Breccia Unit Research Articles

Application of the Analytical Hierarchy Process (AHP) Method for Groundwater Potential Zoning in the Kalianda Area, South Lampung Regency

Management related to groundwater resources is needed, especially in areas experiencing rapid regional development, for example in Kalianda, South Lampung Regency. The initial step in management is identifying groundwater potential, using a geographic information system. This research aims to map groundwater potential zones using the Analytical Hierarchy Process (AHP) method in the Kalianda area. The methods used are geological mapping, AHP processing via GIS, and comparative analysis with aquifer productivity maps and the numbers of well distribution in the research area. From geological mapping, lithology was obtained in the form of Alluvium Unit, Mount Rajabasa Laharic Deposit Unit, Mount Rajabasa Andesite Lava Unit 1, Mount Rajabasa Andesite Lava Unit 2, Mount Rajabasa Andesite Lava Unit 3, Mount Pandan Pyroclastic Breccia Unit 1, and Mount Pandan Pyroclastic Breccia Unit 2. The results of the groundwater potential zone analysis divide the research area into 4 zones, namely the low potential zone covering 42.34%, medium 21.17%, quite high 15.45%, and very high 21.03% in the research area. The low and medium potential zones are the zones with the largest constituents spread across the southeast and south, and the moderately high and very high groundwater potential zones spread across the north and along the coast. In addition, the zoning results are directly proportional to the number of wells in each zone.

Preliminary Conceptual Model of Hydrogeological System in The Pandanduri Dam and its Surrounding Area on the Lombok Island

Abstract the availability of water resources is increasingly limited and even tends to be increasingly scarce; an in-depth study of geological-hydrogeological analysis of springs and groundwater is needed to support various community activities. This research was conducted to determine the hydrogeological system in the Pandanduri Dam area and its surroundings. Geological conditions and geomorphology determine the hydrogeological system and groundwater flow direction patterns. Geological conditions were obtained by conducting field investigations, and groundwater level data was obtained by measuring dug wells from 36 points and measuring 13 points of spring locations. Volcanic sedimentary rocks and volcanic breccia dominate the study area. Three (3) rock units can be distinguished, namely (1) the Andesite tuff breccia – pumice unit is located in the southern part of the study area, precisely in the reservoir area, and (2) the Andesite tuff breccia unit dominates located in the southern part of the study area. The study area’s eastern, western, and northern parts and (3) alluvial deposit units located in the study area covered the andesite volcanic breccia. The aquifer consists of volcanic sedimentary rock and volcanic breccia with a sandy bottom. The 2D interpretation of the dam area shows that the sandy volcanic breccia unit has a resistivity value between 5 ohms - 25 ohms in the form of lapilli tuff sand interspersed with fine tuff, located at a depth of 8 meters below the surface. The pattern of the direction of groundwater flow indicates that the movement of groundwater follows the shape of the topography that flows from the hilly area west-northwest of Santong Village to the southeastern river valley of Pandanduri Village; geological and geomorphological conditions affect this groundwater flow pattern.

Geology and Basalt Petrogenesis in The Amerrung Area Barru Regency South Sulawesi Province

The research location is in the Amerrung area, Barru Regency, South Sulawesi Province. This area is interesting to learn about the geology and petraceability of the basalt. This study aims to determine the geological conditions and petogenesis of the basalt. This study uses observation, field data collection and petrographic analysis. The geomorphology of the research area is composed of denudasional mountain geomorphological units and denudional steep mountain geomorphological units. The stratigraphy of the research area consists of 3 rock units from m to young rocks, namely porphyry basalt, basalt and volcanic breccia units. The developed geological structure is a combination of the Unsystematic and the Amerrung Inverted Fault. The excavation material consists of basalt and rocks mixed with sand. The geological history of the Amerrung area began during the Middle Miocene and eruptions were effusive. Basalt petrogenesis is formed from the presence of volcanic activity that is effusive in the form of basaltic lava flows that undergo a relatively fast freezing process and form basalt. Basalt is a member of the Tefrite Leussite Formation (Tmca) produced by lava and breccia. This formation has a Middle Miocene-Pliocene Age including the Camba Formation.

