Breccia Rocks Research Articles

Sedimentation mechanism and provenance of sediment deposition in Sidenreng Lake, Sidrap District, South Sulawesi Province

Sedimentation is the deposition of rock material that has been transported by water or wind power. One result of the accumulation of sediment in a basin is siltation, which can cause flooding as it did at Lake Sidenreng. This research located in Teteaji Village, Tellu Limpoe District, Sidenreng Rappang Regency, South Sulawesi Province.. This research aims to determine the characteristics of the Sidenreng Lake Quaternary sediments, specifically in the mechanism of transportation and provenance. Determining the sediment characteristics is important as the basis of planning in overcoming various problems in the lake. The methods used in this study are granulometric analysis and petrographic analysis. The sieve analysis results that the average grain size at the study site consists of 3 (three) types of sedimentary fractions, namely medium sand, fine sand, and very fine sand. This material deposited with a bed load transport distribution system and weak depositional energy. Sand material is spreading from the southwest and is gradually smoothing to the northeast at the study site. The petrographic analysis results that the provenance of sediment deposited material in Lake Sidenreng comes from volcanic breccia rocks of the Camba Formation, lava tracts of Parepare Volcano Members, and the Sandstones of the Camba Formation and Walanae Formation.

New Insight Into Lunar Regolith‐Forming Processes by the Lunar Rover Yutu‐2

AbstractThe Yutu‐2 rover of the Chang'E‐4 spacecraft observed many meter‐sized shallow pits fully covered with small fragments, distinct from the typical rock‐free impact craters with comparable sizes in the landing area. The unique morphology of the pits and the visible and near‐infrared spectra of the fragments suggest that the fragments are broken pieces of impact melt‐conglutinated regolith breccia projectiles, which were excavated from preexisting craters. The rareness of rock on the landing area surface suggests that the preexisting craters were probably small in size (e.g., <60 m in diameter), not large enough to penetrate the thick regolith (~12 m) and to excavate the beneath rock breccia and/or bedrock. The presence of the impact melts was confirmed by the glass‐like spectra of some fragments with unusually high albedo and blue‐green tint in the centers of the pits. These observations reveal the gardening and consolidating processes on the Moon.

Integrated Geophysical Methods to Determine Subsurface Structure of PSK-1 Mini Hydro Power Plant, Citeurep Creeping Area

Citeurep area of PSK-1 mini hydro power plant is one of the areas passed by waterway to flow water into the power plant turbine and it resides on a foothill with some natural water springs. As time passes, this waterway suffered continuous damage due to continuous slow movement of land mass (creeping). Therefore, integration of geological data, drill data, remote sensing (drone data), Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), and Very Low Frequency (VLF) were carried out, creating a 3D VES model, 2D ERT model, and 2D VLF model. Geological data, drill data, and the drone data are used for elevation model and utilized as supporting data to create a better electrical and VLF model to determine the subsurface lithology. VES and ERT models show a subsurface structure that formed an appearance of a natural “weir” from breccia rock of Koleberes Formation (140-380 Ωm) and thick low resistivity zones that contain sandy grains up to 50 meters deep (6-11) Ωm in the Citeurep area. VLF model shows some conductive zones that are interpreted as a flow of underground water. All processed data indicates that Citeurep area is an alluvial that is dominated with breccia as a bedrock. It can be concluded that the causes of creeping are due to: 1) heavy load from the top of the hill coupled with thick sedimentary layers saturated with water which influence the addition of mass and 2) lack of layer cohesion. The absence of sudden landslides is largely caused by hard breccia rocks that form a structure in appearance of a natural “weir

Analysis of hydraulic conductivity of fractured groundwater flow media using artificial neural network back propagation

