‘Strangelove ocean’ before the Cambrian explosion

Prominent Lower Cambrian K-Bentonites In South China: Distribution, Mineralogy, and Geochemistry

“…Platinum-group elements (PGEs) in the K-bentonite in the base of the Shiyantou Formation (bed 9) at the Meishucun section and its equivalents on the Yangtze Block were analyzed by several workers (Hsu et al 1985). The results showed that the K-bentonite has an Ir anomaly compared with its overlying and underlying sequences.…”

“…However, a number of scientific problems urgently need to be clarified for the Lower Cambrian strata in this region. Firstly, although several schemes for the placement of the Precambrian-Cambrian (PC/C) boundary in South China have been proposed by geologists, they have not reached a general consensus (Hsu et al 1985;Shen and Schidlowski 2000;Zhu et al 2001;Zhu et al 2003;Steiner et al 2007;Wille et al 2008;Zhou et al 2008;Jiang et al 2009;Li et al 2009;Wen et al 2009;Zhu et al 2009). Secondly, the regional correlation across different facies of the successions is still uncertain due to the scarce fossil records in the Lower Cambrian of the deep-water facies on the Yangtze Block, which hampers understanding of environmental changes of the paleo-ocean Chang et al 2012;Fan et al 2013).…”

SHRIMP U-Pb zircon age of tuff at the bottom of the Lower Cambrian Niutitang Formation, Zunyi, South China

“…The wide-spread outcrops of the early-Cambrian sequences over the Yangtze Platform in South China represent an important window for studying the Cambrian bio-radiation, the secular paleo-seawater isotope variations, the ore-forming events of terminal Neoproterozoic-Cambrian times, and in particular, for investigating the Cambrian subdivision and global correlation [1][2][3][4][5][6][7][8][9] . Since the last century, these sequences have been studied from a number of different aspects, and paleontological studies have acquired many unique findings [10][11][12][13][14][15][16][17][18][19] .…”

“…Figure 1 shows that the two successions are highly correlatable. At present, the Precambrian-Cambrian boundary in the Kunming region is often placed at the base of the Zhongyicun Member of the Zhujiaqing Formation [27] , but it has not reached a general consensus [3,[31][32][33]36,37] . One of the reasons is the disconformity between the Zhujiaqing Formation and the underlying Dengying Formation, which makes carbon isotope chemostratigraphic studies difficult.…”

Isotopic chemostratigraphy of the microbialite-bearing Permian–Triassic boundary section in the Zagros Mountains, Iran

“…The Permo-Triassic transition is one of the most wellstudied bioevents, and has been the focus of many δ 13 C isotopic studies (Hsu et al, 1985;Holser et al, 1989;Kump, 1991;Jin et al, 2000;Baud et al, 1989). The interval spanning the Permian-Triassic boundary (PTB) witnessed a mass extinction during a period of enhanced continental weathering (Jin et al, 2000, Cao et al, 2002.…”