GEOLOGY AND THE STUDY OF HEAVY METAL IMPACTS ON ENVIRONMENTAL QUALITY ASSESSMENT USING ARCGIS FOR INTERPRETATION DISTRIBUTION

The Boto area, Jatiroto District, Wonogiri Regency, Central Java, Indonesia, is a traditional gold mining site with inadequate waste management practices, particularly mercury usage. This study aims to assess mercury contamination and evaluate phytoremediation potential in the area. Geological mapping, petrographic analysis, fossil analysis, stereographic analysis, soil Hg measurement, soil and water chemistry analysis, and XRF analysis were conducted to characterize the geology, geomorphology, and heavy metal distribution. The study area is divided into four geomorphological units: Intrusive Hill Unit (V1), Homoklin Hill Unit (S1), Karst Hill Unit (K1), and Alluvial Plain Unit (F1). Stratigraphically, the area consists of the Nglanggeran Breccia Unit interbedded with early Miocene lava, the early Miocene andesite Intrusion Unit with a terrestrial depositional environment, the Wonosari Limestone Unit of Middle-Late Miocene age, and the Holocene Alluvial Deposit Unit. Geological structures include left-lateral normal faults trending relatively north-south (Sesar Boto), left-lateral normal faults trending southeast-northwest (Sesar Brenggolo), and right-lateral downthrown faults trending southeast-northwest (Sesar Mesu). Fractures and veins are also present. Mercury (Hg), manganese (Mn), arsenic (As), and lead (Pb) distribution mapping was conducted. The contaminated zone falls into TCLP-A, and waste management falls into category 1, located in Boto Village, which is a gold mining and processing area. Phytoremediation is proposed as a remediation strategy. Keywords: gold mining, heavy metals, XRF, phytoremediation, distribution

ANALISIS STRUKTUR GEOLOGI BERDASARKAN DATA PERMUKAAN DAERAH BANJARHARJO, KABUPATEN BREBES, PROVINSI JAWA TENGAH

The research area is administratively located in Banjarharjo Village, Banjarharjo District, Brebes Regency, Central Java Province. Geographically, the research area is located at coordinates 108o 49 '15.4 "- 108o 52' 30.8" East Longitude and 06o 59 "21.8" - 07o 02 '04.8 "LS. The research area is included in The North Central Java Basin (The North Serayu Through/Basin) which is a Back Arc Basin. Based on the stratigraphic and sedimentological composition, the research area is classified into five geological units, (old to young), namely: (1) Sandstone and Claystone Interchange Unit, (2) Carbonate Claystone Unit, (3) Sand Limestone Unit, (4) Volcanic Breccia Unit and (5) Andesite Intrusion Unit. According to Pulonggono and Martodjojo (1994) Java Island, there are three straight lines of dominant structure, including: (1) East Laur - Southwest (Meratus Pattern), (2) North - South (Sundanese Pattern) and (3) West - East (Pattern Java). Based on the strike dip and stockiness data at the research location, the results of the force with the direction of the main stress are relatively Northeast-Southwestern, with the combination of Harding modeling, (1977) and Moody and Hill, (1956). The structural arrangements in the research area that are formed are (1) Cibuluh thrust fault, (2) Maibah sinistral strike-slip fault, (3) Cikuya sinistral strike-slip fault, and (4) Cikuya dextral strikeslip fault.

