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Late Pennsylvanian cyclothems are documented from the carbonate platform margin in Guizhou, South China, providing a unique opportunity to study glacio-eustatic fluctuations and their impact on reef development. This paper focuses on a shallow-water, reef-bearing succession and a deep-water succession in the Houchang area of Guizhou. Fourteen microfacies, grouped into seven associations, represent distinct depositional environments. These microfacies associations exhibit vertical cyclicity, interpreted as cyclothems, similar to those observed globally, which are attributed to the waxing and waning of the Gondwana ice sheet. The cyclothems are primarily composed of sediments below the wave base within a shallow-water platform margin and deep-water settings. Those cyclothems show strong correlations with those observed in South China, Ukraine, and the North American Midcontinent, suggesting a potential connection to global glacio-eustatic processes. A brief and rapid sea-level rise during the late Kasimovian may correspond to a recently recognized global warming event. A microfacies analysis indicates that these cyclothems reflect glacial-type sea-level fluctuations ranging from 15 to 35 m. Notably, the reef-bearing cyclothems correspond to intermediate, major cyclothems identified in South China and the Midcontinent from the late Moscovian to early Kasimovian stages. The global cyclothem correlations and reef development patterns in South China suggest that intermediate, major cycles were the primary controls on reef growth and demise, while minor cycles influenced biostromes and community succession within the reefs. These findings underscore the pivotal role of the Late Paleozoic Ice Age (LPIA) in shaping reef development in far-field regions during the Late Pennsylvanian. [ABSTRACT FROM AUTHOR]

Abstract The transition from the Late Paleozoic Ice Age (LPIA) to fully postglacial conditions in SW Gondwana is under increasing discussion due to either the radiometric ages of its boundary or the stratigraphic nature of this transition. The record of this transition in the Paraná Basin is found in the glacial and glacially influenced deposits of the upper Mafra and Rio do Sul Formations (upper Itararé Group) and postglacial strata of the Rio Bonito Formation (Guatá Group). Here we address the depositional architecture and stratigraphic evolution of these deposits in the Rio do Sul depocenter, eastern Paraná Basin, Brazil, the main area of subsidence in the basin during this transition in Pennsylvanian-Cisuralian time, bringing an opportunity to examine the characteristics of glacial to postglacial transition. Analyses of facies, stratigraphic logs, stratigraphic correlations, and paleocurrent dispersal trends allowed us to define three evolutionary stages. The first stage registers glacial advance from the south-southwest represented by an erosive surface and subglacial tillites. Gravitational deposits covered the tillites in response to ice retreat (upper Mafra Formation), and the Lontras Shales (lower Rio do Sul Formation) correspond to the marine maximum flooding. The second stage comprises co-genetic deepwater (Rio do Sul Formation) to shallow (Rio Bonito Formation, Triunfo Member) progradational deposits after the Lontras Shale maximum flooding. Paleocurrent data and glacially related features point to glaciated source areas located to the NE, E, and SE for the Rio do Sul depocenter during this stage. The third stage corresponds to retrogradational stacking pattern upon a fluvial subaerial unconformity (incised valley), starting with fluvio-deltaic beds (Triunfo Member), followed by fine-grained deposits of the Paraguaçu Member of Rio Bonito Formation. No features related to glacial influence characterize this third stage. As previously suggested, tectonic uplift likely drove the additional NE source and created the space that allowed the transitional contact between Rio do Sul and Rio Bonito formations in the Rio do Sul depocenter.

Competing end‐member models for the late Paleozoic Variscan orogeny (ca. 360‐290 Ma) alternatively suggest moderate 2–3 km elevations underlain by relatively thin crust (<50 km) or a thick crust (>55 km) that supported high 4–5 km elevations. We tested these models and quantified the crustal thickness and elevation evolution of the Variscan orogeny using igneous trace element geochemical proxies and geochronologic data. These data suggest that thick crust (55–70 km) capable of supporting 3–5 km elevations developed diachronously from east to west between ca. 350 and 315 Ma. Crustal thinning occurred from ca. 315 to 290 Ma across the orogen. Crustal thickness and elevation changes at ca. 340‐325 and 315‐290 Ma correspond with increases in silicate weathering recorded by Sr and Li isotopes, consistent with models in which silicate weathering of the Variscan orogen contributed to global cooling associated with the late Paleozoic ice age. Plain Language Summary: It is debated whether the Variscan mountains at the core of the supercontinent Pangea had thick crust capable of supporting high topography and influencing past climate. We used trace element geochemical data from igneous rocks to estimate past crustal thickness and surface elevation. The data suggest a high elevation, Himalayan‐length mountain belt formed first in central Europe and expanded westward between 350 and 315 Ma. Crustal thickness and paleo‐elevation decreased across the entire mountain belt between 315 and 290 Ma indicative of orogenic collapse. Changes in Variscan surface elevation correspond with time periods of greater chemical weathering and global cooling, suggesting that tectonics may have influenced past climate. Key Points: Sr/Y‐La/Yb ratios of igneous rocks quantitatively track Variscan crustal thickness and elevationThick crust capable of supporting high elevations developed by ca. 350 Ma and expanded westwardResults consistent with chemical weathering of the Variscan hinterland as a contributor to late Paleozoic environmental change [ABSTRACT FROM AUTHOR]

The transition from the Late Paleozoic Ice Age (LPIA) to fully postglacial conditions in SW Gondwana is under increasing discussion due to either the radiometric ages of its boundary or the stratigraphic nature of this transition. The record of this transition in the Paraná Basin is found in the glacial and glacially influenced deposits of the upper Mafra and Rio do Sul Formations (upper Itararé Group) and postglacial strata of the Rio Bonito Formation (Guatá Group). Here we address the depositional architecture and stratigraphic evolution of these deposits in the Rio do Sul depocenter, eastern Paraná Basin, Brazil, the main area of subsidence in the basin during this transition in Pennsylvanian-Cisuralian time, bringing an opportunity to examine the characteristics of glacial to postglacial transition. Analyses of facies, stratigraphic logs, stratigraphic correlations, and paleocurrent dispersal trends allowed us to define three evolutionary stages. The first stage registers glacial advance from the south-southwest represented by an erosive surface and subglacial tillites. Gravitational deposits covered the tillites in response to ice retreat (upper Mafra Formation), and the Lontras Shales (lower Rio do Sul Formation) correspond to the marine maximum flooding. The second stage comprises co-genetic deepwater (Rio do Sul Formation) to shallow (Rio Bonito Formation, Triunfo Member) progradational deposits after the Lontras Shale maximum flooding. Paleocurrent data and glacially related features point to glaciated source areas located to the NE, E, and SE for the Rio do Sul depocenter during this stage. The third stage corresponds to retrogradational stacking pattern upon a fluvial subaerial unconformity (incised valley), starting with fluvio-deltaic beds (Triunfo Member), followed by fine-grained deposits of the Paraguaçu Member of Rio Bonito Formation. No features related to glacial influence characterize this third stage. As previously suggested, tectonic uplift likely drove the additional NE source and created the space that allowed the transitional contact between Rio do Sul and Rio Bonito formations in the Rio do Sul depocenter. [ABSTRACT FROM AUTHOR]

Far-field effects of the Late Paleozoic glaciation (∼340–260 Ma) recorded in well-dated stratigraphic intervals of the Pangea can be instrumental in detecting the short-term variability of icehouse climate and deconvolving the climate mechanisms. This study examines the Cracow Sandstone Series (CS), which provides a snapshot of the Middle to Late Pennsylvanian (∼306–314 Ma) fluvial sedimentation in the eastern equatorial Pangea (Upper Silesian Basin, ∼2°N paleolatitude). Spectral estimates of borehole lithological data suggest predominant ∼100-kyr eccentricity pacing of coal-bearing fluvial cycles and persistence of this pattern across the onset of Late Pennsylvanian aridification. The immediate climatic and depositional controls involve changes in seasonal precipitation along the Intertropical Convergence Zone and resulting fluctuations in sediment input. The prominence of eccentricity pacing and suppression of precession-scale variability in the fluvial environment contrasts with the frequency spectra of seasonal insolation series – an issue comparable to the "100-kyr problem" of the Late Pleistocene. The traditional explanation considers the eccentricity component being imposed as a far-field response to glaciation, analogous to the Pleistocene carbon-cycle feedback. Here we propose an alternative possibility that calls upon time-integrated insolation at the equator and the role of semi-annual wet/dry cyclicity in transferring variance from precession-scale insolation changes to the modulating eccentricity term. Autogenic processes in the fluvial system might have participated in "shredding" the precessional and semi-precessional signals. The alternative scenario is decoupled from high-latitude climate and would imply a muted climate sensitivity of the eastern equatorial Pangea to glaciation. The individual options cannot be evaluated with the Upper Silesian data alone, but offer testable hypotheses, potentially helpful in revealing the short-term structure of glaciation and climate teleconnections during the Late Paleozoic. • Astronomically paced fluvial cyclicity in the tropics during LPIA. • Persistent eccentricity control, insensitive to aridification. • Far-field response to glaciation possible. • Proposed alternative by seasonally integrated equatorial insolation. [ABSTRACT FROM AUTHOR]