Groundwater flow in the Grasberg open-pit mine is governed by fractured flow media. Groundwater modeling in fractured media requires detailed hydraulic conductivity (K) value distribution to illustrate hydrogeological conditions of the Grasberg open-pit mine properly. The value of K is estimated by using the hydraulic conductivity (HC) system method based on rock quality designation (RQD), lithology permeability index (LPI), depth index (DI), and gouge content designation (GCD) data. Accordingly, all parameters must be available, but in this case, this information are only partially available. This paper proposes a method to solve this problem with artificial neural network (ANN) through a five approach scenario to find the K value with a model of incomplete empirical parameters. The artificial neural network back propagation (ANNBP) method is used to estimate the distributed K value based on the distributed observed RQD and LPI, as shown in the block model. This paper uses five optimum architectural schemes consisting of learning rate selection, momentum coefficient, number of nodes, number of hidden layers, activation method (sigmoid, tangent hyperbolic and Gaussian). Verification of the results of the K value is approached by the statistical approaches determination coefficient (R2), correlation coefficient (R), standard error of estimate (SEE), root-mean-squared (RMS), and normal root mean square (NRMS). ANNBP modeling used data for training and testing based on packer test and slug test as many as 49 points. Through five scenarios, it was found that scenario with learning rates of 10–5, momentum coefficient 0.1, number of nodes 10, number of hidden layer 5, with hyperbolic tangent activation methods is the most optimum result with R2 = 0.822, the accuracy of predicting/validating results is expressed by using R2 = 0.863, with R = 0.929, and the error percentage = 3.67%. The K value prediction results are used as an input for groundwater modeling. The modeling results show a significant correlation with high validity between the data extracted from the model and field observation. In a 3D model, the K value distribution is similar to the field RQD data distribution. Furthermore, the K value distribution results are clustered in order to understand the relationship between geological as well as geotechnical data. The highest K values are found in volcanic breccia rocks (DLMVB), volcanic sediments (DLMVS), volcanic andesite (DLMVA) and quaternary glacial till. The geological condition is confirmed by the average rock RQD value between 12.4 and 39.6%.

Subsurface mapping of University Diponegoro Tembalang campus based on resistivity data

Subsurface mapping using the geoelectric method has been carried out in the area of Undip Campus, Tembalang to determine the distribution of subsurface layers resistivity. This study employs the Wenner configuration geoelectric method. Data were collected at seven points with a track length of 100 meters and a distance among electrodes of 5 meters. Data processing is carried out using RES2DINV software packages that produce rock resistivity values and depth estimates, then the interpretation of each track is carried out in detail by taking into account the geological information available in the Undip campus, Tembalang. The results of the interpretation show that the study area is dominated by breccias which are Kaligetas formations. The breccia rocks themselves are claystone which tends to be water-resistant and there is also sandstone. Nearly every data collection point has the same cross-section. Claystone with resistivity ranges from 3.05 Ωm to 26.5 Ωm. Sandstones with resistivity range from 20.0 Ωm to 135 Ωm. The rest found alluvium and sand with a resistivity of almost more than 100 μm.

Study of Hydrogeomorphological Springs in Tlegung Watershed, Kulonprogo Regency

The spring characteristics such as spring discharge, temperature, EC, TDS, pH, spring stream character, and spring emergence type can be linked to geomorphology. This link is the main study in this research. This research was conducted in Tlegung Watershed, which is mostly located in Samigaluh and Kalibawang District, Kulonprogo Regency. The purposes of this study are to determine the springs distribution pattern and the springs hydrogeomorphology characteristics, also to analyze the hydrogeomorphological factors which control the springs’ emergence and characteristics. Data collection method which used in this research is survey method to determine the source of spring emergence, measure spring discharge, test springs’ physical and chemical quality, and validate geomorphological interpretation. The other method which used is collecting secondary data from institution such as RBI maps, geological maps, satellite imagery, etc. The result showed that all springs in Tlegung Watershed classified as perennial springs and gravitational springs with depression, contact, and fracture springs type. Springs discharge in the Tlegung Watershed are classified in Q3 class (10-100 liters/sec) to Q5 class (<1 liter/sec). Electric Conductivity (EC) of all springs are classified in the EC1 (fresh water) with an average of 229,24 μmhos/cm, whereas the average value of TDS is 116,09 mg/L. The value of EC and TDS in the upstream watershed tend to be lower than the value of EC and TDS in the middle and downstream watershed. Hydrogeomorphological factors that control the emergence and characteristic of springs, including rock contact between old vulcanic rocks and limestone, crack structures found in andesitic breccia rocks, and slope class changes between slope 13-20% and 20-55% and 20-55% and 55-140%.

