Comment on “Evaluation of palaeo-oxygenation of the ocean bottom cross the Permian–Triassic boundary” by Kakuwa (2008): Was the Late Permian deep-superocean really oxic?

Massive volcanism at the Permian–Triassic boundary and its impact on the isotopic composition of the ocean and atmosphere

“…Filter-feeder ostracods (Cavellinidae and Hollinacea) indicative of low-oxygen bottom water conditions (common in dysoxic Palaeotethyan sediments) are absent. Consequently, this cerium anomaly is not an indicator of anoxic water conditions (see also Kato and Isozaki, 2009).…”

“…To complicate matters, Kakuwa (2008) demonstrated that the duration of anoxia for low-latitude Panthalassa had been overestimated. This argument is weakened, however, by the fact that Kakuwa (2008) did not measure Pr as it is necessary to know the concentration of this element in order that anoxia be reliably identified using Ce-anomalies (Kato and Isozaki, 2009). Moreover, at the same time that anoxia prevailed in the Boreal seas, low-latitude Panthalassa, Palaeotethys and adjacent seas, oxic conditions existed in the southern high-latitude Panthalassa (Arrow Rock, Waipapa Terrane, Northern Island, New Zealand; see Takemura et al, 2003;Yamakita et al, 2003) and in the Neotethys (Kozur, 1998a(Kozur, ,b, 2007Heydari et al, 2003;Richoz, 2006).…”

Carbon-isotope stratigraphy across the Permian–Triassic boundary: A review

“…These results show that Kakuwa and Matsumoto's (2006) negative Ce-anomaly about two metres below the BC could not have been caused by suboxic/anoxic conditions. In addition, Kakuwa and Matsumoto (2006) did not analyse the critical element praseodymium (Pr) and this is necessary to identify fairly a subtle Ce-anomaly (Kato and Isozaki, 2009). …”

Geochemistry of the Igdekoy-Doganlar Na-Ca borate deposit, Emet Province (western Anatolia, Turkey)

“…-Ce val ues and neg a tive anom a lies show that the bo rates were de pos ited in an ox y gen ated en vi ron ment. How ever, the ab sence or weak neg a tive Ce anom a lies in some samples show a partly ox y gen ated en vi ron ment (Kato and Isozaki, 2009), and H 2 S-bear ing hy dro ther mal flu ids are thought to had em a nated from some parts of the lake, which is sup ported by the pres ence of realgar, orpiment and native sul phur min er als in bo rate de pos its at Igdekoy-Doganlar;…”