Trace fossils play a fundamental role as biotic records in glacial deposits associated with the Late Paleozoic Ice Age, especially in the upper units of the Itararé Group in the Paraná Basin, where they are widely described and studied. The absence of ichnological studies for the lower interval of the Itararé Group, represented by the Campo do Tenente Formation, creates a significant gap in understanding the interaction between organisms and glacial environment during the middle Pennsylvanian period in the Paraná Basin. Addressing this gap provides new insights into adaptive strategies and paleoecological aspects related to extreme climatic events. Through macro and microscopic descriptions, we documented for the first time the occurrence of eight ichnotaxa in a siltstone interval of the Campo do Tenente Formation: Dimorphicnus isp., Diplichnites gouldi, Helminthoidichnites tenuis, Hormosiroidea meandrica, Irichnus saltatorius, Merostomichnites narragansettensis, Monomorphicnus lineatus, and Umfolozia sinuosa. This trace fossil association, dominated by arthropod trackways and burrows of wormlike organisms, indicates the coexistence of the Mermia and Scoyenia ichnofacies. Combined with the sedimentological data, these results reflect marginal continental conditions of shallow and restricted environments, with occasional input of glacial freshwater. These contributions not only provide new insights into the understudied ichnological content of this interval of the Itararé Group but also offer important paleoenvironmental and paleoecological perspectives on the middle Pennsylvanian during the most significant glaciation of the Phanerozoic. • Arthropod trackways and burrows from wormlike organisms dominate a siltstone interval in the Campo do Tenente Formation. • Ichnospecies suggest Mermia and Scoyenia ichnofacies in a marginal marine setting with glacial freshwater input. • First documentation of Dimorphichnus isp. and Merostomichnites narragansettensis in the Itararé Group. [ABSTRACT FROM AUTHOR]

[Display omitted] • The glacially influenced lower Ansilta Formation was sourced from local Protoprecordillera sources. • The non-glacial upper Ansilta formation was sourced from more distal sources within the Sierras Pampeanas and Famantinian terranes. • The Protoprecordillera was a topographic high until collapsing during the late Pennsylvanian-Cisurlian. The Late Paleozoic Ice Age (LPIA) was a principal control of sedimentation across Gondwana from the late Devonian through early Permian. We assess the hypothesis that glacial to interglacial transitions in western Argentina were the primary control influencing sediment routing patterns among the various Carboniferous-Permian basins in western Argentina. The Carboniferous Ansilta Formation consists of glaciomarine, nearshore, and fluvial systems deposited during the LPIA along the eastern margin of the Calingasta-Uspallata Basin in Argentina. The lower, glacially influenced succession of the Ansilta Formation records at least five glacial advances; the upper succession of consists of progradational shallow marine, deltaic, and fluvial strata. We combine 1225 new U–Pb zircon ages from six samples of the Carboniferous Ansilta Formation in the Calingasta-Uspallata Basin with 5864 U–Pb ages from 147 published samples in the detritalPy-mix forward mixture model to characterize provenance shifts. For the glacially influenced lower Ansilta Formation, sediment was derived locally from the Protoprecordillera, which was a prominent highland with alpine glaciers flowing west and east into the Calingasta-Uspallata and Paganzo basins, respectively. Thus, there was little or no connection between these two basins during Serpukhovian-Bashkirian glaciation. The fluvial/deltaic upper Ansilta had distal sediment sources in the Sierras Pampeanas. Furthermore, our results support the collapse of the Protoprecordillera topographic barrier, enabling drainage patterns connecting the Paganzo and Calingasta-Uspallata basins by late Pennsylvanian-early Permian time. [ABSTRACT FROM AUTHOR]

The near-field glacial record of the late Paleozoic Ice Age in Gondwanan basins is widely used in global paleogeographic and paleoclimatic models. Nevertheless, several late Paleozoic glacial successions still lack a detailed depositional history or reassessment of their genesis under modern glacial sedimentology concepts. One such example is the Aquidauana Formation in the western Paraná Basin, Brazil, which corresponds to about 65 % of the total outcrop area of the late Paleozoic glacial strata (Itararé Group) within the basin. Yet, the stratigraphic architecture and depositional environments are full of uncertainties as the strata are very poorly exposed. This study brings new insights on the depositional history and stratigraphic architecture for the upper half of the Aquidauana Formation by describing a 290-m-thick section cropping out along a recently developed highway in the Mato Grosso do Sul state. A subaqueous slope and glaciated outer shelf depositional setting is interpreted for the upper half of the Aquidauana Formation, which differs considerably from the glacioterrestrial and postglacial arid context traditionally proposed. More specifically, deposition chiefly took place under ice-free conditions on a subaqueous slope within an erosionally-confined channel–levee complex through sediment density flows and subaqueous landslides. Episodic glacial influence on sedimentation is recorded within the uppermost portion of the section by glacially-modified and iceberg-rafted debris as well as a deglacial trace fossil assemblage within proglacial deposits. Sediment transport toward the southeast into the basin indicates a glacial source placed westward of the Paraná Basin, reinforcing the hypothesis of ice-spreading centers located westward of the basin. The outcomes of this study also emphasize the relevance of subaqueous gravity-driven resedimentation in emplacing the late Paleozoic glacial record. [ABSTRACT FROM AUTHOR]

Abstract The late Paleozoic ice age was one of the three major glaciations in the Phanerozoic. However, the influence and characteristics of this glaciation and deglaciation remain unclear. In this study, we present lithostratigraphy, biostratigraphy, and chemostratigraphy during the Late Mississippian to the Early Permian in Tarim, Northwestern China. Tarim records two Gondwana glacial events in the Serpukhovian‐Moscovian (Glacial II) and the Asselian‐Sakmarian (Glacial III). Together with the global evidence of isotopes and sea level changes, multipulsed growth and decay of Glacial II and III are confirmed. The Serpukhovian isotopic pattern in Tarim exhibits a negative δ13C excursion of −6.6‰, which is comparable to those recorded in other continents. This negative excursion and contemporaneous sea level fall are triggered by the expansion of the ice sheets of Glacial II. The glaciation maximum is marked by the global sea level fall during the Bashkirian. A two‐stage transgression and positive shifts of δ13C from the Tarim and Laurussia represent evidence of stepwise deglaciation of Glacial II during the Moscovian. Positive δ18O excursions in Tarim and other two global sections from Laurussia and the regression during early Asselian to early Sakmarian are linked to the Glacial III, confirming this event is of global origin. The eustatic rise and the negative δ18O shifts indicate the retreat of this Gondwana glacier in late Sakmarian. These continuous data sets in Tarim coupled with time equivalent stratigraphy and geochemical records provide insights into the multistage evolution of the discrete Glacial II and III events.

Abstract During the Late Paleozoic Ice Age (LPIA, 345–260 Ma), an expansion of ice house conditions at ∼330 Ma caused a nearly synchronous, global unconformity. Subaerially exposed paleotropical carbonates were dissolved by meteoric waters, mixed with the light terrestrial carbon, and recrystallized with overprinted, diagenetic δ13C values. In Northern Spain, development of a rapidly subsiding foreland basin kept local sea level relatively high, allowing continuous carbonate deposition to record δ13C without meteoric overprint. The Spanish sections show a 2‰ increase in δ13C that can be modeled as the ocean's response to the creation of a significant light carbon sink through widespread meteoric diagenesis of marine carbonates during the near‐global hiatus. About 15–35 m of sea level fall would have exposed a large enough volume of carbonate to account for the positive excursion in δ13C of oceanic DIC. Combining the δ13C data with high resolution biostratigraphy and new ID‐TIMS U‐Pb zircon ages from interbedded tuffs, we calculate that the depositional hiatus and glacioeustatic fall caused by the early Serpukhovian phase of ice growth lasted for approximately 3.5 My.

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The late Paleozoic ice age was one of the three major glaciations in the Phanerozoic. However, the influence and characteristics of this glaciation and deglaciation remain unclear. In this study, we present lithostratigraphy, biostratigraphy, and chemostratigraphy during the Late Mississippian to the Early Permian in Tarim, Northwestern China. Tarim records two Gondwana glacial events in the Serpukhovian‐Moscovian (Glacial II) and the Asselian‐Sakmarian (Glacial III). Together with the global evidence of isotopes and sea level changes, multipulsed growth and decay of Glacial II and III are confirmed. The Serpukhovian isotopic pattern in Tarim exhibits a negative δ13C excursion of −6.6‰, which is comparable to those recorded in other continents. This negative excursion and contemporaneous sea level fall are triggered by the expansion of the ice sheets of Glacial II. The glaciation maximum is marked by the global sea level fall during the Bashkirian. A two‐stage transgression and positive shifts of δ13C from the Tarim and Laurussia represent evidence of stepwise deglaciation of Glacial II during the Moscovian. Positive δ18O excursions in Tarim and other two global sections from Laurussia and the regression during early Asselian to early Sakmarian are linked to the Glacial III, confirming this event is of global origin. The eustatic rise and the negative δ18O shifts indicate the retreat of this Gondwana glacier in late Sakmarian. These continuous data sets in Tarim coupled with time equivalent stratigraphy and geochemical records provide insights into the multistage evolution of the discrete Glacial II and III events. Plain Language Summary: The late Paleozoic ice age (LPIA) spanning from Late Devonian to Late Permian is among the major global icehouses in the Phanerozoic. Previous studies of the LPIA in southern Gondwana proposed a hypothesis of a single, prolonged LPIA. An alternative hypothesis argues for a more dynamic view that the LPIA consisted of a series of discrete, short‐lived, and possibly asynchronous glaciations. However, the onset, development, and demise of the discrete glaciations are not clearly understood. In this contribution, we provide continuous data sets of carbon and oxygen isotopes from the biostratigraphically constrained strata covering the LPIA in Tarim, China. Evidence of microfacies and sedimentology, as well as isotope data, provide clues for sea level changes related to waxing and waning of the late Paleozoic glaciations. A global synthesis of carbon and oxygen isotope data and sea level evidence provides insights into the LPIA and supports the second hypothesis of a dynamic LPIA. Key Points: δ13C and δ18O data sets covering the late Paleozoic ice age from Tarim record two Gondwana glacial events in the Serpukhovian‐Moscovian and Asselian‐Sakmarianδ13C excursion and sea level fall were triggered by the Serpukhovian‐Moscovian glaciationδ18O excursion and reef complex indicate the retreat of the Asselian‐Sakmarian glaciation [ABSTRACT FROM AUTHOR]

