Pleistocene plants from Zarzal Formation, middle valley of the Cauca River Basin, Colombia

We report macro and meso palaeobotanical records from the Zarzal Formation, in the Cauca River Depression, and the Quindío-Risaralda Basin between the Western and the Central Cordilleras of Colombia. The fossils correspond to leaves and seeds obtained from layers of mudstones, diatomites, and tuffaceous sandstones deposited in the inter-Andean valleys of Cauca and La Vieja rivers, separated by the Serranía Santa Bárbara ridge between the Valle del Cauca and Quindío departments. The sediments of the Pleistocene Zarzal Formation were deposited in a fluvial-lacustrine environment, with volcanic influence originated in the Central Cordillera to the east of the depositional area. The study here presented allowed the identification of thirteen morphotypes of leaf impressions grouped in six Angiosperm families: Poaceae?/Cyperaceae? and Araceae of the Monocots group, Melastomataceae, Fabaceae and Lauraceae belonging to the Eudicots group and one family of Lycopsida: Thelypteridaceae. On the other hand, very well-preserved silicified micro-seeds were grouped in eight morphotypes, belonging to the botanical groups Cyperaceae and Asteraceae. The fossils found allowed us to identify two types of plant associations that exhibit paleofloristic richness. In the Cauca River Basin, an autochthonous to parautocthonous plant association could correspond to a sub-Andean gallery forest, whilst in the La Vieja River Basin a parautocthonous plant association indicates a swamped floodplain. Keywords: paleoflora, leaves, seeds, Cauca River, La Vieja River, lacustrine deposit.

Igneous Activity and Structural Development of the Mianhua Terrace, Offshore North Taiwan

Using bathymetric and multichannel seismic (MCS) data, we explored the volcanic influence on the bathymetric and stratigraphic features of the Mianhua Terrace. The Mianhua Terrace occupies the marine counterpart of the Northern Taiwan Volcanic Zone (NTVZ) along the collapsed Taiwan orogenic wedge and is dominated by post-collisional magmatism and extensional structures. The bathymetric data showed several semicircular-shaped features near the shelf break. The MCS profiles showed that the Pleistocene unconformity buried beneath the Mianhua Terrace is partly difficult to observe due to seafloor multiples, suggesting that the seafloor is dominated by physically hard lithology, probably volcanic lavas. We interpreted the high-amplitude reflectors and their projected seafloor relief as intrusive sills and associated extrusive edifice. Similarly, we interpreted high-amplitude reflectors in the vicinity of normal faults as intrusive sills emplaced and facilitated by fault structures. A volcanic or hydrothermal mound was also recognized. We propose that the Mianhua Terrace is a breached ramp in a transfer zone between the tips of two successive normal faults along the shelf break. Once the fault tips reactivate and extend toward each other, the Mianhua Terrace may continue to collapse, leading to catastrophic volcanic or associated hydrothermal events.

Volcanoes and ENSO: a re-appraisal with the Last Millennium Reanalysis

The potential for explosive volcanism to affect the state of the El Niño-Southern Oscillation (ENSO) has been debated since the1980s. Several observational studies, largely based on tree rings, have since found support for a positive ENSO phase in the year following large eruptions. Models of different complexities also simulate such a response, detectable above the backdrop of internal variability – though they disagree on the underlying mechanisms. In contrast, recent coral data from the heart of the tropical Pacific suggest no uniform ENSO response to all eruptions over the last millennium. Here we leverage paleoclimate data assimilation to integrate the latest paleoclimate evidence into a consistent dynamical framework and re-appraise this relationship. Our analysis finds only a weak statistical association between volcanism and ENSO, suggestive of either no causal association, or of an insufficient number of large volcanic events over the past millennium to obtain reliable statistics. While currently available observations do not support the model-based inference that tropical eruptions promote an ENSO response, there are hints of a response to hemispherically asymmetric forcing, consistent with the "ITCZ shift" mechanism. We discuss the difficulties of conclusively establishing a volcanic influence on ENSO given the many degrees of freedom affecting the response, including eruption season, spatial characteristics of the forcing, and ENSO phase preconditioning.

