Abstract A critical step in 3-D reservoir model construction is interpretation of stratigraphic-framework surfaces that guide data distribution between wells. Application of outcrop-scaled Walther’s Law depositional models that include information on depositional dip and facies-tract width is a basic guide for subsurface correlations. Ramp-crest grainstone complexes from the Permian of the Guadalupe Mountains, southeast New Mexico, and the Cretaceous of the Comanche Shelf, South Texas, form the bases for models with constrained depositional dips and facies-tract widths. Facies partitioning between transgressive and highstand systems tracts (TST and HST) as shown in outcrops of the Comanche Shelf Cretaceous along the Pecos River indicates that Walther’s Law models must be calibrated to the systems tracts level to gain maximum prediction of facies distribution and stratal geometry. Lacking these calibrated Walter’s Law models, correlations tend to produce an overly homogeneous lithostratigraphic correlation scheme, such as that applied to the Permian Seminole San Andres Unit of the Permian Basin.

The Palms Formation in Wisconsin and Michigan and the correlative Pokegama Quartzite in Minnesota are interpreted as tidal deposits formed along the margins of the early Proterozoic Animikie basin. The well-exposed Palms Formation, which extends for 85 km along the Gogebic range, is 150 m thick and can be divided into three units on the basis of rock types and bedding styles: (1) a thin lower unit of thin-bedded argillaceous rocks that unconformably overlies a low-relief surface of Archean granite and greenstone and older Proterozoic sedimentary units; (2) a thick middle unit of thin alternating beds of argillite, siltstone, and sandstone that vary considerably in texture and composition. Bedding types include parallel, wavy, cross, and flaser lamination, and a variety of sedimentary structures are present; (3) an upper unit of thicker beds of parallel and cross-bedded sandstone. A total of 199 cross-bedding measurements and 52 measurements of other paleocurrent indicators from the Palms Formation yields a crude bimodal-bipolar distribution, with a broad primary mode to the west and a weaker mode to the east. The sandstones are mineralogically mature; most of the framework grains are rounded quartz grains. The sandstones of the middle unit have an abundant sericitic matrix, whereas those of the upper unit are texturally more mature. The Pokegama Quartzite is exposed at only a few places along the 130 km long Mesabi range near the northwestern margin of the Animikie basin. However, the entire formation can be viewed in two drill cores in which it is 50 m and 26 m thick. Sedimentary sequences and the mineralogical attributes are similar to the Palms. The paleocurrent plot (N = 38) is crudely bimodal-bipolar with primary modes to the north and south. By utilization of Walther’s Law of Succession of Facies and comparisons with modern environments, it is postulable that both formations were deposited under transgressive tidal conditions. In this model, the lower (shaly) facies was deposited in a low-energy domain of the upper (shoreward) tidal flat; the middle facies (shale-siltstone-sandstone) was deposited on a middle tidal flat under alternating low- and high-energy conditions; and the upper facies (sandstone) was deposited in a lower tidal flat or subtidal high-energy environment. The Palms and Pokegama formations pass upward into the Ironwood and Biwabik Iron Formations, respectively. Again using Walther’s Law, it can be postulated that the iron-formations were deposited on a shelf located seaward from the subtidal sandstone facies. The “cherty” (coarser-grained, thicker-bedded, iron oxide-chert) facies was deposited in shallower water than was the “slaty” (finer-grained, thinner-bedded, iron silicate-iron carbonate) facies. The tidal-subtidal facies model developed here provides an independent approach in evaluating the environment of deposition of one kind of Superior-type banded iron-formation. The model is primarily based upon the siliciclastic lithologies associated with iron-formation rather than upon the iron-formation itself.

This paper describes the deposition of Miocene carbonates around Sarawak in a tectono-stratigraphic framework. The onset, termination, and location of the two main carbonate units, the Subis or Lower Cycle II limestones and the Luconia limestone, were controlled by tectonic processes, each beginning with a subsidence event, and terminated by influxes of siliciclastic sediments due to hinterland uplift. New data are presented on the intra–late Miocene decline of Luconia Limestone platforms that is correlated to the uplift of onshore Sarawak (Tinjar Province) and renewed siliciclastic sedimentation, which is dated as being at the same time as major uplift in northern Borneo. Miocene sedimentation around Sarawak was controlled mostly by extensional tectonics with several rapid subsidence events, which produced transgressive unconformities with mappable focal areas. Away from these focal areas, the contrast in facies, before and after the event, gradually diminishes in a predictable manner. This property of the unconformity is governed by Walther’s Law in that one well or field section cannot be exempt from the mappable trends in facies contrast observed in surrounding wells. This relationship constrains the interpretation of seismic, mapping, and analytical data, as illustrated by an example of a misdated unconformity that previously violated this balance of facies change in space and time. The tectono-stratigraphic model is a refinement of an existing empirical scheme devised in the area, with units called “Cycles” (Cycles I to VIII). This evidence-based framework is argued to be a genetic description of depositional units that developed in a dynamically evolving depocenter, subject to geographic rotation and relative variations in sea level that were dependent on location. This shifting basin configuration precludes use of a passive margin sequence stratigraphic approach, which assumes and requires a constant proximal to distal sedimentary direction and steady basement subsidence.