This study reports several Late Paleozoic dropstone‐bearing formations in Peninsular Malaysia which were not previously investigated. Additionally, the source, formation mechanisms, and correlation to the global Late Paleozoic Ice Age (LPIA) of these dropstones are discussed. Dropstones occur as subrounded to rounded single clasts ranging in size from 0.5 to 20 cm, scattered in red mudstone, black shales, sandstones and shales, and are composed of granite, quartzite, and sandstone. Occurrence of dropstones as rounded, single clasts, and soft‐sediment deformation of the host rock with striations in the dropstones suggest a glaciomarine origin. Precambrian basement rocks and Cambrian–Ordovician quartzite and sandstones are the main sources of the dropstones. Dropstones hosted by shallow‐marine sediments are formed by dropping of clasts from icebergs, while, dropstones present in deep‐marine sediments are formed by dropping of clasts from an ice sheet. The oldest glaciomarine rocks of the Rebak and Chepor members (Singa Formation) can be correlated to the Early Carboniferous global glaciation of the LPIA episode of Gondwana. These sediments are considered as the first record of Lower Carboniferous (Mississippian) glaciomarine rocks in Southeast Asia. However, the glaciomarine deposits of the Kentut and Bukit Raja members (Singa and Kubang Pasu formations, respectively) are correlated with the global Middle Carboniferous glaciation. In addition, the glaciomarine deposits of the "undifferentiated" member (Kubang Pasu Formation), Ulang and Selang members (Singa Formation), as well as the Kenny Hill Formation, are correlative to the Late Carboniferous‐Early Permian glaciation episode known as the apex of the LPIA. These results confirm the paleomagnetic and paleontological data which suggest that the Sibumasu Terrane initially was attached to the Late Paleozoic Gondwana. [ABSTRACT FROM AUTHOR]

An integrated study of biostratigraphy, microfacies, and stable carbon isotope stratigraphy was carried out on the late Famennian-early Asselian carbonates of the Long'an section in Guangxi, South China. Stable carbon isotope studies in the Long'an section have revealed four major positive shifts of δ13C values in the Carboniferous strata in South China. The first shift occurred in the Siphonodella dasaibaensia zone in the Tournaisian, with an amplitude of 4.19‰. The second shift occurred near the Visean/Serpukhovian boundary, with an amplitude of 2.63‰. The third shift occurred in the Serpukhovian, with an amplitude of 3.95‰. The fourth shift occurred in the Kasimovian, with an amplitude of 3.69‰. Furthermore, there were several brief positive δ13C shifts during the late Famennian to early Tournaisian. All of these shifts can be well correlated globally, and each corresponds to sea-level regressions in South China and Euro-America, indicating increases in ocean primary productivity and global cooling events. Chronologically, the four major positive excursions of δ13C, together with several brief positive δ13C shifts that were observed during the late Famennian to the early Tournaisian, correspond to the well-accepted Glacial I, II, and III events. [ABSTRACT FROM AUTHOR]

Rifting of continental blocks away from northern Gondwana resulted in the development of several Tethyan oceanic branches, the number of which and the timing of tectonic processes are actively debated. Within the Mesozoic Bangong-Nujiang suture, locally exposed Paleozoic strata are potential witnesses of the early development of Tethyan basins, yet their origin and tectonic significance remain poorly understood. In this study, Paleozoic limestone and sandstone units exposed in the Dongkaco area are identified as part of an independent Dongkaco microcontinent, differentiated from the South Qiangtang terrane by the Dongqiao suture on the north and from the Lhasa Block by the Beila suture on the south. The Upper Paleozoic deltaic to shallow-marine feldspatho-quartzose and quartzose sandstones within the microcontinent are interbedded with glaciogenic sequences and exhibit provenance characteristics that align with the Lhasa Block. These stratigraphic and provenance features suggest that during the Carboniferous to Early Permian the Dongkaco microcontinent was attached to the Lhasa Block. The discovery of Middle Triassic (Anisian) radiolarian chert associated with the Beila ophiolite indicates that sea-floor spreading was active within the Beila Ocean at that time. Data presented here show that the detachment of the Dongkaco microcontinent from the Lhasa Block resulted in the Beila Ocean, a branch of Bangong-Nujiang Ocean that expanded through Middle Permian to Early Triassic times. These findings shed new light on the paleogeographic evolution that preceded India-Asia collision and final amalgamation of the Himalayan-Tibetan orogen. • Lhasa-like provenance recognized in the glacially-influenced Upper Paleozoic strata of the Dongkaco microcontinent. • Middle Triassic ophiolite-related radiolarian chert supports active spreading in the Bangong-Nujiang ocean. • Dongkaco microcontinent rifted from the Lhasa Block in the Permian to Early Triassic developing a Beila oceanic branch. [ABSTRACT FROM AUTHOR]

The beginning of the Late Paleozoic Ice Age was characterized by localized events with small ice depocenters occurring in South America and a series of cyclic shallow-water limestones in far-field regions, in late Visean to Serpukhovian. This paper documents two topmost Visean–Serpukhovian sections in Guangxi, South China: a stromatolite-bearing deep-water succession in Helv village and a shallow-water succession in Dujie village. Seventeen microfacies types have been recognized and grouped into six microfacies associations. The vertical evolution of the microfacies associations from deep-water to shallow-water depositional environments in both sections indicate a major relative sea-level fall in the latest Visean. The repetitive successions comprising different morphological stromatolites in Helv section and the cyclic alternation of subtidal and peritidal facies in Dujie section imply high-frequency sea-level fluctuations during latest Visean to Serpukhovian, most likely eustatic in origin. The carbon isotope data of Dujie limestone exhibit a pronounced positive δ13C excursion with ± 4.3‰ in the peritidal deposits. This shift is interpreted as the result of enhanced organic carbon burial in other regions and depletion of the ocean in light carbon. The widespread coeval cyclicity occurring in settings in South China, Western Europe, and North America is most likely the results of glacio-eustatic sea-level fluctuations, possibly with local influences of tectonic movements. This pattern is interpreted to represent the expression of the onset of the major glaciation during the LPIA in low-latitudinal successions. [ABSTRACT FROM AUTHOR]

Carboniferous glaciogenic strata (Itararé Gp.) in the southernmost Paraná Basin, Brazil exhibit soft-sediment deformation features previously interpreted as glaciotectonism. These sediments were studied in detail to confirm that they were deformed by ice and to assess the nature of the glaciation, depositional environments, and paleoclimate in this region during the Carboniferous. Five outcrops were described along a railroad transect that contains a conglomerate and diamictite facies with striated and faceted clasts, a medium sandstone facies, a fine grained silt/clay rhythmite and mudstone facies with dropstones and diamictite pellets, a sandy clinoform facies, and a folded sandstone with interbedded mudstone facies. The depositional environment for these sediments is interpreted as an outwash fan and fan delta from an ice-proximal, transitional terrestrial-to-estuarine setting. Rb/K values from the rhythmites reflect a transition from a freshwater to brackish environment and the Chemical Index of Alteration (CIA) of the rhythmites ranges from 65 to 73, reflecting a relative increase in the degree of chemical weathering through time. Deformation features include widespread folding, thrust faults, hydrofractures, décollement surfaces, and piggyback fold-thrust complexes. The deformation is interpreted as evidence of a push-moraine complex formed by at least two complete ice advance/retreat cycles. The occurrence of décollement surfaces, plastically deformed proglacial sediments, and hydrofractures indicate a dynamic, warm-based or polythermal glacier. Abundant outwash sediments, rhythmites with dropstones, and the shift to average CIA values all support a temperate paleoclimate. Deformation structures indicate a NW direction of ice shove that is in agreement with the regional-scale hypothesis that a NNW flowing lobe extended out of Uruguay during the Carboniferous and terminated in the southernmost Paraná Basin. This study demonstrates that late Paleozoic glaciation in this region was more dynamic than previously understood, with high frequency fluctuations in ice marginal positions. [ABSTRACT FROM AUTHOR]

Earth's transition from an icehouse to hothouse during the Late Paleozoic was characterized by a series of high paleolatitude glacial-interglacial events. However, the exact timing of these events remains unresolved. Here, we report on fifty-five calcitic shells of brachiopods and bivalves screened to obtain reliable 87Sr/86Sr ratios for Cisuralian (298.9-272.95 Ma) and Guadalupian (272.95-259.1 Ma) seawater. Specifically, we used well-preserved shells to build a 87Sr/86Sr seawater curve for the Sydney Basin, and then with the marine Look-up Table of the Permian calculated numerical ages of the stratigraphic succession. This allowed us to match seawater changes to the coeval P1 – P3 glacial-interglacial cycles recorded in the sedimentary successions of the Sydney Basin. Evaluation of the 87Sr/86Sr results revealed that onsets of the P2 and P3 glaciations in the Sydney Basin should be assigned to the early Artinskian and late Wordian, respectively. The range of 87Sr/86Sr values recorded by brachiopods from the Wandrawandian Siltstone coupled with recent geochronological dating of the Broughton Formation suggest that glacial phase P3 lasted about 2 Myr and was confined to the late Wordian – early Capitanian. Dating obtained using the Sr-isotope proxy from brachiopods agrees with the geochronologic ages, and they suggest that the glacial phases P1 to P3 became progressively shorter in duration and less intense. Conversely, the corresponding interglacials became progressively longer, and thus, documenting the gradual transition of the Permian icehouse to an ice-free greenhouse world. Our study confirms that strontium isotopes measured in screened brachiopod shell archives are sufficiently robust to date Paleozoic marine sedimentary successions, and are most valuable in sedimentary successions that otherwise lack geo-chronological dating. • Strontium isotope stratigraphy applied to dating late Paleozoic marine sediments. • Geochemistry of brachiopod low magnesium shells. • Multiple-screening approach to the study of carbonate diagenesis. • Numerical dating of glacial-interglacial cycles characterizing the Lower and Middle Permian in the southern paleo-latitudes. [ABSTRACT FROM AUTHOR]

