Felsmechanische Untersuchungen am Hauptrogenstein (bjHR) der Vorbergzone des südlichen Oberrheingrabens

Der Hauptrogenstein ist im Ober- Bajocium, im Braunen Jura(bjHR), gebildet worden. Im Bereich des südlichen Oberrheingrabens ist der Hauptrogenstein als hellgrauer bis hellbräunlicher, schräggeschichteter bis massiger Kalkoolith ausgebildet. Die Gesamtmächtigkeiten dieser durch Mergelbänke und Schill-Lagen gegliederten Einheit reichen von 40m bis ca. 80 m. Durch mehrere große Steinbrüche der Kalkindustrie ist der Hauptrogenstein in der Vorbergzone hervorragend aufgeschlossen. Mit Uniaxial- und Triaxialexperimenten sollen felsmechanische Kennwerte für den Hauptrogenstein bestimmt werden, auch in Hinblick auf die mögliche zukünftige Nutzung als Heisswasseraquifer für die Gewinnung geothermischer Energie.conferenc

Understanding the Weathering Process of Antimony Minerals: Case Study Sb-Mine Sulzburg, Black Forest, Germany

Concerns about heavy metal and metalloid contamination from mine dumps is one of the most intensively discussed issues in society, politics, and academia, because of the levels of pollution, and its toxic properties. During the Middle Ages the Black Forest was one of the most successful mining areas in Southwestern Germany. Historical records show that Sulzburg was a mining town in the Black Forest since the 10th century, but was abandoned in the 19th century. Nowadays this town is considered as an important recreation area in the country. Therefore, soil and water quality and any contamination are of great concern. The purpose of this research was to understand the weathering process and environmental impact of heavy metals and metalloids from the old antimony (Sb) mine sites in Sulzburg. In this study, we examined the mineralogy and whole-rock chemistry and performed soil sequential extraction and water chemical analysis around mine sites. The results show that the Sb deposits in Sulzburg contain mixtures of antimony-lead-bearing sulfides and sulfosalts in hydrothermal quartz veins. The primary ore stibnite (Sb2S3) and boulangerite (Pb5Sb4S11) occur associated with pyrite, arsenopyrite, and sphalerite. The whole-rock chemistry of Sb-Mine Sulzburg is characterized by considerable Sb2O3 (4-25 %) and PbO contents (2-7 %). This agrees with the chemical composition of Sb minerals. Based on soil sequential extraction, toxic elements (Sb, Pb, As) mostly remain in the residual fraction. Comparing the water analysis at and around Sb-mine Sulzburg, Sb concentrations are lower than those of As and Pb for all water samples. This is possible due to the strong affinity of Sb to Fe-oxides-hydroxides and amorphous material and a lower mobi-lity, from the source into water. Based on these findings, we argue that sources of toxic elements and weathering process in Sulzburg are important from the ecotoxicity perspective. Changes in oxidizing or reducing conditions can lead to release and mobilization of Sb, As, and Pb into the environment

Geochemical Characteristics of Three Hot Springs from Western Thailand

At present a total of 118 hot springs are distributed throughout Thailand. Several studies with a focus on high-temperature hot springs related to geothermal resources were conducted in the northern and southern part of the country. Geochemical data, however; especially isotopes of medium-low temperature hot springs are still scarce. In this study, we aim to investigate the geochemical composition of hot spring waters from western Thailand. The examination of elemental compositions and stable isotopes (δ18O, δD) of 3 hot springs; Hin Dad, Bor Klueng and Baan Samorthong (surface water temperatures of 40–50 °C), contributes to a better understanding of reservoir temperatures and recharge. The results from elemental compositions show that the chemical type of the hot spring waters from Baan Samorthong and Bor Klueng are alkaline-carbonate, while the hot spring from Hin Dad is a calcium-carbonate type with a high amount of sulfate related to bedrock. Based on the silica geothermometer approach, reservoir temperatures are calculated to be between 65–90 °C. The stable isotopes δD and δ18O of all hot spring waters suggest a recharge with meteoric waters as well as mixing with groundwater. The three hot springs in this study are well-known for public water recreation and health therapy. Regarding toxic elements, Baan Samorthong hot spring has high fluoride (F-) (14.84 mg L-1); while Hin Dad hot spring shows concentrations of Pb2+ (0.07 mg L-1) and Bor Klueng of Pb2+ (0.02 mg L-1), As5+ (0.01 mg L-1) and F- (4.35 mg L-1) which are above drinking water limits and might lead to health problems. Therefore, we recommend not to drink the water from the hot springs. In conclusion, a better understanding of geochemical data is beneficial for the sustainable development of medium-low temperature hot springs in Thailand.

