Sedimentology of SPICE (Steptoean positive carbon isotope excursion): A high-resolution trace fossil and microfabric analysis of the middle to late Cambrian Alum Shale Formation, southern Sweden

2015 ◽  
pp. 87-102 ◽  
Author(s):  
Sven O. Egenhoff ◽  
Neil S. Fishman ◽  
Per Ahlberg ◽  
Jörg Maletz ◽  
Allison Jackson ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Trace Fossil ◽  
Southern Sweden ◽  
Late Cambrian ◽  
Alum Shale ◽  
Carbon Isotope Excursion ◽  
Shale Formation

Integrated Cambrian biostratigraphy and carbon isotope chemostratigraphy of the Grönhögen-2015 drill core, Öland, Sweden

2018 ◽  
Vol 156 (06) ◽  
pp. 935-949 ◽  
Author(s):  
PER AHLBERG ◽  
FRANS LUNDBERG ◽  
MIKAEL ERLSTRÖM ◽  
MIKAEL CALNER ◽  
ANDERS LINDSKOG ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Global Scale ◽  
Carbonate Facies ◽  
Southern Sweden ◽  
Middle Ordovician ◽  
Alum Shale ◽  
Carbon Isotope Excursion ◽  
Upper Stage ◽  
Shale Formation ◽  
Isotope Analyses

AbstractThe Grönhögen-2015 core drilling on southern Öland, Sweden, penetrated 50.15 m of Cambrian Series 3, Furongian and Lower–Middle Ordovician strata. The Cambrian succession includes the Äleklinta Member (upper Stage 5) of the Borgholm Formation and the Alum Shale Formation (Guzhangian–Tremadocian). Agnostoids and trilobites allowed subdivision of the succession into eight biozones, in ascending order: the uppermost Cambrian Series 3 (Guzhangian) Agnostus pisiformis Zone and the Furongian Olenus gibbosus, O. truncatus, Parabolina spinulosa, Sphaerophthalmus? flagellifer, Ctenopyge tumida, C. linnarssoni and Parabolina lobata zones. Conspicuous lithologic unconformities and the biostratigraphy show that the succession is incomplete and that there are several substantial gaps of variable magnitudes. Carbon isotope analyses (δ13Corg) through the Alum Shale Formation revealed two globally significant excursions: the Steptoean Positive Carbon Isotope Excursion (SPICE) in the lower–middle Paibian Stage, and the negative Top of Cambrian Excursion (TOCE), previously referred to as the HERB Event, in Stage 10. The δ13Corg chemostratigraphy is tied directly to the biostratigraphy and used for an improved integration of these excursions with the standard agnostoid and trilobite zonation of Scandinavia. Their relations to that of coeval successions in Baltoscandia and elsewhere are discussed. The maximum amplitudes of the SPICE and TOCE in the Grönhögen succession are comparable to those recorded in drill cores retrieved from Scania, southern Sweden. The results of this study will be useful for assessing biostratigraphic relations between shale successions and carbonate facies on a global scale.

Synchronizing Rock Clocks in the Cambrian

2021 ◽  
Author(s):  
Zhengfu Zhao ◽  
Nicolas Thibault ◽  
Tais W. Dahl ◽  
Niels H. Schovsbo ◽  
Aske L. Sørensen ◽  
...  
Keyword(s):  
High Resolution ◽  
Amplitude Modulation ◽  
Anchor Point ◽  
Detailed Understanding ◽  
Late Cambrian ◽  
Alum Shale ◽  
Shale Formation ◽  
The Way

<p>Profound environmental and biological changes took place during the Cambrian, yet, compared to other Phanerozoic intervals, the Cambrian time framework remains poorly constrained, which severely hinders a detailed understanding of the timing and progression of these major geological events. In this study, we report a radiometrically anchored astrochronologic framework across the late Cambrian interval, using high-resolution aluminum (Al) series (1 mm resolution) through the Alum Shale Formation in Scania, southernmost Sweden, based on the fully cored Albjära-1 well. Significant cycles with periods of 405 kyr (long eccentricity), 108 kyr (short eccentricity), 30.4 kyr (obliquity) and 18.8 kyr (precession), associated with long-term amplitude modulation of obliquity and precession, confirmed the orbital imprint on late Cambrian climate. Using the U-Pb dating at 486.78±0.53Ma for the Cambro-Ordovician boundary as anchor point, our timescale spans from ~483.9 to ~500.0 Ma, covering 7 trilobite superzones and 3 graptolite zones. The calibration indicates ages of 491.2±0.54 Ma, 493.9±0.67 Ma, 497.3±0.67 Ma and 500.4±0.67 Ma for the lower boundaries of provisional Stage10, Jiangshanian, Paibian and Guzhangian stages, respectively. This radiometrically anchored astrochronology also provides precise age constrains on regional superzones or even biozones within Scandinavia, and hopefully pave the way for better understanding the late Cambrian major geological events globally.</p>

The geochemistry of the late Cambrian carbonate in North China: the Steptoean Positive Carbon Isotope Excursion (SPICE) record suppressed in a coastal condition?