Abstract Ice-contact deposits emplaced by Late Paleozoic Ice Age (LPIA) glaciers are rarely exposed due to a low degree of preservation and their capping by thick glaciomarine deglaciation sequences. In this paper, we present new data on glacial cyclicity, relative age constraints and paleoice flow interpretations for an ice-contact succession of the lowermost Itararé Group in eastern Paraná Basin (Brazil). The 80 m-thick ice-contact complex rests over the Itararé Group basal unconformity and comprises four stacked informal stratigraphic units regarded as the depositional/deformational record of three ice lobes advance/retreat cycles. Glacial cycle 1 comprises a sheet of massive diamictite resting on striated pavements carved on Devonian sandstones and topped by grooved/fluted surfaces, which indicate subglacial emplacement from a northward flowing ice lobe. The glacial cycle 2 succession was deposited in a proglacial to ice-marginal marine setting and subsequently deformed due to minor ice margin fluctuations of a westward/southwestward flowing grounded ice lobe. Glacial cycle 3 is interpreted as a thick overridden push moraine composed of grounding-line fan deposits capped by a subglacial diamictite emplaced by grounded ice advancing northwestward. A middle Visean-early Serpukhovian palynomorph assemblage was recorded in cycle two deposits, representing the oldest late Paleozoic glacial rocks in the Paraná Basin. The ice-contact complex elucidates multiple waxing and waning phases of the Windhoek Ice Sheet onto the eastern margin of the Paraná Basin during the Mississippian-Early Pennsylvanian, demonstrating that ice sheets of the early stages of the LPIA were also present in the Brazilian-African domain of southwestern Gondwana. Highlights • 3 glacial cycles with variable ice lobe kinematics are defined for an ice-contact complex in the lowermost Itararé Group. • The basal age of the Itararé Group is older than previously interpreted ranging from the middle Visean. • Ice sheets covered the west-central domain of Gondwana during the Mississippian. [ABSTRACT FROM AUTHOR]

U-Pb dating and Hf-isotope provenance analysis of detrital zircons from the glaciogenic lower Permian Grant Group of the Canning Basin indicate sources principally from basement terranes in central Australia, with subordinate components from terranes to the south and north. Integrating these data with field outcrop and subsurface evidence for ice sheets, including glacial valleys and striated pavements along the southern and northern margins of the basin, suggests that continental ice sheets extended over several Precambrian upland areas of western and central Australia during the late Paleozoic ice age (LPIA). The youngest zircons constrain the maximum age for contemporaneous ice sheet development to the late Carboniferous (Kasimovian), whereas palynology provides a minimum age of early Permian (Asselian-Sakmarian). Considering the palynological age of the Grant Group within the context of regional and global climate proxies, the main phase of continental ice sheet growth was possibly in the Ghzelian-Asselian. The presence of ice sheets older than Kasimovian in western and central Australia remains difficult to prove given a regional gap in deposition possibly covering the mid-Bashkirian to early Ghzelian within the main depocentres and even larger along basin margins, and the poor evidence for older Carboniferous glacial facies. There is also no evidence for extensive glacial facies younger than mid-Sakmarian in this region as opposed to eastern Australia where the youngest regional glacial phase was Guadalupian. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age (LPIA) was the longest and most extensive glacial interval during the Phanerozoic, lasting from the Late Devonian to the late Permian (362–254 Ma). Numerous questions remain on the spatial and temporal extent of the ice centers, the timing of expansion and contraction of the ice sheets, and the distribution of ice across Gondwana through time. The Tepuel–Genoa Basin, in Patagonia (Argentina) was situated within the paleo South Polar Circle and contains a nearly continuous lower Carboniferous (Tournasian) to lower Permian (Artinskian) succession. The Mojón de Hierro Formation has been described as both non-glacial and glacial in origin, but lacks detailed sedimentological descriptions. This research investigates a ∼50 m succession with sedimentological and geochemical analysis within strata in the upper portion of the Mojón de Hierro Formation at Arroyo Garrido (Chubut Province). Five stratigraphic sections were measured and the strata were categorized into five lithofacies: 1) deformed sandstones, 2) thin-bedded diamictites, 3) graded rhythmites, 4) laminated mudstones with dispersed clasts, and 5) laminated mudstones. Deposition occurred in a slope environment from debris flows, turbidity currents, mass-movements, hemipelagic sedimentation, and ice rafting. The Chemical Index of Alteration (CIA) indicates values similar to average marine shales, which suggests that the muds were supplied from temperate terrestrial sediment sources. This indicates that icebergs from a distant source transited the basin and grounded glaciers were not present in the catchment area. Vanadium/chromium ratios (V/Cr) indicate dysoxic (restricted water circulation) values in samples between the mass-transported blocks and oxic values (well circulated water) in samples stratigraphically above the filled/leveled ponded mini basin. These oxygenation conditions suggest that the mass-transport deposit formed a topography on the sea floor, resulting in a mini basin that ponded sediments within the blocks. A local glacial source was not substantiated for the upper Mojón de Hierro Formation at Arroyo Garrido neither through the detailed facies analysis nor through geochemical proxies. [ABSTRACT FROM AUTHOR]

Abstract This paper explores microbially induced sedimentary structures (MISS) preserved in Late Paleozoic Ice Age deposits to evaluate the potential microbe-substrate physical interactions in ancient glacial settings. MISS have been recorded worldwide in different modern and ancient settings, mostly in tidal flats. However, their record in ancient glacial settings is still underrepresented. The reported MISS are preserved in the siltstone-claystone glacigenic rhythmites in Trombudo Central region of the Rio do Sul Formation (Paraná Basin, Pennsylvanian, southern Brazil). The recorded structures in these deposits are composed of wrinkle structures, dome structures, mat fragments, mat microfabrics, sinoidal structures, laminated leveling structures, oriented grains and mat-layer bound small grains, kinneyia structure, discoidal microbial colony, elongated filaments, and drab-haloed filaments. They represent the development of endobenthic and epibenthic microbial mats, as well as microbial earths. Endobenthic mat structures predominate in the siltstone beds, suggesting less time for development of microbial mat during deglaciation events and meltwater input. Epibenthic mat structures preserved in the claystone layers indicate episodic quiescence periods that allowed the mat achieve maturity and that cyanobacteria and sulfate-reducing bacteria composed a significant part of the microbial community. The set of MISS observed in the studied rhythmites have been commonly reported in tidal settings, and the presence of microbial earths structures indicate periods of drainage of the water bodies, at least partially. Thus, the microbial communities played an important role in ancient glacial settings during climatic amelioration periods, opening the colonization window for macroorganisms in outwash plains and marginal marine settings. This paper provides a characterization of different sorts of preserved MISS, and evaluate the physical interactions between microbial mats and the substrate, in the ancient glacigenic deposits from the Itararé Group. Highlights • Preserved MISS in glacigenic rhythmites of Pennsylvanian Paraná Basin in southern Brazil. • Preserved records represent the development of endobenthic and epibenthic microbial mats, as well as microbial earths. • The microbial communities enhancing the colonization window for macroorganisms during climatic amelioration periods. [ABSTRACT FROM AUTHOR]

Abstract: During the Late Paleozoic Ice Age (LPIA, 345–260 Ma), an expansion of ice house conditions at ∼330 Ma caused a nearly synchronous, global unconformity. Subaerially exposed paleotropical carbonates were dissolved by meteoric waters, mixed with the light terrestrial carbon, and recrystallized with overprinted, diagenetic δ 13C values. In Northern Spain, development of a rapidly subsiding foreland basin kept local sea level relatively high, allowing continuous carbonate deposition to record δ 13C without meteoric overprint. The Spanish sections show a 2‰ increase in δ 13C that can be modeled as the ocean's response to the creation of a significant light carbon sink through widespread meteoric diagenesis of marine carbonates during the near‐global hiatus. About 15–35 m of sea level fall would have exposed a large enough volume of carbonate to account for the positive excursion in δ 13C of oceanic DIC. Combining the δ 13C data with high resolution biostratigraphy and new ID‐TIMS U‐Pb zircon ages from interbedded tuffs, we calculate that the depositional hiatus and glacioeustatic fall caused by the early Serpukhovian phase of ice growth lasted for approximately 3.5 My. [ABSTRACT FROM AUTHOR]

A well-exposed glacial surface sculpted on Precambrian crystalline basement rocks occurs below the glacial succession of the San Gregorio Formation on the eastern border of the Chaco-Parana Basin in Uruguay and was formed in the context of the late Paleozoic Gondwana Ice Age. On the glacial surface are asymmetric parallel streamlined bedrock landforms interpreted as whalebacks. The downglacier (lee-side) faces of the whalebacks have gentle slopes dipping NNW with striated and sometimes polished surfaces on crystalline rocks. These landforms are covered by 10–100-cm-thick layers of tillites and shear-laminated siltstones, suggesting glacial abrasion produced mainly by subglacial till sliding. The subglacial facies are ice-molded, and exhibit meso-scale glacial lineations such as ridges and grooves up to 30 m long and 30 cm deep. The subglacial association is directly overlain by proglacial fine-grained facies (rhythmites) with dropstones indicating a subaqueous depositional environment following ice-margin retreat. The fine-grained facies are erosively cut by a succession of sandstones with wave-generated stratification resting on a basal conglomerate. Intraformational striated surfaces, NNE-oriented, were found on four distinct bedding planes within the sandstone package and interpreted as ice keel scour marks produced by floating ice. The San Gregorio deposits are partially confined in a wide and shallow subglacial trough and the stratigraphic succession is interpreted as the record of a glacial advance-retreat cycle comparable to deglacial sequences from other late Paleozoic localities. The paleo-ice flow to the NNW indicated by subglacial lineations is parallel to that verified in the southernmost Paraná Basin located north of the study area, suggesting a paleogeographic scenario in which glaciers advanced northward into a glaciomarine environment. The proposed palaeogeography does not confirm the previous hypothesis of an ice center on the Sul-Riograndense Shield but, instead, it corroborates a south-derived Uruguayan Ice Lobe advancing to the north, probably with provenance far afield in terranes of the present-day southern African. [ABSTRACT FROM AUTHOR]

