Tertiary Rocks Research Articles

Site Characterization In Champhai Town Area Of Mizoram State In Northeast India: Geological And Geophysical Studies

The Mizoram state of northeast region (NER), India located in close proximity to Indo-Burma subduction zone, recently experienced an earthquake swarm; eight severely felt earthquakes (Mw 5.0–5.9) occurred during April–October, 2020 around Champhai town that caused damages to several buildings and ground cracks with maximum reported MSK intensity VIII. The largest event Mw 5.9, at depth 15 km, occurred on April 16 (ISC catalog). The present study deals with site characterization of the Champhai town area by geological and geophysical investigations. The geological investigation involves detailed mapping of the lithounits, and the geophysical investigation includes shallow (down to 30 m) shear wave velocity (Vs 30) and site amplification (SA) measurements in an about 50 sq km area in the town. Some 23 sites are selected for Vs 30 measurements using the Multichannel Analysis of Surface Wave (MASW) technique. The observed Vs 30 ranges from 200 m/s to 1060 m/s classifying the area into three categories: Class-B (hard rock), class-C (soft rock), and class-D (stiff soil) as per National Earthquake Hazard Reduction Program (NEHRP) guidelines. Geologically, the class B and C sites are represented by arenaceous and argillaceous Tertiary rocks, respectively, whereas the class D is represented by the Quaternary sediments. Site amplification (SA) studies, on the other hand, are carried out by making ambient noise surveys at some 52 selected stations using a digital seismograph. The ambient noise data are analyzed by the Nakamura method of H/V spectral ratio. The overall variation of peak amplification of the sites ranges from 1.26 to 6.65. A good correlation is obtained; the observed Vs 30 and site amplification (SA) maps are fairly comparable with the detailed geological or lithounit map. These maps are much useful for seismic hazard microzonation of the town area to mitigate seismic hazard-risk

Seismic vulnerability distribution of the earthquake prone area in Central Aceh

Abstract Central Aceh is known as an earthquake-prone area due to the presence of the Sumatra Fault and secondary fault crossing the area resulting the M 6.1 earthquake in 2013. The objective of the research is to investigate seismic vulnerability of Central Aceh. Microtremor observations were conducted at 25 locations in Central Aceh analysed using the Horizontal to Vertical Spectral Ratio (HVSR). Seismic amplification is represented by the maximum values of H/V. The dominant frequency f0 representing the sediment thickness was obtained when the H/V curve is maximum. The frequency values ranged from 14.9 to 25.9 Hz, and the seismic vulnerability values varied from 0.02 to 3.1. The top soil consists of thin layers of sedimentary material dominated by tertiary rocks. The rocks are classified as Type IV and Class I based on the dominant frequency values. This result is consistent with the geology, consisting of sedimentary and volcanic rocks. Areas with a seismic vulnerability value > 1.0 is considered to have a high risk of earthquake damage because they are likely to experience earthquake amplification. Areas with seismic vulnerability value > 1.0 are found in West Aceh and the Geureudong volcano area.

Structural Analysis for Slope Stability Assessment of Selected Sites at ShurShirin Valley, Zurbatiyah Region, Eastern Iraq

Shurshirin Valley and surrounding areas are the most wonderful places as tourist areas in the east of Iraq. Many rock slopes appear as dangerous geological locations along this valley. One of the most effective geological structures on the rock slope stability is the orientation of the joints concerning the attitude of the bedding plane and the slope (inclination angle and direction), thus a geometrical analysis for joints has been performed for rock slopes along Shurshirin Valley to assess their instability; Five stations have been studied for both Tertiary rocks and Alluvial fan sediments which exist in three stations only. The main failure types in the study area are rock fall in all stations, toppling in two stations, and (potentially wedge sliding )in one station along the intersection line of the joint sets concerning the lateral slope of station No.2. While the suggested ways to improve the slope stability and protection versus rock failures are re-slope, trimming, ditches, and wire mesh.