Geologi Daerah Buyat Dan Sekitarnya, Kecamatan Kotabunan, Kabupaten Bolaang Mongondow Timur, Provinsi Sulawesi Utara

This research focuses on the eastern part of the northern arm of Sulawesi to understand the geological conditions, including geomorphology, lithology, stratigraphy, and geological structure. The goal is to determine the geological history and map the geological conditions to identify potential mineral resources. The research methods include a qualitative approach through field observations such as morphology, outcrop descriptions, lithology, geological structure measurements, stratigraphic relationships, as well as an inventory of natural resources and geological disaster risks. The quantitative approach involves calculations and analyses, including geomorphological analysis, petrography, paleontology, geological structure, stratigraphy, and the reconstruction of geological history. The research results identify four geomorphological units (karst, denudational, volcanic, alluvial) and six geological units at the research site. Andesite and volcanic breccia are the oldest units dating back to the Miocene. At the end of the Miocene, uplift and subsidence formed intrusive hills of diorite and limestone. Volcanic activity ceased in the Miocene. In the Pliocene, sandstone formed due to river transport. The rock formation process continues to the present, with alluvial deposit units resulting from the breakdown of rocks around the lake. Geological structure analysis reveals fault lines with the main stress direction from northwest to southeast. Relative fault data indicates fault inclination values suggesting the main stress direction is northwest-southeast. The geological history in the research area began in the Miocene with magmatism and tectonic activities, forming andesite and volcanic breccia units. This history extends to the formation of alluvial deposit units in the present. The research provides in-depth insights into the geological history and potential mineral resources in the region, serving as a foundation for further research.

Hot carbonates deep within the Chicxulub impact structure.

Constraining the thermodynamic conditions within an impact structure during and after hypervelocity impacts is extremely challenging due to the transient thermal regimes. This work uses carbonate clumped-isotope thermometry to reconstruct absolute temperatures of impact lithologies within and close to the ∼66 Myr old Chicxulub crater (Yucatán, México). We present stable oxygen (δ18O), carbon (δ13C), and clumped-isotope (Δ47) data for carbonate-bearing impact breccias, impact melt rock, and target lithologies from four drill cores on a transect through the Chicxulub structure from the northern peak ring to the southern proximal ejecta blanket. Clumped isotope-derived temperatures (T(Δ47)) are consistently higher than maximum Late Cretaceous sea surface temperatures (35.5°C), except in the case of Paleogene limestones and melt-poor impact breccias outside of the crater, confirming the influence of burial diagenesis and a widespread and long-lived hydrothermal system. The melt-poor breccia unit outside the crater is overlain by melt-rich impact breccia yielding a much higher T(Δ47) of 111 ± 10°C (1 standard error [SE]), which likely traces the thermal processing of carbonate material during ejection. Finally, T(Δ47) up to 327 ± 33°C (1 SE) is determined for the lower suevite and impact melt rock intervals within the crater. The highest temperatures are related to distinct petrological features associated with decarbonation and rapid back-reaction, in which highly reactive CaO recombines with impact-released CO2 to form secondary CaCO3 phases. These observations have important climatic implications for the Cretaceous-Paleogene mass extinction event, as current numerical models likely overestimate the release of CO2 from the Chicxulub impact event.

Petrogenetic of Igneous Complex of Ilota Nanasi Gold Deposit, Gunung Pani, Gorontalo, Indonesia

Ilota Nanasi Au-Ag deposit located in the western flank of the Gn. Baganite, a part rhyodacite dome in Gn. Pani district, Gorontalo Province, where the extensive exploration programs were carried out by PT Gorontalo Sejahtera Mining (a subsidiary of PT J Resources Nusantara) from 2012 – 2020. As the result, a total of 72.7 Mt @ 0.98 g/t Au and 0.85 g/t Ag (2.3 Moz Au and 2.6 Moz Ag) mineral resource was delineated in 2019. This paper mainly aimed to the petrogenesis association of granitoid basement and rhyodacite unit as the host rock in the Ilota Nanasi gold deposit. The geology of Ilota Nanasi is overlain by Late Miocene granodiorite, andesite and diorite basement, Pliocene volcanic complex predominantly dacite – rhyodacite, tuff, breccia, and quaternary deposit as alluvial and surface breccia. Hydrothermal alteration and gold – silver mineralization centered in the porphyritic rhyodacite host rocks where the intense silicification forming a zone around the hydrothermal crackle breccia unit and/or high-density quartz vein, veinlets and stockworks. Mineralization in Ilota Nanasi is interpreted as a low sulfidation epithermal system dominated by a large volume of hydrothermal crackle breccia, intense quartz veining, veinlets, and high-density fracturing. A combined analytical result of petrography and whole-rock geochemistry has been used to assess the petrogenetic association of the rhyodacite and granitoid basement in the Ilota Nanasi. The result of the AFM diagram plot shows sample trends in calc-alkaline magma field. In contrast, the SiO2 – K2O plot distributed in two trends: the older unit was associated with high-K calc-alkaline and the shoshonite series for the younger unit. The changing of magma series is considered as product of crystallization differentiation of evolved parental magma or derived from the melting of mantle material after the mantle or lower crustal was metasomatized during a former episode of subduction.