ABSTRACT This chapter presents parasequences—the next larger and more aerially extensive three-dimensional stratal unit of the stratigraphic hierarchy found consistently across most depositional environments. The parasequence scale is the key scale at which we interpret depositional environments, apply Walther’s Law to recognize significant stratal discontinuities, correlate and construct maps, and make tie-ins with well-log signatures. A parasequence is a distinctive succession of relatively conformable beds and bedsets bounded by surfaces of flooding, abandonment, or reactivation and their correlative surfaces. They can be recognized in a variety of depositional settings through specific and objective attributes of their stratal stacking and bounding surfaces. The definitive interpretation of any particular interval as a parasequence requires two components: (1) recognizing its character in vertical section and (2) establishing its lateral distribution over an area significantly broader than any single component bedset or geomorphic element of the depositional environment (i.e., many hundreds of square kilometers). Although it might be difficult to recognize parasequences in a particular interval or location, they still are extremely likely to exist even there because they appear to be a universal feature of sedimentation. This chapter introduces the general concepts of parasequences, illustrates those concepts with marine-shelfal examples, and provides practical guidelines for recognizing and correlating parasequences. It then discusses common variations in vertical and lateral aspects, presents an application to building quantitative models of depositional environments, and introduces the expression of parasequences in other depositional settings. Recognition of parasequences is essential because they are the building blocks of the next larger scales in the stratigraphic hierarchy: parasequence sets (systems tracts) and depositional sequences, which are discussed in Bohacs et al. (2022b, Chapter 6 this Memoir). The following excerpt from table 12 of Lazar et al. (2022a, Chapter 3 this Memoir, p. 72) places parasequences in their context in the sequence-stratigraphic interpretation workflow: III. Group the lithotypes and stratal characteristics at the bed and bedset scale into facies packages based on recurring associations of attributes. IV. Relate the stacking patterns of facies packages to the depositional environment: A. Facies stack in distinctive manners and proportions according to their depositional environment. B. Calibrate well-log response of each facies association or depositional environment. V. Use the stacking patterns and lateral relations of rock packages from the different depositional environments, and their bounding surfaces, to interpret the sequence stratigraphy. A. Divide the stratigraphic section into large-scale packages bounded by significant surfaces: key discontinuities and major flooding surfaces (Chapter 3, figure 5). B. Group bedsets of depositional environments into parasequences. Group parasequences into parasequence sets according to their stacking patterns (progradational, aggradational, retrogradational), location relative to preexisting shelf break, and relations to bounding surfaces. Note the relation of the parasequence sets to the significant surfaces recognized in step V(A), and refine your estimation of systems tracts.

Abstract The approximately 300-m (984.2 ft)-thick Oligo–Miocene carbonates of the Perla field consist of an overall deepening-upward sequence predominantly composed of larger benthic foraminifera and red algae (oligophotic production) with a minor contribution from shallow-water (euphotic) carbonate components (green algae and corals). Two types of facies successions occur. In the lower part, lithofacies persistently occur in transgressive-regressive sequences bounded by erosional surfaces (Type 1). In Type 1 successions, the interactive analysis of the skeletal components and textures, along with the order of the facies succession (Walther’s Law) permit the establishment of the depositional model, the architecture of the building blocks, and their stacking patterns. Deposited in a context of tectonic subsidence, the building blocks progressively onlapped with backstepping configuration onto a paleoisland. In the upper part, volumetrically less important, lithofacies recurrence is sporadic, while fining-upward successions are common. They commonly have gray-black coloration (pyrite, phosphate, and glauconite) and planktonic foraminifers and nannofossils are abundant (Type 2). They are interpreted as gravity-flow deposits deposited below a chemocline. This requires a younger carbonate factory updip of the cored area, consistent with the subsidence, to supply the rhodolith-rich deposits of the upper part of the Perla limestone. A gentle distally steepened ramp model (distal bulge) is considered. Nevertheless, waves fail to explain the facies distribution in the Perla ramp; the turbulence induced by breaking internal waves is the best candidate to explain the facies distribution in the outer ramp.

