Abstract The pre-1980s literature on modern carbonates was biased toward tropical examples because non-tropical carbonates had not been studied extensively. Though non-tropical carbonates have received considerable attention in the past decade, the variety of low-energy, temperate ramp examples in the literature is limited. In contrast, examples of modern and ancient low-energy, tropical ramps are well represented. They are characterized by a gradual change from calcarenites updip to calcilutites downdip, by a photozoan biota, abundant non-skeletal aragonitic grains, such as ooids and peloids, and by widespread and rapid marine cementation. The Balearic Platform in the western Mediterranean is an isolated, low-energy, temperate ramp. This paper describes the Balearic ramp bathymetry, environmental regimes and depositional facies, which include (from the shoreline seaward): coastal lagoons, beach–dune complexes, inner-ramp seagrass meadows with mixed terrigenous–foraminiferal–molluscan muddy calcarenites, middle-ramp bryozoan–rhodalgal facies and outer ramp clastic–carbonate muds. Biotic and textural characteristics vary with depth, with hydrological conditions and with environmental factors, such as temperature, salinity, light and nutrients. Seagrasses extend across the inner and part of the middle ramp, where the grasses offer shelter to a variety organisms, including epibionts, molluscs, bryozoans, echinoderms and red algae. Most of the beach and dune sediments consist of bioclasts derived from the communities that thrive in the seagrass meadows, but the greatest volume of skeletal carbonates is produced as bryozoan, rhodalgal and molluscan gravels that occur as patchy blankets, primarily on the middle ramp. The Balearic Platform is characterized by an oligotrophic, clear water, microtidal environment. The dominant biota of the Balearic ramp – bryozoans, red algae, echinoderms and molluscs – is common in other non-tropical modern environments as well as in ancient temperate settings. This fact, combined with the absence of aragonitic non-skeletal grains, abundant marine cements and photozoans other than red algae, establishes the modern Balearic ramp as a model for comparison with low-energy, non-tropical ramps in the global rock record.

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.

Abstract The phylloid algal genera Eugonophyllum and Archaeolithophyllum are common constituents of Virgilian and Wolfcampian reef limestones in the Hueco Mountains of Texas. These algae form bioherms and biostromes and are volumetrically important contributors to both the reef and offreef sediment budget. Reefs constructed by phylloid algae have long been considered as ecologically simple communities that lack dominant framebuilding organisms. The previously accepted constructional mechanism for reef formation has been inferred to be sediment baffling and trapping, mainly by erect phylloid algae. This new, detailed analysis of phylloidalgal growth framework, however, clearly shows that these algae were in fact capable of forming a rigid framework. Phylloid algae, mostly Eugonophyllum, together with the problematicum Tubiphytes and the red alga (?) Archaeolithoporella, formed complex, multiple encrustations (both in vivo and post mortem) and were a fundamental element of reef construction. Much of the micrite in these reefs, often regarded as a sediment, has been identified as microbialite; this microbialite is important in binding and stabilizing the initial reef framework created by the phylloid algae. A dominant ecological succession was identified from the Eugonophyllum communities: 1. a pioneer community of phylloid algae would initially stabilize the substrate; 2. this would enable an encrusting community of mostly Tubiphytes, Archaeolithoporella, and microbialite to develop, followed by 3. a climax community of larger calcisponges. In the Archaeolithophyllum communities, the thalli were largely constratal (organisms not substantially elevated above the substrate) and lacked any obvious microbialite association. The resultant Archaeolithophyllum communities therefore did not develop any significant depositional relief and thusformed biostromes.

Abstract Dome-shaped mud mounds ranging in size from 2 m to 25 m thick and from 2 m to 100 m in diameter are present in the Upper Viséan of Sierra de la Estrella, Guadiato Valley, in the Sierra Morena region of SW Iberian Peninsula. The mounds are composed of up to 70% peloidal matrix and contain a varied but sparse assemblage including bryozoans, crinoids, brachiopods, calcareous algae, foraminifers, and gastropods. A three-stage biotic succession is recognizable in the mounds. The first stage consists of crinoid-sponge spicule packstones. The second stage is represented by a low-diversity, autochthonous assemblage of scattered sponges and up to 40-60% by volume of the microproblematical taxon Saccamminopsis fusulinaeformis (McCoy). The third stage consists of peloidal framework and cementstone with abundant primary growth cavities. These rocks are interpreted to be microbial boundstone-cementstone. The three stages of mound growth developed below storm wave base, and the probable coeval, level-bottom beds consisting of marls are interpreted to have been deposited in a dysphotic environment.

