Abstract The bromide “ nothing is constant but change ” could have been coined to describe the geological history of the Permo-Carboniferous—the Mississippian, Pennsylvanian, and Permian Periods. Global tectonics, fluctuations in atmospheric and oceanic chemistry, changes in global climate, and evolutionary changes in survivors of mass extinctions created the backdrop for the shifting panorama of this remarkable time in earth history. Catastrophic extinctions during the Frasnian-Famennian crisis decimated global plant and animal populations, leaving survivors to initially struggle through the Devonian-Carboniferous transition. The ensuing evolutionary diversification into less-populated niches was brought to an abrupt end at the close of the Permian Period by the largest of all mass extinctions. Upheavals in plate motion changed the configuration of continents and oceans during this time, resulting in the docking of Gondwana and Euramerica to create the supercontinent Pangea and the “world ocean”, Panthalassa . Within the evolving Permo-Carboniferous “landscape,” a wide diversity of carbonate platforms and reefs flourished. They ranged in size from small mounds a few square meters in size to mega-platforms occupying hundreds of square kilometers, some of which are important mineral and petroleum reservoirs. It is the diversity (carbonate sequence stratigraphy, platform architecture, diagenesis, reservoir characterization, and the composition of reefs and mounds) which Permo-Carboniferous rocks offer that has led to their intensive study by researchers from industry and academia around the globe. This book stems mostly from presentations given at the SEPM-and IAS-sponsored research conference Permo-Carboniferous Carbonate Platforms and Reefs , held May 12-19, 2000, in El Paso, Texas. To an extent, the

Abstract This paper evaluates the limits of using well-cuttings data and wireline logs in conjunction with limited core and outcrop data to generate a regional, high-resolution sequence stratigraphy for upper Mississippian (Chesterian) Greenbrier carbonates, West Virginia, U.S.A. These data are then used to document the stratigraphic response of the distal to proximal foreland basin to tectonics and Carboniferous glacio-eustasy during the transition into ice-house times. The major mappable sequences are fourth-order sequences, a few meters to over a hundred meters thick. They consist of updip red beds and eolianites, lagoonal muddy carbonates, ooid grainstone and skeletal grainstone-packstone shoal complexes, open-ramp skeletal wackestone, and slope-basinal laminated argillaceous carbonates. The sequences are bounded downdip by lowstand sandstones and calcareous siltstones, and locally on the ramp by basal transgressive shales; only a few sequence boundaries are calichified, compared with updip sections in Kentucky, where caliche and breccias are common. Transgressive systems tracts range from thin units to others that constitute the lower half of the sequence. The highstand systems tracts contain significant grainstone units. Maximum flooding surfaces on the ramp slope occur at the base of slope or basinal facies that rest on lowstand to transgressive complexes, whereas on the ramp they occur beneath widespread grainstones that overlie nearshore shale or lime mudstone. In the Greenbrier succession, fourth-order sequences are arranged into weak third-order composite sequences bounded updip by red beds, and by lowstand sands and oolite along the ramp slope. The composite sequences contain three to four fourth-order sequences. Correlation of the foreland basin units with third-order global sea-level curves, and with high-frequency sequences within the intracratonic Illinois Basin, shows that in spite of differential subsidence rates ranging from 2 to 30 cm/ky across the foreland, global third-and fourth-order sea-level changes whose amplitude increased with time were a strong influence on sequence development. Thrust-load-induced differential subsidence of fault blocks of the foreland basement controlled the rapid basinward thickening of the depositional wedge, and modified the eustatic effects on the accumulating succession. Moderate-amplitude eustatic sea-level change and semiarid climate were the dominant causes of the widespread reservoirs of ooid grainstone and lowstand sands. The overall stratigraphy suggests upward increase in amplitudes of sea-level change, and cooling, which likely records the initiation of Gondwana ice-sheet growth.