Quality Improvement of Low-Grade Calcium Carbonate Using Induced Roll Magnetic Separator

Calcium carbonate (CaCO3) is an essential raw material in the manufacture of goods and industrial products like cement, rubber, paper, paints, food, and medicines. For this compound to be economically valuable, however, its quality needs to meet the standard market requirements. Among the various impurities found in natural CaCO3-bearing ores, iron (Fe) is one of the most problematic. In this study, the upgrading of low-grade CaCO3 from a processing plant in Thailand by magnetic separation was investigated. Detailed characterization of the low-grade material was also carried out to identify the solid-phase partitioning of Fe. The results showed that Fe was mainly associated with magnetite and pyrrhotite in the ore, and during processing, additional Fe was introduced from the ball milling process. To improve the quality of this low-grade CaCO3, the effects of magnetic field intensity, feed rate, and repetition on the induce roll magnetic separation were investigated. Based on the results, higher magnetic field intensity, lower feed rate, and more repetition are required for the upgrading of low-grade CaCO3

Slaughter weight rather than sex affects carcass cuts and tissue composition of Bisaro pigs

Carcass cuts and tissue composition were assessed in Bisaro pigs (n=64) from two sexes (31 gilts and 33 entire males) reared until three target slaughter body-weights (BW) means: 17 kg, 32 kg, and 79 kg. Dressing percentage and backfat thickness increased whereas carcass shrinkage decreased with increasing BW. Slaughter weight affected most of the carcass cut proportions, except shoulder and thoracic regions. Bone proportion decreased linearly with increasing slaughter BW, while intermuscular and subcutaneous adipose tissue depots increased concomitantly. Slaughter weight increased the subcutaneous adipose tissue proportion but this impaired intramuscular and intermuscular adipose tissues in the loin primal. The sex of the pigs minimally affected the carcass composition, as only the belly weight and the subcutaneous adipose tissue proportions were greater in gilts than in entire males. Light pigs regardless of sex are recommended to balance the trade-offs between carcass cuts and their non-edible compositional outcomes.Work included in the Portuguese PRODER research Project BISOPORC – Pork extensive production of Bísara breed, in two alternative systems: fattening on concentrate vs chesnut, Project PRODER SI I&DT Medida 4.1 “Cooperação para a Inovação”. The authors are grateful to Laboratory of Carcass and Meat Quality of Agriculture School of Polytechnic Institute of Bragança ‘Cantinho do Alfredo’. The authors are members of the MARCARNE network, funded by CYTED (ref. 116RT0503).info:eu-repo/semantics/publishedVersio

Influence of admixtures on the performance of soundless chemical demolition agents and implications for their utilization

Soundless Chemical Demolition Agents (SCDAs) are an environmentally friendly and safer alternative to traditional rock fragmentation methods. Admixtures are used to change the rheological properties and performance of SCDAs. This study aimed to investigate the effect of various concentrations of chemical accelerators (chloride salts) and viscosity enhancing agents (VEAs: Xanthan gum, Guar gum, and Gellan gum) on the fracture onset compared to an unmodified SCDA (BRISTAR 100®). All experiments were conducted on Portland Type 1 (OPC 1) cement blocks. The flowability of the mixtures was determined by mini-slump tests. Results show that 4wt% MgCl2 and 3wt% CaCl2 have accelerated the fracture onset by 47.4% and 61.2%, respectively. VEAs have a decelerating effect, which is mitigated by the addition of the aforementioned chloride salts. Combining 4wt% MgCl2 with 0.2wt% Xanthan gum reduced the fracture onset time by 66.8%. A cost analysis shows that the initial price of the SCDA mainly determines a potential cost reduction by using admixtures. For a low-cost SCDA, the focus is likely to shift to saving time. This study can serve as a basis for future studies to further improve performance and cost as well as diversify the range of applications for SCDAs

Late Holocene coastal dynamics south of the Chanthaburi estuary, eastern Gulf of Thailand

Beach ridges are depositional features that allow reconstruction of past sea-level variations, sediment dynamics, and storm activity. However, there are still very few systematic studies focusing on beach ridges available from the Gulf of Thailand. Along the east coast, satellite images provide evidence of beach ridges in the Chanthaburi Province, extending as far as 6 km inland, oriented parallel to the current coastline. These can be divided into a set of landward ridges (5.3–6.0 km inland) and seaward ridges (0.4–1.8 km inland) that are separated by an arm of the Chanthaburi estuary. Optically stimulated luminescence dating of 26 sand samples from 12 pits of ridge profiles suggests that the landward set of beach ridges formed ca. 3500 yr ago, while the seaward set of ridges formed between ca. 2100–1200 years ago, which also includes the modern active beach. It appears that the landward set of beach ridges developed during a period of relatively stable sea level followed by a rapid regression presently occupied by the arm of the Chanthaburi estuary. The seaward set of beach ridges apparently reflects a millennium of slowly retreating coastline until the modern beach ridge formed

