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The partial skeleton of a small tetrapod, collected from the lower Buchenstein Formation (uppermost Illyrian, Anisian Middle Triassic) of Piz da Peres (Northern Dolomites, Italy) is described. Incomplete ossification of some bones indicate that the specimen is a juvenile. Its absolute size and proportions, along with several skeletal structures show striking similarities with a juvenile specimen of Eusaurosphargis dalsassoi from the slightly younger Prosanto Formation (Switzerland), a taxon known also from the Anisian/Ladinian Besano Formation (Italy and Switzerland). The finding may suggest that during the middle-late Anisian the basins of the Northern Dolomites, of the Besano Formation and Prosanto Formation shared not only several taxa of fishes but also the emerged lands nearby had a similar reptilian fauna. [ABSTRACT FROM AUTHOR]

In the Dolomites (Southern Alps), the original stratigraphic relationships and depositional geometries of Middle Triassic carbonate systems are exceptionally preserved and exposed, and well-constrained in a high-resolution sequence stratigraphic and bio-chronostratigraphic framework. During the late Ladinian, the region experienced a strong tectono-magmatic event, leading to local uplifts and sinks, partial collapses of carbonate edifices and large submarine landslides, as well as the emplacement of thick volcanic and volcanoclastic deposits. The relationships between carbonate and magmatic bodies can be observed in detail in the area between the Sciliar/Schlern mountain group and the Alpe di Siusi/Seiser Alm. In order to better constrain the distribution, geometries and relationships between carbonate, volcanic and volcanoclastic facies, a 3D geological model of the Anisian-Ladinian platform-to-basin system of the Sciliar and Catinaccio carbonate platforms has been developed. The input data set is composed by a net of geological sections built on an updated geological map, field data and formation boundaries digitized on a high-resolution DTM. The resulting pre-volcanic, platform-to-basin system shows a slightly arcuate shape of the margin part facing a starved basin. The volcanic stage is accompanied by strong tectonic subsidence in local sectors of the investigated area, with infilling by mass flow deposits, volcanic rocks, and volcanoclastic material. Major fault-scarps related to the collapse of pre-volcanic carbonate platforms have been modeled. The distribution and thickness of magmatic bodies in the area is however quite variable. The modeled post-volcanic platform-to-basin system shows the impact of the Late Ladinian irregular sea bottom on the distribution and thickness of the younger (mixed carbonate and volcanoclastic) basinal sediments. The model also show that the post-volcanic edifices extended beyond the collapsed portions and occupied an area slightly larger than their pre-volcanic predecessors. The last interval documents the development of lowstand fringing reefs around the older carbonate platform and possibly around demised volcanic areas. • 3D geological model based on field data occurring over a seismic size area. • Evolution of carbonate platforms before and after a tectono-volcanic event. • Strongly subsiding areas are created and filled during the tectono-volcanic event. • Volcanic products create irregular topography in the basin. • The paleo-bathymetry controls the occurrence and thickness of basinal carbonate sediments. [ABSTRACT FROM AUTHOR]

Abstract: The Triassic of the Dolomites offers a valuable opportunity to investigate the relationships between climate fluctuations and the changing depositional dynamics of carbonate platforms. The reconstruction of the large palaeoclimatic modification is based on the synthesis of multiple sedimentological, palaeobotanical, pedological, and geochemical proxies. The Triassic climate fluctuations were generally fast in nature and were probably associated with a latitudinal shift of the monsoon belts. During the Triassic, the Dolomites were placed at an intertropical northern latitude of about 16–18° and were generally dominated by dry climate and elevated temperature. At least five pulses toward moister climate are however documented, dated to Early Olenekian, Middle Anisian, Late Ladinian, “Middle” Carnian, and Late Norian times. Within this variable climatic scenario, the carbonate systems record a global evolutionary trend from Late Permian–Early Triassic regional shelves, rich in loose micrites and bio-calcarenites, to Anisian–Ladinian, synsedimentary cemented, steep sided (35–40°), high-relief platforms, and back to Carnian low angle ramps. Moist transgressive episodes were surprisingly prone to the spreading of corals and other colonial reef organisms, probably because of the reduced space competition by syndepositional cementation structures. The Permo-Triassic boundary extinction dramatically impacted on the calcified organism communities, but the carbonate depositional architecture nevertheless stayed almost unaffected through the boundary. The Early Triassic and earliest Anisian were commonly associated with hyperhaline, sometimes evaporitic conditions. Intervals of moister climate and efficient river discharge are however documented by earliest Induan and early Olenekian sediments. The latter terrigenous deposits matched a crisis in the carbonate production. After a return to arid conditions, during the Anisian, a fluctuation toward moister climate developed, associated to a massive continental vegetation cover. The Anisian tectonic activation of the region fragmented the previous carbonate shelf, triggering the development of three generations of fast prograding, but globally backstepping, isolated platforms, recording an increasing role of the synsedimentary cementation. A dry climate dominated the Late Anisian and Early Ladinian interval. At the time, a fast subsidence pulse was associated with platform drowning and basinal anoxia. Only a few aggrading pinnacles were able to survive, providing the nuclei for larger prograding platforms. During a dry climate interval, massive syndepositional cementation generated a major source of carbonate. Carbonate production stayed active through the Ladinian magmatic phase, but the onset of volcanism was associated with a large modification in the platform carbonate facies, which became dominated by automicrites. Moist climate phases are well documented again during the Late Ladinian, followed by a return to dry conditions. The Late Ladinian–Early Carnian platforms prograded toward the eastern Dolomites depocentre, eventually infilling almost the whole of the accommodation space. The middle portion of the Carnian recorded renewed, sharply moist phases, associated with the demise of the rimmed platforms and with the return to loose sediment ramps. At least four separated humid fluctuations can be identified in this Carnian interval alone. Climate then returned to persistent aridity, until the Late Norian moist phase. [Copyright &y& Elsevier]

