Platinum-group elements link the end-Triassic mass extinction and the Central Atlantic Magmatic Province

Abstract

elevated concentrations of iridium (ir) and other platinum-group elements (pGe) have been reported in both terrestrial and marine sediments associated with the end-Triassic mass extinction (ETE) c. 201.5 million years ago. the source of the pGes has been attributed to condensed vapor and melt from an extraterrestrial impactor or to volcanism. Here we report new pGe data for volcanic rocks of the central Atlantic Magmatic province (cAMp) in Morocco and show that their pd/ir, pt/ir and pt/Rh ratios are similar to marine and terrestrial sediments at the ETE, and very different from potential impactors. Hence, we propose the pGes provide a new temporal correlation of cAMp volcanism to the ete, corroborating the view that mass extinctions may be caused by volcanism.

Widespread elevated iridium in Upper Triassic–Lower Jurassic strata of the Newark Supergroup: implications for use as an extinction marker

“…The mean Pt/Ir (= 16) and Pd/Ir (= 24.8) ratios derived from these data accord well with the data from the western Newark basin intrusives 50 (Fig. 3) as well as recently published data for Moroccan CAMP volcanics 53 .…”

“…The authors noted that the Pd/Pt and Ir/Pt ratios and chondrite-normalized PGE profile all show close affinity to previous analyses of CAMP volcanics and do not resemble the PGE ratios of the K-Pg boundary clays. NMBm, North Mountain Basalt mean ratios 51 ; WNBr, approximate range of ratios for western Newark basin intrusions 50 ; MORr, approximate range of ratios for Moroccan CAMP units 53 ; SK, Stevns Klint K-Pg layer 54 ; RB, Raton Basin 54 ; CI, CI chondrite 54 ; UCC, mean upper continental crust ratio 73 1b, 2b, 3b) include a subset of four REEs (Ce, Eu, Tb and Yb). Chondrite-normalized profiles for these samples match closely (Fig.…”

“…Therefore, we examine alternative mechanisms of enrichment in sediments. As the impact hypothesis for the Ir enrichment 30 is no longer considered viable 36,53 , the CAMP volcanics are the remaining logical source for Ir and other PGEs in sediments surrounding the TJB at abundances beyond typical crustal levels. The presence of anomalous concentrations of Hg also has been observed in TJB sediments in both terrestrial and marine sediments 29 , including the multiple horizons at the same stratigraphic level in the uppermost Blomidon Formation where Ir enrichment is documented 35,36 , supporting a volcanic source for the Ir.…”

Sedimentary record of Upper Triassic impact in the Lagonegro Basin, southern Italy: Insights from highly siderophile elements and Re-Os isotope stratigraphy across the Norian/Rhaetian boundary

“…5B), which are abundantly found in ejecta layers of Manicouagan (Onoue et al, 2012;Sato et al, 2013). The Late Triassic is marked not only two large impact craters of Manicouagan and Rochechouart but also large volcanic activities documented by LIP formations such as the Angayucham Province cropping out in the Alaska and the CAMP emplaced in the central portion of Pangea, both of which might be invoked as the potential causes of PGE enrichments in sedimentary successions (e.g., Tegner et al, 2020;Whiteside et al, 2021). However, based on the above arguments and several lines of evidence summarized below, we propose that the shaley bed with PGE anomaly in the study section is sourced by Rochechouart impact melt, probably transported as fine particulates from the continental Massif Central in France by high-energetic erosion related to impact-triggered tsunami, rather than atmospheric fallout of dust and melt droplets as with the case of PGE-enriched ejecta layers in K/Pg boundary and Manicouagan.…”

Paleozoic–Mesozoic Eustatic Changes and Mass Extinctions: New Insights from Event Interpretation

“…The next big mass extinction is known from the end-Triassic, and it occurred during most of the Rhaetian Stage [ 54 , 55 , 96 , 97 , 98 , 99 , 100 ]. This biotic catastrophe corresponds to an outstanding global sea-level fall followed by a similar rise and subsequent changes of lesser magnitude as depicted by Haq [ 33 , 34 ] ( Figure S1 ).…”