Both global and regional climate drivers contributed to glaciation during the late Paleozoic Ice Age (LPIA). However, the transition from icehouse to greenhouse conditions was asynchronous across Gondwana suggesting that, in some cases, regional controls played a significant role in deglaciation. Of particular interest to understanding changing LPIA climatic conditions, is the eastern Paganzo Basin. This region was flanked by ice centers in the Precordilleran and Sierras Pampeanas regions of Argentina on the west, and major ice sheets in the Paraná, Chaco-Paraná, and Sauce Grande basins to the east, all of which resided between ∼40 and 65° S latitude. Hypotheses on the occurrence of ice in the eastern Paganzo Basin are based on interpretations of the narrow, steep-walled, Olta-Malanzán paleovalley as carved by an alpine glacier or by an outlet glacier draining an eastern ice sheet, and that glaciers deposited coarse clastics within the paleovalley. However, we found no evidence for glaciation. Rather, gravel from prograding alluvial fans/fan deltas and rock falls ponded drainage resulting in lacustrine activity in the eastern end of the valley. A transition from either subaerially or shallow subaqueously deposited sandstones to marine mudstones in the western end of the Olta paleovalley suggest a marine transgression, which, in turn, was overlain by deposits of prograding Gilbert-type deltas. Dropstones were from rock falls off valley walls and rafting by lake ice rather than from icebergs. Therefore, we conclude that the climate in western Argentina resulted from uplift induced glaciation in the Precordilleran region and along the western margin of the Paganzo Basin, and the occurrence of a precipitation shadow to the east. The disappearance of the western glaciers during the mid-Carboniferous, prior to deglaciation elsewhere at the same paleolatitude, resulted from a westward shift in the position of the active margin, collapse of the glaciated upland(s), and an expansion of the precipitation shadow across the whole of western Argentina. [ABSTRACT FROM AUTHOR]

Reconstructions of paleo-seawater chemistry are largely inferred from biogenic records of epicontinental seas. Recent studies provide considerable evidence for large-scale spatial and temporal variability in the environmental dynamics of these semi-restricted seas that leads to the decoupling of epicontinental isotopic records from those of the open ocean. We present conodont apatite δ 18 O PO 4 and 87 Sr/ 86 Sr records spanning 24 Myr of the late Mississippian through Pennsylvanian derived from the U–Pb calibrated cyclothemic succession of the Donets Basin, eastern Ukraine. On a 2 to 6 Myr-scale, systematic fluctuations in bioapatite δ 18 O PO 4 and 87 Sr/ 86 Sr broadly follow major shifts in the Donets onlap–offlap history and inferred regional climate, but are distinct from contemporaneous more open-water δ 18 O PO 4 and global seawater Sr isotope trends. A −1 to −6‰ offset in Donets δ 18 O PO 4 values from those of more open-water conodonts and greater temporal variability in δ 18 O PO 4 and 87 Sr/ 86 Sr records are interpreted to primarily record climatically driven changes in local environmental processes in the Donets sea. Systematic isotopic shifts associated with Myr-scale sea-level fluctuations, however, indicate an extrabasinal driver. We propose a mechanistic link to glacioeustasy through a teleconnection between high-latitude ice changes and atmospheric p CO 2 and regional monsoonal circulation in the Donets region. Inferred large-magnitude changes in Donets seawater salinity and temperature, not archived in the more open-water or global contemporaneous records, indicate a modification of the global climate signal in the epicontinental sea through amplification or dampening of the climate signal by local and regional environmental processes. This finding of global climate change filtered through local processes has implications for the use of conodont δ 18 O PO 4 and 87 Sr/ 86 Sr values as proxies of paleo-seawater composition, mean temperature, and glacioeustasy. [ABSTRACT FROM AUTHOR]

The last glaciation during the late Paleozoic ice age commenced at around the Guadalupian–Lopingian (G–L) boundary and is synchronous with the emplacement of the Emeishan large igneous province. Using CA-TIMS zircon U–Pb dating, we obtained an age of 259.51 ± 0.21 Ma for the uppermost tuff from the Puan volcanic sequence in the eastern Emeishan large igneous province, constraining the timing of Emeishan volcanism and providing another candidate age for the G–L boundary. In addition, we determined an age of 259.69 ± 0.72 Ma for a basal claystone in the immediately overlying Longtan Formation from a drill core section in southwest South China. These ages, along with source weathering trends of mudstones from the lower Longtan Formation, and compiled paleotemperature records, indicate an earliest Wuchiapingian cooling coinciding with the onset of the last Permian glaciation. This global cooling is associated with positive shifts in both organic and carbonate carbon isotopic records and likely a decrease in atmospheric p CO 2 . A hypothesised causal linkage is proposed in which the rapid post-eruptive basaltic weathering of the Emeishan province in an equatorial humid belt may accelerate the atmospheric CO 2 consumption and lead to climate cooling. Our work supports the long-term climate cooling effects of large igneous provinces. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age (ca. 335–260 Ma, LPIA) has long been considered as an analogy for the Cenozoic ice age since the Oligocene. The impact of astronomical forcing on the LPIA glaciation has been hampered due to the low-resolution (multi-million year scale) time framework. In the present study, high-resolution cyclostratigraphy based on magnetic susceptibility (MS), covering the Serpukhovian to late Moscovian icehouse climate, has been investigated in the Luokun section of South China. Power spectral analysis of the MS series reveals 3.44–4 m, 0.8–1.07 m, 0.3–0.32 m, and 0.17–0.19 m thick sedimentary cycles. Based on the available biostratigraphic constraints, calibrating the 3.44–4 m cycles to the 405 kyr eccentricity cycles indicates short eccentricity (136 and 100 kyr), short obliquity (34 kyr), and precession (19 and 15.9 kyr) orbital bands in addition to long eccentricity (405 kyr) band. We assigned the basal Serpukhovian and Moscovian stages in Luokun with the numerical ages from Geological Time Scale 2012 to construct two floating time scales ranging from 331.55 ± 0.5 Ma to 323.2 ± 0.5 Ma, and from 315.34 ± 0.35 Ma to 310.17 ± 0.35 Ma, respectively. The modulation of main obliquity ( s 4 – s 3 term) has a main periodicity of ∼1200 kyr. The modulation of ∼100 kyr eccentricity ( g 4 – g 3 term) shows a main periodicity of ∼2400 kyr with subordinate periodicities of ∼1620 and ∼1200 kyr for the Serpukhovian, and a main periodicity of ∼1600 kyr for the Moscovian. They may provide the geological evidence for a chaotic resonance associated with interactions between the orbits of Mars and the Earth in the Carboniferous. A duration of 7.68 ± 0.15 Myr was estimated for the Serpukhovian Stage. Eight higher accumulation rate events due to glacioeustatic drawdown were temporally constrained, and show close correspondence to far-field and near-field reconstructions of the LPIA glaciation. Glacioeustasy was paced with 405-kyr-long eccentricity and 1.2-Myr obliquity amplitude cycles during the Serpukhovian and Moscovian stages, likely indicating the nature in the warmer icehouse world similar to that of the Oligocene to Pliocene. [ABSTRACT FROM AUTHOR]

The Late Paleozoic is widely recognized as a 'high-fire' world. However, the impact of wildfires on the vegetational change as well as the relationship between fire and low atmospheric p CO 2 and high p O 2 in the Late Paleozoic remains a matter of debate. New data on fossil charcoal and pyrogenic PAHs in coal deposits from the Yuzhou Coalfield, the southern part of the North China Basin, are integrated into previous studies to increase our current understanding of the role of wildfires on land and in marine environments during the late Carboniferous and early Permian. Analyses of bulk petrographic and organic geochemical data indicate that during deposition of the Taiyuan Formation (late Gzhelian and early Asselian Stage) wildfires were more prevalent and were characterized by a large proportion of crown fire. A previous plant macrofossil assemblage study of the Taiyuan and Shanxi formations, together with fire traits of ancient plant lineages, indicates that wildfire may likely be one of the major drivers of the thriving of the Cathaysian Flora during this period. Wildfire and post-wildfire processes might have acted as important controlling factors for organic carbon burial. Persistent organic carbon sequestration (as coals or charcoal) on land and increasing organic carbon burial in the ocean are coincident with the peak in p O 2 during the apex of the Late Paleozoic Ice Age. • This study integrates understanding of wildfire impact on vegetation and glacial system during the late Paleozoic. • Wildfires were prevalent during the late Carboniferous and early Permian in the North China Basin. • Wildfire may have been one of the major drivers for the thriving of Cathaysian Flora during the Shanxi Formation. • Wildfire and post-fire processes enhanced the organic carbon burial both on land and in marine environments. [ABSTRACT FROM AUTHOR]