In the Dolomites (Eastern Southern Alps, Italy), a diffuse Middle Triassic igneous activity is now present mostly as lava flow and pyroclastic successions, with rare shallow-depth intrusive bodies cropping out at Predazzo, Monzoni and Cima Pape areas. In this work, the emplacement modes of the Predazzo and Monzoni bodies were investigated by means of petrographic and anisotropy of magnetic susceptibility (AMS) data coupled with a field geological study. The presence of intrusive rocks in between these two bodies and the continuity of the metamorphic aureola from west of the Predazzo to east of the Monzoni body suggest that they are parts of a ∼20 km wide SW-NE oriented continuous pluton, sub-parallel to Ladinian strike-slip faults. AMS and petrographic data from the Predazzo body are consistent with a multistage ring-dyke emplacement mode, with areas of upward flow of the magma located in the NW and ESE part of the intrusion, whereas in the southern sector of the pluton our data suggest prevalently horizontal flows. In general, the Predazzo sheets indicate either upward magma flow or along-strike lateral magma transport, and the round shape suggests no influence of Ladinian tectonic structures. On the contrary, the ENE-WSW elongated shape of the Monzoni body was controlled by the occurrence of strike-slip faults associated with Ladinian-tectonics, the feeder being likely located at the NE edge of the body. However, the absence of deformation at the field- and micro-scale is consistent with a post Ladinian-tectonics timing of emplacement, as for the Predazzo pluton. [ABSTRACT FROM AUTHOR]

A higher precipitation regime during the early Late Triassic Carnian Pluvial Episode (CPE; 232–234 Ma) in many marine basins is evidenced by thick siliciclastic deposits, which are coeval with C-cycle perturbations and global warming. However, the mechanisms driving higher siliciclastic deposition are still not fully explored and could be linked to different effects of the climate change on depositional environments. Here, we present the first major, minor and trace elements, and mineralogical data from fine-grained sediments across the CPE in the Dolomites (Southern Alps, Western Tethys). Combining weathering indices (CPA and Rb/K 2 O), and qualitative and quantitative mineralogical analysis, we recognize two main phases during the CPE. Pre-CPE conditions show no significant weathering variations and some peaks of clay minerals referable to the weathering of Ladinian igneous material. The first C-isotope excursion of the CPE is coincident with an increase of CPA, Rb/K 2 O and kaolinite, with no change in the sediment-source and depositional setting, that indicate an enhancement of chemical weathering and confirm a shift to more humid conditions at the onset of the CPE. Such a signal from the Dolomites can be correlated with other similar observations from marine and terrestrial settings worldwide. After this first phase, a major sea level fall, probably linked to aquifer-eustasy and/or limno-eustatism, and following important transgression led to the erosion and recycling of older rocks marked by a decoupling of CPA and Rb/K 2 O and a substantial increase of K-feldspar from older volcanic rocks. The eustatic signal overwhelmed the humid climatic signal that is inferred by independent palynological and paleosol data within the same interval. After the CPE, data show high physical weathering under arid climate. Our results are compatible with the general view that the CPE was linked to injections of volcanic CO 2 from Large Igneous Province activity and consequent global warming and enhanced hydrological cycle. This first intensified rock chemical weathering at the onset of the CPE, then promoted higher storage of freshwater on land and a substantial increase of erosion and transport of unweathered material into the basins of the western Tethys, that were rapidly infilled. • Geochemical and mineralogical analysis of Carnian pelites from the Dolomites. • Onset of the CPE is synchronous with enhanced chemical weathering. • Data indicate humid conditions in the Western Tethys since the beginning of the CPE. • After, under still humid conditions, sea-level changes influence sediment supply. • Data confirm enhanced hydrological cycle during the CPE. [ABSTRACT FROM AUTHOR]

In this paper, sea-level fluctuations during the Carnian Pluvial Episode (CPE) are investigated. A revision of published data from multiple successions worldwide indicates a sea-level drop that occurred in different geodynamic settings after the onset of the first of multiple carbon-isotope perturbations that characterize the CPE. New stable isotope data, zircon U-Pb geochronology, carbonate petrology, conodont and foraminifer biostratigraphy from the Carnian of the Sichuan Basin and comparison to the well-dated coeval successions of the Dolomites allow pinpointing with unprecedented precision this sea-level fall and determine that it occurred after the onset of the first, but prior to the third negative δ 13 C shift of the CPE. These lines of evidence indicate that such sea-level oscillation was eustatic. Facies analysis and sequence stratigraphy of units deposited during the ensuing sea-level rise in the Sichuan and Dolomites, further show that a Tethys-wide crisis of microbial carbonate production and drowning of carbonate platforms were followed by a recovery of marine calcification, widely testified by the deposition of oolitic bodies. Whereas a Tethys-wide recovery of microbial carbonate production is documented at the end of the Carnian, this increase in chemical calcification occurred earlier, at the beginning of the Tuvalian, and suggest that global transformations in carbonate systems coincident with the CPE were complex and share commonalities with other times in the geological record when a similar evolution was linked to ocean acidification. • New bio-, chrono-, chemostratigraphic and sedimentological data on the CPE. • Tethys wide correlation of carbonate platform successions across the CPE. • Correlations and sequence stratigraphy highlight an eustatic sea-level fall. • Results suggest global fluctuations in carbonate production during the CPE. [ABSTRACT FROM AUTHOR]