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Foraminifera are important components of tropical marine benthic ecosystems and their recovery pattern from the end-Permian mass extinction can yield insights into the Mesozoic history of this group. Here we report the calcareous and agglutinated foraminifera recovered from five measured stratigraphic sections on the Great Bank of Guizhou, an uppermost Permian to Upper Triassic isolated carbonate platform in the Nanpanjiang Basin, south China. The material contains >100 Triassic species, including three that are newly described (Arenovidalina weiin. sp.,Meandrospira?enosin. sp., andSpinoendotebanella lehrmannin. gen., n. sp.), ranging from Griesbachian (Induan) to Cordevolian (Carnian) age. The species belong to the classes Miliolata, Textulariata, Fusulinata, Nodosariata, and to an unknown class housing all aragonitic forms of the orders Involutinida and Robertinida. Based on previously established conodont zones and carbon isotope chemostratigraphy, the Griesbachian (early Induan) through Illyrian (late Anisian) interval has been subdivided into 12 foraminiferal zones and two unnamed intervals devoid of foraminifera. Following the extinction at the Permian-Triassic boundary, habitable ecological niches of Griesbachian age were invaded by disaster taxa that subsequently became extinct during the Dienerian (late Induan) and left no younger descendants. The disaster taxa were replaced by Lazarus taxa with Permian origins, which were then decimated by the Smithian-Spathian (mid-Olenekian) boundary crisis. The tempo of recovery appears to have been modulated by environmental changes during the Griesbachian through Smithian that involved both climate change and expansion of anoxic ocean bottom waters. Uninterrupted and lasting recovery of benthic foraminifera did not begin until the Spathian.UUID:http://zoobank.org/2a6e9061-b163-402a-9098-8765a80576b3

We appreciate Kershaw et al.'s comment and continued interest in our Permian–Triassic research in the Nanpanjiang Basin. Kershaw et al. comment on aspects of our recent study that contradict results from the study of Collin et al. (2009). Specifically their comments center around two questions: (1) whether the truncation surface at the base of the Permian–Triassic microbialite shows evidence for subaerial exposure, and (2) whether data support the model of genesis of the microbialites by upwelling of anoxic, alkaline waters with elevated carbonate saturation from bacterial sulfate reduction (Kershaw et al. 1999, 2007, 2012). We note that our recent study is much broader in scope than the issues addressed in this comment and reply. Our study presented extensive stratigraphic, geochemical, biostratigraphic and petrographic analyses from multiple sections, introduced new sections that have not been presented in the literature, and evaluated multiple models for the genesis of the microbialite and underlying truncation surface. We welcome this opportunity to respond to Kershaw et al.'s comment and to further illuminate studies of the Permian–Triassic boundary in the Nanpanjiang Basin. ### Two Generations of Fibrous Cement Fringe? Maybe, But There is Still no Evidence for Pendant Geometry Kershaw et al. comment that there are two generations of bladed fringing cement adhered to grains and that only the second generation has a pendant geometry. Collin et al. (2009) made the same interpretation. From the photographs in Collin et al. (2009, fig. 5Aa–5Ab) and from our thin section observations, we interpreted this to be a single generation of fibrous cement fringe adhered to grains, with a faint zonation of clear-cloudy-clear alternation within the fringe, in which the cloudy zone contained a greater concentration of fluid inclusions (fig. 1A, 1B). Note that the photos presented in the comment by Kershaw et al. (figs. 3, 4) are also consistent with this interpretation. The entire bladed cement fringe was used …

A widespread marine microbialite and underlying truncation surface occur in Permian–Triassic sections of South China. We interpret the microbialite to have formed as a shallow, open-marine benthic framework stimulated by high seawater CaCO3 saturation. The widespread distribution across platform interiors and lack of asymmetry or thickening toward platform margins is incompatible with an alternative hypothesis, that microbialite deposition was stimulated by upwelling anoxic, alkaline waters. The truncation surface beneath the microbialite is irregular with overhangs and small caverns extending up to 30 cm beneath the surface indicating a dissolutional origin. Petrographic observations refute the interpretation that strata immediately beneath the surface contain pendant cements, meniscus cements, and vadose silt. Measurements of the anisopachous fibrous cements show that thickened areas have random, not downward orientations. Pores retain the pointed geometry consistent with isopachous cement. Car...