Abstract High-resolution sequence stratigraphic cross sections (based on outcrops and shallow cores) of Mississippian (Meramecian to Chesterian) strata in the Appalachian Basin, Kentucky, U.S.A, are the marine stratigraphic record of the interaction of tectonics on a slowly subsiding distal foreland, with the Carboniferous glacio-eustatic transition into icehouse conditions. Late Mississippian paleoslopes were to the southeast into the foreland basin, probably because of thrust loading and accompanying block faulting of the distal foreland. The succession is dominated by fourth-order sequences that are only a few meters to 15 meters thick, which is an order of magnitude thinner than those of the proximal foreland. Regional disconformities marked by paleosols, caliche, micro-karsting, brecciation, tepee formation, or sharp contacts between limestone and the overlying transgressive marine shale bound fourth-order sequences. The sequences are stacked into several siliciclastic-bounded third-order or composite sequences that make up the broadly transgressive Mississippian supersequence. Facies are dominated by oolitic grainstones passing downslope into skeletal grainstone-packstone and updip into lagoonal muddy carbonates, green shale, eolianites, and rare red beds. Marine shales occur at bases of the younger sequences. The fourth-order sequences can be correlated from the Appalachian distal foreland, into the proximal foreland, as well as into the intracratonic Illinois Basin, suggesting a eustatic origin. However, local and regional tectonics strongly influenced thickness and distribution of sequences as well as the distribution and timing of unconformities locally. The facies stacking in the lower sequences indicates that they formed under the influence of moderate sea-level changes that effectively flooded the ramp to depths of 10 m or less. This resulted in grainstones within sequences being partitioned by caliches and muddy carbonates near or at sequence boundaries. Facies stacking in the upper sequences suggests that the magnitude of fourth-order sea-level changes increased in the later Chesterian, causing flooding of the ramp to depths of tens of meters, probably synchronous with buildup of ice sheets on Gondwana. This was accompanied by a change to more humid climates, which decreased oolite deposition on the ramp and favored deposition of open marine skeletal limestones bounded by marine siliciclastic units. Such moderate-amplitude global eustasy may account for the widespread, highly partitioned grainy reservoirs typical of the Mississippian worldwide.

Abstract Sierra de la Estrella outcrops belong to the Sierra del Castillo Unit, which is defined in the Guadiato Area, SW Spain, where sedimentation occurred during the Late Viséan. The Guadiato Area is located on the boundary between the Ossa-Morena and Central Iberian structural zones, in the southwestern Iberian Peninsula, where Lower Carboniferous outcrops are common. The stratigraphic succession from Sierra de la Estrella is dated precisely by means of foraminifers (Zone 15). The studied rocks are interpreted as having developed on a storm-dominated ramp. Microbial buildups occur interbedded between tempestites and marls. Two main types of mud mounds have been distinguished: large tabular and smaller dome-shaped mud mounds, which were developed in a middle-ramp setting.

Abstract Numerous biohermal buildups occur in Mississippian (Lower Carboniferous) strata in the Illinois Basin and adjacent regions. They developed as mud mounds, biodetrital calcisiltite mounds, and bryozoan frame thickets (fenestrate-frame coquina or rudstone) during the Kinderhookian and early Meramecian (Tournaisian and early Viséan), and as microbial mud mounds, microbial-serpulid-bryozoan boundstones, and solenoporoid (red algal) boundstones during the Chesterian (late Viséan and Serpukhovian). True Waulsortian mounds did not develop in the Illinois Basin, but echinoderm (primarily crinoids)-bryozoan carbonate banks and bryozoan frame thickets generally occupied the same niche during the Kinderhookian-early Meramecian. Nutrient availability and the resulting increase in the productivity of echinoderms and bryozoans were apparently detrimental to Waulsortian mound development. Deposition of crinoidal-bryozoan carbonates during the Kinderhookian-Osagean initially occurred on a ramp setting that later evolved into a platform with a relatively steep margin through sediment aggradation and progradation. By mid-Osagean-early Meramecian, two such platforms, namely the Burlington Shelf and the Ullin Platform, developed adjacent to a deep, initially starved basin. Sedimentologic and petrographic characteristics of the Kinderhookian-earliest Meramecian carbonates resemble the modern cool-water Heterozoan Association. This is in contrast with post-earliest Meramecian carbonates, which are typically oolitic and peloidal with common peritidal facies. The post-earliest Meramecian carbonates, therefore, resemble those of the warm-water Photozoan Association. The prevalence of Heterozoan carbonates in the Illinois Basin correlates with a rapid increase in the rate of subsidence and a major second-order eustatic sea-level rise that resulted in deep-water starved basins at this time. In the starved Illinois Basin, deposition was initially limited to a thin phosphatic shale that was followed later by deposition of up to 200 m of siliceous, spiculitic, and radiolarian-bearing limestone. The starved basin was connected to the deep open ocean through a bathymetric depression, which was centered over the failed late Precambrian-Early Cambrian Reelfoot Rift, which extended from the deep-water Ouachita Trough in central Arkansas to southern Illinois, approximately parallel to the trend of the modern Mississippi River. We believe that upwelling of cool, nutrient-and silica-rich deep oceanic water, which entered the basin through this bathymetric depression, resulted in proliferation of pelmatozoans and bryozoans. The subsequent change from cool-water-like carbonates to warm-water-like carbonates appears to be related to decreased subsidence and gradual shallowing of the basin.