Abstract A variety of buildup types occur in the upper Paleozoic Auernig and Rattendorf Groups, Carnic Alps, at the present-day Austrian-Italian border, including coral, diverse algal (Anthracoporella, Archaeolithophyllum,Rectangulina, and phylloid green), bryozoan, brachiopod, and sponge buildups. Thin mounds and banks have a diverse fossil association (e.g., Archaeolithophyllum-bryozoan- brachiopod mounds) and occurin siliciclastic-dominated intervals, as do coral buildups. Some of the biodiverse thin mounds occur in stratathat were deposited in cooler water. However, the thickest mounds are nearly monospecific (e.g., Anthracoporella mounds) and grew in carbonate-dominated, warm-water environments. Most of the mounds considered in this paper, particularly algal mounds, grew in quiet-water environments below wave base but within the photic zone. Mound growth was variously stopped by siliciclastic input, e.g., auloporid coral mounds, sea-level rise, e.g., the drowning of Anthracoporella mounds of the RattendorfGroup, influence of cool water, e.g., algal mounds of the Auernig Group overlain by limestone of cool-water biotic association, or sea-level fall, e.g., phylloid algal mounds that were subsequently exposed subaerially. Thereis no indication of ecological succession during mound growth. Growth, dimensions, biotic association, and termination of mounds seem to have been controlled by extrinsic factors, mainly sea level and water temperature. Phylloid algal mounds are similar to those described from other late Paleozoic settings. Auloporid coral buildups, and Rectangulina and Anthracoporella algal buildups, however, have not previously been reported from other regions, although these fossils are described from several localities outsidethe Carnic Alps.

Abstract Algal buildups from five stratigraphic intervals in the Pennsylvanian of eastern Kansas, Midcontinent, U.S.A., display three basic fabrics based on their: a) dimension, b) morphology, c) fossil content, d) algal growth forms, and e) nature of framework cavities. Type 1. Constructional mounds composed of cup-shaped in situ algal growth forms are typically small bioherms, either isolated (e.g., Frisbie Limestone Member) or thickened intervals within carbonate banks(e.g., Sniabar Limestone Member), and are basically formed by phylloid green algae. Fossil diversity is very low. Mud and cement fill the abundant small intercup voids within individual mounds. Calcareous sponges, crinoids, and bryozoans, probably cavity dwellers, fill the larger intermound cavities between the smaller mounds. Type 2. Constructional mounds of algae with undulatory growth forms are basically red algae with recognizablethalli characteristics of Archaeolithophyllum, and, only rarely, of phylloid green algae. Buildups of this kind are laterally persistent. Thickening of the banks is generally recognizable at a large scale (ten of meters to kilometers). Smaller, meter-scale bioherms constructed of algae with undulatory growth forms donot occur in the sites studied. Fossil diversity is higher than in type (1) mounds, with calcareous sponges, brachiopods, and bryozoans common throughout the mound, rather than exclusively in cavities between small mounds ofthe type 1 cup-shaped algae. When built by green algae (e.g., parts of the Captain Creek Limestone Member), mounds have a lower diversity than those constructed by red algae (e.g., Spring Hill Limestone Member). Solitary corals, calcareous sponges, and bryozoans occur attached to the walls of the cavities. The abundance of open pores is striking. Type 3. Mounds of accumulated algae with undulatory growth forms are formed by the red algae Archaeolithophyllum missouriense, Archaeolithophyllum lamellosum, and the green alga Eugonophyllum. Depositional relief is not visible on the outcrop, but large-scale variations in bank thickness are notable (e.g., lower part of the Captain Creek Limestone Member). Bryozoans and Thartharella (a probable worm tube) are common. Multiple types of cavities occur, and most are cement-filled. Although the mound types differ in their form, fossil content, and type and distribution of voids, they sharean overall common peloidal clotted matrix that accumulated in specific areas, along with an abundance of gravity-defying peloidal micritic structures in the matrix, and of thin crusts within marine cement that may be relatedto microbial activity. Microbes probably played a crucial role in carbonate precipitation and in lithificationofalgal-dominated buildups.