Identification of igneous rock distribution in Kalisonggo area using geomagnetic method

Shallow intrusions of igneous rocks are often found in the Kalisonggo area and form a columnar joint. The presence of shallow intrusions of igneous rocks in the study area is closely related to Mount Mujil as an ancient volcanic system. This study aims to prove the existence of igneous intrusion and subsurface conditions using the geomagnetic method. First Horizontal Derivative (FHD) is used to determine the edge boundaries of the anomalous source of the rock’s magnetic field. Quantitative interpretation is done by using 2.5 D modeling to determine the distribution of igneous intrusion in the study area. The results of data processing show the total anomaly value in the study area has a range of values ranging from -400 nT to 600 nT. Whereas the local anomaly value that has been reduced to the equator has a range of values between 350 nT and the lowest -400 nT with a closed contour closure pattern between the high anomaly and the low anomaly. Based on the cross-section results of 2.5 D incision 1 and 2, there are 3 layers of rock in the presence of boulder lava andesite. The andesite lava has a susceptibility value of 0.00004 SI which penetrates the bedding above it. The top layer is soil with a susceptibility value of 0.00001 SI. The next layer is the andesite breccia rocks with a susceptibility value of 0.00003 SI. The third layer is sandstone with a susceptibility value of 0.000005 SI. The model shows that the andesitic lava lumps did not break through the basement, this is following Van Bemmelen’s opinion that igneous rock in Kalisonggo is an avalanche.

Calcium isotopic composition of the lunar crust, mantle, and bulk silicate Moon: A preliminary study

Abstract Calcium isotopes have the potential to explore genetic links between the Moon and Earth. Here, we constrain calcium isotopic composition of the bulk silicate Moon (BSM), using petrological, geochemical and calcium isotopic data obtained from five lunar meteorites (two basalts and three feldspathic breccia rocks), and on four anorthite crystals from two feldspathic breccia meteorites. The δ44/40Ca of lunar feldspathic breccias are 0.76 ± 0.06‰ (2SD, n = 3), 0.78 ± 0.10‰ (2SD, n = 6) and 0.82 ± 0.02‰ (2SD, n = 3), respectively, consistent with previously determined calcium isotopic composition of feldspathic breccias. Four anorthite crystals yield a mean δ44/40Ca value of 0.75 ± 0.13‰ (2SD, n = 4), inferred to represent the δ44/40Ca value of the lunar crust. The δ44/40Ca values of the two lunar basalts are 0.90 ± 0.07‰ (2SD, n = 3) and 0.96 ± 0.11‰ (2SD, n = 4), respectively, slightly heavier than the feldspathic breccias and anorthites. The δ44/40Ca of the studied lunar basalts and literature data show negative correlations with CaO, Al2O3, and anorthite mode, pointing to the effect of contamination by lunar crust rocks. Using the heaviest δ44/40Ca found in the least contaminated lunar basalts and a 0.10–0.20‰ fractionation of calcium isotopes during partial melting, we estimate the δ44/40Ca value of the lunar mantle to be 0.96–1.11‰. The δ44/40Ca values of the BSM is estimated to be 0.89–0.95‰, using a two-end member mixing model. The Ca isotopic composition of the BSM is within error to that of the bulk silicate Earth (0.94 ± 0.05‰), providing insights into the information of the comparison of the Earth-Moon system and the planets of inner Solar System.