Geochronology, geochemistry, and tectonic setting of the Neoproterozoic magmatic rocks in Pan-African basement, West Ethiopia

The West Ethiopian plateau lies in the transition zone between the Arabian-Nubian shield and the Mozambique belt of the Pan-African orogen, underlain by Precambrian to Tertiary rocks in the Gimbi-Nejo area. The Precambrian basement consists mainly of intrusive-meta-intrusive and meta-sedimentary rocks with ice-rafting deposits. Based on the field survey, unique material records, deformation features, magmatism, and metamorphism indicate that the Gimbi-Nejo area likely underwent four tectonic stages during the Neoproterozoic era.The sedimentary formation of 980 ± 3.9 Ma rift valleys is represented by meta-clastic rocks, calc-silicate rocks, meta-basic rocks bearing marble in Chochi, and the Kata domain. Geochemically, meta-peridotite and meta-gabbros show tholeiitic features, while meta-granitoids are medium-K calc-alkaline peraluminous to metaluminous A-type (Ce/Nb 2.1–11.9; Y/Nb 1.2–8; Yb/Ta 2.6–14). Meta-gabbro samples with immobile HFSE (Th, Ta, Hf) and REE (La, Sm, Yb) fall in the within-plate alkaline basalt, oceanic island basalt (OIB), and continental rift basalt field. Meta-granitoid samples also fall in the within-plate granite field. The lithospheric subduction stage magmatic arc, composed of gabbros and granitoids, was emplaced around 827 ± 3.2 Ma. The granitoids include calcic tonalite and trondhjemite showing an adakitic signature with high Sr/Y (14.2–48.2) ratios. Gabbro samples fall in the island arc basalt and continental arc basalt field. Meta-peridotites and meta-gabbros to gabbros originated from the partial melting of garnet-spinel lherzolite to spinel lherzolite (<10 %) and garnet lherzolite to garnet-spinel lherzolite (<30 %) mantle source, respectively. The continental collisional area contains thrust folds and faults trending in a north–south direction. The ca. 797 ± 3.7 Ma calc-alkalic granitoid rocks along the suture zone are high-K peraluminous I-type granitoids (ASI < 1.1). The strike-slippage area is represented by sinistral ductile shearing deformation. The alkali-calcic granitoid rocks associated with shearing and decollements are low to high-K calc-alkaline peraluminous-metaluminous I-S type granitoids (ASI = 0.95–1.17). The U-Pb age of alkali-calcic granitoid is 564 ± 3.4 Ma. Syn-collisional calc-alkalic and late-post orogenic alkali-calcic granitoid samples both fall within the category of within the plate granite.The εHf (t) values of meta-granitoid (+9.4 to + 15.5), calcic granitoid (+7.6 to + 13.2), calc-alkalic granitoid (+7.4 to + 15.5), and alkali-calcic granitoid (+7.11 to + 17.12) suggest that these Neoproterozoic granitoids have been derived from a Meso-Neoproterozoic juvenile crust that formed through depleted mantle source. Depleted mantle magma likely ascended to the juvenile crust and remained there for a certain period (mean time = 122 Ma, 257 Ma, 248 Ma, and 256 Ma, respectively).

Microtremor array observation in Southern Part of the Bandung basin: deep 1d s-wave velocity structure

Site amplification factor become crucial in seismic hazard microzonation, which depends on local geological condition, therefore identification of bedrock depth is very important related to sediment thickness. One of the Geophysical method that can be applied for subsurface investigation is microtremor array survey method (MAM). This method doesn’t require seismic source, so it is very possible to be applied in the urban area. Bandung basin is a research project for seismic hazard and risk study, where most of this area covered by high population and settlements that becomes the obstacle in this field survey. Geologically, Bandung basin consists of volcanic rock and floodplain, and we can find outcrop of Tertiary rock in some parts the basin. Seismicity in Bandung basin is very active because there are many seismic sources around it, such as shallow crustal and megathrust segment in the southern part. The microtremor array survey was conducted in Southern basin at 3 sites observation represent shallow and deep bedrock depth by using triangular array in shape. The result shows the bedrock depth in BB12 is 139 m, BB13 is 211 m and BB14 is 192 m. This condition represents the feature of bedrock position in Southern Bandung basin.