Gold mineralization in the Panikaban area, Banyumas, Central Java Province, Indonesia

Abstract Our research was conducted in Panikaban Area, Ponorogo Regency, Central Java, Indonesia. Based on the result of field data collection and analysis which has been carried out in the laboratory, stratigraphy study area was divided into 6 unofficial lithostratigraphy units and 2 litodem with the sequence of an old rock to young as follows: Halang volcanic breccia unit (Tmb), Halang sandstone unit (Tmbp), Kumbang andesite lava unit (Tma), Andesite intrusion (Tmi), Tapak volcanic breccia unit (Tpb), Tapak sandstone unit (Tpbp), Tapak limestone unit (Tpbg) and Alluvial (Qa). Rock lithology conditions in the research area are also included in the category in experiencing the process of alteration and minerallization, making the study area was being divided into three zones of alteration, namely: argillic zoning, propylitic zoning, and sub-propylitic zoning. Mineralization found in the research area is relatively associated to quartz veins (veins or veinlets) in the Halang sandstone unit, as well as on the intrusion body in the study area. Ore mineralization contained in research area such as sulfide minerals, such as: pyrite (FeS 2), chalcopyrite (CuFeS 2), galena (Pbs) and bornite (Cu 5 FeS 4). Results of the analysis of AAS (Atomic Absorption Spectroscopy) or atomic absorption spectrophotometry is used to determine the content of sulfide mineral elements contained in a sample. The analysis shows increase in sulfide mineralization which is characterized by the abundance of the elements Cu, Pb, Zn, Ag, Au, some places elements of Au increases compared with other elements.

Sedimentological infill of the Middle Triassic half-graben below Mt. Vernar in Julian Alps, Slovenia

Early beginnings of the Middle Triassic extension in the areas surrounding the western embayment of the Neotethys are evidenced in formation of small half-graben basins, local emergences of the underlying platform, and/or deposition of coarse-grained breccia. The succession related to the creation and infilling of one of these half-grabens is exposed on the slopes of the base of Mt. Vernar in eastern Julian Alps, Slovenia. The lowermost exposed unit within the half-graben is the Uggowitz Breccia, which attains thickness of up to 150 m. It is followed by a few tens of meters of red nodular limestone (the informal 'Vernar member'), followed by the second, thinner Uggowitz Breccia unit, succeeded by sandstone and sandy limestone (the informal “Krma member”), rich in shallow marine foraminifers and plant material. The basin-filling succession is followed by indistinctly bedded and then massive limestone of the Schlern Formation. Late Anisian (Ilyrian) age is assumed for the sediments of the half-graben based on the clast composition and comparison with regional sequence stratigraphic schemes. Breccias likely deposited in shallow marine or marginal marine setting. Individual beds are interpreted as subaqueous debris-flow deposits.