Development of pedotransfer functions for water retention in tropical mountain soil landscapes: spotlight on parameter tuning in machine learning

Machine-learning algorithms are good at computing non-linear problems and fitting complex composite functions, which makes them an adequate tool for addressing multiple environmental research questions. One important application is the development of pedotransfer functions (PTFs). This study aims to develop water retention PTFs for two remote tropical mountain regions with rather different soil landscapes: (1) those dominated by peat soils and soils under volcanic influence with high organic matter contents and (2) those dominated by tropical mineral soils. Two tuning procedures were compared to fit boosted regression tree models: (1) tuning with grid search, which is the standard approach in pedometrics; and (2) tuning with differential evolution optimization. A nested cross-validation approach was applied to generate robust models. The area-specific PTFs developed outperform other more general PTFs. Furthermore, the first PTF for typical soils of Páramo landscapes (Ecuador), i.e., organic soils under volcanic influence, is presented. Overall, the results confirmed the differential evolution algorithm's high potential for tuning machine-learning models. While models based on tuning with grid search roughly predicted the response variables' mean for both areas, models applying the differential evolution algorithm for parameter tuning explained up to 25 times more of the response variables' variance.

Geochemical characteristics of No. 6 coal from Nanyangpo Mine, Datong coalfield, north China: Emphasis on the influence of hydrothermal solutions

This paper discusses the volcanic influence on the mineralogical and elemental geochemistry of No. 6 coal from Nanyangpo Mine in the Datong coalfield, north China. Sixteen samples (14 coal and 2 partings) were analyzed by different geochemical methods. The results revealed that the No. 6 coal is a medium–high volatility, highly calorific, bituminous coal with a low-ash and medium-sulfur content. The minerals mainly consisted of kaolinite, calcite, dolomite, and pyrite. In addition, traces of apatite, sphalerite, and anatase were also found. Calcite, dolomite, and pyrite in the coal samples were mainly derived from epigenetic hydrothermal solutions, whereas kaolinite and apatite originated from volcanic ash. Harmful trace elements including Pb, Cu, Mo, Tl, and Hg in the No. 6 coal samples were higher than those of common global coals. These harmful elements mainly occurred in sulfide minerals, which were probably influenced by hydrothermal inputs.

Volcanic influence on STRATOCLIM aircraft observations 2017 in the Asian Monsoon, studies with the transient CCM EMAC

<p>Results from a transient 28 year simulation with the chemistry climate model EMAC with interactive modal aerosol scheme nudged to observed tropospheric meteorology (ERA-Interim) which includes about 500 volcanic SO<sub>2</sub> injections are compared with in situ aircraft observations in the UT/LS in the Asian Monsoon anticyclone. Enhanced SO<sub>2</sub> observed by STRATOMAS and enhanced sulfate aerosol observed by ERICA in the LS point to impact of several explosive eruptions of the Indonesian volcano Sinabung during summer 2017 seen by the OSIRIS satellite instrument. This is supported by freshly nucleated particles observed by COPAS in the UTLS. We present several sensitivity studies with EMAC with different assumptions on the injection patterns in comparison to the observations in July/August 2017.  <br>The monsoon dynamics distributes the volcanic material together with Asian pollution into the global lower stratosphere.</p>

Development of pedotransfer functions for tropical mountain soilscapes: Spotlight on parameter tuning in machine learning

Machine learning algorithms are good in computing non-linear problems and fitting complex composite functions, which makes them an adequate tool to address multiple environmental research questions. One important application is the development of pedotransfer functions (PTF). This study aims to develop water retention PTFs for two remote tropical mountain regions of rather different soil-landscapes, dominated by (1) organic soils under volcanic influence, and (2) tropical mineral soils. Two tuning procedures were compared to fit boosted regression tree models: (1) tuning by grid search, which is the standard approach in pedometrics and (2) tuning by differential evolution optimization. A nested cross-validation approach was applied to generate robust models. The developed area-specific PTFs outrival other more general PTFs. Furthermore, the first PTF for typical soils of Páramo landscapes, i.e. organic soils under volcanic influence, is presented. Overall, results confirmed the differential evolution algorithm’s high potential for tuning machine learning models. While models based on tuning by grid search roughly predicted the response variables' mean for both areas, models applying the differential evolution algorithm for parameter tuning explained up to 22 times more of the response variables' variance.