Weather Trends Research Articles

Managing Vineyard Topography and Seasonal Variability to Improve Grape Quality and Vineyard Sustainability

Topography may induce variability in meteorological conditions at the meso-scale level and could influence grape quality. Understanding the impact of topography on grape ripening allows for the development of sustainable management practices that include topographical influences in their consideration. This is also important for applying proactive strategies able to counter the expected changes of climate. This study was conducted on cv. Nebbiolo vineyards in North-West Italy. The topographic traits were performed in 17 vineyards within the region, which had previously been identified as belonging to different terroir units. An analysis of historical meteorological data series was also carried out to characterize the units from the meteorological point of view. The grape composition was investigated during 2012 and 2013. Based on the topography traits, a Cluster Analysis classified the 17 vineyards into four groups. Differences among groups mainly concerned insolation and heat accumulation. Topography influenced the individual components of grape quality differently depending on the seasonal weather trend. Interactions between topography and vintage were observed for a few parameters. Better understanding the grapevine reaction to external factors/site characteristics can allow for improved site and season-specific management decision making and can contribute to improving vineyard sustainability while maintaining winery objectives and wine typicity.

The development of climate services to inform decisions about winter maintenance at different timescales

Snow and ice control programs are critical for the efficiency and safety of transportation systems in all winter climates. Tools that help road authorities plan for, assess, and communicate the relationship between climate and winter road maintenance (WRM) activities are needed. There is increasing evidence that the development of such Climate Services (CS) tools is an iterative, evolving, and long-term process between the producers and users of this climate information, which increases the usability and application of climate science. This paper presents a case study describing the co-production of a climate translation service for a Canadian road authority. The purpose of this study is to: 1) refine an existing Winter Severity Index (WSI) to better understand how winter weather translates into inter-annual variations in WRM activities using publicly available data; 2) apply the index to historical weather observations to assess the magnitude and significance of historical winter weather trends, and 3) apply the index to modelled climate data to project the impacts of climate change on WRM operations in Ontario, Canada. Results indicate that the WSI for Ontario highways has strong fit with maintenance activity, when measured as equipment-hours. Analysis of WRM trends over more than three decades shows that winter severity has increased in some areas and decreased in others. The climate change analysis reveals that winters will experience a reduction in winter severity into the coming century.

Incidence of gummosis disease in silky hakea under natural conditions in South Africa

The pathogen Colletotrichum acutatum J.H.Simmonds was developed in South Africa during the 1980s as a mycoherbicide to control invasive silky hakea (Hakea sericea Schrad. & J.C.Wendl.) and was subsequently widely used by a variety of land managers to induce gummosis disease. To determine persistence under natural conditions, disease incidence and severity were monitored annually at five sites in the Western Cape and Eastern Cape provinces, from 2008 until 2017. Disease incidence ranged between 12% and 95% of trees with gummosis in the first year. At four of the sites, high levels of mortality were recorded during the first four years of monitoring. In the year with the highest mortality, between 38 and 64% of trees were dead. No mortality was recorded at the fifth site. Disease incidence and mortality were reduced in the latter years, coinciding with drier conditions. At three of the sites, fires occurred once during the course of monitoring and the disease reappeared one to three years post-fire. It was concluded that although the disease will persist under natural conditions, for maximum benefit the fungus should be actively applied to maintain high levels of incidence and mortality. Depending on site characteristics and weather trends, this should be on an annual, bi- or triennial basis, or following fires or dry years.

Levels of Uncertainty in Infrastructure Asset Management

The management of infrastructure assets is often challenged by uncertain factors such as changing weather trends and usage patterns. To reliably maintain the assets above a specified level of service, the extent of this uncertainty should be identified, and adequate methods for analyzing the risk factors should be implemented. The analysis of risk is well-defined in the field of strategic management. In the current study, four levels of uncertainty that are widely discussed in strategic management were used as a benchmark to determine the levels of uncertainty in infrastructure asset management. These levels range from known issues, to statistically predictable factors, to complete indeterminacy. The current methods of treating uncertainty in infrastructure asset management were reviewed to determine how they overlap with the four levels of uncertainty and whether or not asset managers handle this uncertainty in an optimal fashion. The current approaches in asset management were found to be primarily deterministic and probabilistic. A shortcoming was found in regard to the incorporation of risk analysis into asset management planning for large-scale networks. The researchers concluded that the level of uncertainty present in asset management at the network planning level can be best described as a range and addressed through the use of representative scenarios within that range.