Evolution of the Munali Intrusive Complex: Host to a carbonate-rich Ni-(Cu-PGE) sulfide deposit

The Munali Intrusive Complex is hosted within supracrustal metasedimentary rocks located along a major structural lineament within the Zambezi Belt in southern Zambia. The complex comprises unmineralised gabbro surrounded by a marginal heterogeneous mafic–ultramafic breccia unit that is host to Ni-Fe sulfide. This marginal unit comprises a range of variably evolved brecciated mafic–ultramafic rocks that include gabbro, olivine-gabbro and dolerite, alongside younger, pegmatitic, apatite-magnetite-bearing clinopyroxenite, wehrlite and dunite. The magmatic evolution is most consistent with a model whereby early mafic rocks interact with hot, MgO- and volatile-rich melts along gabbro contacts, causing localised metasomatism of gabbro and pyroxenites, and progressively replacing pyroxene-rich rocks with olivine, forming pegmatitic ‘replacive dunites’. Sulfide mineralisation is characterised by a carbonate-rich apatite-magnetite-bearing assemblage predominately present as lenses of semi-massive to massive sulfide ore. The complex is enveloped almost entirely within a unit of marble, yet C and O isotope signatures of carbonate at Munali have revealed a clear mantle signature for some of the carbonate associated with sulfide, alongside a more dominant, crustally derived component. The carbonate occurring alongside sulfide displays micro to macro textures signifying the presence of carbonate melts formed from anatectic melting of the country rocks. The presence of fracture sets that define coarse breccia clasts (>1 m) indicate that the host rock was significantly crystallised and brittly deformed prior to carbonate and sulfide melt infiltration. Both carbonate and sulfide melts appear to have independently utilised these pre-existing weaknesses producing a pseudobreccia, and accounting for the seemingly chaotic nature of the orebody. The indication of sulfide being a significantly later phase suggests that the sulfide did not form in situ and was mobilised from elsewhere to be subsequently emplaced late within the Munali system.

ANALISIS ARUS PURBA PADA DAERAH KEDUNGWRINGIN, KECAMATAN SEMPOR, JAWA TENGAH

The exposed sandstone unit in the research area located in the Kedungwringin area, Sempor District, Central Java Province is included in the Waturanda Formation. At the research location, there are 4 exposed rock units, namely Tuff Unit, Sandstone Unit, Breccia Unit, and Alluvial Unit. The sandstone unit in the study area has a type of Arkosic Wacke Sandstone. Measurable stratigraphic measurements were carried out on the three tracks and it was found that the research area was stratigraphically in the sandstone unit and the breccia unit in the south of the study area, and had a southwest-southeast current direction which was obtained based on measurements of sedimentary structures that developed in the study area.

Curtain Grouting To Reduce Seepage Foundation Access Road To The Top Of The Dam At Tugu Dam

The construction of a complementary access road to the top of the dam is to the left of the Tugu dam pedestal. Based on geological studies, it is feared that there is a potential for seepage that passes through the left pedestal through joints, fractures, and fault areas/rock layers below the foundation surface. To anticipate this, the allowable seepage requirement is the lugeon value (Lu) < 3. This study aims to determine the geological conditions and the amount of seepage before and after foundation repairs are carried out using the grouting method. The type of this research is field research, qualitative descriptive because this research tries to collect lugeon population and cement material absorbed into the rock from water pressure test and grouting injection work by grouping each type of hole, pilot hole, primary hole, secondary hole, tertiary hole, and check hole. The study results by taking rock cores found that the constituent rocks were volcanic breccia units and colluvial rocks. Furthermore, a water pressure test before grouting with a water passing value of (k) = 6.62E-05 to 4.73E-04 cm/sec or with a lugeon value (Lu) of 5.07 to 36.21. After repairing the foundation using rim curtain grouting, the seepage that occurs decreases with a water passing value (k) = 1.96E-05 to 3.03E-05 cm/sec or lugeon (Lu) 1.50 to 2.32, so the requirements the target value of Lu < 3 was achieved with the effectiveness in the good category.