Abstract This study analyzes the three-dimensional variability of a 20-meter-thick section of Pennsylvanian (Missourian) strata over a 600 km 2 area of northeastern Kansas, USA. It hypothesizes that sea-level changes interact with subtle variations in paleotopography to influence the heterogeneity of potential reservoir systems in mixed carbonate-siliciclastic systems, commonly producing build-and-fill sequences. For this analysis, ten lithofacies were identified: (1) phylloid algal boundstone-packstone, (2) skeletal wackestone-packstone, (3) peloidal, skeletal packstone, (4) sandy, skeletal grainstone-packstone, (5) oolite grainstone-packstone, (6) Osagia-brachiopod packstone, (7) fossiliferous siltstone, (8) lenticular bedded-laminated siltstone and fine sandstone, (9) organic-rich mudstone and coal, and (10) massive mudstone. Each facies can be related to depositional environment and base-level changes to develop a sequence stratigraphy consisting of three sequence boundaries and two flooding surfaces. Within this framework, eighteen localities are used to develop a three-dimensional framework of the stratigraphy and paleotopography. The studied strata illustrate the model of “build-and-fill”. In this example, phylloid algal mounds produce initial relief, and many of the later carbonate and siliciclastic deposits are focused into subtle paleotopographic lows, responding to factors related to energy, source, and accommodation, eventually filling the paleotopography. After initial buildup of the phylloid algal mounds, marine and nonmarine siliciclastics, with characteristics of both deltaic lobes and valley fills, were focused into low areas between mounds. After a sea-level rise, oolitic carbonates formed on highs and phylloid algal facies accumulated in lows. A shift in the source direction of siliciclastics resulted from flooding or filling of preexisting paleotopographic lows. Fine-grained siliciclastics were concentrated in paleotopographic low areas and resulted in clay-rich phylloid algal carbonates that would have made poor reservoirs. In areas more distant from siliciclastic influx, phylloid algal facies with better reservoir potential formed in topographic lows. After another relative fall in sea level, marine carbonates and siliciclastics were concentrated in paleotopographic low areas. After the next relative rise in sea level, there is little thickness or facies variation in phylloid algal limestone throughout the study area because: (1) substrate paleotopography had been subdued by filling, and (2) no siliciclastics were deposited in the area. Widespread subaerial exposure and erosion during a final relative fall in sea level resulted in redevelopment of variable paleotopography. Build-and-fill sequences, such as these, are well known in other surface and subsurface examples. Initial relief is built by folding or faulting, differential compaction, erosion, or deposition of relief-building facies, such as phylloid algal and carbonate grainstone reservoir facies, or siliciclastic wedges. Relief is filled through deposition of reservoir-facies siliciclastics, phylloid algal facies, and grainy carbonates, as well as nonreservoir facies, resulting in complex heterogeneity.