Indications of Lateral Growth of Anticlines. Examples from Kurdistan Region, Northern Iraq

The Kurdistan Region of Iraq (KRI) forms the northeastern part of the Arabian Plate that is colliding with the Eurasian Plate. Due to the ongoing collision, the whole KRI territory is folded; accordingly, long anticlines are developed in NW – SE trend, they change west wards to almost E – W. The Cretaceous carbonate rocks form the bulk of the anticlines; in the central part of KRG. North and northwest wards, rocks of Paleozoic, Triassic and Jurassic ages are exposed in the core of some anticlines. Whereas southwards, Tertiary rocks are exposed in the core of anticlines. From tectonic point of view, the KRI territory is located in four tectonic zones; each has its own characteristics. Majority of the developed anticlines at the KRI are thrusted and exhibit lateral growth. We have presented many examples of laterally growing anticlines with clear indications for their growth.

Diverse shear behaviors of clayey materials: Implications for differing landsliding behaviors within the same area in Niigata, Japan

In Niigata, Japan, many landslides have occurred in Tertiary rocks. Although most of these landslides were slow-moving, some underwent catastrophic failure, and different types of landslides sometimes occurred nearby under almost identical geological and hydrological conditions, but their mechanisms remain unclear. This study introduces a landslide triggered by Typhoon Hagibis in 2019 in an area in Niigata prone to landslide disasters. The landslide was small in scale, but the displaced materials were fluidized and deposited on a flat field at the toe of the slope after a long runout. To unravel this landslide's initiation and movement mechanisms, we conducted ring shear tests on the samples (clayey soils) taken from the landslide source area to examine their shear behaviors under both undrained and naturally drained conditions. Our results of undrained shear tests showed that shearing of the saturated landslide material can develop high pore-water pressure, lowering the shear resistance and elevating the mobility of the landslide. The results of shear tests under naturally drained conditions at different shear displacement rates (V) revealed that landslide materials behave rate-weakening at low and rate-strengthening at high rates, respectively. Further, it was found that during continuous shearing, a sudden change in V results in a sharp but temporal change in the mobilized shear strength. Different accelerations through which the shear rate was increased to a given V also result in different mobilized peak shear strengths. Our results indicate that the different landsliding phenomena occurring in the same area might be regulated by the diverse shear behaviors of the landslide materials involved in the sliding: contractive behavior may result in catastrophic failure, while the shear rate- and state-dependent shear behavior of the landslide material regulates the slow landsliding phenomena. Our results provide new insights for better understanding and predicting different landsliding phenomena within the same geological settings.

Natural radioactivity and its radiological implications from soils and rocks in Jaintiapur area, North-east Bangladesh.

Natural radioactivity concentrations in recent alluvial soils from swampy areas and Tertiary rocks from Jaintiapur were measured using gamma-ray spectrometer equipped with HPGe detector. The average radioactivity concentration of 226Ra, 232Th and 40K were 47 ± 6, 64 ± 5 and 762 ± 40 Bqkg−1 in soils, whereas, 25 ± 2, 37 ± 4 and 884 ± 41 Bqkg−1 in rock samples, respectively. Average radioactivity concentrations of studied soil and rock samples exceeded the world average except 226Ra for rocks. Radio-elemental ratios suggest that an oxic depositional environment with low uranium and high thorium content. Regarding radiological hazard indices, radium equivalent activities (Raeq), external hazard index (Hex) and internal hazard index (Hin) was found to be below the world permissible limits. Whereas, absorbed dose rate (D), and annual effective dose equivalent (AEDE) averages exceeded the world admissible values. Statistical studies show that radioactivity for 226Ra and 232Th linked to a source enriched in radioactive minerals and 40K related to a different sources high in K enriched minerals.

Normal and abnormal porosity-depth relationship of tertiary rocks in Soluq depression, NE-Libya.