The detailed morphological formation based on geological investigation in Somawangi and surrounding areas, Mandiraja District, Banjarnegara Regency, Central Java

Geological mapping is an activity to be able to know the geological conditions of a field. Somawangi Village and its surroundings have a geological history depicting the history of the past that continues until now. This location is located in Mandiraja District, Banjarnegara Regency with a morphology consisting of rock outcrops that record past history which can be used as learning media for the field of geological science. This study aims to determine the geological conditions and resource potential as well as geological disasters at the research site. From the results of the study, it can be concluded that the Geomorphology of the research area can be divided into 3 geomorphological units, namely the Sloping Structural Hills Unit (S3), Structural Sloping Lowland Unit (S1), and Volcano Denudational Hills Unit (V14) with the composition The stratigraphy of the study area is divided into 5 rock units, from the oldest to the youngest, the Somawangi Volcanic Breccia Unit, the Sandstone Unit, the Andesite Lava Unit, the Tuff Rock Unit, and the Kaliwungu Volcanic Breccia Unit. The geological structure of the research area is the Left Fault which is found along the rivers and hills in the eastern area of the research location with an emphasis on northeast-southwest. And the geological potential of the research area can be divided into 2, namely positive potential such as mining of sand and rocks around the river, the use of red soil as a ceramic and brick material, the use of andesite lava which has the potential to mine minerals, and the presence of mineralization alteration in the research area. While the negative potential is the potential for land movement or landslides

The landscape formation history based on the detailed geological investigation in Aribaya and surrounding area, Pangetan district, Banjarnegara regency, Central Java

The research site is in the Aribaya area and surrounding areas with an area of 16 km2 which is administratively included in Pagentan Subdistrict, Banjarnegara Regency, Central Java Province. The research area consists of 13 villages, namely: Suwidak, Pandansari, Karangtengah, Gumingsir, Karangnangka, Aribaya, Larangan, Talunamba, Clapar, Gununggiana, Pakelen, and Nagasari. Research objects in the form of Geomorphology, Stratigraphy, Geological Structure, Geological History, and Geological Potential. The geomorphology of the research area is divided into the Aribaya Fault Zone Unit, Gununnggiana Lava Flow Ridge Unit, and Aribaya Intrusion Unit. Based on unofficial lithostratigraphic units, the research area is divided into three rock units and the order from old to young, namely: Sandstone - Claystone Distribution Unit, Pyroclastic Brection Unit, and Diorit Intrusion Unit. Precipitated Sandstone - Claystone In the middle-upper neritic bathymetry environment, which belongs to the formation of the early Miocene – Middle-aged vines. Furthermore, tectonic activity occurs that causes the research area to form faults and syncline folds. Then at the time of the Early Pliocene, there was an influence from the activity of Mount Maung which provided sediment supply in the form of andesite fragments and matrix-sized Tuff Crystals so as to form a pyroclastic breccia unit. At the Time of the Pliocene, there was also diorite intrusion. The next process is the exogenous process that causes morphological form as it is today. The geological potential contained in the research area in the form of diorite mining excavations (positive potential) and landslide movement (negative potential) is quite a lot in the research area.

Volcanology, geochemistry and geodynamic setting of the Neoarchean Sunrise volcanogenic massive sulfide deposit, Beaulieu River volcanic belt, Slave craton, Northwest Territories, Canada