Investigations on mineralogy and geochemistry of a black shale profile on the northern Yangtze platform, China: Weathering fate of rare earth elements and yttrium (REY) and its implications

The mineralogical and geochemical compositions of an 11.5 m black shale weathering profile on the northern Yangtze platform, China, are documented to investigate the fate of rare earth elements and yttrium (REY) and their potential implications during chemical weathering. Our results signify that the profile has experienced an expected weathering trend in initial to moderate weathering stages based on the chemical index of alteration (CIA) values (54.45–75.50). Major elements (Ca, Mg, Na and K) have been leached to various degrees throughout the profile, roughly coupled with the weathering trends of primary minerals. Most REY were released from the black shale matrix, transported downwards and partially precipitated in a fracture. Lanthanum, Ce and Pr exhibited less mobility than other REY, which was connected with the weathering-resistant rhabdophane ((La,Ce)PO4). The REY enrichment in the fracture resulted from the adsorption of Fe–Mn oxyhydroxides and kaolinite. Negligible Ce anomalies (Ce/Ce* values of 0.95–1.12) and prominent negative Eu anomalies (Eu/Eu* values of 0.40–0.77) are observed throughout the profile. The Ce/Ce* values are covariant with the sizes of the first tetrad effect, while Eu anomalies were inherited from the bedrock, and the variation in Eu/Eu* values is related to plagioclase dissolution. LREE/HREE, Sm/Nd and Y/Ho fractionation occurred during black shale weathering. The LREE/HREE fractionation was mainly controlled by primary and secondary minerals (e.g., rhabdophane and kaolinite). The Sm–Nd and Y–Ho fractionation was affected by the tetrad effect. Fracture zones in black shales would be new potential targets for REY prospecting and extraction. Highly REY-enriched zones may occur in soils and underground aquifers, which would pose potential threats to crops and humans. Our findings, combined with previous studies, suggest that LREE/HREE fractionation is indicative of the weathering degree of continental rocks.

Spheroidal weathering of basalt from Gebel Qatrani, Fayum Depression, Egypt

BackgroundThree stages of basalt weathering are known: early or incipient weathering, intermediate weathering and advanced weathering. The Late Oligocene basalt of Gebel Qatrani in Fayum Depression, Egypt, shows signs of early weathering, particularly exhibited in basalt spheroids found at the top of the basalt flow. The present paper gives the results of detailed petrographical, mineralogical and geochemical study of the weathering of these basalt spheroids.ResultsThe core-stones of the basalt spheroids are composed of phenocrystals of plagioclase feldspars and clinopyroxenes set in a groundmass of tiny feldspars and pyroxenes, relatively altered olivine and opaque minerals. The basalt is subalkali (tholeiitic). The outer weathered shells surrounding the core-stones are composed of partly altered feldspars and pyroxenes. The calculated weathering indices show that there is marked weathering trend from the core-stones of the spheroids to the outer shells. The chemical mobility of the elements shows marked depletion of Mg, Ca, Na and K from the core-stones to the outer shells due to the weathering of olivine, pyroxene and feldspars. The trace elements Rb, Sr, Ni, V, Cr and Zn are also depleted.ConclusionsThe weathering of basalt spheroids from Gebel Qatrani, Fayum Depression, Egypt, is of the incipient type. The degree of weathering from the core-stones of the basalt spheroids to the corresponding weathered shells indicates that the weathering occurred under predominantly semiarid to arid conditions.

Urban Green Infrastructure Monitoring Using Remote Sensing from Integrated Visible and Thermal Infrared Cameras Mounted on a Moving Vehicle.