Abstract The ichnofacies paradigm endures as the elegant, unifying framework within which accurate ichnological observations and their reliable environmental interpretations can be derived from the rock record. These recurring, strongly facies-controlled groupings of trace fossils, reflecting specific combinations of organism behavior (ethology), constitute the benchmark animal-sediment responses to optimum environmental conditions. Seilacherian ichnofacies are therefore distinctive, recurrent, archetypal associations of traces, made most useful when placed into the context of the original suites (i.e. traces that record the activities of coherent, environmentally related infauna). Ichnofacies are part of the total aspect of the rock, and consist of primary features imparted by the organisms inhabiting the depositional environment (biogenic structures). Insights into the depositional environment are derived from the fact that organisms respond in predictable ways to variations in energy conditions, food resource types, substrate consistency, water salinity, oxygenation, subaerial exposure, substrate moisture, temperature and others. Although in the marine realm many of these conditions change progressively with increasing water depth, ichnogenera display, at most, a passive relationship to bathymetry. Additionally, like lithofacies, ichnofacies are subject to Walther's Law. The utility of ichnofacies to paleoenvironmental reconstruction, therefore, also lies in their lateral continuity and predictable vertical succession, leading to mappable constructs. Accurate interpretations of depositional environments favor reliable predictions of laterally adjacent settings and their associated ichnofacies. Like all facies analyses, interpretations of ichnofaunas are improved substantially when they are evaluated in the context of the host rocks and their sedimentologic (i.e., lithofacies) and stratigraphic implications. Archetypal ichnofacies are especially effective for characterizing deep marine through to shallow marine settings, though more recent studies have investigated and expanded their utility in continental regimes as well. Intergradations between the archetypal ichnofacies are also common and demonstrate a continuum of changing depositional conditions. As a result, very high-resolution analyses can be achieved. Departures from the archetypal ichnofacies are common, but their recognition and interpretation are only possible by comparison with these established temporally and globally recurring groupings. By their very nature, such anomalous ichnological suites yield valuable insights into the specific characteristics of the depositional setting, highlighting animal-sediment interactions in response to imposed environmental stresses. In this way, brackish-water environments, anoxic to dysaerobic settings, and areas of fluvio-deltaic deposition can be readily recognized. Thirteen temporally and geographically recurring archetypal ichnofacies that demonstrate temporal and global recurrence have been defined. Most are named for a representative ichnogenus: Scoyenia , Mermia , Coprinisphaera , Trypanites , Entobia , Gnathichnus , Teredolites , Glossifungites , Psilonichnus , Skolithos , Cruziana , Zoophycos , and Nereites . Traces in freshwater (continental) (i.e., Scoyenia , Mermia , Coprinisphaera ), and brackish-water settings are in need of further study. The marine softground ichnofacies (i.e., Psilonichnus, Skolithos, Cruziana, Zoophycos, and Nereites ) are comparatively better understood and constitute robust models. Current research has demonstrated that the marine softground ichnofacies form a continuum along the depositional profile, adding precision to paleoenvironmental interpretations. Traces in the firmground ( Glossifungites ), woodground ( Teredolites ), and hardground ( Trypanites , Entobia , and Gnathichnus ) ichnofacies are principally distributed on the basis of substrate type and consistency. Ongoing research of these substrate-controlled ichnofacies continues to highlight subtle, previously overlooked complexities, expanding their utility in the rock record.

Abstract Deltas are discrete shoreline protuberances formed where a river enters a standing body of water and supplies sediments more rapidly than they can be redistributed by basinal processes, such as tides and waves. In that sense, all deltas are river-dominated and deltas are fundamentally regressive in nature. The morphology and facies architecture of a delta is controlled by the proportion of wave, tide, and river processes; the salinity contrast between inflowing water and the standing body of water, the sediment discharge and sediment caliber, and the water depth into which the river flows. The geometry of the receiving basin (and proximity to a shelf edge) may also have an influence. The simple classification into river-, wave-, and tide-dominated end members must be used with caution because the number of parameters that control deltas is more numerous. Other depositional environments, such as wave-formed shorefaces or barrier-lagoons can form significant components of larger wave-influenced deltas, but conversely smaller bayhead or lagoonal deltas can form within larger barrier-island or estuarine systems. As deltas are abandoned and transgressed they may also be transformed into another depositional systems (e.g., transgressive barrier-lagoon system or estuary). Delta plains also contain distributary river channels and their associated floodplains and bays, which can equally be classified as both fluvial and deltaic environments. Sharp-based blocky sandstones, tens of meters up to about a hundred meters thick, within many ancient mid-continent deltas have routinely been interpreted in the rock record as distributary channels, although many of these examples are now reinterpreted as incised fluvial valleys. Distributary channels may show several orders of sizes and shapes as they bifurcate downstream around distributary-mouth bars. Bifurcation is inhibited in strongly wave-influenced deltas, resulting in relatively few terminal distributary channels and mouth bars flanked by extensive wave-formed sandy barriers or strandplain deposits. In shallow-water river-dominated deltas, tens to hundreds of shallow, narrow and ephemeral terminal distributary channels can form intimately associated with mouth bars that form larger depositional lobes. Tides appear to stabilize distributary channels for hundred to thousands of years, inhibiting avulsion and delta switching. As deltas prograde they form upward-coarsening facies successions, as sandy mouth bars and delta-front sediments build over muddy deeper-water prodelta facies. Deltas display a distinct down-dip clinoform cross-sectional architecture. Many large muddy deltas show separate clinoforms, the first at the active sandy delta front and the second on the muddy shelf. Along-strike facies relationships may be less predictable and depositional surfaces may dip in different directions. Overlapping delta lobes typically result in lens-shaped stratigraphic units that exhibit a mounded appearance. All modern deltas grade updip from marine into non marine environments, and Walther’s Law predicts that deltas should show a marine to nonmarine transition as they prograde. However, in many low-accommodation settings, topset alluvial or delta-plain facies can be removed or reworked by wave or tidal erosion during transgression, resulting in top-eroded deltas. Historically, some of these top-eroded deltas have been interpreted as distal shelf deposits, not related to shoreline processes. Sequence stratigraphic concepts, however, allow facies observations to be placed within a larger context of controlling allocyclic mechanisms which allow the correct interpretation of larger delta systems of which only small remnants may be preserved.