The Nanpanjiang Basin of south China contains four exceptionally well-exposed, isolated Triassic carbonate platforms. Detailed mapping of two-dimensional transects and description of stratigraphic sections allow the reconstruction of facies architecture, sequence stratigraphy, and evolution of the platforms. Biostratigraphy, magnetic-susceptibility profiles, and volcanic-ash horizons allow chronostratigraphic correlation and, thus, a basinwide evaluation of mechanisms controlling platform evolution. A comparison of platform architecture demonstrates that southerly platforms have substantially greater thickness, backstepping geometry, pinnacle development, and earlier drowning that resulted from greater tectonic subsidence proximal to a probable convergent margin along the southern perimeter of the basin. Felsic volcanics thicken southward and contributed to the termination of the southernmost platform, indicating the development of a volcanic arc along the southern margin of the South China tectonic block. The northernmost isolated platform had greater longevity and lesser accumulation and lacks backstepping and pinnacle phases of development. Basin-margin intertonguing relationships, or lack thereof, demonstrate that earlier siliciclastic influx into the basin to the south and concurrent starved-basin conditions to the north impacted the evolution of platform-margin geometries. Comparative analysis of platform evolution shows that the timing and rates of tectonic subsidence controlled the timing of platform termination by drowning, backstep geometries, pinnacle development, and overall platform thickness. The timing of siliciclastic basin fill dictated differences in platform-margin geometries such as slope angle, relief above basin floor, and the presence or absence of basinward platform progradation. Despite the dramatic differences in platform architecture, eustatic sea level fluctuations imparted a basinwide sequence-stratigraphic signal.

The Great Bank of Guizhou (GBG) is an isolated Late Permian to Late Triassic carbonate platform in the Nanpanjiang Basin of Guizhou Province, southwest China. A faulted syncline exposes a cross section of the platform margin, including a well-preserved Anisian (earliest Middle Triassic) reef complex approximately 1 km wide and 800 meters thick. Geochronologic constraints from associated basin-margin strata indicate that reef development initiated late in the Early Triassic, making it the oldest-known platform-margin reef complex of the Mesozoic Era. The reef framework consists primarily of microspar-filled tubes ∼100 μm wide and up to a few cm long that are embedded in irregular to branching, mm-scale masses of micrite, traditionally assigned to the problematic genus Tubiphytes. Based on preserved sporangia, the Nanpanjiang structures are interpreted as microbially induced micritic precipitates that formed in association with an otherwise uncalcified alga. A low-diversity metazoan and algal commu...

Permian-Triassic boundary (PTB) sections from isolated carbonate platforms in the Nanpanjiang Basin of south China contain Upper Permian skeletal packstones with diverse open-marine fossils overlain by a 7–15 m thick boundary horizon composed of calcimicrobial framestone constructed by globular to tufted, calcified cyanobacteria similar to Renalcis. The framestone contains interbeds of lime-grainstone with abundant thin-shelled bivalves and brachiopods. The overlying Lower Triassic strata contain microgastropod lime-packstones followed by a thick succession of thin-bedded lime-mudstones. The PTB event horizon is interpreted to occur at the top of the packstone containing diverse, open-marine fauna and Palaeofusulina and coincident with the abrupt change to calcimicrobial framestone lacking Permian macrofossils. The conformable biostratigraphic boundary occurs at the first appearance of Hindeodus parvus within the basal meter of the calcimicrobial framestone. Intensively studied PTB sections in so...

Stanley’s model (1988) proposed that a Permiantype reef fauna survived the Early Triassic reefless period in yet undiscovered refuges in the ancestral Pacific ocean and then reappeared as the builders of Middle Triassic reefs. Flugel (1994), in contrast, suggested that the Middle Triassic reefbuilding fauna are not holdovers from the Permian, but bear only a superficial resemblance to Permian fossils. Recent publications reflect a consensus that the Early Triassic lacked reefs and reef mounds although some authors acknowledged the possibility that reef-like structures may have existed in poorly explored areas such as south China and Russia (Senowbari-Daryan et al., 1993; Flugel, 1994). It is shown herein that Calcimicrobial framework mounds and biostromes existed in the Early Triassic in the Nanpanjiang basin of south China. Organic framework in this paper refers to a three dimensional, biologically-constructed network of calcified fossils that forms a rigid mass and supports an interconnected network of internal cavities that were open during accumulation. Although the calcimicrobial frameworks discussed herein are much smaller than frameworks of modern metazoan reefs, the term framestone is more appropriate for these fabrics than other reef-rock terms such as bindstone or bafflestone (Embry and Klovan, 1971). These calcimicrobial mounds and biostromes are important as the first organic framestones documented from the Early Triassic.