Climate change forecasts higher temperatures in urban environments worsening the urban heat island effect (UHI). Green infrastructure (GI) in cities could reduce the UHI by regulating and reducing ambient temperatures. Forest cities (i.e., Melbourne, Australia) aimed for large-scale planting of trees to adapt to climate change in the next decade. Therefore, monitoring cities’ green infrastructure requires close assessment of growth and water status at the tree-by-tree resolution for its proper maintenance and needs to be automated and efficient. This project proposed a novel monitoring system using an integrated visible and infrared thermal camera mounted on top of moving vehicles. Automated computer vision algorithms were used to analyze data gathered at an Elm trees avenue in the city of Melbourne, Australia (n = 172 trees) to obtain tree growth in the form of effective leaf area index (LAIe) and tree water stress index (TWSI), among other parameters. Results showed the tree-by-tree variation of trees monitored (5.04 km) between 2016–2017. The growth and water stress parameters obtained were mapped using customized codes and corresponded with weather trends and urban management. The proposed urban tree monitoring system could be a useful tool for city planning and GI monitoring, which can graphically show the diurnal, spatial, and temporal patterns of change of LAIe and TWSI to monitor the effects of climate change on the GI of cities.

Redefining southern Australia’s climatic regions and seasons

Climate scientists routinely rely on averaging over time or space to simplify complex information and to concisely communicate findings. Currently, no consistent definitions of ‘warm’ or ‘cool’ seasons for southern Australia exist, making comparisons across studies difficult. Similarly, numerous climate studies in Australia use either arbitrarily defined areas or the Natural Resource Management (NRM) clusters to perform spatial averaging. While the NRM regions were informed by temperature and rainfall information, they remain somewhat arbitrary. Here we use weather type influence on rainfall and clustering methods to quantitatively define climatic regions and seasons over southern Australia. Three methods are explored: k-means clustering and two agglomerative clustering methods, Ward linkage and average linkage. K-means was found to be preferred in temporal clustering, while the average linkage method was preferred for spatial clustering. For southern Australia as a whole, we define the cool season as April–September and warm season as October–March, though we note that a three-season split may provide more nuanced climate analysis. We also show that different regions across southern Australia experience different seasons and demonstrate the changing spatial influence of weather types with the seasons, which may aid regionally or seasonally specific climate analysis. Division of southern Australia into 15 climatic regions shows localised agreement with the NRM clusters where distinct differences in rainfall amounts exist. However, the climate regions defined here better represent the importance of topographical aspect on weather type influence and the inland extent of particular weather types. We suggest that the use of these regions would provide consistent climate analysis across studies if widely adopted. A key requirement for climate scientists is the simplification of data sets into both seasonally or regionally averaged subsets. This simplification, by grouping like regions or seasons, is done for a number of reasons both scientific and practical, including to help understand patterns of variability, underlying drivers and trends in climate and weather, to communicate large amounts of data concisely, to reduce the amount of data required for processing (which becomes increasingly important with higher resolution climate model output), or to more simply draw a physical boundary between regions for other purposes, such as flora and fauna habitat analysis, appropriate agricultural practices or water management.

Climate Change: Threat to Agricultural System and Food Security in Africa

Climate change is unequivocal and nothing hides itself from its negative repercussions. Countries in sub-Saharan Africa will continue to be impacted due to their low adaptive capacities and geographic position. Unfavourable weather trends coupled with climatic variations will have adverse effect on agricultural sector which is the main source of livelihood to rural households on the continent. This literature review article assessed the impacts of climate change on agriculture and food security in Africa. The lives of several in Africa cling on agriculture as it supports majority of the population. However, since over 90 percent of agriculture system in the region depends on rainfall, livelihoods of the citizens on the continent have been hit hard due to rising temperature, erratic rainfall and extreme weather conditions.

Geochemical and Petrological Studies of Permo-Carboniferous Sandstones from the Rangit Pebble-Slate Formation, Sikkim Lesser Himalaya, India: Implication for Provenance, Tectonic Setting, and Paleoclimate

The Permo-Carboniferous depositional sequence of Lower Gondwana in Sikkim Lesser Himalaya was investigated through an integrated approach of lithological, petrological, and geochemical studies. Lithologically, it is characterized by glacial diamictite at the base and shale-sandstone facies at the top of a sequence which is interpreted as a glaciomarine deposit. Coarser sandstone and massive diamictite composed of quartz, feldspar, muscovite, zircon, and other lithic fragments are observed in thin section. Geochemistry of all studied samples from the Rangit Pebble Slate Formation shows the dominance of silicon dioxide compared to other elemental oxides. The tectonic discrimination diagram positively infers passive margin sedimentation from a felsic-rich provenance. Chemical Index of Alteration was used to depict the weathering trends of all studied samples which reflect paleo-sedimentation under humid to sub-humid climatic conditions.