Recent studies in the eastern margin of the Paraná Basin, about the initial deposition of the Taciba Formation (Itararé Group) revealed a preserved, partially exhumed glacial trough as indicated by the morphology of its basal nonconformity. In this work, we reinforce the importance of the glacially-carved topography controlling the subsequent sedimentation by emphasizing turbidity currents and their deposits. This glacial trough is large enough to confine part of the following deglacial sediments, including a sand-rich turbidite system that represent phases of more consistent sand supply, a result from high sedimentation rates associated either with direct influx of meltwater-derived jets and/or with a rapid delta progradation at the trough head, causing over-steepening, unsteadiness, and eventual failure of the delta-front deposits. This turbidite system consists of three sand-rich stages (Ts1 to Ts3) intercalated with three fine-grained intervals (F1 to F3). Ts stages form bedsets with an overall lenticular geometry, thinning-out toward the trough flanks where the individual sandstone beds pinch-out close to the metamorphic Precambrian bedrock. They are ascribed to sinuous, laterally extensive channelized bodies representing different phases of channel activity through time. In general, each stage consists of an initial deposition derived from long-lived turbidity currents triggered by flood-driven hyperpycnal flows followed by short-lived, surge-type turbidity currents. F1, F2 and F3 deposits consist of fine-grained intervals that separate Ts1, Ts2 and Ts3 stages by an abrupt change in grain size and bed thickness. They comprise thin, sand-to-mud couplets showing granule-to-boulder sized basement-affinity dropstones, and several minor slumps, which are interpreted as overbank/levee sedimentation taking place during the successive passage of turbidity currents. A paleogeographic reconstruction of the glacial landscape reveal some similarities with modern fjords of British Columbia, Canada, that can be used to geometries and facies distribution prediction as an analog to assist seismic and well-log data. [ABSTRACT FROM AUTHOR]

Glaciation during the Late Paleozoic Ice Age climatic interval (~370–260 Ma) was likely dynamic; consisting of numerous ice centers that grew and shrank asynchronously through time. Improvements in understanding of the spatial and temporal depositional complexity of glaciomarine sedimentary systems have shown that in order to characterize the conditions of Late Paleozoic glaciation, glaciogenic depositional systems and their stratigraphy must fundamentally be understood at the local level. To that end, this study reexamines the physical sedimentology and sequence stratigraphy of the type-section of the Permo-Carboniferous, glaciomarine Wynyard Formation (Wynyard Tillite) of the Tasmanian Basin by describing a 415 m thick interval of the formation, beginning at its basal erosional unconformity with the Proterozoic Burnie (Oonah) Formation. The glaciogenic nature of the Wynyard Formation stratigraphy is indicated by the characteristics of clasts throughout the succession (striated, faceted, angular, and variable lithologies and grain sizes). Three glacial depositional environments were interpreted: a grounding zone wedge deposited in an ice-contact setting, glacier-proximal portion of a grounding line fan and/or morainal bank, and cyclopelites deposited in a glacier-intermediate to glacier-distal setting. Mass transport and turbidite deposits are common throughout all facies associations, as is soft sediment deformation likely caused by slumping. Several boulder pavements occur throughout the succession, indicating periodic glacier grounding. Together, these facies associations indicate that this Wynyard Fm succession is composed of glaciogenic sediments that were deposited in sub-aqueous, marine, predominantly proglacial environments. The sequence stratigraphic analysis indicates that this entire succession of the Wynyard Fm was likely deposited during the single retreat phase of the "Wynyard Glacier", with one notable readvance over the area. The interpretations made by this work enhance the understanding of glaciation of the Tasmanian Basin during the LPIA through facies analyses and a sequence stratigraphic approach, which allowed for detailed subdivision of lithologies that enabled inferences regarding the type, timing, and extent of the "Wynyard glacier". This Wynyard Fm succession was likely deposited during a single glacier retreat with some minor readvances that may have occurred on the order of decades to years. Additionally, the glacier's grounding line was likely never more than a few kilometers upglacier (south) of this location during deposition. These findings are significant, because the massive diamictites that comprise this succession had previously been considered homogenous and therefore resisted detailed interpretations. Constraining the often-complex depositional histories of glaciogenic strata in similar fashions across the Tasmanian Basin allows us to better understand how these glaciogenic deposits fit into the global climate system of the Late Paleozoic Ice Age. [ABSTRACT FROM AUTHOR]

This paper examines a glacial diamictite-bearing succession from the upper Itararé Group (Taciba Formation) in eastern Paraná Basin, Brazil. The object of study provides the opportunity to investigate in detail the late stages of glacial sedimentation during the Late Paleozoic Ice Age (LPIA) in this sector of SW Gondwana, with implications for glacial cyclicity and regional paleo-ice flow reconstructions. Sedimentology, geological mapping and palynological analysis allowed the recognition of four facies associations, comprising subaqueous outwash, mass-transport, tide-influenced delta-front, and tide-influenced delta plain deposits. The succession records at least two episodes of ice-margin advance and retreat into a marine-influenced environment and can be placed in the earliest Permian based on the palynomorph assemblage. Cross stratification in outwash facies and deltaic deposits indicate sediment transport to the SW, the same revealed by deformational structures in mass-transport diamictites derived from downslope resedimentation of glaciomarine sediments during deglaciation. A glacial source to NE is therefore indicated and is in agreement with paleo-ice flow directions obtained from previously studied localities to the north. This north-derived early Permian glaciation contrasts with glacial sources to the SE recognized in the lower and middle intervals of the Itararé Group. The scenario suggests a geometric reconfiguration of the Paraná Basin during the LPIA and the migration of ice centers with time during the Late Paleozoic Ice Age in SW Gondwana. [ABSTRACT FROM AUTHOR]

Saline giants are vast marine evaporite deposits that currently have no modern analogues and remain one of the most enigmatic of chemical sedimentary rocks. The Mississippian Windsor Group (ca. 345 Ma), Maritimes Basin, Atlantic Canada is a saline giant that consists of two evaporite-rich sedimentary sequences that are subdivided into five subzones. Sequence 1 is composed almost entirely of thick halite belonging to Subzone A (Osagean). Sequence 2 is in unconformable contact and comprised of stacked carbonate-evaporite peritidal cycles of Subzones B through E (Meramecian). Subzone B, the focus of research herein, documents the transition from wholly evaporitic to open marine conditions and thus, preserves an exceptional window into the processes forming saline giants. Lithofacies stacking patterns in Subzone B reveal that higher-order fluctuations in relative sea level produced nine stacked parasequences interpreted to reflect high frequency glacioeustatic oscillations during the onset of the Late Paleozoic Ice Age. Each parasequence reflects progradation of intertidal and sabkha sediments over subtidal carbonate and evaporite deposits. Dissimilarities in cycle composition between sub-basins imply the development of contrasting brine chemistries from differing recharge rates with the open ocean. What the Windsor Group shows is that evaporite type is ostensibly linked to the amplitude and frequency of sea level rise and fall during deposition. True saline giants, like the basinwide evaporites of Sequence 1, apparently require low amplitude, long frequency changes in sea level to promote the development of stable brine pools that are only periodically recharged with seawater. By contrast, the high amplitude, short frequency glacioeustatic variability in sea level that controlled the accumulation of peritidal evaporites in Subzone B produce smaller, subeconomic deposits with more complex facies relationships. [ABSTRACT FROM AUTHOR]

The Ansilta Formation is located 5 km southeast of the Astronomical Observatory El Leoncito near Barreal, San Juan Province, Argentina. It consists of glacimarine, nearshore, and fluvial systems deposited during the Late Paleozoic Ice Age along the eastern margin of the Calingasta-Uspallata Basin. Glacial environments are unique in that facies changes occur because of glacial ice margin fluctuations that may be independent from changes of eustatic sea-level. For this reason, an alternative conceptual framework outside of the traditional sequence stratigraphic approach is necessary to understand the genesis of these strata. The lower glacially influenced succession (0–427 m) records at least five glacial advances, where glacial dynamic signatures are interpreted using glacial sequence stratigraphy and glacial systems tracts (GST). The upper succession of the Ansilta Formation (427–700 m) consists of progradational shallow marine shelf, deltaic, and fluvial strata. This assemblage shows no direct evidence of ice contact deposition in the outcrop belt due to an absence of glacially shared diamictites and glacially modified clasts, representing a major deglaciation phase in western Argentina and is part of the stepped deglaciation across Gondwana that ended elsewhere during the late Permian. • We provide a stratigraphic analysis of the lower Ansilta Formation in the Calingasta-Uspallata Basin of Argentina. [ABSTRACT FROM AUTHOR]

Whalebacks, roche moutonnées, and S-forms carved on Ediacaran granitoids near Cerro de las Cuentas, Uruguay, along with overlying diamictites, siltstones, and sandstones displaying soft-sediment grooved and striated surfaces in the Pennsylvanian San Gregorio Formation, record the glacial to post-glacial transition in the linked Norte, southern Paraná and Chaco-Paraná basins of Uruguay, Brazil, and Argentina respectively. Early authors reported these features resulted from subglacial abrasion and deposition as lodgement tills and glaciotectonites. Our re-examination reveals a nuanced setting with changing ice thicknesses, subglacial kinematics, and ice proximal glaciomarine dynamics associated with advance and retreat of an ice stream, or multiple advances of the Uruguayan Ice lobe, during glaciation of the Late Paleozoic Ice Age (LPIA) in these basins. The preserved landforms indicate temperate glacial conditions. Whalebacks formed under 1.6 to 2.5 km-thick ice and likely formed when the lobe extended across the Uruguayan and Rio Grande do Sul shields into the adjacent Paraná Basin. Previously unidentified m-scale roches moutonnées cut into one whaleback developed under thinner ice where reduced basal pressure allowed for the opening of air and water-filled cavities, thus facilitating quarrying on the lee side of basement bumps. S-forms provide additional evidence for the occurrence of subglacial waters, indicating that the basal ice was at or above its pressure melting point. The lower meter of the overlying strata consists of interstratified trace fossil-bearing, laminated siltstones; thin-bedded diamictites; and current-rippled sandstones. Trace fossils belonging to the Mermia ichnofacies within the basal siltstones, as well as acritarchs in the overlying siltstones, suggest that these sediments were deposited in ice-proximal subaqueous settings with contributions from meltwater discharge. Graded siltstone laminae suggest settling from suspension likely from meltwater plumes, while thin-bedded diamictites were deposited either as debris flows or as two-component sedimentation with fines settling from suspension and coarser particles introduce as iceberg-rafted dropstones. Current-rippled sandstones indicate the occurrence of underflow currents. Soft-sediment troughs, grooves, and striations cutting these sediments display curved and sinuous paths with some features oriented perpendicular, and one oriented opposite to the overall trend. They contain marginal and terminal berms typical of iceberg scour marks suggesting transit across the area by icebergs calving from a tidewater ice front located to the SE. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age is characterized by diverse stratigraphic records with extensive spatial-temporal distribution in the Gondwana. The Lhasa terrane located in northeastern Gondwana during the late Paleozoic developed successive glacial sedimentary records, but the depositional evidence, as well as age constraint for the onset of glaciation, is unknown. This paper provides the first full description of the basal glacial deposits in the Xainza area of Lhasa terrane, southern Tibet. Conodonts present in the carbonate overlying the glacial bed (1 m) dominantly consist of Declinognathodus intermedius , indicating that the initiation of the Late Paleozoic Ice Age in the Lhasa terrane took place in Bashkirian. Three facies associations were recognized: (i) tidal flat association (subtidal channel, bar, intertidal mixed flat), (ii) subglacial association (megaclasts and melt-out diamictite), and (iii) lonestone-bearing heterolithic association (grounding-line fan and iceberg). These facies associations are vertically arranged into a complete transgressive-retrogressive glacial succession. Ice movement direction reconstructed from the imbricated megaclasts, the concordant folds and the lateral distribution of subglacial deposits and glacial marine deposits is consistently from NNE to SSW. These characteristics suggest that the Bashkirian glaciation in the Lhasa terrane is irrelevant to western Australia, implying that these two blocks were separated during the Late Carboniferous. • The initiation of the LPIA in the Lhasa terrane took place in Bashkirian. • The tidal flat, subglacial and lonestone-bearing heterolithic associations were recognized. • The reconstructed ice movement direction is from NNE to SSW. • The Bashkirian glaciation in the Lhasa terrane is irrelevant to western Australia. • The Lhasa terrane was separated from Australia during the Late Carboniferous. [ABSTRACT FROM AUTHOR]