2019 ◽  
Vol 156 (10) ◽  
pp. 1805-1819 ◽  
Author(s):  
Jing Huang ◽  
Yali Chen ◽  
Xuelei Chu ◽  
Tao Sun
Keyword(s):  
Sea Level ◽  
Carbon Isotope ◽  
North China ◽  
Coastal Environment ◽  
Sedimentary Records ◽  
Late Cambrian ◽  
Geochemical Proxies ◽  
Carbon Isotope Excursion ◽  
Globally Distributed ◽  
Shallow Coastal Environment

AbstractThe Steptoean Positive Carbon Isotope Excursion (SPICE) is globally distributed in late Cambrian sedimentary records but controversially heterogeneous in its magnitudes. Here we use multiple geochemical proxies to investigate the late Cambrian carbonates from the Tangwangzhai section in North China, which were deposited in a shallow coastal environment with three depositional sequences (S1–S3). Each sequence comprises a transgressive systems tract (TST) and a highstand systems tract (HST). The REE + Y and trace element records are consistent with the depositional condition and indicate that terrigenous influence was more significant in the TST than HST. δ13Ccarb and δ34SCAS are low in the TST relative to HST, consistent with the scenario that terrigenous inputs were profoundly aggressive to seawater by introducing 13C-depleted and 34S-depleted materials. Within the TST of S2, the SPICE excursion shows a scaled-down δ13Ccarb positive shift (∼1.7 ‰) relative to its general records (∼4–6 ‰); the corresponding δ34SCAS show no positive excursion. This ‘atypical’ SPICE record is attributed to enhanced 13C-depleted and 34S-depleted terrigenous influence during the TST, which would reduce the amplitude of δ13Ccarb excursion, and even obscure δ34SCAS excursion. Meanwhile the subaerial unconformity at the base of TST would also cause a partially missing and a ‘snapshot’ preservation. Our study confirms significant local influence to the SPICE records, and further supports the heterogeneity and low sulphate concentrations of the late Cambrian seawater, because of which the SPICE records may be vulnerable to specific depositional conditions (e.g. sea-level, terrigenous input).

scholarly journals The Furongian (late Cambrian) Steptoean Positive Carbon Isotope Excursion (SPICE) in Avalonia

2011 ◽  
Vol 168 (4) ◽  
pp. 851-862 ◽  
Author(s):  
Mark A. Woods ◽  
Philip R. Wilby ◽  
Melanie J. Leng ◽  
Adrian W.A. Rushton ◽  
Mark Williams
Keyword(s):  
Carbon Isotope ◽  
Late Cambrian ◽  
Carbon Isotope Excursion

Skeletal carbonate productivity and phosphogenesis at the lower–middle Cambrian transition of Scania, southern Sweden

2009 ◽  
Vol 147 (1) ◽  
pp. 59-76 ◽  
Author(s):  
J. JAVIER ÁLVARO ◽  
PER AHLBERG ◽  
NIKLAS AXHEIMER
Keyword(s):  
Primary Productivity ◽  
Microbial Mats ◽  
High Energy ◽  
Nutrient Supply ◽  
Energy Conditions ◽  
Southern Sweden ◽  
Middle Cambrian ◽  
Alum Shale ◽  
Shale Formation ◽  
Reducing Environment

AbstractThe lower–middle Cambrian transitional interval of Scania is largely represented by condensed limestone beds, lithostratigraphically grouped in the Gislöv Formation (1–5.7 m thick), and the Forsemölla and Exsulans Limestone beds (lower part of the Alum Shale Formation, up to 4 m thick). The strata display a combination of skeletal carbonate productivity, episodic nucleation of phosphate hardground nodules, and polyphase reworking recorded on a platform bordering the NW corner of Baltica. The shell accumulations can be subdivided into three deepening-upward parasequences, separated by distinct erosive unconformities. The parasequences correspond biostratigraphically to the Holmia kjerulfi, Ornamentaspis? linnarssoni and Ptychagnostus gibbus zones, the latter two generally being separated by a stratigraphic gap that includes the middle Cambrian Acadoparadoxides oelandicus Superzone. Except for the Exsulans Limestone, the carbonates reflect development of a prolific epibenthic biota, dominated by filter-feeding nonreefal chancelloriid–echinoderm–sponge meadows, rich in trilobites and brachiopods, and which were subjected to high-energy conditions. The absence of microbial mats or veneers encrusting the erosive surfaces of these event-concentration low-relief shoal complexes may be related to long hiatal episodes resulting in microboring proliferation. High levels of nutrient supply resulted in high primary productivity, eutrophic conditions, glauconite precipitation, phosphogenesis (in some case microbially mediated) and microendolithic infestation. An early-diagenetic mildly reducing environment is suggested by the presence of authigenic (subsequently reworked) pyrite, which contrasts with the syndepositional normal oxygenated conditions reflected by macroburrowing and the abundance of benthic fossils.

