Sulfur and fluorine degassing from Deccan Traps lavas inferred from pyroxene chemistry: potential for end-Cretaceous volcanic winters

The Cretaceous-Paleogene (K-Pg) mass extinction was a pivotal event in Earth's history and is attributed to the interplay of two major events—the Deccan Traps volcanism and the Chicxulub asteroid impact. We contribute to refine of our understanding of the volcanic stressor for this extinction by investigating the sulfur and fluorine budgets of Deccan lavas from the Western Ghats (India), spanning the K-Pg boundary. Sulfur and fluorine concentrations were analyzed in clinopyroxene phenocrysts from Deccan Traps lavas, by Synchrotron-light X-ray fluorescence (beamline I18, Diamond Light Source, U.K.), and ion probe (CAMECA IMS 1280 at Nordsim Laboratory, Swedish Museum of Natural History, Stockholm, SE), respectively. The results were divided by experimentally determined partition coefficients to calculate melt concentrations. Our analyses reveal variable magmatic volcanic fluorine concentrations ranging from 400 to 3000 parts per million, suggesting the potential for regional environmental impact. The highest sulfur concentrations, reaching up to 1800 parts per million, are observed in Deccan lavas emplaced just prior to the extinction interval, within a timeframe of 0.1 million years. In contrast, later basalts generally exhibit lower sulfur concentrations, only up to 750 parts per million. Independent evidence supports that eruption of the Deccan flood basalts occurred in multiple voluminous eruptive pulses each lasting on the order of centuries, as typical of continental flood basalts. Our findings propose that the volcanic sulfur degassing associated with such activity may have led to repeated, short-lived global temperature drops, too short to be recorded by global paleotemperature record, albeit coupled with a global cooling trend. Sulfur-induced cold snaps likely imposed stress on ecosystems long before the decisive impact of the Chicxulub bolide at the end of the Cretaceous

Biotic, mineralogical, petrographic, and geomorphological characterization of the Falerno-Domitio shoreline (Campania region, southern Italy), with implication for environmental health studies: preliminary results

We report the first results of an ongoing study related to the project FARO (i.e. the Italian “Fund for original research projects”, granted by the Università di Napoli Federico II and IMI bank partner). This research project aims to the enhancement of the physical and biotic features of the coastal landscape related to the Falerno-Domitio shoreline, located in the mid-north coast of the Campania region (southern Italy), from the Garigliano river and Torregaveta. In the national scenario, this area can be considered as a valuable “natural laboratory”, for its wildlife (i.e. the Natural Reserve Foce Volturno, the Regional Park of Campi Flegrei, etc.), famous archaeological sites (i.e. Cuma excavations), and peculiar geological and volcanological characteristics (i.e. Phlegraean Fields). Unfortunately, it also suffers for a strong pollution and environmental degradation due to human activities. The research consists of a multidisciplinary analysis, mainly based on a bathymetric sensing, sampling of both the sea bottom sediments and the beach sands; it comprises: 1) integrated monitoring of the quality of environmental health through a biological study, 2) geomorphological and sedimentological analyses of the area and of the whole sample sets, with GIS data processing, 3) taxonomic and ecological analyses of selected benthic meiofauna assemblages, 4) mineralogy, petrography and geochemistry of beach sands along the shoreline, as well as of sea bottom samples. A complete sampling work of the beach sands, from the Garigliano estuary to the Cuma site, has been done, and the results of mineralogical, petrographic and chemical features, mainly in relation to major and trace elements data, as well as the granulometric curves, are presented. The ecologic and eco-toxicological studies are also carried out on selected samples, revealing the structure of meiofauna (benthic foraminifers and ostracods) assemblages. Tests on the occurrence of the bio-indicator organism Artemia salina have also performed, showing a relatively low toxicity of the samples analysed up to now. Preliminary bathymetric data are also presented

Origin and evolution of Cenozoic magmatism of Sardinia (Italy). A combined isotopic (Sr-Nd-Pb-O-Hf-Os) and petrological view

The Cenozoic igneous activity of Sardinia is essentially concentrated in the 38-0.1 Myr time range. On the basis of volcanological, petrographic, mineralogical, geochemical and isotopic considerations, two main rock types can be defined. The first group, here defined SR (Subduction-Related) comprises Late Eocene-Middle Miocene (~ 38-15 Ma) igneous rocks, essentially developed along the Sardinian Trough, a N-S oriented graben developed during the Late Oligocene-Middle Miocene. The climax of magmatism is recorded during the Early Miocene (~ 23-18 Ma) with minor activity before and after this time range. Major and trace element indicators, as well as Sr-Nd-Pb-Hf-Os-O isotope systematic indicate complex petrogenetic processes including subduction-related metasomatism, variable degrees of crustal contamination at shallow depths, fractional crystallization and basic rock partial melting. Hybridization processes between mantle and crustal melts and between pure mantle and crustally contaminated mantle melts increased the isotopic and elemental variability of the composition of the evolved (intermediate to acid) melts. The earliest igneous activity, pre-dating the Early Miocene magmatic climax, is related to the pushing effects exerted by the Alpine Tethys over the Hercynian or older lower crust, rather than to dehydration processes of the oceanic plate itself. The second group comprises volcanic rocks emplaced from ~ 12 to ~ 0.1 Ma. The major and, partially, trace element content of these rocks roughly resemble magmas emplaced in within-plate tectonic settings. From a Sr-Nd-Pb-Hf-Os isotopic point of view, it is possible to subdivide these rocks in two subgroups. The first, defined RPV (Radiogenic Pb Volcanic) group comprises the oldest and very rare products (~ 12-4.4 Ma) occurring only in the southern sectors of Sardinia. The second group, defined UPV (Unradiogenic Pb Volcanic), comprises rocks emplaced in the remaining central and northern sectors during the ~ 4.8-0.1 Ma time range. The origin of the RPV rocks remains quite enigmatic, since they formed just a few Myr after the end of a subduction-related igneous activity but do not show any evidence of slab-derived metasomatic effects. In contrast, the complex origin of the mafic UPV rocks, characterized by low 206Pb/204Pb (17.4-18.1), low 143Nd/144Nd (0.51232-0.51264), low 176Hf/177Hf (0.28258-0.28280), mildly radiogenic 87Sr/86Sr (~ 0.7044) and radiogenic 187Os/188Os ratios (0.125-0.160) can be explained with a mantle source modified after interaction with ancient delaminated lower crustal lithologies. The strong isotopic difference between the RPV and UPV magmas and the absence of lower crustal-related features in the SR and RPV remain aspects to be solved