Factors for Self-Protective Behavior against Extreme Weather Events in the Philippines

We report the results on factors for self-protective behavior against weather extremes such as extreme heat events, drought, and heavy precipitation. Our research draws on the Model of Private Proactive Adaptation to Climate Change (MPPACC). We developed a survey instrument incorporating the main aspects of the MPPACC and other factors from related research work that are assumed to explain why some people show self-protective behavior while others do not. The interview survey was conducted with a non-random sample of 210 respondents from three Philippine cities, namely Baguio, Dagupan, and Tuguegarao. The results reveal the importance of adaptation appraisal, including the perceived feasibility of self-protective measures, the perceived adaptation knowledge, and, with limitations, the perception of actions taken by neighbors or friends. We also show that perceptions of past weather trends are closely linked to risk perception but are only partly corroborated by weather station data. Implications for fostering self-protective behavior are making use of time windows right after an extreme weather event and focusing on enhancing adaptation appraisal.

Finite Difference Methods for Weather Prediction in Abuja, Nigeria

In this research, we have been able to simulate some finite difference schemes to predict weather trends of Abuja Station, Nigeria. By analyzing the results from these schemes, it has shown that the best scheme in the finite difference method that gives a close accurate weather forecast is the trapezoidal scheme hence we use it to simulate numerical weather data obtained from Federal Airports Authority of Nigeria (FAAN), Abuja and corresponding numerical weather data obtained by the compatible finite difference schemes, using MATLAB (R2012a) software to obtain future numerical weather trends.

Continental records of organic carbon isotopic composition (δ13Corg), weathering, paleoclimate and wildfire linked to the End-Permian Mass Extinction

The late Permian was the acme of Pangea assembly, with collision and subduction of global plates accompanied by major changes in atmospheric composition, paleoclimates and paleoenvironments of the Earth's surface system. These events are extensively recorded in marine successions from the Tethys, but much less are known from continental successions that typically lack high-resolution stratigraphic control. In order to reveal these fluctuations in terrestrial strata and their relationship with the End-Permian Mass Extinction (EPME), we investigate continental δ13Corg, mercury and nickel concentrations, wildfire, and climate change proxies from the late Permian Changhsingian stage to Early Triassic Induan stage in the Yuzhou coalfield in the North China Plate (NCP). Results show two negative organic carbon isotope excursions (CIE) within the Changhsingian aged Sunjiagou Formation, the first (CIEI, 2.2‰) during mid-Changhsingian and a second, larger, excursion (CIE-II, 2.7‰) near the end of the Changhsingian that coincides with the peaks in the Chemical Index of Alteration (CIA) value and extinction of plant species. We infer CIE-II to be the global negative excursion of δ13Corg associated with the EPME. Arid climates prevailed in the study area from the Changhsingian to the early Induan inferred from the low kaolinite contents and weak continental weathering, except for two short-duration episodes with higher humidity that correspond with CIE-I and CIE-II. Extremely high fusinite content (x̄ = 63.1%) and its increasing abundance through the Changhsingian indicates that frequent wildfires may have been a direct cause for both the destruction of terrestrial vegetation ecosystems and the rapid decline of terrestrial biodiversity at the EPME. We consider that terrestrial ecosystems may have played an important role in the extinction of marine communities at the EPME. This represents the first time the EMPE has been demonstrated in the NCP based on combined evidence from negative carbon isotope excursion, concurrent weathering trends, Ni/Al ratio and biotic extinctions, representing an important step in accurately identifying and correlating the EPME in continental settings from the NCP.