scholarly journals New Chronostratigraphic Constraints on the Lower Jurassic Pliensbachian–Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina)

2021 ◽  
Author(s):  
Aisha H. Al-Suwaidi ◽  
Micha Ruhl ◽  
Hugh C. Jenkyns ◽  
Susana E. Damborenea ◽  
Miguel O. Manceñido ◽  
...  
Keyword(s):  
High Resolution ◽  
Carbon Isotope ◽  
Volcanic Ash ◽  
Lower Jurassic ◽  
Zircon Geochronology ◽  
Organic Carbon Isotope ◽  
Carbon Isotope Excursion ◽  
Isotope Record ◽  
Age Model ◽  
Zonal Boundary

Abstract The Pliensbachian–Toarcian boundary interval is characterized by a ~3‰ negative carbon-isotope excursion (CIE) in organic and inorganic marine and terrestrial archives from sections in Europe, such as Peniche (Portugal) and Hawsker Bottoms, Yorkshire (UK). A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from the Southern Hemisphere Arroyo Chacay Melehue section, Chos Malal, Argentina, corroborating the global significance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment is accompanied by high-resolution ammonite and nannofossil biostratigraphy together with U-Pb CA-ID-TIMS geochronology derived from intercalated volcanic ash beds. A new age of ~183.71 ± 0.40/-0.51 Ma for the Pliensbachian–Toarcian boundary, and 182.77 +0.11/-0.21 for the tenuicostatum–serpentinum zonal boundary, is assigned based on high-precision U-Pb zircon geochronology and a Bayesian Markov chain Monte Carlo (MCMC) stratigraphic age model.

scholarly journals Stratigraphy and geochemical composition of the Cambrian Alum Shale Formation in the Porsgrunn core, Skien–Langesund district, southern Norway.

2018 ◽  
Vol 66 ◽  
pp. 1-20
Author(s):  
Niels Hemmingsen Schovsbo ◽  
Arne Thorshøj Nielsen ◽  
Andreas Olaus Harstad ◽  
David L. Bruton
Keyword(s):  
Gamma Ray ◽  
Geochemical Composition ◽  
Middle Cambrian ◽  
Alum Shale ◽  
Carbon Isotope Excursion ◽  
Lower Ordovician ◽  
Shale Formation ◽  
Sedimentary Succession ◽  
Southern Norway ◽  
Spice Event

The fully cored BHD-03-99 borehole (hereafter referred to as the Porsgrunn borehole and core) penetrated Ordovician and Cambrian strata in the Skien–Langesund district, southern part of the Oslo region in Norway. Hand-held X-ray fluorescence (HH-XRF) measurements combined with spectral gamma ray and density core scanning of the Middle Cambrian – Furongian Alum Shale Formation have been made and compared with similar measurements obtained on Alum Shale cores from Scania (southernmost Sweden) and Bornholm (Denmark). The Porsgrunn drill site is located in an area that was only mildly overprinted by Caledonian tectonics and represents one of the few sites in the Oslo area where a nearly untectonised sedimentary succession can be studied in terms of thickness and geochemistry. The Alum Shale Formation is 28.8 m thick in the Porsgrunn core, excluding the thickness of five 0.9–5.5 m thick dolerite sills of assumed Permian age. In the Alum Shale Formation the bulk densities are around 2.7 g/cm3 with a slightly decreasing trend up through the formation. The shale has total organic carbon (TOC) values up to 14 wt%, which is comparable to the TOC levels for the Alum Shale elsewhere in the Oslo area and for dry gas matured Alum Shale in Scania and Bornholm. The basal Furongian is characterised by a gamma ray low and an increase in Mo interpreted to reflect the Steptoean Positive Carbon Isotope Excursion (SPICE) event. The Porsgrunn core data suggest that the Mo concentration remained high also after the SPICE event. Characteristic, readily identified features in the gamma log motif are named the Andrarum gamma low (AGL), base Furongian gamma low (BFGL), Olenus triple gamma spike (OTGS) and the Peltura gamma spike (PGS). No Lower Ordovician Alum Shale is present. The 14.8 m thick Furongian part of the Alum Shale represents the Olenus, Parabolina, Leptoplastus, Protopeltura and Peltura trilobite superzones judging from log-stratigraphic correlations to Scania and Bornholm. The Middle Cambrian interval is 14.0 m thick and includes the Exsulans Limestone Bed and 1.4 m of quartz sandstone. A 0.3 m thick primary limestone bed may be an equivalent to the Andrarum Limestone Bed. The succession represents the Paradoxides paradoxissimus and P. forchhammeri superzones. The Alum Shale Formation rests atop the 13.0 m thick Lower Cambrian Stokkevannet sandstone (new informal name) that in turn directly overlies the basement. Overall, the stratigraphic development of the comparatively thin Alum Shale Formation resembles the condensed sequence seen on Bornholm.

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