Preliminary Result: Identification of Landslides Using Electrical Resistivity Tomography Case Study Mt. Betung

Institut Teknologi Sumatera (ITERA), ITB and local governments had been cooperated in establishing an astronomy observatory of ITERA Lampung (OAIL), which was located at Mt. Betung in the Pasawaran area. Geological setting of this area showed that the dominant lithology of Mt. Betung is pyroclastic, andesite, and breccia rocks. These volcanic deposits have the potential to move the materials down-slope by the force of gravity, steep slope, and high water-content. We have investigated some area with the potential of a landslide along OAIL construction area, which may be the cause of the landslip as well. We applied electrical resistivity tomography to analyse the electrical properties of the subsurface soil and determine the vulnerable area of the landslide. The result indicated that the area is divided into high resistivity at the top of the soil and low resistivity below. These high resistivity numbers are caused by pyroclastic flow while the lower one is caused by fracture-filled, mostly with water and clay.

Stable isotope constraints on the fluid source of hydrothermal breccia pipes in the Tankwa Karoo depocentre, South Africa: Breakdown of authigenic minerals during sill intrusion

AbstractThe Karoo Basin covers much of South Africa and is an area of prospective shale gas exploration, with the Whitehill Formation the target shale unit. However, the sedimentary succession, including the Whitehill, has been intruded by a series of sills and dykes associated with the Karoo Large Igneous Province (~183 Ma), which are expected to have modified the thermal history of the basin dramatically. Here, we investigate a secondary effect of these intrusions: a series of hydrothermal vent complexes, or breccia pipes, focusing on using O, H, and C isotopes to constrain the origin and evolution of fluids produced during the intrusion of basaltic sills. A cluster of breccia pipes have been eroded down to the level of the Ecca Group at Luiperdskop on the western edge of the Karoo basin; a small isolated pipe of similar appearance crops out 13 km to the east. The Luiperdskop pipes are underlain by a Karoo dolerite sill that is assumed to provide the heat driving fluidization. The pipes consist of fine‐grained matrix and about 8% clasts, on average, of mostly sedimentary material; occasional large rafts of quartzite and dolerite are also present. The presence of clasts apparently from the Dwyka Group is consistent with the depth of formation of the pipes being at, or near, the base of the Karoo Supergroup, between 400 and 850 m below present surface. The presence of chlorite as the dominant hydrous mineral is consistent with an emplacement temperature between 300 and 350°C. The major and trace element, and O‐ and H‐isotope composition of the Tankwa breccias is homogenous, consistent with them being derived from the same source. The δ18O values (vsVSMOW) of the breccias are relatively uniform (7.1‰–8.7‰), and are similar to that of the country rock shale, and both are lower than expected for shale. The water content of the breccia is between 2.7 and 3.1 wt.% and the δD values range from −109‰ to −144‰. Calcite in vesicles has δ13C and δ18O (VSMOW) values of −4.2‰ and 24.0‰, respectively. The low δD value of the breccia rocks does not appear to be due to the presence of methane in the fluid. Instead, it is proposed that low δD and δ18O values are the result of the fluid being derived from the breakdown of clay minerals that formed and were deposited at a time of cold climate at ~290 Ma.

Identification of Slope Stability Analysis

Landslide was natural events that most often occur in Indonesia. South Sumatra Province has a lot of areas susceptible to landslide risk. The aim of this study is to the identification of slope stability analysis. A adjustment in the constancy of a slope can be caused by several factors: geological conditions, high rainfall, and the topography. The research location in Muara Enim regency (Cases: SP. Sugihwaras-Muara Enim and SP. Sugihwaras-Baturaja). The results of this research indicated Muara Enim-SP.Sugihwaras-Baturaja was the typology defined in this type of zone C because the area was included in the areas with slope 0 % to 20 %. The zone classification explained some of the caused landslides were natural factors, type of soil, and human activities. Natural factors such as heavy rainfall were 79-82 mm/month. Muara Enim regency conditions were a category of landslide because it was an area that had breccia rock types that were not compact and were weathered and bentonite clay that readily absorbs water. Based on the results of Slope/W analysis, safety factor (SF) in the case of SP. Sugihwaras-Muara Enim was 1.104 and the case of SP. Sugihwaras-Baturaja was 1.186. The value of SF was included in the criteria landslides where the SF less than 1.250.