Abstract Lower Carboniferous (Mississippian) mud mounds in Ireland developed in two main depositional settings: on the distal part of ramps and on the outer shelf margins. They formed predominantly during the Late Tournaisian and Late Viséan, associated with major transgressive episodes. The majority of the massive mounds have peloidal mud-matrix textures and stromatactoid cavities. Waulsortian mud mound complexes reached maximum development (geographical extent and total thickness) in Late Tournaisian times. These mounds initiated in relatively deep water (150-300 m) on the distal parts of ramps in low-energy, aphotic environments. Their characteristic biota comprises crinoids, fenestellid bryozoans, and sponge spicules (Type 1 mounds). Apart from stromatactoid cavities, they may also exhibit sheet spars, fissure fills, and dewatering structures associated with slumping. Waulsortian complexes contain laterally extensive mounds and banks ranging typically from 20 to 100 m thick, which may coalesce and when stacked can be over 900 m in total thickness, as in the Shannon Trough. Individual lensoid mounds are often enclosed by thin-bedded, crinoidal, argillaceous limestones. Except from the upper parts of mounds, calcareous algae are normally absent. “Waulsortian-type” mud mounds (Type 1A mounds) extend through the Viséan and into the Upper Carboniferous sections as a continuum. They are recorded from relatively deep- water ramps and basins in Arundian and Asbian rocks in NW and SW Ireland. These younger mounds have a biota similar to the Waulsortian, but they often have colonial corals and dasycladacean green algae towards the top, indicative of growth up into the dysphotic or lower euphotic zone. In Viséan time, massive shallow-water mud mounds developed at outer shelf margins facing deep-water basins. These carbonate shelves resulted from active tectonism in Early Viséan time. In the northern margin of the Dublin Basin, isolated domical mounds occur, ranging in thickness from 10 to 100 m and enclosed by bedded, skeletal grainstones. These mounds have a much more diverse and richer biota than Waulsortian mounds, most notably including locally abundant red and green calcareous algae, foraminifers, and cyanophytes (Type 2 mounds). Unlike most Waulsortian mounds, they have encrusting foraminifers ( Tetrataxis and Aphralysia ), encrusting bryozoans, Problematica ( Fasciella ), and calcimicrobes ( Renalcis and Ortonella ). In the Upper Viséan sections the upper parts of some large mounds contain in situ colonial rugose corals ( Siphonodendron and Lithostrotion ), which, together with the microbiota, can form a framework or meshwork in the upper parts of mounds (Type 2A mounds). Oncoids, pillars, and stromatolitic microbial laminae (microbialites) occur within the cores of the mounds. Some of the upper Viséan (Asbian-Brigantian) mud mound complexes show intervals of peloid-rich lime mudstone and wackestone (“core” facies), and coarser-grained foraminiferal-algal packstone and grainstone (“flank”, “crest”, or “intermound” facies). The latter are rich in green algae ( Koninckopora, Kamaena ) and red algae ( Ungdarella, Stacheoides ). Rare phylloid algae (? Archaeolithophyllum ) at the tops of some mounds, together with colonial rugose coral thickets and encrusting cyanophytes, may have formed an effective wave-resistant bindstone (Type 2B mounds). These phylloid algae became the dominant biota of buildups (Type 3 mounds) in the Late Carboniferous.

Abstract Small, isolated carbonate buildups are a common feature of many Upper Carboniferous-Lower Permian cyclic platform successions whereas larger buildup complexes are mostly confined to outer-ramp and slope settings. The Moscovian (Upper Carboniferous) platform succession at southern Amdrup Land, North Greenland, is unusual in including larger, stacked buildup complexes of limited lateral distribution. The buildup complexes developed as the result of stacking of shallow marine, algal-dominated buildups in areas that temporarily experienced increased rates of subsidence due to tectonic flexuring of the platform. The location of the buildup complexes is controlled by the interplay of short-term glacioeustatic fluctuations in sea level and tectonic subsidence. On the Amdrup Land platform, the buildup complexes are located 1-2 km seaward of the line of flexuring in areas that experienced moderately increasing subsidence rates and thereby new accommodation space. The location of Amdrup Land buildups highlights the importance of differential tectonic subsidence on localization and stacking of buildups in platform settings. In contrast to most published examples, the buildups are not associated with the development of positive sea-floor relief but are located in more rapidly subsiding parts of the platform where buildup morphology prevented destruction during glacioeustatic sea-level falls. The creation of new accommodation space allowed stacking of buildups during successive glacioeustatic sea-level rises and highstands. The platform was affected by two Moscovian tectonic flexuring events, each lasting for 1-2 My and separated by times of uniform platform subsidence and deposition of cyclic carbonates and siliciclastics, including laterally more widespread but vertically confined buildups.