ABSTRACT What causes recurrent mass extinctions of life? We find that the ages of 10 of the 11 well-documented extinction episodes of the last 260 m.y. show correlations, at very high confidence (>99.99%), with the ages of the largest impact craters or the ages of massive continental flood-basalt eruptions. The four largest craters (≥100 km diameter, impact energies ≥3 × 10 7 Mt trinitrotoluene [TNT]) can be linked with recognized extinction events at 36, 66, 145, and 215 Ma, and with stratigraphic distal impact debris correlative with the extinctions. The ages of 7 out of 11 major flood-basalt episodes can be correlated with extinction events at 66, 94, ca. 120, 183, 201, 252, and 260 Ma. All seven flood-basalt–extinction co-events have coincident volcanogenic mercury anomalies in the stratigraphic record, closely linking the extinctions to the volcanism. Furthermore, the seven major periods of widespread anoxia in the oceans of the last 260 m.y. are significantly correlated (>99.99%) with the ages of the flood-basalt–extinction events, supporting a causal connection through volcanism-induced climate warming. Over Phanerozoic time (the last 541 m.y.), the six “major” mass extinctions (≥40% extinction of marine genera) are all correlated with the ages of flood-basalt episodes, and stratigraphically with related volcanogenic mercury anomalies. In only one case, the end of the Cretaceous (66 Ma), is there an apparent coincidence of a “major” mass-extinction event with both a very large crater (Chicxulub) and a continental flood-basalt eruption (the Deccan Traps). The highly significant correlations indicate that extinction episodes are typically related to severe environmental crises produced by the largest impacts and by periods of flood-basalt volcanism. About 50% of the impacts of the past 260 m.y. seem to have occurred in clusters, supporting a picture of brief pulses of increased comet or asteroid flux. The largest craters tend to fall within these age clusters. Cross-wavelet transform analyses of the ages of impact craters and extinction events show a common, strong ~26 m.y. cycle, with the most recent phase of the cycle at ~12 Ma, correlating with a minor extinction event at 11.6 Ma. The stream of life flows so slowly that the imagination fails to grasp the immensity of time required for its passage, but like many another stream it pulses irregularly as it flows. There are times of quickening, the expression points of evolution, which are almost invariably coincident with some great geologic change, and the correspondence so exact and so frequent that the laws of chance may not be invoked by way of explanation. —Richard Swann Lull ( Organic Evolution , New York, Macmillan, 1929, p. 693)

Abstract: Gondwana was an enormous supertarrane. At its peak, it represented a landmass of about 100 × 10 6 km 2 in size, corresponding to approximately 64% of all land areas today. Gondwana assembled in the Middle Cambrian, merged with Laurussia to form Pangea in the Carboniferous, and finally disintegrated with the separation of East and West Gondwana at about 170 Ma, and the separation of Africa and South America around 130 Ma. Here we have updated plate reconstructions from Gondwana history, with a special emphasis on the interactions between the continental crust of Gondwana and the mantle plumes resulting in Large Igneous Provinces (LIPs) at its surface. Moreover, we present an overview of the subvolcanic parts of the Gondwana LIPs (Kalkarindji, Central Atlantic Magmatic Province, Karoo and the Paraná–Etendeka) aimed at summarizing our current understanding of timings, scale and impact of these provinces. The Central Atlantic Magmatic Province (CAMP) reveals a conservative volume estimate of 700 000 km 3 of subvolcanic intrusions, emplaced in the Brazilian sedimentary basins (58–66% of the total CAMP sill volume). The detailed evolution and melt-flux estimates for the CAMP and Gondwana-related LIPs are, however, poorly constrained, as they are not yet sufficiently explored with high-precision U–Pb geochronology.

This paper integrates, analyzes, and interprets the existing geological and geophysical information related to the opening of the Gulf of Mexico. The analysis of this information has the objective to consider the opening of the Gulf of Mexico as a result of global tectonic processes. Without doubt, the opening of the Gulf of Mexico has its origin in the interaction of two important tectonic events that generated the separation of Pangea: the Farallon Plate subduction in the Pacific and on the opening of the Central Atlantic, whose start is marked by the presence of the Central Atlantic magmatic province. A proposal of this work is that as much oceanic crust was generated in the Oxfordian, as part of the stage in the Central Atlantic Jurassic opening. This Oxfordian period is characterized by a large positive geomagnetic chron, which explains the absence of polarity changes in the magnetic response for the Gulf of Mexico. Another proposal is that the Sierra de Chiapas is the transpressional front that represents the final stage in the gulf opening and is associated with the edge effect of gravity anomaly that can be observed in the overall gravimetric maps. The proposed model assumes that the magmatic arc causes continental rifting, creating basins containing red beds deposits that are located parallel to the orientation of the arc; these rifting areas evolve to form the subbasins of Chihuahua, Sabinas, and Burgos in the northeast of Mexico and Tampico Misantla, Veracruz, and Southeastern basins in eastern Mexico.

We present here the first geochemical data from adakitic rocks from an extensional system—the U.S. East Coast rifted margin. Adakitic magmas are high-K melts that have been petrogenetically interpreted to be partial melts of subducting slab and/or lower crustal lithologies in delamination events. The adakitic rocks presented here are from a small volcanic region in the Valley and Ridge province in Virginia and were probably emplaced around the time of continent rupture and Central Atlantic magmatic province activity. They are bimodal in character (high Si and low Si) and have the typical high- and low-Si adakitic geochemical characteristics such as high K 2 O (up to 9.88 wt%) abundances, steep rare earth element patterns, and significantly high Sr (2473 ppm) and relatively low Rb (35 ppm) contents for high-Si adakitic rocks. The petrogenetic relation of these melts to partial melting of metagabbroic rocks (high-Si adakites) and interaction of these melts with ambient peridotite (low-Si adakites) suggests that the geodynamic process for the formation of the studied Jurassic central Virginia igneous rock succession is delamination of mantle lithosphere and lower crust below the volcanic rifted margin. We present with geodynamic models that negatively buoyant mantle lithosphere instabilities developed below this passive margin during continent rupture. After foundering, warm asthenosphere welled up and heated the lower crust of the East Coast margin. This lithosphere was interspersed in our study area with fragmented hydrated metamorphic mafic to ultramafic lithologies. In situ and/or dripping melting of such meta-igneous rocks reproduces the observed geochemistry of the studied high-Si adakitic rocks. Further recycling processes within the convecting mantle of delaminated floating fertile meta-igneous rock packages could be responsible for Atlantic melting anomalies such as the Azores or Bermuda.