3D geological modelling of the Renard 2 kimberlite pipe, Québec, Canada: from exploration to extraction

The Renard 2 kimberlite pipe is one of nine diamondiferous kimberlite pipes that form a cluster in the south-eastern portion of the Superior Province, Quebec, Canada and is presently being extracted at the Renard Mine. It is interpreted as a diatreme-zone kimberlite consisting of two Kimberley-type pyroclastic units and related country rock breccias, all cross-cut by coherent kimberlite dykes and irregular intrusives. Renard 2 has been the subject of numerous diamond drilling campaigns since its discovery in 2001. The first two geological models modelled kimberlite and country rock breccia units separately. A change in modelling philosophy in 2009, which incorporated the emplacement envelope and history, modelled the entire intrusive event and projected the pipe shape to depth allowing for more targeted deep drilling where kimberlite had not yet been discovered. This targeted 2009 drilling resulted in a > 400% increase in the volume of the Indicated Resource. Modelling only the kimberlite units resulted in a significant underestimation of the pipe shape. Current open pit and underground mapping of the pipe shape corresponds well to the final 2015 geological model and contact changes observed are within the expected level of confidence for an Indicated Resource. This study demonstrates that a sound understanding of the geological emplacement is key to developing a reliable 3D geological and resource model that can be used for targeted delineation drilling, feasibility studies and during the initial stages of mining.

A low-δ18O intrusive breccia from Koegel Fontein, South Africa: Remobilisation of basement that was hydrothermally altered during global glaciation?

Abstract The Cretaceous Koegel Fontein igneous complex is situated on the west coast of South Africa, and has a high proportion of rocks with abnormally low δ18O values. The rocks with the lowest δ18O values (− 5.2‰) belong to intrusive matrix-supported breccia pipes and dykes, containing a variety of clast types. The breccia rocks range in SiO2 from 44 to 68 wt% and their whole-rock δ18O values vary between − 5.2‰ and + 1.8‰. The major and trace element composition of the breccia rocks is consistent with them containing variable proportions of clasts of Cretaceous intrusive rocks and basement gneiss and the matrix being fluidized material derived from the same source as the clasts. Based on the nature of the clasts contained in the breccia, it was emplaced just prior to intrusion of the main Rietpoort Granite at 134 Ma. All components of the breccia have low δ18O value and, at least in the case of the gneiss clasts, this predates incorporation in the fluidized material. Although the early Cretaceous appears to have been a period of cold climate, it is unlikely that the δ18O values of ambient precipitation (~− 10‰) would have been low enough to have generated the required 18O-depletion. The basement gneiss was probably ~ 2–3 km below the Cretaceous surface, minimizing the possibility of interaction with isotopically unmodified meteoric water, and there is no evidence for foundered blocks of cover rocks in the breccia. There is, therefore, no evidence for downwards movement of material. We favour a model where basement gneiss interacted with extremely 18O-depleted fluid during crustal reworking at ~ 547 Ma, a time of global glaciation. Low-δ18O metamorphic fluids produced by dehydration melting of 18O-depleted gneiss became trapped and, as the fluid pressure increased, failure of the seal resulted in explosive upwards movement of fluidized breccia. Migration was along pre-existing dykes, incorporating fragments of these dykes, as well as the country rock gneiss.

STUDY OF GEOLOGICAL CONDITION OF MELUKOTE REGION FOR FINDING THE SUITABILITY OF MINERALS AND ROCKS FOR CONSTRUCTION AND FINDING ECONOMICAL MINERALS

A study was carried out to understand the geological condition in and around MELUKOTE region. THE MELUKOTE located in Mandya district, Karnataka. During the geological survey we have found different minerals and rocks such as Gneiss, foliated and non-foliated rocks, foliated schist, sedimentary rock (Breccia), metamorphic rocks, mica sheets, mica schist, pink granite gneiss rock, Biotite, muscovite, sillimanite. The samples collected were analyzed for various physical properties that is form, colour, streak, lustre, cleavage, fracture, hardness, specific gravity, chemical composition. Among all these minerals quartzite and mica minerals are abundant and can be extracted economically. The rocks undergone physical, chemical, biological, weathering. Chemical weathering processes are among the most fundamental natural processes operating at and near the surfaces of earth [1]. These rocks are not suitable for construction. By the study of pediments near the new tank project, shows that Kaveri river is dried.

