Application Of Geochemical Methods Research Articles

Geochemical Study of Chert Artefacts from Xicotó Rockshelter (NE Iberia) Archaeological Site. New Data on Neolithic and Mesolithic Human Occupations

Xicotó Rockshelter (Alòs de Balaguer, Lleida, Spain) is located in the eastern Pre-Pyrenean range in north-east Iberia, in the middle Segre River Basin. Since 2013, archaeological works have been developed by a team from the Prehistoric Studies and Research Seminar (SERP) at the University of Barcelona and up to three sedimentary levels have been identified. The preserved archaeological remains have allowed determining that the site was occupied during at least two different periods: the Ancient Neolithic and the Middle Mesolithic. The relative chronology given by the archaeological assemblage has been confirmed by several radiocarbon dates that place the occupations of the site to be during the VI and VII millennia cal BC. This paper presents the results obtained after the analysis of lithic raw materials from the entire lithic assemblage. The analysis was performed using the classic petroarchaeological approach, comprising textural and micropalaeontological descriptions, combined with the application of geochemical methods, using energy-dispersive X-ray fluorescence (ED-XRF) and laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICP-MS). The results show that several rock types were selected for confectioning the lithic tools, among which chert was the preferred. Different types and origins have been identified, with similar sourcing strategies that involved local and regional procurement.

Characterizing the lithic raw materials from Fuente del Trucho (Asque‐Colungo, Huesca): New data about Palaeolithic human mobility in north‐east Iberia

Fuente del Trucho cave (Asque‐Colungo, Huesca, Spain) is located in the central Pre‐Pyrenean range in north‐east Iberia, in the Arpán ravine, a tributary of the Vero River. The mouth of the cave is 22 m wide and it is oriented to the south‐east. The entrance gives access to a 24 m‐deep hall. Palaeolithic paintings were discovered in the cave in 1978. The Fuente del Trucho art comprises two sectors: the external with some engraved motifs and the internal featuring more than 100 painted motifs distributed in 21 panels. Archaeological works have been undertaken since 1979, identifying several human occupations from the Middle and Upper Palaeolithic. This paper presents results obtained after the analysis of lithic raw materials. The analyses were performed using the classical archaeopetrological approach, which comprises textural, micropalaeontological and petrographical analyses, combined with the application of geochemical methods, using energy‐dispersive X‐ray fluorescence (ED‐XRF) and laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS). The results show that chert and quartzites were the most commonly used rocks. Different types and origins of chert were identified, demonstrating the existence of a wide mobility for lithic raw material procurement during all the Palaeolithic occupations.

Age Boundaries and Stratigraphic Importance of Microbiota of the Lower Riphean Kaltasy Formation of the Volga–Uralia Area

The association of organic-walled microfossils of the Kaltasy Formation, which includes morphologically complex large forms, is considered on the basis of previous and new materials. In general, the Kaltasy microbiota is similar to many associations of the Neoproterozoic (Late Riphean and Vendian) microfossils and, originally, was erroneously interpreted as Late Riphean, in spite of missing Late Riphean index taxa and geological evidence of its Early Riphean age. The Early Riphean age of the formation was supported by results of Re–Os, U–Pb, and other modern methods of isotope geochronology, whereas the low 87Sr/86Sr ratios and almost invariant δ13C values of its rocks are comparable with isotopic characteristics of the Mesoproterozoic sequences of >1300 Ma. The application of geochemical methods using high-reagent Fe (FeHR) and C and S isotopes has showed that relatively deep rocks of the Arlan Subformation of the Kaltasy Formation accumulated under aerobic oxidation conditions (ratio FeHR/FeT < 0.38). This contradicts a common concept of the presence of an anoxic ocean in the Mezoproterozoic, but explains the presence of morphologically complex large eukaryotic forms of microbiota, which were abundant in Neoproterozoic oxygenic basins.

