We present a comprehensive data set of organic and inorganic geochemistry from a lower Cretaceous pelagic bedded chert succession of the Shimanto accretionary belt in the Yokonami Peninsula (Kochi, Japan). Based on stable isotopic composition of total organic carbon (δ 13 C org ), in conjunction with radiolarian biostratigraphic data, we propose that a 1.3-m-thick interval within the examined section is correlative with Tethyan Selli Level (Apennines, Italy), a sedimentary expression of oceanic anoxic event (OAE) 1a. Specifically, the δ 13 C org record illustrates a discernible negative shift and subsequent positive excursions upsection, a pattern that resembles the typical δ 13 C org pattern across OAE 1a reported from various sites such as the Mediterranean Tethys and Pacific seamount flanks. Our δ 13 C org record from the deep Pacific basin supports the idea that the δ 13 C variation across OAE 1a was induced by a significant perturbation of global carbon cycle. The slight increase in total organic carbon contents of sediment deposited during OAE 1a suggests slight or no expansion of oxygen-deficient water mass in the overlying water column. Rare earth elements and lead isotopic compositions indicate relatively higher contributions of volcanic or hydrothermally altered components before and after OAE 1a. The volcanic or hydrothermal source may be associated with emplacement of the Ontong Java Plateau during the early Aptian, or tectonically induced hydrothermal alteration associated with the formation of the accretionary complex.

The Boltysh meteorite impact crater formed in the Ukrainian Shield on the margin of the Tethys Ocean a few thousand years before the Cretaceous-Paleogene boundary and was rapidly filled by a freshwater lake. Sediments filling the lake vary from early lacustrine turbidites and silts to ~300 m of fine silts, organic carbon–rich muds, oil shales, and lamenites that record early Danian terrestrial climate signals at high temporal resolution. Combined carbon isotope and palynological data show that the fine-grained organic carbon–rich lacustrine sediments preserve a uniquely complete and detailed negative carbon isotope excursion in an expanded section of several hundred meters. The position of the carbon isotope excursion in the early Danian stage of the Paleogene period, around 200 k.y. above the Cretaceous-Paleogene boundary, leads us to correlate it to the Dan-C2 carbon isotope excursion recorded in marine sediments of the same age. The more complete Boltysh carbon isotope excursion record indicates a δ 13 C shift of around -3‰, but also a more extended recovery period, strikingly similar in pattern to the highest fidelity carbon isotope excursion records available for the Toarcian and Paleocene-Eocene hyperthermal events. Changes in floral communities through the carbon isotope excursion recorded at Boltysh reflect changing biomes caused by rapidly warming climate, followed by recovery, indicating that this early Danian hyperthermal event had a similar duration to the Toarcian and Paleocene-Eocene events.

There are at least a dozen Phanerozoic continental flood basalts and oceanic plateaus (large igneous provinces) that roughly obey a “rule of two times one million” (volume of extruded lava of one million cubic kilometers and duration of volcanic activity ~1 m.y.). The correlation between large igneous province ages and mass extinctions (and oceanic anoxia events) is excellent, but quantitative scenarios are still wanting. We hypothesize that the temporal sequences of extrusions determine the severity of extinction: Volcanic pulses separated by thousands of years allow the ocean-atmosphere system time to recover, whereas large volcanic pulses occurring in a shorter sequence may result in a runaway effect and cause a mass extinction. Detailed flow-by-flow magnetic stratigraphies of thick sections have identified directional groups (sequences of superimposed lava flows with the same paleomagnetic direction that cooled in a time too short to record secular variation). With help of this simple tool, many single eruptive events with a volume larger than 1000 km 3 , some in excess of 10,000 km 3 , emplaced in possibly less than a decade, have been identified. We review this evidence, mainly for the following flood basalt provinces: Columbia, Brito-Arctic, Deccan, Karoo-Ferrar, Central Atlantic magmatic province, and Siberian Traps. Large igneous province volcanism occurs in a highly discontinuous way, on embedded time scales, on the order of 10 m.y., 1 m.y., 100 k.y., and 10 yr. This provides constraints for models of plume-lithosphere interaction and magma production. A next step is to model the consequences of massive injection of gases that can be derived from these time and duration estimates. Early attempts are reviewed in a companion paper in this volume.