A geochemical approach for identifying marine incursions: Implications for tsunami geology on the Pacific coast of northeast Japan

Potential tsunami inundation areas can be predicted by the distribution of paleo tsunami deposits on land, which are mainly composed of marine-derived sands and muds. These exotic sandy and muddy layers have been identified by multiple approaches. However, there still remain uncertainties regarding the sources and weathering trends over the long term, and other useful proxies need to be investigated to identify of tsunami deposits. We examined the geochemical signatures of modern tsunami deposits from the Pacific coast of northeast Japan (2011 Tohoku tsunami) and those paleo tsunami deposits taken from the Tohoku District (Jogan, ~1080 calibrated ages before present [cal BP] and Yayoi, ca. 2000 cal BP). A geochemical ternary diagram (Seawater-Rock-(As + Metals)) showed the weathering trends of tsunami deposits over approximately 2000 years in the Sendai plain in the Tohoku. In the tsunami layers from the Tohoku, the Na/Ti atomic ratios markedly increased to 23.4 with an average value of 19.3 ± 3.0 (Jogan and Yayoi tsunami deposits), which was clearly higher than those of other layers (soil deposits, 10.3 ± 3.5 on average). These results show that Na/Ti ratios and other geochemical proxies are useful indicators of marine incursions in our case, and may contribute to the detection of muddy tsunami deposits close to the limit of inundation.

Fostering real-time climate adaptation: Analyzing past, current, and forecast temperature to understand the dynamic risk to Hawaiian honeycreepers from avian malaria

Various vector control options are increasingly being considered to safeguard forest birds in their natural habitats from avian malaria transmission. However, vector control options require localized deployment that is not logistically, ethically, ecologically, nor economically viable everywhere and all the time. Based on thermal tolerances of the sporogonic stages of avian malaria (Plasmodium relictum) parasite and its vector, the southern house mosquito (Culex quinquefasciatus), we examined the long-term weather trends for three high value, forest bird refuges (Alakai Wilderness Preserve on Kaua’i, Hanawi Natural Area Reserve on Maui, and Hakalau Forest National Wildlife Refuge on Hawai’i Island) to understand the temporal and site-specific differences of temperature-driven suitability for localized avian malaria transmission.On average, Alakai had mean ambient temperatures suitable for both the vector’s immature stage development and parasite sporogonic development most of the time (85.3%), indicating that observed variability in vector abundance or disease transmission may be driven by other factors. At higher elevation sites like Hakalau and Hanawi, current mean ambient temperatures suitable only for vector development prevail (91.7% and 96.6%, respectively), while mean ambient temperatures for both vector and parasite sporogonic development seldom occur (4.4% and 0% respectively). Our results not only show differences in the temperature suitability for transmission across elevation, but also different levels of vulnerability to avian malaria transmission with any additional projected increase in temperature. For instance, under a conservative warming scenario of 1.0 °C, the joint temperature suitability of parasite and vector development increases at higher elevation sites such as Hakalau (+35.8%) and Hanawi (+15.4%). While mean ambient temperatures suitable for both vector and parasite development already occur most of the time at Alakai, the occurrence also increases (+8.4%) as well under this conservative warming scenario.By linking current site-specific weather data to real-time weather forecasts, we developed a real-time avian malaria warning system to assist managers in identifying conditions when vector control is most needed at these three selected study sites. This online tool determines when conditions are likely to be suitable for local development of P. relictum and C. quinquefasciatus at Alakai, Hanawi, and Hakalau. This tool illustrates how managers can incorporate climate and current weather patterns into decision making without having to consider the uncertainties of long-term climatic and ecological projections.

Continental chemical weathering during the Early Cretaceous Oceanic Anoxic Event (OAE1b): a case study from the Fuxin fluvio-lacustrine basin, Liaoning Province, NE China