Evolution and Mineralization of Water Chemistry in the Aquifer systems of the Terminal Complex of the Wadi Righ Valley

Groundwater resources in the Wadi Righ valley are represents an important part into the eastern basin of the Algerian Sahara. It characterized by a superposed of two main major aquifers: the former represented by the Intercalary Continental (IC) and the latter by Terminal Complex (TC). This study is focused on the quality aspects of water hosted into Terminal Complex which chow a multi-layers lithology. From a qualitative point of view, various studies have highlighted indicates that the waters in this region showed displays an excessive mineralization, including the waters of the Terminal Complex (EC= 5854.61 S / cm). The application of geochemical methods on applied to the analytical data obtained from wells in the region where the appurtenance of water car reach different layers of the water system of multi-layered aquifer waters of Terminal Complex of the Wadi Righ valley. Therefore, the linear correlations between the chemical elements were composition calculated and it indicates water composition which reflects the water and the lithological nature of different layers of the aquifer. It highlights also the connection between different formation, and predicts possible connection of water between three levels groundwater's in these's layers on one hand and it indicates the mineralization origin of water that represented by the influence highly influenced by various lithological formations. The results show that the mineralization of water is from geological origin. It concerns the composition of the layers that make up the Terminal Complex.

Primeros avances en la caracterización de vulcanitas de afloramientos de Antofagasta de la Sierra (prov. de Catamarca, Argentina)

En distintos sectores de la microrregión de Antofagasta de la Sierra (Provincia de Catamarca, Puna Meridional Argentina) se registran afloramientos de vulcanitas (rocas volcánicas con proporciones de vidrio menores a 80%, sensu Aschero et al. 2002/2004) macroscópicamente muy similares. Con el objetivo de diferenciarlas y aportar, de esta forma, a su identificación en el registro arqueológico, se aplicaron diversos métodos y técnicas sobre muestras de estas rocas procedentes de los distintos afloramientos. En esta instancia, se exponen los resultados obtenidos a partir de caracterización geoquímica por medio de Fluorescencia de Rayos X de Energía Dispersiva. Las vulcanitas procedentes de los diferentes afloramientos tienden a presentar disímiles concentraciones de ciertos elementos. Estos resultados son prometedores y estimulan a continuar investigando la aplicación de métodos geoquímicos en la diferenciación y determinación de la procedencia de estas rocas volcánicas. Cabe destacar que en el Noroeste Argentino los métodos geoquímicos fueron exclusivamente aplicados sobre una roca volcánica específica, la obsidiana, y aún no habían sido utilizados en otras rocas volcánicas anisótropas, con superficies, texturas y estructuras más irregulares.

Application of Geochemical Methods in Geothermal Exploration in Kenya

The major goals of geochemical exploration are to obtain the subsurface composition of the fluids in a geothermal system and to use this to obtain information on temperature, origin, and flow direction, which help in locating the subsurface reservoir. Subsurface waters have been classified into meteoric water, ocean water, evolved connate water, magmatic water, and juvenile water. Geothermal water is mostly meteoric and oceanic water, although andesitic waters near subduction areas often contain significant proportions of evolved connate and magmatic waters. Geothermal waters have been classified with respect to their anion and cation contents into alkali-chloride water, acid sulphate water, acid sulphate-chloride water, and bicarbonate water. Acid waters are generally unsuitable for elucidation of subsurface properties. Conservative constituents are used for tracing the origin and flow of geothermal fluids, stable isotopes (especially 2H and 18O), along with B and Cl being most important. Rock forming constituents SiO2, Na, K, Ca, Mg, CO2, and H2) are used to predict subsurface temperatures and potential production problems such as deposition and corrosion. Kenya is located on the Great Rift Valley in Eastern Africa and has a huge potential for geothermal production of power and other direct uses. In this paper, we report on the geochemical methods used in Kenya to explore, develop, and monitor the available geothermal resources for power production and other direct uses.

