Late Pennsylvanian Calcareous Paleosols from Central New Mexico: Implications for Paleoclimate

Late Pennsylvanian and Early Permian Stratigraphy of the Northern Sacramento Mountains, Otero County, New Mexico

Red sedimentary units as indicators of Early Pleistocene tectonic activity in the southern Negev desert, Israel

An overview and interpretation of autocyclic and allocyclic processes and the accumulation of strata during the Pennsylvanian–Permian transition in the central Appalachian Basin, USA

A high‐resolution peat humification record is obtained from Hani peatland, northeastern China to study climate change. An absorbance value time series from alkali‐extraction is used as a peat humification indicator. In addition, Hani peat magnetic susceptibility and trace elements have also been investigated. There is a sensitive response to abrupt climate changes when comparing a high‐resolution peat humification record with a Hani δ18O temperature proxy record and a drift ice record from the North Atlantic Ocean. Based on analyses of factors that affect peat decomposition, we suggest similar paleoclimate significance between the Hani and Dajiuhu peat on the degree of humification with a higher peat humification indicating colder and drier climate conditions. In contrast, a warm and moist climate provides a deoxidized condition that results in lower peat humification. Moreover, the Rb/Sr ratios and χlf in Hani peatland also indicate different climate conditions, especially in late Holocene. According to the Hani peat data, regional paleoclimate variations can be divided into the following five phases: 11.5–10.0 cal. kyr BP with warm climate conditions; 10.0–8.8 cal. kyr BP with sharply cooling and warming climate conditions; 8.8–4.8 cal. kyr BP with alternating cooling and warming climate conditions; 4.8–1.6 cal. kyr BP with warm climate conditions overall and 1.6–0 cal. kyr BP with cold climate conditions.

40Ar/39Ar ages and stable isotopes of supergene jarosite from the Baiyin VHMS ore field, NE Tibetan Plateau with paleoclimatic implications

The stratigraphy and geological relationships of upper Paleozoic limestones in the Cariboo gold belt are discussed in the light of 49 new conodont collections. Combined with lithological criteria, these define three units: the Lower Mississippian Greenberry Formation, the new Alex Allan Formation, and the new (informal) Sugar limestone. The Greenberry Formation is largely an upper Tournaisian limestone composed of transported bioclastic debris that was deposited in shallow water. Limestone of the Alex Allan Formation disconformably overlies the Greenberry Formation and contains a mixed conodont fauna representing the Early and Middle Pennsylvanian and possibly the Late Mississippian and Late Pennsylvanian. The mixing is ascribed to the influx of eroded Mississippian? and Pennsylvanian strata. Where observed, the Greenberry and Alex Allan Formation limestones are less than 30 m thick, and they apparently represent deposition during anomalous sedimentary pulses in an otherwise nondepositional interval. Conodont faunules from both limestones include many elements previously unrecorded in western Canada, the most notable of which are Mestognathus from the Greenberry Formation and Gondolella and Neogondolella from the Alex Allan Formation. The Wolfcampian crinoidal Sugar limestone is spatially and apparently structurally and stratigraphically unrelated to the Greenberry and Alex Allan formations.

Chapter 4 Continental Carbonates as Indicators of Paleoclimate

A new amphibamid,Milneria huberi, is described from the Pine Shadow Member of the Wild Cow Formation (Late Pennsylvanian: middle Virgilian: middle Stephanian) at the Kinney Brick Company quarry, Manzanita Mountains, Bernalillo County, New Mexico, USA.M. huberi is distinguished from other members of the family by deep embayments of the occipital borders of the skull so that the midline portion of the postparietals projects posteriorly beyond the rest of the skull table and the post-parietals have a midline length greater than half that of the parietals.

Carbonate clumped isotope thermometry has been applied to fossil mollusk shells from Tibet to reconstruct the paleoclimate and paleoelevation of the region. However, inferred paleoelevation and climatic conditions from this proxy are inconsistent with paleontological evidence. Here, we report new clumped isotope data from both modern and fossil (5–4 Ma) freshwater mollusk shells with the results of X-ray diffraction (XRD) analyses of fossil shells from the Himalayan-Tibetan Plateau. Although all of the fossil shells analyzed in this study appeared pristine based on visual inspection, XRD data reveal that more than half of these apparently “pristine” fossil shells contain trace amounts of calcite. Clumped isotope temperatures derived from the fossil shells display a large range of variation (>22 °C). Among the fossil shells analyzed, those containing traces of calcite have yielded temperatures that are on average ∼10 °C lower than those with no detectable calcite from the same strata. These observations suggest that clumped isotope alteration can occur in aragonite shells in low-temperature environments and even in shells with no visible signs of alteration that contain only traces of calcite. The temperatures derived from fossil shells with no detectable calcite are on average 4 °C higher than those derived from modern shells, indicating that southwest Tibet was warmer 4–5 Ma than today. After accounting for temperature change due to global cooling, the difference in clumped isotope temperatures between pristine fossil shells and modern shells suggests that the paleoelevation of the southwestern Tibetan Plateau in the Pliocene was similar to its present-day elevation.