Aquifer Distribution Based on 1D Resistivity Method at Jatinangor Educational Area, Sumedang Regency, West Java Province

Continuous development in the area of Jatinangor campus is becoming one of the problems threatening the groundwater supply. To support the availability of groundwater in the area of Jatinangor campus, a geophysical investigation with the geo-electric method is conducted to determine the condition of the subsurface based on the value of resistivity of rock. Based on Bandung’s regional geological map of Silitonga in 2003, rocks in the Jatinangor area consist of volcanic rock breccia, tuffs, and lapilli that makes it possible to contain the groundwater. 32 stations of 1-Dimensional (DC sounding) geo-electric measurement using Schlumberger configuration are performed in Jatinangor area. We integrated the results of measurement with geological and hydrogeological observation information with the aim of producing images of subsurface rocks and distribution models. Based on the model, the type of aquifer contained in the study area as well as its potential reserve can be determined. This research aims to know the potential groundwater zone region to support the availability of groundwater for Jatinangor education region. Furthermore, the results are expected to provide insights in implementing conservation strategies for Jatinangor educational area, Sumedang Regency.

A review and new descriptions of Elk Point Group outcrops in the Athabasca Oil Sands mining region

Abstract Elk Point Group outcrops in the Athabasca Oil Sands mining region (AOSMR) and adjacent areas include exposures of the La Loche, Contact Rapids, Keg River, and Prairie Evaporite formations. Here, we review prior investigations of these formations in outcrop, followed by new descriptions of some outcrops, including those previously unpublished or newly discovered. The fluvial to marginal marine sandstone and conglomerate of the La Loche Formation, informally known as the granite wash, outcrops along the Clearwater River in Saskatchewan, where it is sandwiched between the Precambrian basement and the Contact Rapids Formation. In Alberta, the La Loche Formation is exposed at a locality along Whitemud Falls, where it directly underlies the Keg River Formation as a lithic sandstone and fills paleokarst crevices in the Keg River dolostone. From these two outcrops we recognize three facies in the La Loche Formation: regolith, lithic conglomerate, and lithic to arkosic sandstone. The marginal marine shale, silt, and dolomite of the Contact Rapids Formation outcrops in Saskatchewan at its namesake Contact Rapids, but is exposed only as a slumped bank of grey to greenish mud. We examined Keg River Formation dolostone from three outcrops along the Clearwater River at Contact Rapids in Saskatchewan and Whitemud Falls and Cascade Rapids in Alberta. We also describe an outcrop on the Firebag River in Alberta. From these outcrops, we recognize three general facies: bedded to laminated cryptalgal dolomitized bindstone (originating from an intertidal paleoenvironment), coral and stromatoporoid-bearing dolomitized floatstone to rudstone (originally a reef), and crinoid and brachiopod dolomitized floatstone (from off-reef or inter-reef areas). A newly recognized outcrop of the collapse residue from the dissolved Prairie Evaporite Formation occurs along the Clearwater River, where cobbles and boulders of breccia and other less soluble Prairie Evaporite rock weather out of the river bank between several sulfur springs.