Abstract Coral-bearing bioconstructions are described for the first time from upper Lower Carboniferous (Upper Mississippian) shallow-water limestone olistoliths of the southern Montagne Noire (Mont Peyroux Nappe), southern France. Microbial-induced wackestones and microbial boundstones dominate major parts of the Brigantian Roque Redonde Formation and Serpukhovian Roc de Murviel Formation, which follows on top of a paleokarst. Further subtidal facies are intercalated. The short-lived bioconstructions consist of thin monospecific and polyspecific coral biostromes, coral bioherms (patch reefs) growing in high-energy turbulent environments, and a single example of a large shallow-water microbial buildup that formed below fair-weather wave base in dimmed light. The contribution of rugose corals to the bioconstructions varies from active framebuilding in the biostromes and bioherms to passive dwelling of sparse fauna in the microbial buildup. Microbial structures are of special importance within polyspecific biostromes and patch reefs. In a delicate balanced system they are responsible for growth or suffocation of the coral-dominated bioconstructions. That co-occurrence of coral boundstones and microbial boundstones appears to be a widespread characteristic of small reefs in Late Viséan and Early Serpukhovian time. Factors limiting the growth of the bioconstructions in southern France include rapid sea-level variations, tectonic instability of the shelf, and intrinsic paleobiological features of the rugose corals, like their fragility and inability to encrust mobile substrates. Comparable upper Lower Carboniferous coral-bearing bioconstructions of the Paleotethys realm and the epeiric seas of northwestern Europe are discussed.

Abstract Twenty-six reef-mounds of Early Permian (Middle or Late Asselian) age crop out along the north shore of Greely Fiord on west-central Ellesmere Island, Canadian Arctic Archipelago. Each reef was attributed the name of a character from J.R.R. Tolkien’s “The Lord of the Rings”. The reefs interfinger with evaporites in the upper part of the Mount Bayley Formation, immediately below the Tanquary Formation. The reefs grew at the northern margin of a large depression of the Sverdrup Basin referred to as the Fosheim-Hamilton sub-basin, which is separated from the main Sverdrup Basin by the Elmerson high, an elongated structure of probable compressional origin. The Tolkien reefs range from 50 m to over 130 m in thickness and between 50 m and 500 m in width and length. The buildups have a massive core around which are wrapped a series of well-defined, variably steep beds (flanks), many of which display a sharp erosional base. Facies of the core and inner flank comprise: bryozoan-Tubiphytes-stromatactoid (sponge) boundstone; bryozoan cementstone; bryozoan mudstone-wackestone; and bryozoan (fusulinacean) packstone-grainstone. Facies of the outer flank include: algal boundstone; and fusulinid-algal grainstone-rudstone. Facies that occur both in the inner and outer flanks include carbonate breccia and moldic dolomicrite. The Tolkien Reefs of west-central Ellesmere Island recorded the transition from an evaporite-dominated succession (Mount Bayley Formation) to an evaporite-free succession (Tanquary Formation). The reefs grew south of a major structural element—the Elmerson high—through the complex interplay between high-order to low-order relative sea-level fluctuations driven by tectonics, glacio-eustasy, and evaporative drawdown. The Tolkien Reefs recorded the rapid transition between a long episode of differential, and in part fault-controlled, syntectonic subsidence and a long period of slower, regional post-tectonic passive subsidence. While the former can be associated with a pulse of compressional tectonics that affected many areas of the Sverdrup Basin, the latter represents a phase of tectonic quiescence.

Abstract Lower Carboniferous (Upper Viséan and Pendleian) rocks from the Guadiato Area, in the southwestern part of Spain, comprise mixed carbonate-siliciclastic platform facies, with siliciclastics predominant. The calcareous intervals contain a highly diversified foraminiferal fauna, composed mainly of endothyroids, although some primitive fusulinids are also present. Fourteen families, 9 subfamilies, 67 genera, and 134 species or species groups of foraminifera have been identified. These allow the identification of zones 14 to 18 of Mamet’s classification. Within this zonal framework the appearance, disappearance, and maximum abundance of selected taxa in the Guadiato Area are described and discussed. The first appearance of foraminiferal species and genera in the Guadiato Area is compared to that in other European (Montagne Noire, northern France and Belgium; Britain; and Ireland) and North African (Algéria and Morocco) basins. It shows that some foraminifera occurred earlier in Spain whereas other taxa occurred later than in these regions. These early or late appearances of taxa are grouped in two trends, which are probably related to tectonic movements coeval with sedimentation in the Guadiato Area. Moreover, cluster analysis comparing the foraminifera of the twelve neighboring Carboniferous basins or regions establishes the paleobiogeographical relationship between the Guadiato Area and these other regions.