This study focuses on Early Cretaceous mudstones from the Shahai and Fuxin formations in the Fuxin continental basin. We analyse chemical weathering, land surface temperatures and palaeoclimates based on chemical weathering indices, and emphasize the implications of continental chemical weathering on nutrient fluxes into lakes and oceans. According to Cr and Ni abundance, Al2O3-TiO2, La/Sc-Th/Co and V-Ni-Th×10 plots, as well as rare earth element (REE) analysis, mudstone samples from the Shahai and Fuxin formations were derived from the same type of provenance comprising mainly felsic igneous rocks. Chemical weathering trends reflected by the Chemical Index of Alteration (CIA), Weathering Index of Parker (WIP) and the Mafic Index of Alteration for Oxidative weathering environments (MIA(O)) are consistent with each other and allow the geological succession to be divided into four stages. Land surface temperatures of the Shahai and Fuxin formations are estimated based on the linear relationship of CIA to temperature, and also can be divided into four stages consistent with those determined from chemical weathering trends. During Stage A (early part of the late Aptian) chemical weathering and land surface temperatures were relatively low and showed characteristic high fluctuations, while Stage B (latest Aptian) represented a transitional period where weathering rates and temperatures increased, and high amplitude fluctuations continued. Conditions changed markedly in Stage C (early Albian) with very high and stable weathering, and warm, humid climates, while in Stage D (middle and late Albian) conditions returned to low chemical weathering and land surface temperatures. These stages of chemical weathering and land surface temperature fluctuations represent responses to global climate fluctuations during the Early Cretaceous, with the early Albian high weathering intensities and warm, humid climates combining to create high nutrient levels that would have flushed through rivers into lakes and ultimately oceans. This correlates stratigraphically with the development of Early Cretaceous black shales during Ocean Anoxic Event 1b, showing the importance of continental weathering regimes as a causal mechanism for lake and ocean anoxia.

MOBILITY AND REDISTRIBUTION OF MAJOR ELEMENTS IN WEATHERED PROFILE DEVELOPED ON PEGMATITE AT KITIBI-IWOYE, SOUTHWESTERN NIGERIA

Geochemical studies of weathering profiles around Kitibi-Iwoye revealed redistribution of elements from parental pegmatite to the regolith. Geological mapping showed that the pegmatite intrudes diorite and migmatite gneiss. Weathered samples from B-horizon were air-dried, pulverised and analysed using X-ray Fluorescence Spectrometry (XRF) in the Department of Geological Sciences, University of Cape Town, South Africa. Chemical Index of Alteration (CIA), Weathering Index of Parker (WIP), Mass balance calculation and Al2O3 – CaO+Na2O – K2O (A–CN–K) ternary plot were employed to determine elemental mobility and distribution caused by weathering. SiO₂ (74.2 and 43.4 wt %), CaO (0.43 and 0.03 wt. %), Na2O (7.14 and 0.04 wt. %), K2O (1.90 and 0.67 wt. %), MnO (0.11 and 0.03 wt. %) and P2O5 (0.20 and 0.05wt. %) displayed depletion from parent rock to the regolith respectively. But Al₂O₃ (15.5 wt. % and 33.5 wt. %), Fe2O3 (0.39 and 3.40 wt. %), TiO2 (0.04 and 0.35 wt. %) and MgO (0.08 and 0.11 wt. %) showed enrichment from parent rock to the regolith respectively. Fe₂O₃ (3.19) is the most enriched whereas Na2O (-99.8), CaO (-98.9), P2O5 (-95.3), K2O (-89.5), SiO2 (-81.9), MgO (-73.1), MnO (-64.5) and Al2O3 (-23.6) are progressively depleted. Mean CIA value of 97.8 revealed that weathering has almost reached its completion whereas CIA of 62.1 for the pegmatite suggested that the parent rock is at incipient stage of weathering. Pegmatite had a WIP of 110.5 whereas the weathered samples with WIP ranging from 2.66, 3.88, 6.03, 6.23, 6.92, 8.08, 9.08, 9.76 and 14.6 respectively showed decreasing trend of weathering. This study confirmed contrasting behaviour of CIA and WIP. A-CN-K diagram suggested strongly weathered samples plotted at the apex of Al2O3 field whereas pegmatite plots along the A-CN line.

Artificial Neural Network for Prediction of Full-Scale Seepage Flow Rate at the Equity Silver Mine

The Equity Silver mine site, British Columbia, Canada, is known for its management and treatment of acid rock drainage. The accurate prediction of full-scale seepage flow rate in field conditions is critical for mine site management, flood control, and contaminant treatment strategies. In this study, a machine learning methodology based on artificial neural network (ANN) is proposed to correlate measured seepage flow rate with the weather monitoring data collected from the field of Equity Silver mine. Comparing with traditional numerical and water balance approaches, the ANN approach generally requires much fewer investigations on hydrogeological mechanisms or definitions of parameters and equations. The measured seepage flow rates from the Bessemer Dump and the weather monitoring data during 1998–2017 are used for training the proposed ANN. The calculated results from the trained ANN show good agreement with the measurements. In addition, the proposed ANN approach is further refined by including time tags of the monitoring data in the input layer, which enable the ANN to investigate the effects of long-term weather trends, climate change, and dynamics inside waste rock piles on seepage flow. The prediction results for the following year (2017–2018) from the refined ANN and the original ANN are compared, which shows the improvement of the refined ANN approach.