Petrochemical and geochronological data of Permian-Lower Triassic clastic sedimentary rocks in the northwestern Junggar basin, NW China: Implications for provenance, tectonism and paleoclimate

The Sohnari Member of the Early Eocene Laki Formation is massively deposited in the Southern Indus Basin of Pakistan and is considered a potential source rock to generate hydrocarbons. However, the detailed paleoclimatic, paleoweathering, and depositional conditions of the Sohnari Member have not been studied earlier. This research mainly discusses the detailed mineralogical (bulk and clay) and elemental geochemistry of the Laki Formation from two outcrop sections (Jhimpir and Lakhra) in the Southern Indus Basin, Pakistan. The bulk minerals, including quartz (low), hematite, calcite, halite, gypsum, and clay minerals such as kaolinite, chlorite, smectite and illite have been discussed here. These results demonstrate the paleo-environment of studied area was arid with enhanced saline and weak to strong oxidizing depositional conditions. The chemical index of alteration (CIA) values in Jhimpir and Lakhra sections are in the ranges of 41.30–97.93 and 22.30–96.19, respectively, indicating that the Sohnari sediments experienced weak to intense chemical weathering in the source area. The interpretation of the A–CN–K ternary diagram is consistent with the clay mineral contents in the studied sediments, which is characterized by the predominance of kaolinite, gibbsite and chlorite, demonstrating the weak to strong weathering state under warm and humid climatic conditions. The chemical indices such as Sr/Ba, δU, V/Cr, Ni/Co, and Cu/Zn, U/Th and Ba/Ga show that Sohnari rocks of Early Eocene Laki Formation underwent strong evaporation, oxic water column with warm to humid and minor contact of cold climatic conditions. Based on our present data, it can be concluded that the sediments of Sohnari Member of Laki Formation from Jhimpir and Lakhra areas of Southern Indus Basin in Pakistan are related to Indio-Eurasian collision and came from the Indian shield rocks that were deposited in a brackish water body with a minor contact of the freshwater oxidizing paleo-environment depositional conditions.

Occurrences of Early Cretaceous fossil woods in China: Implications for paleoclimates

Deposition of the basal fluvial sediments of the Miocene-Pliocene Ogallala Formation in western Texas and eastern New Mexico was controlled by topography on the underlying erosional surface. Paleovalley-fill facies consist of gravelly and sandy braided-stream deposits interbedded with and overlain by eolian sediments deposited as sand sheets and loess. Uplands on the pre-Ogallala erosional surface are overlain primarily by similar eolian sediments. Calcic paleosols, consisting mostly of glaebules and rhizoconcretions of CaCO/sub 3/, occur throughout the eolian facies. Massive to laminated and locally pisolitic, brecciated, and recemented pedogenic calcretes occur primarily near or at the top of the Ogallala Formation. Eolian facies preserve numerous superposed calcretes and calcic paleosols, reflecting slow episodic aggradation on a savannah or grassland under arid to subhumid climatic conditions. The change from fluvial to mostly eolian sedimentation probably resulted from diversion of streams that deposited fluvial sediments of the Ogallala Formation to form the Pecos and Canadian rivers. Source areas for eolian sediments may initially have been flood plains of Ogallala braided streams and later the flood plains of the newly formed Pecos and Canadian rivers. 38 references.

Changes in global climate from the Late Pennsylvanian to early Permian resulting from the destabilization of ice sheets in the Southern Hemisphere had important effects on terrestrial landscapes around the Paleozoic world. In the northern Appalachian Basin (U.S.A.), evidence for this transition and its effects on terrestrial systems is preserved in numerous paleosols in the Conemaugh, Monongahela, and Dunkard groups that formed in various alluvial environments. Several studies along a 50 km west–east and 40 km north–south transect through southeast Ohio and southwest West Virginia resulted in the recognition of 24 different pedotypes. An up-section shift in pedotypes from Argillisols to Vertisols and Calcisols as well as an overall upward increase in the diversity of pedotypes records a significant change in soil-forming processes and landscapes. The landscapes of the Late Pennsylvanian were largely characterized by well-developed, clay-rich Alfisols of woodland ecosystems on distal floodplains bordered by poorly developed Inceptisols of early successional or marshland ecosystems on proximal floodplains. By the early Permian, these landscapes began to experience strongly seasonal climates and increasingly prolonged dry periods, resulting in the production of pronounced shrink–swell features and well-developed carbonate horizons. These landscapes were characterized by Vertisols and Inceptisols of highly heterogeneous brakeland ecosystems, with rapid changes in sedimentation, hydrology, and vegetation over short distances. Climatic conditions were prone to fluctuations between wet and dry states during the transition, resulting in a highly heterogeneous landscape that changed significantly through time.

Post-glacial Permian debris flow deposits and their paleoclimatic implications (Mariana Pimentel paleovalley, southern Paraná Basin)