Abstract Approximately 2,125 km of high-resolution seismic reflection profiles was collected within a 900-km 2 area of offshore Alabama, Mississippi, and Florida to determine how the nature of changes in the rate of Holocene sea-level rise (fast, slow, punctuated) impacts evolution of the stratigraphic architecture of an incised valley fill and deposition on associated interfluves on a passive continental margin with low storm and wave energy, microtidal range, and low to moderate sediment supply. These data were subjected to sequence stratigraphic and seismic facies analyses, and the products of this work provided input for the statistical analyses that were employed to produce the stochastic model. Quantifiable and statistically significant lateral seismic facies associations and vertical facies successions were identified within a chronostratigraphic framework for the incised valley and interfluves by using Repeated Measures ANOVA, Q-Mode Factor Analysis, and Binomial Markov process analysis. The Oxygen Isotope Stage 2 lowstand led to bifurcation of the Mobile-Tensaw River system and yielded two distinct incised valleys, eastern and western. These major incised valleys have very different geometries and orientations relative to the paleo-shoreline, and they contain both similar and dissimilar quantifiable seismic facies assemblages, which vary as a result of lateral variations in shelf gradient, sediment supply, and subsidence. The response to punctuated sea-level rise in the late Pleistocene and Holocene yielded three parasequences and associated transgression (retrogradation) of depositional systems within the incised valleys. The western incised valley received the majority of sediment input, as indicated by a thicker lowstand component and a fluvial-dominated lowstand delta at the shelf edge. The analyses revealed the presence of nine assemblages of distinctly different seismic facies and stratigraphic-surface composition. Analyses of vertical facies successions within each assemblage revealed that one of the most statistically significant vertical facies successions is from one of a large array of facies, upward to a flooding surface, and then from the flooding surface to a large array of facies. The fact that there are nine assemblages (and that the most significant vertical facies succession is upward toward a flooding surfce, comprising a wide variety of facies, and then from a flooding surface to a wide variety of facies) is a consequence of the interaction of sediment supply, basin subsidence, and most importantly the magnitude of the rapid rise in sea level. Variation in the magnitude and rate of rapid rises in sea level following stillstands or intervals of very slow sea-level rise results in rapid landward translations of seaward depositional systems over landward depositional systems. The rate of lateral translation of basinward facies over landward facies is so rapid that the vertical facies successions do not follow Walther’s law; therefore, virtually any landward depositional facies will lie under the transgressive surface and nearly any basin-ward facies may lie above the flooding surface. The net result is that fill of the incised valley is highly compartmentalized and contains many relatively small reservoir sand bodies that are sealed in impermeable, organic-rich muds. Ice sheets that are capable of rapid collapse, and therefore induce rapid sea-level rise, have been present in Antarctica since at least the mid-Miocene; therefore, successful exploration and production within reservoirs associated with incised-valley-fill deposits that are mid-Cenozoic and younger require use of stochastic models presented in this paper. Our research shows that the facies architecture of the Mobile incised valley system has many counterparts throughout geologic history and supports the validity of using modern depositional systems as analogs to the architecture of ancient systems. Because of the similarity of the Mobile incised valley system to ancient systems, it is important to quantify facies distribution within the modern systems and to develop stochastic models of spatial variability of facies. These stochastic models can be used to assign probability of encountering a particular facies during oil and gas exploration of incised valley systems.