Geochemistry of evaporitic deposits from the Cenomanian (Upper Cretaceous) Maha Sarakham Formation in the Khorat Basin, northeastern Thailand

The Cenomanian (Upper Cretaceous) Maha Sarakham Formation of the Khorat Basin, northeasternThailand consists of three evaporite units (Lower, Middle and Upper Salt) interbedded with clasticsediments and exhibits abundant deposits of potash. Although numerous studies have been carried outon the Khorat potash deposit, results are still equivocal with regard to the origin of the rock salt, whetherit was marine or non-marine (hydrothermal and/or mixedfluids). The purpose of this study is to examinethe origin of rock salt based on elemental compositions and boron isotope analyses in the southwesternpart of the Khorat Basin. A stratigraphic correlation offive boreholes (K-201e205) located in BamnetNarong and Chaturat districts, Chaiyaphum province, Thailand, revealed a salt dome structure. Theelemental composition andd11B values in the longest borehole K-203 indicate a precipitation of haliteand carnallite from seawater. Rare earth elements (REE) of claystone and siltstone fromfive boreholes (K-201e205) are comparable to the REE of sandstone from the Simao Basin in China, which suggest asimilar provenance. Stratigraphic comparisons and geochemical signatures are important for a betterunderstanding of the recharge models of paleoseawater. In agreement with some previous studies, weconclude that the Cenomanian evaporites within the Khorat Basin are marine deposits. (c) 2021 Elsevier Ltd. All rights reserve

Stalagmites from western Thailand: preliminary investigations and challenges for palaeoenvironmental research

Locating suitable caves and stalagmites for palaeoenvironmental and palaeoclimatic studies can be challenging. Isotopic geochemical analyses, albeit comm performed for palaeoclimatic reconstruction, are also time consuming and costly. Therefore, petrographic and non‐destructive morphological studies on speleothems are desirable to facilitate sample selection for further analysis. In this study, 20 caves were surveyed in Ban Rai district, Uthai Thani province in western Thailand. After external physical observations in the field, three stalagmite samples were collected from Tham Nam Cave to test their potential for palaeoclimatic research. Firstly, the stalagmites were scanned by X‐ray computed tomography (CT scanning) and subsequently the CT images were compared with petrographic inspections. Columnar fabrics show the highest density, whereas closed and open dendritic fabrics have medium and the lowest densities, respectively. Layers near the top and bottom of the three stalagmites were dated by U‐Th mass spectrometric techniques. All three samples were deposited between c. 87 and c. 105 ka ago; therefore, they are probably the oldest stalagmites that have been reported so far from mainland Southeast Asia. However, their physical features indicate that all the samples have suffered from postdepositional dissolution, and are unlikely to be suitable for palaeoclimatic research. The internal dissolution feature of stalagmites, however, cannot be identified by visual inspection of uncut samples. We hereby argue that CT images are useful to characterize stalagmite petrography, in particular fabric, porosity and density. Such features can be used to select the ideal plane of a stalagmite for sectioning, to maximize the chances of robust climatic reconstruction

Hydroclimate variability of western Thailand during the last 1400 years

Mainland Southeast Asia is located on the moisture transport route of the Indian summer monsoon (ISM) where hydroclimate records from speleothems have rarely been investigated. Here, we present a new multi-proxy (delta O-18 and delta C-13 values, trace element concentrations, and grayscale values) data set of stalagmite KPC1 from Khao Prae cave in western Thailand spanning the last 1400 years (500-1900 CE; the Common Era). These multi-proxy data reveal a high variability between the wet and dry periods during 500-850 CE and 1150-1300 CE, stable climate conditions during 850-1150 CE, and overall dry conditions since 1300 CE. The delta C-13 values, trace elements concentrations, and grayscale values show centennial-scale fluctuations, which were probably driven by local hydrological processes. In contrast, variations in the stalagmite delta O-18 values reflect integrated changes in rainfall amount from the ISM. The KPC1 record agrees with other speleothem delta O-18 records of Southeast Asian summer monsoon from the last millennium, as well as the lake multi-proxy and tree-ring PDSI data from Mainland Southeast Asia, but diverges from records from the Indo-Pacific equatorial regions and the western Pacific. We conclude that hydroclimate variability at the western side of Mainland Southeast Asia is mainly driven by changes in moisture transport of the ISM. On socially relevant timescales, the KPC1 data set shows that a period of stable rainfall (850-1150 CE) coincides with the early success of the early empires (e.g., Pagan, Angkor, and Dai Viet) in Mainland Southeast Asia. In line with previous studies in the region, we speculate that the high variability in rainfall between 1150 and 1300 CE and droughts during 1300-1550 CE played a significant role in the demise of ancient societies in Southeast Asia. (C) 2020 Elsevier Ltd. All rights reserved