The Sunrise volcanogenic massive sulfide (VMS) deposit is a banded, polymetallic Zn-Pb-Cu-Ag sulfide lens hosted by felsic volcanic rocks of the Neoarchean Beaulieu River volcanic belt in the western Slave craton in the Sunset Lake area of the Northwest Territories, Canada. With historic indicated resources of 1.52 Mt at 5.99% Zn, 2.39% Pb, 0.08% Cu, 262 g/t Ag, and 0.67 g/t Au—it is the largest known VMS deposit in the Northwest Territories.The footwall stratigraphy is interpreted to be the product of subaqueous, largely effusive, bi-modal volcanism with periods of pyroclastic eruptions and concomitant subsidence. It consists of basalt to basaltic-andesite lavas with minor associated volcaniclastic rocks, rhyolite lobe-hyaloclastite flows and rhyolite domes, and felsic volcaniclastic rocks. Though hosted within felsic volcaniclastic lithofacies, the mineralization is spatially associated with the thickest portions of a quartz-feldspar porphyritic lobe-hyaloclastite flow and rhyolite dome. Felsic tuff to lapillistone units, characterized by fine ash, pumice and broken crystal clasts indicate derivation from pyroclastic volcanism and deposition by eruption-fed density currents. Felsic tuff breccia units are characterized by block-sized fragments of quartz-feldspar porphyritic rhyolite and were deposited during mass wasting events along fault scarps or by the oversteepening of domes. Massive to stringer-style sulfide mineralization is dominantly within felsic (seldom heterolithic) tuff to tuff breccia units, but laterally discontinuous argillite units occur at the top of the footwall and commonly contain stringer to semi-massive sulfide mineralization, indicating a hiatus in volcanism before the onset of basaltic andesite lavas that form the hanging wall to the deposit.Volcanic stratigraphy and architecture, and the occurrence of a volcanogenic massive sulfide deposit, combined with major and trace element geochemistry and Nd, Hf, and Pb isotopic data indicate the volcanic rocks and the Sunrise deposit formed on rifted Mesoarchean crust.

Hargraves Crater, Mars: Insights into the internal structure of layered ejecta deposits

Impact craters and their ejecta deposits offer insights into the structure and composition of planetary crusts. The 60 km diameter Hargraves Crater, Mars, demonstrates an unusual balance of exposure and preservation in its ejecta deposits. We investigated the morphologic, morphometric, thermophysical, and stratigraphic characteristics of the Hargraves Crater ejecta blanket. Our work shows that the crater produced two distinct ejecta units. The lower unit, He1, interpreted as a lithic impact breccia, is unsorted and composed of sub-angular clasts. These clasts in the breccia unit have a mean diameter of ~10–12 m but range in size from m to km in size. The overlying unit, He2, is smooth, dark toned, comprises fewer and much smaller clasts (~1 m diameter on average at image resolution) and exhibits polygonal fracturing. We interpret this unit as an impact melt-bearing breccia or impact melt rock unit. A sharp contact is visible between the two ejecta units. These orbital observations are markedly similar to field observations of ejecta deposits on Earth. With the context of both in-situ and orbital impact studies, we interpret these two layers as a ballistic ejecta layer overlain by impact melt-rich flows and ponds. The two distinct layers, separated by a sharp contact, indicate two separate phases of ejecta emplacement. Hargraves Crater thus represents a unique opportunity to observe what may be a common ejecta blanket structure as other craters across the surface of Mars show similar characteristics. Future study of this “Hargraves-type” ejecta will improve our understanding of ejecta and ejecta emplacement processes.

Study of Hydrothermal Alteration and Mineralization in the Lahbako Field, Jember Regency, East Java Province

Administratively, the research location is in Lahbako Field, Jember Regency, East Java Province. This study discusses the geological characteristics, hydrothermal alteration, and mineralization in the study area. The method used is field data collection by mapping and laboratory analysis in the form of petrographic analysis and mineragraphic analysis. The research area is divided into three geomorphology units, namely a unit with steep hills, a unit with undulating hills, and a unit with sloping plains. The stratigraphy of the study area is divided into five-rock units, while the order of rock units from oldest to youngest is the volcanic Breccia unit, the intercalated Sandstone, and Claystone unit with Tuff insertion, the Diorite Intrusion Unit, the Granodiorite Intrusion Unit, and the youngest unit, namely Alluvium Unit. The research area has a high straightness density value and a straight lineage pattern that tends to be dense. The area with high lineament density is assumed to be the area with the best prospect of alteration and mineralization because the lineament reflects the geological structure which is the path of hydrothermal fluid passage that causes alteration and mineralization. Based on petrographic analysis, the research area has undergone alteration with the type of Philic alteration (Chlorite-Quartz-Feldspar), Prophiliic Alteration (Chlorite-Quartz-Feldspar) Feldspar-Quartz-Epidote) and Argillic Alteration (Alunite-Quartz-Biotite). The study area is indicated as an area with high sulfide epithermal mineral deposits where the indication is based on the discovery of vein textures in the form of Vuggy Quartz and ore minerals in the form of Silver, Copper, and Iron in mineragraphic analysis.