Felsic maar-diatreme volcanoes: a review

Felsic maar-diatreme volcanoes host major ore deposits but have been largely ignored in the volcanology literature, especially for the diatreme portion of the system. Here, we use two Mexican tuff rings as analogs for the maar ejecta ring, new observations from one diatreme, and the economic geology literature on four other mineralized felsic maar-diatremes to produce an integrated picture of this type of volcano. The ejecta rings are up to 50 m+ thick and extend laterally up to ∼1.5 km from the crater edge. In two Mexican examples, the lower part of the ejecta ring is dominated by pyroclastic surge deposits with abundant lithic clasts (up to 80% at Hoya de Estrada). These deposits display low-angle cross-bedding, dune bedforms, undulating beds, channels, bomb sags, and accretionary lapilli and are interpreted as phreatomagmatic. Rhyolitic juvenile clasts at Tepexitl have only 0–25% vesicles in this portion of the ring. The upper parts of the ejecta ring sequences in the Mexican examples have a different character: lithic clasts can be less abundant, the grain size is typically coarser, and the juvenile clasts can be different in character (with some more vesicular fragments). Fragmentation was probably shallower at this stage. The post-eruptive maar crater infill is known at Wau and consists of reworked pyroclastic deposits as well as lacustrine and other sediments. Underneath are bedded upper diatreme deposits, interpreted as pyroclastic surge and fall deposits. The upper diatreme and post-eruptive crater deposits have dips larger than 30° at Wau, with approximately centroclinal attitudes. At still lower structural levels, the diatreme pyroclastic infill is largely unbedded; Montana Tunnels and Kelian are good examples of this. At Cerro de Pasco, the pyroclastic infill seems bedded despite about 500 m of post-eruptive erosion relative to the pre-eruptive surface. The contact between the country rocks and the diatreme is sometimes characterized by country rock breccias (Kelian, Mt. Rawdon). Pyroclastic rocks in the diatreme are typically poorly sorted, and ash-rich. They contain a heterolithic mix of juvenile clasts and lithic clasts from various stratigraphic levels. Megablocks derived from the ejecta ring or the country rocks are often found in the diatremes. Evidence for multiple explosions is in the form of steep crosscutting pyroclastic bodies within some diatremes and fragments of pyroclastic rocks within other pyroclastic facies. Pyroclastic rocks are cut by coherent felsic dikes and plugs which may have been feeders to lava domes at the surface. Allowing for the difference in magma composition, felsic maar-diatreme volcanoes have many similarities with their ultramafic to mafic equivalents. Differences include a common association with felsic domes, inside the crater or just outside (Wau), although the domes within the crater may be destroyed during the eruption (Hoya de Estrada, Tepexitl); the dikes and plugs feeding and invading felsic diatremes seem larger; the processes of phreatomagmatic explosions involving felsic magmas may be different.

A computational methodology for the creation of photorealistic mosaic using breccia tiles

A comparison based tile classification technique has been developed and applied computationally in order to compile a mosaic, which constituting tiles emplaced as to form a particular figure. The mosaics are generated using the surficial shapes of the tiles. Unlike the conventional mosaic tiling process, geometric properties of the tiles do not have any role for the proposed methodology. Therefore, square breccia rock tiles, having variable surface appearances, have been used by processing with the developed algorithm and lined up as to form targeted sample images. The technique showed satisfactory results even with a limited number of tiles in the database. The compilation of the mosaic with the proposed methodology is a very fast and cheap process, which makes it ideal to follow the different requirements of the individual customers and eliminates skilled workforce in the production. Since the mosaic contains different ratios of breccia tiles, having variable surface appearances, the gap between the market prices of the tile groups has been eliminated and an extra value to the final product has been added by attributing an artistic value. The technique offers practically no size limitation for a mosaic, which makes it suitable for large coverings such as ones in museums, lobbies and even for open spaces. The methodology presented in this study allows creating photorealistic mosaics having higher engineering properties

Arrested diatreme development: Standing Rocks East, Hopi Buttes, Navajo Nation, USA

