This Special Publication celebrates the life and times of one of the late 20th century's most influential structural geologists, Mike Coward. At various times Mike was H H Read Professor of Geology at Imperial College, Chair of the UK Tectonic Studies Group and Council Member of the Geological Society of London; but these official titles belie a deeply unconventional man who loved to challenge accepted wisdom and dogma. Mike's career was an eclectic mix of pure and applied research in structural geology that straddled continents and geological time. Normal chronological narratives can hardly do justice to a man who could step from theme to theme at times, seemingly to colleagues, almost on a daily basis. This brief biography attempts to draw together some of the strands, in rather the same way as the Special Publication itself, to offer a glimpse of a character who could be very much larger than life. <...>

Deltas, with their economic, political and scientific importance, have long fascinated and attracted Man's attention. The term 'delta' was coined by Herodotus in approximately 450 Bc for the triangular-shaped sedimentary body at the mouth of the River Nile. Today, the concept of a delta, its morphology and its controlling processes, are almost as numerous as the people who work on such systems.
This volume, of 23 papers on many aspects of modern and ancient deltaic sedimentary systems, will be useful to researchers as well as teachers and students alike. The well-balanced content of the book should prove particularly attractive.to those who seek a detailed state-of-the-science overview of this large and ever-expanding subject area. <...>

We report here an investigation of the distribution of Au, As, Sb, Hg, carbonates, K-Al silicates, and pyrite in the Twin Creeks Carlin-type gold deposit. The main objective of the study was to determine the nature and degree of correlation among these variables and use them to identify the process(es) that deposited gold. The study focused on deposit-scale variations in these parameters and was based, in part, on data from two large geochemical databases that were prepared by mine staff.

Country rocks at Twin Creeks include Ordovician-age interlayered calcareous shales and mafic igneous rocks, the overlying Leviathan allochthon, and the Pennsylvanian-Permian Etchart Formation that was deposited unconformably over these rocks. Most gold values are found in calcareous shales in the Ordovician sequence and in limestones in the Etchart Formation, although not all layers contain the same amount of gold. Strongest gold mineralization is not adjacent to faults but its general form and distribution suggest that gold-bearing solutions gained access to favorable layers along the faults. In the Ordovician sequence, gold values are highest in shales that have undergone maximum dissolution of carbonate minerals. Petrographic study shows that some gold is associated with adularia, but deposit-scale comparisons do not show a consistent relation between K/Al ratios and gold values. The distribution of antimony is similar to that of gold, whereas mercury is more concentrated than gold, and arsenic is more widely dispersed than gold.

The relation between gold, iron, and sulfide sulfur values shows that mineralization is concentrated in rocks that have gained sulfur, but not iron, to form gold-bearing arsenian pyrite. Thus, these rocks have undergone sulfidation rather than pyritization. The iron that underwent sulfidation came largely from preore, diagenetic(P) ferroan dolomite and was released into solution by decarbonation, a common form of alteration associated with Carlin-type deposits. The results of this study suggest that wall-rock iron content and decarbonation processes which liberate this iron are the most important factors controlling formation of Carlin-type gold deposits. New deposits should be sought where stratigraphic units containing abundant ferroan dolomite are cut by favorable structures.

Gravity-driven fows of material emanating from volcanoes during or following eruptions can range from fowing molten rock to fowing denser-than-air volcanic gas. But the bulk of volcanic fows involve twophase mixtures of solid rock fragments and a fuid—either liquid water or gas composed of air±volcanic gases. Deposits of the various particle–fuid fows derive their physical characteristics from mixture properties and from the particle–fuid interactions involved in both the transport and deposition of the mixtures. Interactions can differ substantially among emplacement processes.