Abstract The Antarctic continent, which contains enough ice to raise sea level globally by around 60 m, is the last major scientific frontier on our planet. We know far more about the surfaces of the Moon, Mars and around half of Pluto than we do about the underside of the Antarctic ice sheet. Geophysical exploration is the key route to measuring the ice sheetâs internal structure and the land on which the ice rests. From such measurements, we are able to reveal how the ice sheet flows, and how it responds to atmospheric and ocean warming. By examining landscapes that have been moulded by former ice flow, we are able to identify how the ice sheet behaved in the past. Geophysics is therefore critical to understanding change in Antarctica.

Abstract The accurate assessment of trap attributes remains a primary determinant of subsalt exploration success. Gulf of Mexico 3D seismic datasets, subsalt well results, and kinematic models have been integrated into a calibrated methodology for assessing subsalt trap geometry and prospectivity. Subsalt traps can be grouped into genetically distinct archetype families, a classification that reveals the predictable influence of common salt styles on specific trap attributes. The archetype families are qualitatively ranked for exploration value according to their inherent trap risks, forming a basis for evaluating the prospectivity of even poorly imaged subsalt objectives. Within the complex salt systems of the northern Gulf of Mexico, subsalt stratal geometries are highly variable. Narrow, three-way ribbon truncation closures and steep stratal dips pose generic exploration risks, while trap prospectivity may be greatly improved where subsalt strata have been counterrotated, inverted, and/or downwardly flexed. Structural elements that enhance or destroy subsalt trap viability evolve with the deformation of ubiquitous, deeper allochthonous and autochthonous salt. The concept of vertical linkage describes this systematic relationship between deep salt movement and the magnitude and mode of subsalt trap deformation. Empirical observations and kinematic models demonstrate that vertical linkage is, in turn, dictated by local salt root geometry. Three kinematically distinct subsalt root types are recognized: autochthonous salt roots, fore-ramping allochthonous salt roots , and back-ramping allochthonous salt roots. Each root style exerts a predictable influence on subsalt stratal geometry, thereby providing explorationists a means of inferring trap attributes that may be obscured by overlying salt. End-member trap archetypes illustrate frequently occurring subsalt trap styles, and are grouped into four play families: (1) sub-suture traps, (2) autochthon rooted traps, (3) fore-ramping allochthon rooted traps, and (4) back-ramping allochthon rooted traps. Sub-suture traps occur as bilateral stratal truncations against salt base antiforms, and present high-risk objectives having the lowest overall value. In contrast, the top ranked family of autochthon rooted traps includes highly prospective salt cored and inverted subsalt anticlines. The allochthonous fore-ramping and back-ramping trap families fall in between these extremes and are ranked by their generic subsalt fold styles. Fore-ramping roots promote risk-inducing upward stratal flexures, while back-ramping roots yield favorable downward flexures, warranting third and second priority rankings for the respective play families.

Abstract Since the opening of the Space Age, images from spacecraft have enabled us to map the surfaces of all the rocky planets and satellites in the Solar System, thus transforming them from astronomical to geological objects. This progression of geology from being a strictly Earth-centred science to one that is planetary-wide has provided us with a wealth of information on the evolutionary histories of other bodies and has supplied valuable new insights on the Earth itself. We have learned, for example, that the Earth–Moon system most likely formed as a result of a collision in space between the protoearth and a large impactor, and that the Moon subsequently accreted largely from debris of Earth's mantle. The airless, waterless Moon still preserves a record of the impact events that have scarred its surface from the time its crust first formed. The much larger, volcanic Earth underwent a similar bombardment but most of the evidence was lost during the earliest 550 million years or so that elapsed before its first surviving systems of crustal rocks formed. Therefore, we decipher Earth's earliest history by investigating the record on the Moon. Lunar samples collected by the Apollo astronauts of the USA and the robotic Luna missions of the former USSR linked the Earth and Moon by their oxygen isotopic compositions and enabled us to construct a timescale of lunar events keyed to dated samples. They also permitted us to identify certain meteorites as fragments of the lunar crust that were projected to the Earth by impacts on the Moon. Similarly, analyses of the Martian surface soils and atmosphere by the Viking and Pathfinder missions led to the identification of meteorite fragments ejected by hypervelocity impacts on Mars. Images of Mars displayed land-forms wrought in the past by voluminous floodwaters, similar to those of the long-controversial Channeled Scablands of Washington State, USA. The record on Mars confirmed catastrophic flooding as a significant geomorphic process on at least one other planet. The first views of the Earth photographed by the crew of Apollo 8 gave us the concept of 'Spaceship Earth' and heightened international concern for protection of the global environment.

ABSTRACT This contribution attempts to recount our collective progress in understanding the Archean–Hadean Earth system over the past 50 yr. Many realms of the geological sciences (geochemistry, petrology, geophysics, structural geology, geobiology, planetary science, and more) have made substantive contributions to this effort. These contributions have changed our understanding of the Archean–Hadean Earth in five major areas: (1) the expanse of Archean–Hadean time; (2) tectonics and lithospheric evolution, particularly possible analogs for the sites of modern, primary crust production and mantle differentiation (e.g., magmatic arcs, ocean ridges, and large igneous provinces); (3) evolution of the atmosphere-hydrosphere system, and its impact on the evolution of Earth’s endogenic and exogenic systems; (4) the history of liquid water, particularly at the ocean scale; and (5) the origin and development of the biosphere and its impact on the geologic record. We also emphasize that much of the progress made in understanding the evolution of early Earth systems over the past 50 yr has been fueled by important technological advances in analytical geochemistry, such as the advent of ion probes for U-Pb zircon geochronology, inductively coupled plasma–mass spectrometry for trace-element and Hf isotopic analyses, Raman spectroscopy in organic geochemistry, and molecular reconstructions in biology. Within this context, we specifically review progress in our understanding of the Eoarchean history of southern West Greenland as an example of the value of continuous integration of careful geologic observation and mapping with evolving technology, which have combined to further open this window into Earth’s earliest systems.