ABSTRACT The Rotliegend Group in the Netherlands provides a depositional record of fluvial, aeolian, and playa interaction within a major Permian dryland basin. Ephemeral fluvial systems drained off the London–Brabant and Rhenish Massifs and flowed northwards towards the Silverpit Formation desert lake, whilst marginal dune fields expanded and contracted in response to changing aridity and fluvial runoff. There are few modern parallels to the scale of the Southern Permian Basin depositional system as a whole, but recent dryland analogues provide a valuable means to understand the depositional processes which locally operated across the basin during the Late Permian. A variety of modern analogues is required to adequately sample the range of climatic conditions that the Rotliegend depositional systems encountered, with examples selected from modern ergs, fluvial and alluvial fans, playa, lacustrine, and saline-lake settings. However, although the long-term allocyclic controls on deposition and preservation of the Rotliegend have long been recognised, the contrast between the diversity of surficial facies seen in modern dryland settings and that preserved in the ancient record suggests that the Rotliegend also failed to preserve much of the expected facies diversity through aeolian deflation and sustained, polycyclic reworking of interacting fluvial, lacustrine, and aeolian systems. Widespread fluvial activity and lacustrine shoreline facies, which form a visible record of relatively recent pluvial episodes in modern basins, have limited preservation potential, and maps of gross facies belts in the Rotliegend are not true palaeogeographic facies arrangements but time-averaged associations of those facies which ultimately entered the stratigraphic record.

Abstract More than 150 Moz of gold has been added in production and resources from Proterozoic deposits in the last ten years, and many Proterozoic basins are now considered high priority exploration targets. The bulk of Proterozoic gold is produced from lode gold and Cu-Au (U-REE-Ba-F) deposits which are found in northern Australia, South Dakota, West Africa, Canada, South Africa, Scandinavia, and Central America. Proterozoic lode gold deposits are restricted to late collisional stages in the development of Proterozoic orogenic belts. They appear to have a systematic sequence of events in common and occur in linear belts associated with regional ductile structures at, or near, the greenschist facies brittle-ductile transition. Gold occurs in a large variety of rock types and has a close spatial association with regional-scale domes, anticlines, strike-slip shear zones, duplex thrusts, and in some deposits, geochemically distinct granites. Deposit styles can be subdivided into several types, directly related to the host structure and to contrasts in host-rock competency and mineralogy. These deposits have fluids and geochemical associations that overlap those of Archean lode gold deposits. Proterozoic Cu-Au-(Fe) deposits formed in a broader range of crustal and tectonic environments and display a great variety of structural and host-rock controls and styles. It is evident in all districts where the timing relationships are known that these deposits have spatial and temporal relationships to granites. These deposits display a range of fault and shear zone controls and are commonly associated with regions of geometric complexity, structural intersections, or regionally anomalous structural orientations. There is considerable evidence of variable fluid chemistry in Cu-Au-(Fe) deposits. Districts are commonly characterized by regional metasomatism and alteration at both regional and deposit scale which is commonly intense. Fe oxide-Cu-Au environments tend to produce similar alteration assemblages in all aluminous rock types. The influence of magmas as sources of fluid and ore components appears to have been greater in at least some Cu-Au-(Fe) systems and the associated granitoids are typically oxidized and include both mafic and felsic varieties. Sodic alteration styles are commonly prevalent regionally; the larger ore systems in particular are hosted specifically within substantial bodies of rock that are depleted in Na and enriched in K-Fe-(H).