The principle aim in this analysis is to evaluate and interpret the porosity-depth relationships in theTertiary rocks in the Soluq Depression. Generally, the porosity in a formation is a function of its presentdepth only when that depth is its maximum depth of burial. From sonic log interval transit-time for tenwells scattered in the area, the porosity has been estimated, in order to evaluate and analyse the historyof burial and erosion in the sedimentary sequences deposited on the western margin of the SoluqDepression. The comparison of modelled normal compaction trends with actual compaction trends canbe used to quantify zones of over-compaction and under-compaction in a rock column. The porosityanalysis in this research is basically based on the comparison of the observed shale and limestoneregression lines with the normal porosity-depth model. The normal porosity-depth model representsmeasurements on ‘pure’ shales and limestones, which are believed to be at their maximum depth ofburial. The difference between the two curves may allow any depth of burial anomalies to be identifiedthrough the rock columns in the Soluq Depression.

Mapping the near‐surface trace of the seismically active Kachchh Mainland Fault and its lateral extension in the blind zone, Western India

ABSTRACTThe W–WNW‐striking Kachchh Mainland Fault (KMF) is the largest intra‐basinal fault in the Kachchh Rift Basin (KRB) located at the western continental margin of the Indian plate, and is responsible for several historic earthquakes, including the 2001 Bhuj earthquake and the 1956 Anjar earthquake. The objective of the study is to constrain the precise location and near‐surface characteristics of the KMF using field and ground penetrating radar (GPR) studies. Efforts were also made to ascertain and map the eastward continuity of the KMF. The fault has a prominent geomorphic expression up to the east of Devisar, where the KMF scarp finally dies out. The KMF marks the lithotectonic contact between Mesozoic rocks in the south and Tertiary rocks in the north. The segmented nature of the KMF has been previously attributed to transverse faults, complex deformation zones and heterogeneous assemblages of unconformable Quaternary deposits. Eight survey sites between Nirona and Sikra were chosen for near‐surface investigation of KMF using GPR. Comparatively, high‐amplitude radar reflections were received from well‐compacted sand‐ and shale‐rich Mesozoic rocks, whereas low‐amplitude weak reflections were observed from softer and clay‐rich Tertiary rocks. In the upper section of the GPR profiles, Quaternary deposits display low‐ to moderate‐amplitude semi‐continuous to wavy reflections. The traceable length of the KMF has been extended eastward by ∼20 km through the current study, which is considered a blind zone as feeble surficial evidence is present, but the fault trace is confirmed near the surface using GPR. The eastern part of the KMF is inferred to be a near‐vertical north‐dipping normal fault based on GPR data analysis. The tendency of the KMF to transform into a reverse fault in the vicinity of the intersection with transverse faults implies zones of relatively higher stress accumulation that might activate and trigger devastating earthquakes in the future.

Clastic Sediment Characteristics of Gumai Formation: Preliminary Study of Tertiary Rocks in South Sumatra Basin

The depositional environment of Gumai formation is still challenging to be studied. Previous studies of the depositional environment in the Gumai Formation show a debate interpretation of transition, shallow marine, and deep marine environment. The study's objectives are to identify lithology characteristics of Gumai Formation in Baturaja region and determine the potential environment of the Gumai Formation. Miocene clastic sedimentary rocks of Gumai Formation show well-preserved features in Simpang and Muara Dua, South Sumatra. The Gumai Formation discovered in the southern anticline flange, particularly in Muara Dua, composes marl with quartz veins. The opposite flange in the northern part of Simpang region indicates Gumai Formation consists of siltstone, calcareous sandstone, quartz sandstone and sand ball in siltstone layers. Based on the obtained data at Muara Dua and Simpang, the Tertiary rocks of the Gumai Formation are situated in the flange of folded Pre-Tertiary rocks at Garba complex. Gumai Formation in the research area was deposited in transition environment to shallow sea in which the formation in Simpang has shallower marine environment than Muara Dua region.