The deep-time geological record can provide insights into the processes and mechanisms of glacier retreat. Ice sheets of the Late Paleozoic Ice Age (LPIA) collapsed extensively during the early Artinskian (early Permian) approximately 290 million years ago through massive glacial melting that was associated with dramatic increases in global temperature, atmospheric p CO 2 , sea level, and resulted in profound changes in terrestrial plant distribution and diversity. A hypothesized mode of this extensively glacial melting is multiple large-scale volcanic events, but the causes and effects have not yet been clearly established because of the lack of detailed coeval records of volcanism and environmental changes. Here, we present a record of these events from an Artinskian terrestrial succession in the Liujiang Coalfield, North China. Our new U-Pb zircon dating, high-resolution chemostratigraphy, and kerogen maceral data reveal that environmental changes (carbon cycle perturbation, wildfire, and continental weathering) in the region were intricately linked with the large-scale volcanism associated with the Tarim-II, Panjal and Choiyoi volcanic provinces. Our study shows that hypothesized volcanism and wildfire raised temperatures by releasing greenhouse gases, while the ensuing warming led to ice sheet melting, the release of terrestrial Hg and C and resulting Hg and C cycle anomalies. • Two new early Permian U-Pb dates constrain age of Liujiang Coalfield, North China. • Hg confirms presence of Artinskian volcanism and Hg isotopes reveal Hg sources. • Weathering proxies, organic macerals and C/N ratios reveal environmental changes. • Timing of volcanism correlates with high-latitude Artinskian deglaciation. • Volcanism and wildfires co-driven the Artinskian deglaciation and the Hg and C cycles. [ABSTRACT FROM AUTHOR]

The role of mass transport deposits (MTDs) in redistributing sediment from the shelf-break to deep water is becoming increasingly apparent and important in the study of basins. While seismic analysis may reveal the general morphology of such deposits, it is unable to provide information on the detailed geometry and kinematics of gravity-driven transport owing to the limits of seismic resolution. Outcrop analysis of ancient MTDs may therefore provide critical observations and data regarding the internal deformation and behavior during slope failure. One such field area where geometry and kinematics are clearly exposed is Cerro Bola in the Paganzo Basin of northwestern Argentina. This 8 km strike section exposes a mid to late Carboniferous succession, comprising fluvio-deltaic sediments, turbidites and MTDs. Our work focuses on the main MTD that is up to 180 m thick and is characterized by a silty matrix, containing sandstone blocks and siltstone rafts. Although we consider a single slope failure as the most likely scenario, a possible double failure might also explain the occurrence of a folded turbidite marker in the upper zone of the MTD. The MTD is host to a variety of deformational features such as folding, boudinage, shear zones, allochthonous strata, and secondary fabrics among others. These deformational features vary in intensity, scale and style, both vertically and laterally across the deposit. The vertical variation is the most notable, and the entire deposit can be subdivided into lower, middle and upper zones according to variations in texture and structures, including sandstone blocks, sand streaks and blebs in the matrix, folding on a variety of scales, and shear zones. The middle part of the MTD is characterized by the abundance of siltstone rafts. Various models are proposed for the origin of blocks and rafts within the MTD: erosion of underlying strata; fragmentation of the original protolith; or a mixture of both. Significantly, specific strain cells occur around the blocks, and so the kinematics of deformation structures in the matrix of the MTD are very largely governed by their proximity and position relative to blocks, and may not relate to the overall kinematics of the MTD. This casts serious doubt on the ability to interpret overall movement directions from core or dip-meter data in the subsurface. [ABSTRACT FROM AUTHOR]

In the southernmost part of the Parana Basin, records of the late Paleozoic glaciation occur in a discontinuous form preserved in paleovalley systems excavated in the crystalline basement. This paper addresses one of these paleovalleys, the Mariana Pimentel, which extends over 60 km with NW-SE valley direction and a constant width of 2.5 km. With the objective of demonstrating that the paleovalley worked as a fjord during the glaciation period, its origin as well as sedimentary fill and morphology were analyzed. The paleovalley morphology was obtained through electrical resistivity (electrical sounding and lateral mapping) and mathematical modeling in four transverse sections. The morphology of the paleovalley documented by the U-shape, steady width, and high depth reaching up to 400 m are typical features of modern glacial valleys. The sedimentary facies that fill the base of the paleovalley, such as rhythmites and dropstones with thickness up to 70 m and diamictites with faceted pebbles (up to 5 m thick) are signs of its glacial origin. During the glaciation period, the paleovalley had a connection to the epicontinental sea located to the northwest, extended toward Namibia, and was excavated by glaciers from the highlands of this region. Thus, the evidence attests that the Mariana Pimentel paleovalley was a fjord during the late Paleozoic glaciation. The duration of the late Paleozoic glaciation (which is longer than the Quaternary glaciation), the apatite fission track that suggests erosion up to 4 km thick in the study area, and the lack of preserved hanging valleys in the Mariana Pimentel indicate that the paleovalley once featured a higher dimension. Furthermore, the existence of paleofjords excavated in the border of the basement corroborates the idea of small ice centers controlled by topography during the late Paleozoic glaciation. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age is recorded in the Paraná Basin as glacial deposits, deformational features and ice-related erosional landforms of the Itararé Group. Erosional landforms are often employed to build paleogeographic models that depict the location of ice masses and paleo ice-flow directions. This paper provides a review of the literature and new data on micro- to meso- scale ice-related, erosional landforms of the Paraná Basin. Examined landforms can be placed into four broad categories based on their mode of origin. Subglacial landforms on rigid substrates occur on the Precambrian basement or on older units in the Paraná Basin. They include streamlined landforms and striated pavements formed by abrasion and/or plucking beneath advancing glaciers. Subglacial landforms on soft beds are intraformational surfaces generated by erosion and deformation of unconsolidated deposits when overridden by glaciers. Ice-keel scour marks are soft- sediment striated/grooved landforms developed by the scouring of free-floating ice masses on underlying sediments. Striated clast pavements are horizons containing aligned clasts that are abraded subglacially due to the advance of glaciers on unconsolidated deposits. Only those erosional landforms formed subglacially can be used as reliable paleo ice-flow indicators. Based on these data, the paleogeography of the Paraná Basin during the Late Paleozoic Ice Age fits into a model of several glacial lobes derived from topographically- controlled ice spreading centers located around the basin instead of a single continental ice sheet. [ABSTRACT FROM AUTHOR]

Variability in stratigraphic accumulation rates and distribution of stratal hiatuses along with strong endemism of index fossils hinder regional to global stratigraphic correlation of the Visean–Serpukhovian (V–S) boundary interval (late Mississippian) and thus geological inferences regarding the onset of the late Paleozoic ice age. Here we integrate high-resolution δ 13 C time series with detailed sedimentary facies analysis of late Visean–early Serpukhovian (V–S) carbonate platform-to-slope successions from South China to evaluate the influences of local depositional and diagenetic processes on δ 13 C carb and to address the correlation issue. Analysis of 11 sedimentary facies from 5 outcrop sections indicates a restricted platform setting (Yashui section) dominated by bioclastic wacke-packstone to lime mudstone in which paleokarst developed, and contemporaneous carbonate slope settings dominated by thin-bedded lime mudstones intercalated with slumps and calciturbidites. Based on vertical facies assemblages, three depositional units are recognized, recording a significant sea-level drawdown across the V–S boundary. Multiple negative δ 13 C excursions (> 1‰) can be correlated across the V–S boundary interval in several slope sections (Naqing, Luokun, and Narao sections). Variability in the V–S boundary δ 13 C record in some sections is interpreted to record truncation physically by submarine erosion by slumps or chemically during karstification. A long-term decrease in δ 13 C values through the Serpukhovian of the Yashui section likely records local influences on carbon cycling in the restricted platform setting. This negative δ 13 C trend and associated depositional facies at the Yashui section can be correlated to the Arrow Canyon section, USA, which, together with other coeval global sedimentary and geochemical records, indicate a widespread eustatic drawdown in the late Visean with initial buildup of Gondwanan ice sheets. We conclude that integrated sedimentary facies analysis and δ 13 C chemostratigraphy can be used for stratigraphic correlation when interpreted within a well-constrained sedimentary and carbon-isotope regional framework. [ABSTRACT FROM AUTHOR]