Vertical migration of elements from mineral deposits

There is currently widespread interest in the exploration community worldwide in the development of methods to locate deeply buried mineralisation. In the application of geochemical methods, some success has been achieved using the selective extraction of mobile and weakly bonded forms of elements (MWBE) in overburden. Studies in Russia commenced in the 1960s, and have continued in Russia and in other countries to the present time. This paper presents some examples of experimental and applied research carried out in Russia, specifically by members of VITR and then VIRG NPO Rudgeofizika (St. Petersburg). In particular, some characteristics of MWBE anomalies and rates of MWBE migration are illustrated, with reference to several case studies in geochemical exploration for base metal and precious metal deposits.

Application of geochemical methods in the search for geothermal fields

From 1983 to 1985, an orientation study was carried out in about 20 geothermal fields in China. Semi-detailed and detailed surveys were conducted in an area of 90 km 2 in Yangbajing, Tibet. Hg, As, Sb and Bi were used as indicators to extend the promising area of known geothermal fields to 16 km 2. In the northern part of the extended promising area, three drill holes were sunk and high-temperature thermal water of 160°C was obtained. In the southern part, outside the geochemical anomaly, two holes were drilled but no thermal water was found. The inner zone of the Hg anomaly coincides closely with the distribution of drill holes that met thermal water with temperatures higher than 140°C. The distribution of Bi values may indicate that the thermal water in the southern part is at shallower depth. A semi-regional survey in an area of 200 km 2 in Tengchong, Yunnan Province delineated several new prospects, which will possibly extend the resources of the Rehai geothermal field. An element zoning pattern similar to that of hydrothermal mineral deposits was discovered in the Rehai geothermal field. A semi-regional survey conducted in Xiaotangshan near Beijing indicated that the possible extent of the Xiaotangshan geothermal field may reach 30 km 2. Drilling confirmed that the outer zone of the Hg anomaly is in accordance with the distribution of 40°C thermal water, and the intermediate and inner zones of the Hg anomaly are associated with higher temperature thermal water. Research during the three years 1983–1985 demonstrated that exploration geochemistry is an effective tool for finding geothermal fields.

INTEGRATED SATELLITE AND GEOCHEMICAL STUDIES IN NORTHERN SIBERIA

The complex of physicogeographical conditions in northern Siberia limit the possibilities for wide usage of traditional geological-geophysical methods. In such regions, poorly studied and difficult of access, one means of increasing the efficiency of petroleum-exploration work may be the use of remote sensing methods in association with terrestrial geochemical and geological-geomorphic studies. Over the last 10 years, the authors in company with other geologists have carried out satellite-based surveys in northern Siberia. As a result, they have succeeded in revealing new elements in the tectonic structure, of value in the more successful resolution of problems associated with predicting petroleum resource. This relates primarily to fault tectonics and also to the recognition of major and especially local anticlinal structures activated in recent time. The basis for the application of geochemical methods for prospecting hydrocarbon resources within deciphered local structures relates to the hypotheses on the filtration-diffusion mass-transfer of hydrocarbon gases from pools into the overlying sediments up to the present surface and their concentration in surface waters, soils, and vegetation. Results are discussed. 3 references.

The application of geochemical methods in earthquake prediction in China

Several geochemical anomalies were observed before the Haichen, Longling, Tangshan, and Songpan earthquakes and their strong aftershocks. They included changes in groundwater radon levels; chemical composition of the groundwater (concentration of Ca++, Mg++, Cl−, SO4= and HCO3− ions); conductivity; and dissolved gases such as H2, CO2, etc. In addition, anomalous changes in water color and quality were observed before these large earthquakes. Before some events gases escaped from the surface, and there were reports of "ground odors" being smelled by local residents. The large amount of radon data can be grouped into long‐term and short‐term anomalies. The long‐term anomalies have a radon emission build up time of from a few months to more than a year. The short‐term anomalies have durations from a few hours or less to a few months.