been largely based on biostratigraphy and preliminary attempts at cyclostratigraphy, techniques that are hampered by bioprovincialism and the presence of stratigraphic gaps in the succession. In recent years, stable carbon isotope stratigraphy has been proven to be a powerful tool for correlating Upper Cretaceous strata on a global scale. When calibrated with biostratigraphic events, carbon isotope stratigraphy can be used to test the synchroneity of bio-events and reconcile inter-regional biostratigraphic schemes. Therefore, we have generated the first high-resolution stable carbon isotope stratigraphy for the type-Maastrichtian, using the extensive sample set acquired in the context of the Maastrichtian Geoheritage Project. In combination with elemental data generated using µXRF (e.g. Ca, Si, Al, Ti, Fe wt%), our record presents the first high-resolution chemostratigraphy for the type-Maastrichtian. This new chemostratigraphic framework enables us to refine the age-model for studied strata, and allows a better regional and global correlation with the type-Maastrichtian successions, placing the paleontological records from the type-Maastrichtian in a global context.  </p>

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