GEOCHEMICAL APPLICATION IN UNRAVELING PALEOWEATHERING, PROVENANCE AND ENVIRONMENTAL SETTING OF THE SHALE FROM CHIA GARA FORMATION, KURDISTAN REGION, IRAQ

The geochemical characteristics of the shale of the Chia Gara Formation (Middle Tithonian-Berriasian) from the Imbricated Zone (Barsarin section) and High Folded Zone (Banik section) Kurdistan Region, Iraq, was carried out to constrain their paleoweathering, provenance, and depositional environment. There are no clear differences in the major and trace elements of the Chia Gara Formation between the two studied sections. The chemical index of alteration (CIA) is significantly higher in the Barsarin than the Banik shales, suggesting more intense weathering of the Barsarin than the Banik shales. The samples of the Banik and some of Barsarin are clustered near the A-K line in A-CN-K plot suggests intense chemical weathering (high CIA) without any clear-cut evidence of K-metasomatism. The other samples of Barsarin have a weathering trend parallel to the A-CN line, indicating relatively steady state weathering conditions. The geochemical parameters of the shale (Al2O3/TiO2, Th/Sc, La/Th, La/Sc, La/Co, Th/Co, Cr/Th, (La/Lu)cn and Eu/Eu*cn), and the diagrams (Th/Sc-Zr/Sc and La/Th-Hf) indicate that they were derived from felsic (from the Rutba Uplift and/or Mosul High) and intermediate (from volcanic material during the spreading of Southern Neo-Tethys Ocean) components. The chondrite-normalized REE patterns are similar to those of Post Archean Australian Shale (PAAS), with the light rare earth element (REE) enrichment, a negative Eu anomaly, and almost flat heavy REE pattern. The geochemical parameters such as authigenic uranium, U/Th, V/Cr, Ni/Co, and V/Sc ratios, and Al2O3-V and Al2O3-P2O5 diagrams indicate that these shales were deposited under deep marine suboxic to anoxic environment and shale of Banik section was deposited slightly under deeper environment than shale of Barsarin section.

Enhanced continental weathering and large igneous province induced climate warming at the Permo-Carboniferous transition

Tracking climate change and its relationships with chemical weathering and massive volcanic activity in deep-time greatly improves our understanding of the Earth's climate system. The Permo-Carboniferous period is a critical time interval with million year-scale glacial-deglacial cycles and massive basaltic volcanism, such as the Skagerrak-Centered (also named Skagerrak or Jutland) large igneous province. To explore the volcanism-climate interactions in this period, we obtained high precision CA-TIMS U-Pb zircon ages for three tuffaceous layers from a cored upper Pennsylvanian-lower Permian marginal marine succession in southern North China. These ages calibrate the Permo-Carboniferous biostratigraphy between ∼301–296 Ma in North China. From this dated core succession, mudrock samples and their calculated weathering index values were screened to constrain the weathering trends for the source landscapes and demonstrate a rapid increase with a subsequent decrease in source chemical weathering intensity during the period of ∼299 to 296.5 Ma. These trends coincide with the southern Gondwana glacial records, low latitude temperature changes, relative sea-level variations, and shifts in atmospheric pCO2 that together document an earliest Permian climate warming-cooling perturbation with a temperature maximum at ∼298 Ma. This climate warming in the Permo-Carboniferous icehouse correlates with the emplacement of the Skagerrak-Centered large igneous province, which likely released voluminous CO2 that led to climate warming during the Permo-Carboniferous transition. The immediately following cooling could possibly result from the rapid post-eruptional weathering of the massive basaltic rocks of this province in tropical latitudes, which would have sequestered atmospheric CO2 and promoted return to cooler icehouse conditions. This study supports the assertation that massive basaltic volcanism could first cause rapid climate warming and then may have an overall net cooling effect as previously suggested for the Deccan Traps and the Central Atlantic Magmatic Province.