Archaeal Communities of Frozen Quaternary Sediments of Marine Origin on the Coast of Western Spitsbergen

The archaeal composition of permafrost samples taken during the drilling of frozen marine sediments in the area of the Barentsburg coal mine on the east coast of Grønfjord Bay of Western Spitsbergen has been studied. This study is based on an analysis of the V4 region of the 16S rRNA gene, carried out using next-generation sequencing. The general phyla of the Archaea domain are Euryarchaeota, Bathyarchaeota, Thaumarchaeota, and Asgardarchaea. As a result of a phylogenetic analysis of the dominant operational taxonomic units, representatives of methanogenic and methane- and ammonium-oxidizing archaea, as well as heterotrophic archaea, are found. The methanogenic archaea of Euryarchaeota phylum, Methanobacteria class, are found in permafrost with controversial genesis, while the methane-oxidizing archaea of Methanomicrobia class Methanosarcinales order are found in the marine permafrost at cape Finneset: the ANME-2a, -2b group in layers of 8.6 and 11.7 m and the ANME-2d group (Candidatus Methanoperedens) in a layer of 6.5 m. Ammonium-oxidizing archaea of phylum Thaumarchaeota is present in all types of permafrost, while the order of Nitrososphaerales is found in permafrost with controversial genesis and the order Nitrosopumilales is in permafrost with marine and controversial genesis. Representatives of phylum Bathyarchaeota are found stratigraphically in the most ancient samples under study. Asgardarchaeota superfylum is excluded in the layers of permafrost with marine genesis and is represented by the phyla Lokiarchaeota, Thorarchaeota, and an unclassified group belonging to this superphylum. The presence of methane, ethylene, and ethane in the permafrost of the first sea terrace of Cape Finnemet at a depth of 11.7 m, as well as the composition of the archaeal community, give us reason to assume that, before freezing, microbiological processes of anaerobic methane oxidation took place in it, probably received from Tertiary rocks. The results of both this and previous works present the Spitsberen permafrost as a rich archive of genetic information of little-studied prokaryotic groups.

First Occurrence of Willhendersonite in the Lessini Mounts, Northern Italy

Willhendersonite is a rare zeolite, with very few occurrences reported globally (Terni Province, Italy; the Eifel Region, Germany; Styria, Austria). Moreover, the data available from these sites are very limited and do not allow a detailed picture of this zeolite’s mineralogical and chemical characteristics. In this work, a new willhendersonite occurrence is reported from the Tertiary volcanic rocks of the Lessini Mounts, northern Italy. Morphology, mineralogy and chemical composition of selected crystals were studied by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray Diffraction (XRD), and electron probe microanalyser (EPMA). Willhendersonite occurs within basanitic rocks as isolated, colorless, transparent crystals with prismatic to flattened morphologies. Individual crystals often grow together to form small elongated clusters and trellis-like aggregates. The diffraction pattern exhibits 33 well-resolved diffraction peaks, all of which can be indexed to a triclinic cell with unit cell parameters a = 9.239(2) Å; b = 9.221(2) Å; and c = 9.496(2) Å, α = 92.324(2)°, β = 92.677(2)°, γ = 89.992° (Space Group P1¯). The chemical data point to significant variability from Ca-rich willhendersonite (K0.23Na0.03)Σ=0,26Ca1.24 (Si3.06Al3,00Fe3+0.01)Σ=6,07 O12·5H2O) to Ca-K terms (K0.94Na0.01)Σ=0,95Ca0.99 (Si3.07Al2.93Fe3+0.00)Σ=6,00O12·5H2O). Willhendersonite from the Lessini Mounts highlights the existence of an isomorphous series between the Ca-pure crystals and Ca-K compositions, possibly extended up to a potassic end-member.

Modelling hydrocarbon generation and migration in tertiary source rocks of deepwater, Phu Khanh Basin, offshore Vietnam

Modelling hydrocarbon generation and migration in tertiary source rocks of deepwater, Phu Khanh Basin, offshore Vietnam

Stratigraphy, chronology and palaeontology of the Tertiary rocks of the Cheringoma Plateau, Mozambique

