Abstract The National Gas Hydrate Program Expedition 02 was conducted in early 2015 using the Drilling Vessel Chikyu in the western part of the Bay of Bengal, India. During drilling off Vishakhapatnam, NE India, some bottom-simulating reflectors were penetrated, and numerous mass-transport deposits (MTDs) were identified. The recovered cores were composed of post-late Miocene muddy slope deposits containing the late Miocene–Pliocene hiatus that is widespread in that region. Based on detailed visual core descriptions and calcareous nannofossil biostratigraphy, two major MTD-rich intervals were identified: the Pleistocene interval above the hiatus, and the middle–late Miocene interval below it. Although the MTDs in both intervals are composed of variously coloured clay–silt blocks in an olive-black or olive-grey silty clay matrix (muddy MTDs), the Pleistocene MTDs consist of larger-sized blocks (mostly less than a few metres but with some >10 m) without clear shear fabrics, whereas the Miocene MTDs contain smaller blocks (<0.1 m) with asymmetrical shear fabrics. The muddy blocks are composed of older components (Pliocene–Cretaceous) compared with the depositional ages of the MTDs. The high abundance of MTDs above the hiatus and the depositional ages of the interbedded coherent layers indicate that large-scale MTDs occurred repeatedly during the Pleistocene. Such repeated MTDs contributed to maintaining the high sedimentation rate in this area and potentially provided stable pressure and temperature conditions for the formation of gas hydrates.

Abstract This paper provides an overview of the existing knowledge of transform margins including their dynamic development, kinematic development, structural architecture and thermal regime, together with the factors controlling these. This systematic knowledge is used for describing predictive models of various petroleum system concept elements such as source rock, seal rock and reservoir rock distribution, expulsion timing, trapping style and timing, and migration patterns. The paper then introduces individual contributions to this volume and their focus.

Abstract The Elan Bank microcontinent was separated from East India during the Early Cretaceous break-up. The crustal architecture and rifting geometry of East India and the Elan Bank margins document that the early break-up between India and Antarctica was initiated in the eastern portions of the Cauvery and Krishna–Godavari rift zones, and in the southern portion of Elan Bank. However, the westwards break-up propagation along the Krishna–Godavari Rift Zone continued even after the break-up in the overstepping portion of the Cauvery Rift Zone. Eventually, the western propagating end of the Krishna–Godavari Rift Zone became hard-linked with the failed western portion of the Cauvery Rift Zone by the dextral Coromandel transfer fault zone. Consequently, the break-up location between India and Antarctica shifted from its initial to its final location along the northern portion of the Elan Bank formed by the western Krishna–Godavari Rift Zone. The competition between the two rift zones to capture continental break-up and asymmetric ridge propagation resulted in a ridge jump and the Elan Bank microcontinent release.

The recent discovery of the direct link between Deccan volcanism and the end-Cretaceous mass extinction also links volcanism to the late Maastrichtian rapid global warming, high environmental stress, and the delayed recovery in the early Danian. In comparison, three decades of research on the Chicxulub impact have failed to account for long-term climatic and environmental changes or prove a coincidence with the mass extinction. A review of Deccan volcanism and the best age estimate for the Chicxulub impact provides a new perspective on the causes for the end-Cretaceous mass extinction and supports an integrated Deccan-Chicxulub scenario. This scenario takes into consideration climate warming and cooling, sea-level changes, erosion, weathering, ocean acidification, high-stress environments with opportunistic species blooms, the mass extinction, and delayed postextinction recovery. The crisis began in C29r (upper CF2 to lower CF1) with rapid global warming of 4 °C in the oceans and 8 °C on land, commonly attributed to Deccan phase 2 eruptions. The Chicxulub impact occurred during this warm event (about 100–150 k.y. before the mass extinction) based on the stratigraphically oldest impact spherule layer in NE Mexico, Texas, and Yucatan crater core Yaxcopoil-1. It likely exacerbated climate warming and may have intensified Deccan eruptions. The reworked spherule layers at the base of the sandstone complex in NE Mexico and Texas were deposited in the upper half of CF1, ~50–80 k.y. before the Cretaceous-Tertiary (K-T) boundary. This sandstone complex, commonly interpreted as impact tsunami deposits of K-T boundary age, was deposited during climate cooling, low sea level, and intensified currents, leading to erosion of nearshore areas (including Chicxulub impact spherules), transport, and redeposition via submarine channels into deeper waters. Renewed climate warming during the last ~50 k.y. of the Maastrichtian correlates with at least four rapid, massive volcanic eruptions known as the longest lava flows on Earth that ended with the mass extinction, probably due to runaway effects. The kill mechanism was likely ocean acidification resulting in the carbonate crisis commonly considered to be the primary cause for four of the five Phanerozoic mass extinctions.