Abstract Spatial self-organization, the process where coherent spatial patterns emerge through internal interactions, is widely observed in modern natural systems. Compelling examples range from ripple and dune formation in aquatic and terrestrial systems to formation of patterned coral reefs and vegetation in arid regions. Despite this wide range of contemporary cases, the concept of self-organization and its potential effects on geological patterns have not yet been widely discussed by the geological community, especially in carbonate depositional systems. We present four case studies from modern bivalve beds, coral reefs, microbial carbonates, and tidal channels, and one from the rock record considering carbonate cyclicity, where spatial self-organization could explain regularity in preserved strata. Only two of these five case studies, bivalve beds and tidal channel systems, are accompanied by a firm understanding of the mechanisms that generate emergent patterning. Three types of ecosystem spatial self-organization—scale-dependent feedback creating regular patterns, criticality behavior causing scale-free patterns, and oscillating consumer resource interactions causing consumer waves—are well documented. The first two of those appear to hold most relevance for carbonate depositional environments. Considerable work remains to understand the processes and products of spatial self-organization in carbonate deposystems.

Abstract Sedimentary strata are the paramount source of geohistorical information. The ‘frozen accidents’ of individual deposits preserve evidence of past physical, chemical and biological processes at the Earth’s surface, while the spatial relationships between strata (especially superposition) yield successions of events through time. There is, however, no one-to-one relationship between strata and time, and the interpretation of the stratigraphic record depends on an understanding of its limitations. Stratigraphic continuity and completeness are unattainable ideals, and it is the departures from those ideals – the often cryptic gaps in the record – that provide both its characteristic texture and the principal challenge to its analysis. The existence of gaps is clearly demonstrated by consideration of accumulation rates, but identifying and quantifying them in the field is far more difficult, as is assessing their impact on the degree to which the stratigraphic record represents the environments and processes of the past. These issues can be tackled in a variety of ways, from empirical considerations based on classical field observations, to new ways of analysing data, to the generation and analysis of very large numbers of synthetic datasets. The range of approaches to the fundamental questions of the relationship between strata and time continues to expand and to challenge long-established practices and conventions. Superposed sedimentary strata are the most accessible routes into deep time, and acceptance of their historical significance was a major scientific breakthrough. Given that the study of strata has been undertaken in something like its modern form for over two centuries, stratigraphy as a scientific discipline might be expected to have stabilized, as perhaps is indicated by stratigraphy textbooks suggesting that the subject is widely regarded as boring. Yet if there is a problem with stratigraphy, it is the converse: its development is increasingly punctuated by paradigm shifts triggered by new theories (evolution; global tectonics; eustasy; orbital forcing of climate change) and technological breakthroughs (digital computing; continuous seismic profiling; isotopic methods in chronology and palaeoclimatology). With this accelerating progress, it has become increasingly clear that the stratigraphic record yields only snapshots of Earth’s past surface processes – the ‘frozen accidents’ that give the record its character and its enduring fascination. ‘Time is missing from sedimentary sequences on all scales … This discontinuity gives recorded planetary (geological) time a different architecture to human time’ ( Paola, C. 2003 . Floods of record. Nature , 425 , 459). Strata and Time: Probing the Gaps in our Understanding was the title of the Geological Society’s William Smith Meeting for 2012. Its aim was to explore the relationship between the preserved sedimentary rock record and the passage of geological time, identifying, evaluating and updating the models that lie behind current stratigraphic methods. This volume includes contributions by some of those who presented papers at the conference, together with two additional, related papers. The range of topics in these 15 papers is broad; from field-based studies to numerical modelling exercises, from theoretical considerations of the nature of the record to a study of hydrocarbon reservoir distribution. Critical to all of these studies is the relationship between sedimentary rock strata and geological time.

Abstract Continental SE Asia is the site of an extensive Cretaceous–Paleocene regional unconformity that extends from Indochina to Java, covering an area of c . 5 600 000 km 2 . The unconformity has previously been related to microcontinental collision at the Java margin that halted subduction of Tethyan oceanic lithosphere in the Late Cretaceous. However, given the disparity in size between the accreted continental fragments and area of the unconformity, together with lack of evidence for requisite crustal shortening and thickening, the unconformity is unlikely to have resulted from collisional tectonics alone. Instead, mapping of the spatial extent of the mid–Late Cretaceous subduction zone and the Cretaceous–Paleocene unconformity suggests that the unconformity could be a consequence of subduction-driven mantle processes. Cessation of subduction, descent of a northward dipping slab into the mantle, and consequent uplift and denudation of a sediment-filled Late Jurassic and Early Cretaceous dynamic topographic low help explain the extent and timing of the unconformity. Sediments started to accumulate above the unconformity from the Middle Eocene when subduction recommenced beneath Sundaland.

Abstract A commonly assumed element of sequence stratigraphic theory is that incised valleys must feed lowstand deltas. This model persists despite examples in which no lowstand deposit is present at the distal ends of some ancient and recent valley fills. The Clearwater Formation at Cold Lake Field, Alberta, Canada, presents a unique opportunity to investigate in detail the transition from fluvial incised-valley fills to open marine mudstone using over 1000 wells, over 400 with core, from an area of 3,200 km 2 . The presence of prominent marine well-log markers and the abundance and density of well logs allows confident correlation of the incised-valley fills. The Clearwater Formation consists of 13 stacked incised valleys with depths of incision ranging from 30 m to possibly 120 m. All of the valley fills show a depositional facies pattern from sandy fluvial or upper estuarine updip to muddy estuarine or marine deposits downdip. All of the valleys terminate downdip as thin (< 2 m) sheets of marine sandy mudstone. Significantly, none of the valleys are connected to downdip lowstand deltas, or even sandy lowstand shorelines. In addition, the valley-fill lithofacies differ significantly from the marine strata into which they are incised; they are sandier, and the sand fraction is coarser. The valley fills, therefore, are not composed only of reworked material eroded from valley walls, but represent sediment delivered from more proximal sources, presumably by rivers. Our examples demonstrate that the presence of deep incised valleys, even if they are filled with coarse material, cannot by itself be used to predict sand delivery to the paleo-shoreline or more basinward regions. We recognize two primary conditions for valley fills that lack associated sandy lowstand deposits: the lowest point of relative sea level was above the continental shelf edge (for passive-margin settings), and sediment delivery during early rising sea level was limited. For the examples cited we interpret that filling of incised valleys occurs during relative sea-level rise when only limited amounts of sediment can be delivered beyond incised-valley mouths.