The discovery of fossil plants, marine molluscs and mammals in the Mazamba Formation, Cheringoma Plateau, Mozambique, opens a new chapter in the study of this part of the African Rift System. The evidence suggests that the Mazamba Formation is older than previously reported, probably late Eocene rather than Miocene. The fossil wood and stems indicate a frost-free tropical humid environment and a high water table soon after deposition, and the marine molluscs and mammals indicate proximity to the sea. There is also evidence for the occurrence of pans in the area during the late Eocene which also suggest a near-surface water table. This paper discusses the history of interpretation of the geology of the Cheringoma Plateau and describes and interprets the fossil plants, molluscs and mammals collected in 2012 and 2013. It is concluded that the Mazamba Formation, which overlies the fully marine Lutetian-Bartonian Cheringoma Limestone, is a coastal facies (fluvio-deltaic, lagoonal and onshore deposits) that accumulated on top of the marine limestones as sea level dropped late in the Bartonian. Mammalian bones from the White Patch sites represent a heavily built species about the dimensions of a pygmy hippopotamus, probably belonging to the order Embrithopoda. If so, then the Mazamba Formation is likely to correlate to the latest Bartonian or early Priabonian rather than to the Miocene as previously assumed.

Determining the Tectonic Origin of the Gara and Mateen Anticlines Using Geomorphological and Structural Forms, Iraqi Kurdistan Region

Gara and Mateen are 2 major anticlines in the northern part of the Iraqi Kurdistan Region, located in the vicinity of the town Amadiyah. Both anticlines are oriented in an almost east–west (E–W) trend with a steep southern limb. The length and width of the Gara and Mateen anticlines are 87 km and 63 km, and 11 km and 9.5 km, respectively. The 2 anticlines are separated by a wide and shallow syncline filled by the Tertiary rocks of the Pliocene–Pleistocene age. The oldest exposed rocks in the Gara and Mateen anticlines are from the Triassic age. The carapace of both anticlines is built up by the Bekhme and Qamchuqa formations. The geomorphological and structural features were studied through satellite images and geological maps. Based on these studies, it was found that both anticlines show clear geomorphological and structural features that indicate their lateral growth. Among those features are water and wind gaps, different shapes of valleys that indicate lateral growth, abandoned alluvial fans, whale-back shapes, en-echelon plunges, and multiple dome anticlines. Furthermore, the rate of upward movements was calculated using neotectonic data. In addition, the rate of river and stream incisions was calculated on the basis of the height of the river terrace levels.

A tectono-geomorphological perspective of micro-earthquake swarm activity prone areas around Bhavnagar and Jamnagar in Saurashtra, western India

Areas around Bhavnagar and Jamnagar in eastern and northern parts of Saurashtra respectively, are identified previously as prone to recurrent earthquake swarm activity. Sparse seismotectonic studies so far have not revealed any linkage with known faults in Bhavnagar area while no structures are known to occur in the area around Jamnagar. We carried out detailed tectono-geomorphic studies with contrasting geomorphic settings with a view to provide an insight into the swarm activity from a geomorphological perspective. The study is based on extensive field studies and quantitative geomorphic analysis of landscape and drainage. The area around Bhavnagar is divisible into two tectono-geomorphic domains – the E-W trending Sihor Fault zone located to the west of Bhavnagar (domain-I) and the terrain to its south which shows undulating landscape controlled by N–S trending structural trends (domain-II). The quadrant in the SW between these two domains consists of southward titled trappean hills which form source area for drainages flowing northward through Sihor Fault zone and those flowing eastward through domain-II. Late Quaternary, possibly Holocene tectonic activity along the Sihor Fault is indicated by the northward tilt of alluvial plain surface, knickpoint in rivers and small scale minor faults along the fault zone, prominent decrease in depth of fluvial incision away from the fault zone and youthful landscape indicated by drainage basin analysis. Domain-II comprises the largely erosional pediplain developed over trappean and Tertiary rocks to the south of Bhavnagar. The drainages show an early stage of landscape development due to ongoing tectonic activity. The area around Jamnagar is dominantly a peneplain formed over subhorizontal trappean lava flows. The peneplain is a manifestation of the prolonged period of non-erosion and deposition during the Cenozoic. The rivers show youthful landscape in the central part of the peneplain which includes, large knickpoints, rapids, anomalous river bends, steepening of channel gradient and large potholes. This ENE-WSW trending zone of anomalous fluvial geomorphic anomalies points to the existence of a fault or fold in the subsurface. The structure appears to be active as indicated by the denser cluster of earthquake swarm along this zone. We infer that the generation of earthquake swarm activity comprising low to moderate magnitude shocks is caused by the sheared rocks along the Sihor Fault near Bhavnagar and the ENE-WSW trending subsurface structure near Lalpur which provide avenues for downward percolation of rainwater to deeper levels causing loss of frictional resistance along weak planes.

