Using full-colour palaeogeographical maps from the Cambrian to the present, this interdisciplinary volume explains how plate motions and surface volcanism are linked to processes in the Earth's mantle, and to climate change and the evolution of the Earth's biota. These new and very detailed maps provide a complete and integrated Phanerozoic story of palaeogeography. They illustrate the development of all the major mountain-building orogenies. Old lands, seas, ice caps, volcanic regions, reefs, and coal beds are highlighted on the maps, as well as faunal and floral provinces. Many other original diagrams show sections from the Earth's core, through the mantle, and up to the lithosphere, and how Large Igneous Provinces are generated, helping to understand how plates have appeared, moved, and vanished through time. Supplementary resources are available online, making this an invaluable reference for researchers, graduate students, professional geoscientists and anyone interested in the geological history of the Earth.

Earth History and Palaeogeography

The impact-induced deposition of Al13 clusters with icosahedral structure on Ni(0 0 1) surface was studied by molecular dynamics (MD) simulation using Finnis–Sinclair potentials. The incident kinetic energy (Ein) ranged from 0.01 to 30 eV per atom. The structural and dynamical properties of Al clusters on Ni surfaces were found to be strongly dependent on the impact energy. At much lower energy, the Al cluster deposited on the surface as a bulk molecule. However, the original icosahedral structure was transformed to the fcc-like one due to the interaction and the structure mismatch between the Al cluster and Ni surface. With increasing the impinging energy, the cluster was deformed severely when it contacted the substrate, and then broken up due to dense collision cascade. The cluster atoms spread on the surface at last. When the impact energy was higher than 11 eV, the defects, such as Al substitutions and Ni ejections, were observed. The simulation indicated that there exists an optimum energy range, which is suitable for Al epitaxial growth in layer by layer. In addition, at higher impinging energy, the atomic exchange between Al and Ni atoms will be favourable to surface alloying.

Nuclear instruments and methods in physics research section B : beam interactions with materials and atoms

The missing link in the plate boundary between Eurasia and Africa in the central Atlantic is presented and discussed. A set of almost linear and sub parallel dextral strike–slip faults, the SWIM1 Faults, that form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of Africa with respect to Eurasia, was mapped using a new swath bathymetry compilation available in the area offshore SW Portugal. These faults connect the Gloria Fault to the Rif–Tell Fault Zone, two segments of the plate boundary between Africa and Eurasia. The SWIM faults cut across the Gulf of Cadiz, in the Atlantic Ocean, where the 1755 Great Lisbon earthquake, M ~ 8.5–8.7, and tsunami were generated, providing a new insight on its source location.

The Quest for the Africa-Eurasia plate boundary West of the Strait of Gibraltar

Abstract High-resolution grain size and magnetic susceptibility records from the eastern Gulf of Cadiz (site MD99-2339; 1170 m water depth) reveal contourites formed by the Mediterranean Outflow (MOW) during the last 47 kyr BP. Oscillations in the MOW's intensity occurred in phase with Greenland temperature variations with a stronger outflow during northern hemisphere coolings such as Dansgaard-Oeschger stadials, Heinrich events, and the Younger Dryas. Benthic δ13C data implies the Western Mediterranean Deep Water as one of the main sources feeding the outflow current, while differential changes in the properties of the Mediterranean source and entrained North Atlantic Central Water largely control the MOW's strength. Detailed studies for Heinrich events 1, 4 and 5 show that the flow strength peaked only when subtropical surface waters prevailed in the eastern Gulf of Cadiz, while incursions of icebergs and subpolar surface water were not favorable for the MOW's intensification. As the MOW was strong when the Atlantic's thermohaline circulation (THC) was weakened, the heat and salt injected by the MOW into the intermediate North Atlantic waters might have preconditioned the THC to switch from the stadial to the interstadial mode.

Mediterranean Outflow Strengthens during Northern Hemisphere Coolings: A salt source for the glacial Atlantic?

The “Panama Hypothesis” states that the gradual closure of the Panama Seaway, between 13 million years ago (13 Ma) and 2.6 Ma, led to decreased mixing of Atlantic and Pacific water Masses, the formation of North Atlantic Deep water and strengthening of the Atlantic thermohaline circulation, increased temperatures and evaporation in the North Atlantic, increased precipitation in Northern Hemisphere (NH) high latitudes, culminating in the intensification of Northern Hemisphere Glaciation (NHG) during the Pliocene, 3.2–2.7 Ma. Here we test this hypothesis using a fully coupled, fully dynamic ocean-atmosphere general circulation model (GCM) with boundary conditions specific to the Pliocene, and a high resolution dynamic ice sheet model. We carry out two GCM simulations with “closed” and “open” Panama Seaways, and use the simulated climatologies to force the ice sheet model. We find that the models support the “Panama Hypothesis” in as much as the closure of the seaway results in a more intense Atlantic thermohaline circulation, enhanced precipitation over Greenland and North America, and ultimately larger ice sheets. However, the volume difference between the ice sheets in the “closed” and “open” configurations is small, equivalent to about 5 cm of sea level. We conclude that although the closure of the Panama Seaway may have slightly enhanced or advanced the onset of NHG, it was not a major forcing mechanism. Future work must fully couple the ice sheet model and GCM, and investigate the role of orbital and CO2 effects in controlling NHG.

Closure of the Panama Seaway During the Pliocene - Implications for Climate and Northern Hemisphere Glaciation

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Sevasti Modestu

Papers

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change