Despite a lack of detailed sedimentologic analyses, diamictites in the Middle Permian Atkan Formation were previously interpreted as glaciomarine and glacially-influenced marine deposits. This interpretation allowed this unit to play a prominent role in paleoclimatic and biogeographical reconstructions associated with presumed bipolar glaciation during the late Paleozoic ice age (LPIA). In this sense, the LPIA is considered to be a close analog to bipolar glaciation and climate change during the Cenozoic. Here, results are presented that challenge the glacigenic interpretation for these strata and negate interpretations of the bipolar nature of the LPIA. The 400 to 1500-m-thick Atkan Formation was deposited in back-arc basins associated with activity of the Okhotsk–Taigonos volcanic arc along the leading edge of Pangea as it drifted across the North Polar Circle. The occurrence of tuffs, volcanic clasts, and glass shards indicate derivation from a nearby arc. Cooling and solidification of some clasts during sedimentation is suggested by the occurrence of clasts with embayments and protrusions that extend into the surrounding matrix, clasts with columnar-like jointing, and alteration of the matrix surrounding some clasts. CA-TIMS dating of tuff zircons indicate a late Capitanian age, which is consistent with fossils within the strata. Bedded diamictites deposited as debrites dominate. These diamictites, which occur as tens of m thick downlapping packages that thicken then thin upward, were deposited as prograding and abandoning sediment gravity-flow fans. Chaotic and folded strata formed as slumps. Graded sandstones and conglomerates were deposited as turbidites, and mudstones were deposited as mudflows, low-density turbidites, and hemipelagic deposits. Striated clasts and outsized clasts piercing bedding were not observed in the study area. Strata above and below the Atkan Formation contain abundant graded beds and deep-water trace fossils indicating deposition as turbidites. The combination of debrites, turbidites, slumps, volcanic grains (clasts, glass, and tuffs), and an absence of glacigenic indicators suggest that Atkan strata were deposited in deep-water basins associated with the development of the volcanic arc rather than due to glacial activity. These findings are significant as they require reconsideration of current views of LPIA glaciation and suggest that ice sheets were limited to Gondwana. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age (LPIA) is the so far longest-last icehouse climate state during the Phanerozoic, and recorded a complete transition from icehouse to greenhouse climate state since the occurrence of vascular plants and complex terrestrial ecosystem. Therefore, integrated studies on the icehouse-greenhouse transition of the LPIA are critical to understanding the driver and mechanism of the deep-time paleoclimate system, particularly in an icehouse climate state. However, frequent subaerial exposures and stratigraphic discontinuities in low-latitude areas due to glacio-eustatic changes from the Pennsylvanian (Late Carboniferous) to Cisuralian (Early Permian) potentially altered the primary δ13C signals, which hampered a valid global correlation. Here, three carbonate slope successions (Naqing, Shanglong, and Narao) in the Luodian Basin, South China Block, were selected for detailed sedimentology and high-resolution carbonate δ13C study. The variation of δ13C is compared with the sedimentary characteristics and can be correlated with global glacial events and atmospheric p CO 2 during the apex and deglaciation period of the LPIA. It suggests that δ13C of the Luodian Basin can potentially represent the global mean δ13C of the seawater dissolved inorganic carbon and provide a reference for the future study on global carbon cycling. • Detailed sedimentary facies and high-resolution δ13C carb time series in the Luodian Basin • δ13C carb of the Luodian Basin as a reliable proxy for global carbon cycling • A potential linkage between global carbon cycling and evolution of the LPIA [ABSTRACT FROM AUTHOR]

High-resolution (948 samples) measurements of anhysteretic remanent magnetization (ARM) were performed on the ~ 200 m thick Early–Middle Permian Maokou Formation of the Shangsi section, South China. The ARM variations are quasi-periodic and the wavelengths of significant cycles collectively present a ratio of 20:5:2:1 throughout the formation, corresponding to long orbital eccentricity, short orbital eccentricity, obliquity, and precession cycles. A strong obliquity (44 and 33 kyr) signal suggests that waning and waxing of the ice sheet in eastern Australia at the end of the Late Paleozoic Ice Age (LPIA) exerted a significant influence on global climate and sea level. A “floating” astronomical time scale (ATS) is developed using the 405 kyr orbital eccentricity cycle as an astronomical calibration target. This results in estimation of the Roadian and Wordian stages duration as 3.7 ± 0.4 myr and 2.9 ± 0.4 myr, respectively. Prominent ~ 2 myr cycles likely originated from Earth and Mars secular frequencies g 4 –g 3 , and ~ 1 myr cycles from s 4 –s 3 . These periodicities are shorter than those observed in the Cenozoic Era, which may be due to the chaotic behavior of the planets, but still reflecting 2:1 secular resonance between Earth and Mars. Third-order eustatic sequences are linked to the s 4 –s 3 obliquity term, which suggests a glacioeustatic controlling mechanism during this transitional stage from Paleozoic icehouse to Mesozoic greenhouse. [ABSTRACT FROM AUTHOR]

Changes in Mississippian global paleogeography derived from the reconfiguration of the continents have been suggested to result in a change in oceanic circulation, carbon cycling, as well as in global cooling. Here, integrated δ 13 C carb chemostratigraphy and foraminiferal biostratigraphy across the Mississippian (late Tournaisian, Visean, early Serpukhovian; MFZ6–MFZ16 foraminiferal biozones) of the Gongchuan section located in the isolated Bama Platform in the Youjiang Basin, South China, are presented. The δ 13 C carb trend shows an abrupt decline during late Visean (Asbian-early Brigantian; MFZ13–14). This decline is also observed in subequatorial western Euramerica, whereas coeval sections in subequatorial eastern Euramerica show consistently elevated δ 13 C values across the entire Visean. The δ 13 C decline in western Euramerica and the South China Block (eastern Paleo-Tethys) coincides with a global regression with a suggested glacioeustatic origin, the onset of high-frequency climate and sea-level oscillations, and the closure of the Rheic seaway between Euramerica and Gondwana. We propose a model explaining the divergence of δ 13 C records resulting from the closure of the Rheic seaway and development of upwelling zones in the western margin of Euramerica and the eastern Paleo-Tethys realm. Quantitative microfacies analysis across the Mississippian succession in the Gongchuan section shows facies-independent disappearance of corals and increased proportion of cortoids and filter-feeding organisms at the onset of the Asbian δ 13 C decline, which may support an increase in nutrient level that can be expected as a result of upwelling. [ABSTRACT FROM AUTHOR]

The dynamic character of the Late Paleozoic Ice Age is evident from glacial deposits, but its impact on tropical climate is not well constrained. Global changes in climate are overprinted on longer-term paleogeographic variations, resulting in a complex time–space distribution of climate-sensitive lithologies. The significance of such lithologies in Carboniferous successions of the western United States has not been fully explored. In this study, we provide new interpretations for the paleoclimatic context of the Amsden and Tensleep Formations (Pennsylvanian, Northern Wyoming, USA). The Amsden Formation consists of a basal sandstone member overlain by red siltstones containing pisolites. Very large-scale (~ 10 m) cross-bedding within the basal sandstone indicates deposition in an erg environment. Iron pisoid-rich layers in the overlying member suggest an evolution toward more humid conditions. Persistent arid conditions during the middle Pennsylvanian are suggested by eolian sandstones and calcretes in the overlying Tensleep Formation. These formations were deposited on the karst topography that developed on top of the lower to middle Mississippian Madison Group. Although the development of karstic features implies that humid conditions prevailed during the late Mississippian, evaporites and evidence for early dolomitization within the formation suggest that it was deposited under arid conditions. These relationships argue for a long-term climate evolution from arid to humid during the Mississippian, and a return to arid conditions during the Pennsylvanian. This trend can be explained by the northward drift from ~ 15°S to ~ 12°N. A comparison with contemporaneous records reveals a diachronous evolution across western Pangaea, with the climatic conditions documented on the Wyoming Shelf being reached later in eastern North America. These relationships indicate that plate motion considerably overprints long-term climatic records. Departures from this trend, suggested by the presence of erg deposits in the basal Amsden Formation, record the overprinting of shorter periods of climate change. [ABSTRACT FROM AUTHOR]

The Paraná Basin is a key locality in the context of the Late Paleozoic Ice Age (LPIA) because of its location east of the Andean proto-margin of Gondwana and west of contiguous interior basins today found in western Africa. In this paper we document the sedimentary record associated with an ice margin that reached the eastern border of the Paraná Basin during the Pennsylvanian, with the aim of interpreting the depositional environments and discussing paleogeographic implications. The examined stratigraphic succession is divided in four stacked facies associations that record an upward transition from subglacial to glaciomarine environments. Deposition took place during deglaciation but was punctuated by minor readvances of the ice margin that deformed the sediment pile. Tillites, well-preserved landforms of subglacial erosion and glaciotectonic deformational structures indicate that the ice flowed to the north and northwest and that the ice margin did not advance far throughout the basin during the glacial maximum. Consequently, time-equivalent glacial deposits that crop out in other localities of eastern Paraná Basin are better explained by assuming multiple smaller ice lobes instead of one single large glacier. These ice lobes flowed from an ice cap covering uplifted lands now located in western Namibia, where glacial deposits are younger and occur confined within paleovalleys cut onto the Precambrian basement. This conclusion corroborates the idea of a topographically-controlled ice-spreading center in southwestern Africa and does not support the view of a large polar ice sheet controlling deposition in the Paraná Basin during the LPIA. [ABSTRACT FROM AUTHOR]