Abstract Maar–diatreme volcanoes, defined by their relatively large pyroclastic debris-filled subsurface structures and craters that cut into the pre-eruptive land surface, are typically found in small-volume mafic to ultramafic monogenetic volcanic fields. Diatremes are associated with strong explosions throughout most of their development, focused along feeder dikes and generally attributed to magma–water interaction, or high magmatic volatiles. Detailed mapping of the magnificently exposed Standing Rocks East (SRE) diatreme shows evidence of additional eruptive complexity, and offers new insights into how the plumbing and vent structures of small-volume volcanoes evolve during an eruption. SRE is part of a larger, basanitic volcanic complex that includes several diatremes formed along a series of irregular, offset NW–SE trending dikes exposed 300 m below the pre-eruptive land surface. Its similarly oriented elliptical-shaped diatreme structure comprises predominantly country rock lithic-rich breccia of coarse inhomogeneously mixed wall-rock blocks sourced from above and below the current surface, plus sparse juvenile material. Domains of pyroclastic deposits crosscut the country rock breccia deposits, and the best exposed is the NW massif rising 35 m above the current erosional surface. It represents a cross-section of an evolving crater floor, and comprises matrix-rich lapilli tuff and spatter deposits cut by irregularly distributed dikes, some with very complex textures. The most significant deposit, in terms of volume, is an unbedded lapilli tuff that is poorly sorted and has a well-mixed population of wall-rock and juvenile clast varieties, thus resembling deposits typical of diatremes. It is overlain by and locally intercalated with spatter deposits, and this irregular contact demarcates the base of what was during eruption an uneven, evolving crater floor. The generally massive, variably welded spatter deposits constitute mostly lapilli-sized juvenile clasts with fluidal, folded-over shapes and ropy surfaces, subordinate thermally altered wall-rock and variegated domains of lapilli tuff. SRE shows a progressive transition from fissure to diatreme, and overall evolution from more explosive to weakly explosive eruption styles recorded at the conduit-crater transition. Diatreme development was initiated by deep-quarrying explosive eruptions along a fissure to form the country rock-rich breccia. Only parts of the fissure remained active as magma feeding the highly explosive eruptions along the fissure localized into discrete point sources forming the matrix-rich lapilli tuff deposits. These superimposed deposits record the passage of multiple debris-jets and subvertical fallback from shallow cratering arising from explosions triggered by magma–water interaction at numerous, discrete sites. However, instead of continuing to build a well-formed diatreme, the system switched to weak spattering with intermittent explosive activity and near-surface dike emplacement into the unconsolidated anisotropic, pyroclastic debris of the crater floor. Dominant spatter from strombolian-style bursts accumulated on the topographically varied, evolving unstable syn-eruptive crater floor, and led to local failure and remobilization. This study demonstrates how the combination of fissure behavior and sensitivity of the shallow plumbing system to local conditions during an eruption can lead to a decrease in eruptive footprint within the diatreme structure, and an overall decrease in explosivity resulting in the arrested development of an immature diatreme.

Subsurface Mapping of Ground Water using Schlumberger Configuration in Upstream of Brantas River, Batu area, East Java, Indonesia

A Resistivity sounding survey of groundwater was performed around the upstream of Brantas river, Batu area, East Java, Indonesia. The goal of this study is to identify the water resources. In order to determine the aquifer thickness and the ground water flow, it was done a mapping in the 6-spring water area, as a representative of 108 spring water in the study area. Acquisitions are taken by six lines using Schlumberger configuration around the spring water at length of measurement line about 400 m with electrode spacing 10 m. Data processing and interpretation were using IP2WIN, Progress 3, and Rockwork 15, which allowed in 1D and 3D scheme to present the distribution of real resistivity below the surface. Interpretation of the results indicate the presence of a layer of rock that is formed due to volcanic activity. The rock structure is composed of volcanic rock breccia, tuff breccia, sandy tuff, tuff and lava. Rocks of volcanic breccia, tuff breccia, tuff and lava have small porosity due to having a small grain size and smooth, and have the low permeability, so it is not able to store and drain water. This rock layer is expected to function as an impermeable layer and can further serve to hold water that can seep into the ground below, so that the ground water will flow horizontally. While sandstone has a great porosity because it has a rounded rock grains with large permeability, so as to save water and running it in a number of significant.