Chemostratigraphic correlations across the first major trilobite extinction and faunal turnovers between Laurentia and South China

Abstract

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower–middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2–Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of the Miaolingian Series and Wuliuan Stage. This study provides detailed chemostratigraphy coupled with biostratigraphy and sequence stratigraphy across this critical boundary interval based on eight sections in North America and South China. Our results show robust isotopic evidence associated with major faunal turnovers across the Cambrian Series 2–Series 3 boundary in both Laurentia and South China. While the olenellid extinction event in Laurentia and the gradual extinction of redlichiids in South China are linked by an abrupt negative carbonate carbon excursion, the first appearance datum of Oryctocephalus indicus is currently the best horizon to achieve correlation between the two regions.

Phylogenetic response of naraoiid arthropods to early–middle Cambrian environmental change

“…(2012b), Lin et al . 2019, and the International Chronostratigraphic Chart v2020/03 (Cohen et al . 2013).…”

Corynexochine trilobites of the Harkless Formation and Mule Spring Limestone (Cambrian Series 2, Stage 4), Clayton Ridge, Nevada

“…The outer-shelf depositional setting and the highly condensed interval of the lower Emigrant Formation have been discussed by Sundberg and McCollum (2003), Sundberg et al (2011. Stable isotope studies on the Mule Spring Limestone and lower Emigrant Formation have been reported and discussed by Wotte et al (2011), Lin et al (2019), andCordie et al (2020). These studies included δ 13 C carb , δ 13 C org , δ 34 S CAS , and δ 18 O carb , as well as Sr, Mn, V, Mo, U, Na+Cl, Mg, and Fe.…”

“…This is especially true in shale deposits (e.g., Hollingsworth, 2005;McCollum and McCollum, 2011;Webster, 2011a, b, c, d;Webster et al, 2011), but less so in carbonates in which pagetiids, ptychoparioids and corynexochines can be locally abundant (e.g., Fritz, 1972;Hopkins and Webster, 2009;Geyer and Peel, 2011;Webster, 2011a, e). Whereas the endemic olenelline trilobites have become the major focus for biostratigraphic correlation of Series 2 strata in Laurentia, corynexochines-especially the oryctocephalids-have the potential to allow international correlations (e.g., Sundberg and McCollum, 1997;Sundberg et al, 1999Sundberg et al, , 2016Fletcher, 2001Fletcher, , 2003Fletcher, , 2007Zhao et al, 2001;Geyer and Peel, 2011;Lin et al, 2019;Peng et al, 2020).…”

“…Biostratigraphy.-The Harkless Formation, Mule Spring Limestone, and lowermost Emigrant Formation represent part of the regional Dyeran Stage, Waucoban Series of Laurentia (Palmer, 1998b;Webster, 2011a), which is equivalent to the global upper, but not uppermost, Series 2, Stage 4 (Sundberg et al, 2016(Sundberg et al, , 2020. The LAD of olenellines in the N. multinodus Biozone marks the traditional lower-middle Cambrian boundary of Laurentia (see Sundberg et al, 2016;Lin et al, 2019). The FAD of Eokochaspis nodosa Sundberg and McCollum, 2000 marks the lower boundary of the regional Delamaran Stage, Lincolnian Series (Palmer, 1998b;Sundberg and McCollum, 2003).…”

“…Above that traditional boundary are the E. nodosa and Amecephalus arrojosensis biozones of the basal Delamaran Stage. Above these two biozones at Split Mountain is the FAD of Oryctocephalus indicus (Reed, 1910), which marks the lower boundary of the global Wuliuan Stage, Miaolingian Series (Sundberg, 2018;Lin et al, 2019. Based on these biostratigraphic relationships, both the E. nodosa and Am.…”