WOOD OF BURSEROXYLON FOSSIL FROM BARA FORMATION OF RANI KOT FORT AREA, DISTRICT JAMSHORO SINDH, PAKISTAN

The paper describes a fossil wood identifiable as Burseroxylon baranesis from Bara formation of Sindh, Pakistan. Three dimension sections (transverse, radial and tangential) were prepared from the fossil wood collected from Bara formation, Ranikot. The anatomical characters such as presence of growth rings, parenchyma scanty, paratracheal, vasicentric. Rays are homogenous rays consist of procumbent cells indicate that the species belong to the family Burseraceae of petrified Bursera wood and are assigned name as Burseroxylon on the basis of form genus. This is the first record of genus Burseroxylon from tertiary rocks of Pakistan. Presence of diffuse porous wood indicate that the plants were growing in tropical type of climate.

Predictive modeling for U and Th concentrations in mineral and thermal waters, Serbia

The objective of this paper was to determine background values (BV) and anomalous values (AV) of U and Th in groundwater and to establish hydrogeochemical conditions which lead to the elevated concentrations of these elements in groundwater. The methodology included planning and collecting of water samples, laboratory work, and assessment of BV and AV concentrations in accordance with the dataset distribution, based on consideration of hydrogeochemical conditions in the hydrogeological system. Groundwater sampling included 144 occurrences of mineral and thermal water from Serbian territory, belonging to different hydrogeological systems. Field parameters were measured for temperature (T), pH, electrical conductivity (EC), oxidation–reduction potential (ORP), dissolved oxygen (DO), and carbon dioxide (CO2). Standard laboratory measurements were applied for the determination of major chemical components (Ca, Mg, Na, K, Cl, HCO3, and SO4) and U and Th concentrations were measured by ICP-MS. The first step for obtaining U and Th threshold values was based on non-parametric statistical analysis on the data sets. Further analysis of threshold values enabled establishing hydrogeochemical conditions influencing elevated concentrations of U and Th and setting up the logistic regression (LR) model. Differences in the hydrochemical properties of U and Th can be observed based on predictor variables from LR models. Physico-chemical parameters Eh and pH, groundwater type, and geochemical environment (cretaceous igneous rocks) were significant predictors for elevated uranium concentrations, while significant predictors in the thorium LR model were the pH value, the concentration of SO4 in the solution, and the water-bearing rocks (tertiary igneous rocks).

Water quality in Ci Lutung Watershed (Case study: Ci Jurey Sub-Watershed and Ci Deres Sub-Watershed)

Natural waters such as rivers are environmental components that need to be considered especially regarding the quality of river water. River water quality can decrease because landuse change as a form of increasing human activity. The purpose of this study is to assess the river water quality of the Ci Lutung Watershed, specifically the Ci Jurey-Sub-Watershed and Ci Deres Sub-Watershed. To assess the quality of the water, a water sample is taken directly from the specified river body. The water quality parameters tested consisted of TDS, pH, conductivity, and turbidity as physical parameters, and nitrate, phosphate, sulfate and chloride as chemical parameters. This water quality assessment is carried out using the STORET method, which is comparing the results of parameter tests with Class III Water Quality Standards as determined by Indonesian Government Regulation No. 82/2001. This research also identified the relationship between landuse and lithology as a watershed characteristic with the river water quality. To be concluded, the water quality of the Jurey River and the Deres River is categorized as light polluted according to the STORET calculation. Also, the water quality in both rivers are spatially influenced by each watershed’s characteristic. TDS value is calculated high because its lithology –age of oligocene Tertiary rocks, and nitrate value is calculated high because it is influenced by agricultural activities.