LITHOLOGICAL AND FACIAL FEATURES, COMPOSITION, AND SEDIMENTATION CONDITIONS OF TERRIGENOUS-CARBONATE ROCKS OF THE MOTY GROUP (SHAMAN CLIFF, IRKUTSK REGION)

We have studied terrigenous-carbonate rocks in the area near the Sayan mountains in the Irkutsk Region (Russia), specifically at the Shaman Cliff, being the stratotype area of rocks that belong to the Moty group. The cliff’s lower part is composed of sandstones, which fragments gradually decrease in size upward the cross-section. The middle and upper parts are composed of sandy dolomites and dolomites, respectively. In terms of material characteristics, the terrigenous rocks correspond to arkoses. According to the genetic typification, the arkoses are composed of destructed primary igneous rocks. The terrigenous-carbonate rocks contain a carbonate component that gradually increases in the upper part of the cross-section. In the Shaman Cliff cross-section, we distinguish 32 lithological units and eight lithologicalgenetic types of deposits. Paleogeodynamic conditions are reconstructed for the formation of the sedimentation basin. Our study of the Shaman formation reveals specific features of the lithological facies, which suggest that these rocks accumulated in a coastal environment affected by tides. In the study area, clastic materials were mainly removed from an orogen that formed due to the Vendian accretion-collision events in the southern folded frame of the Siberian platform. Dolomites composing the upper part of the cliff are attributed to the Irkutsk formation of the Moty group. Their lithological features give evidence of shallow-marine conditions of their formation, without any supply of clastic material, which contributed to mass dispersal of the Cambrian biota described in [Marusin et al., 2021]. It is our first initiative to draw a boundary between the Shaman and Irkutsk formations of the Moty Group along the base of the carbonate eluvial breccia unit that marks the stratigraphic break. In the cross-section, this boundary represents the border between the Upper Vendian and Lower Cambrian.Our conclusions are generally consistent with the ideas of most researchers about the Late Vendian evolution of the southern margin of the Siberian platform. The results of our study can be used in further investigation of this area and provide a basis for correlating the studied strata with the same-age reference cross-sections of other regions in Siberia.

Hydrothermal alteration and Cu–Co mineralization at the peripheral zone (Target H) of the Kitumba iron–oxide copper–gold system, Mumbwa District, Zambia

AbstractTarget H is a new Cu prospect discovered in the Mumbwa district of central Zambia. Copper mineralization in the Mumbwa district is linked to the hydrothermal system associated with the granite‐quartz syenite intrusions of the Hook batholith. The extent of the hydrothermal system has not been documented, but various Cu prospects, including Target H, have been discovered at the margins of the granite‐quartz syenite bodies. The objective of this study is to investigate the geological characteristics of the Target H prospect using petrographic, geochemical, and sulfur isotope data in order to understand the features of mineralization at the margin of the hydrothermal system. The Cu‐ and Co‐rich orebodies are hosted in siltstone and breccia correlated to the Kundelungu Group of the Neoproterozoic Katanga Supergroup rocks. The siltstone consists of alternating beds of sandstone and mudstone that are composed of diagenetic quartz, albite, dolomite, calcite, and muscovite. Breccia occurs parallel to the bedding planes and in the folded and fractured siltstone units. Lithostratigraphy is characterized by three domains: breccia, transition, and host rock, which are defined depending on the proportion of siltstone and breccia. The diagenetic minerals have been modified by hydrothermal alteration, resulting in alteration products controlled by the primary mineralogy of the host rocks: K‐feldspar and muscovite replace albite and muscovite in siltstone, while siderite and hematite replace dolomite and calcite in breccia. Hydrothermal calcite is observed in the veinlets with or without siderite and hematite. Copper mineralization is associated with hydrothermal alteration and occurs as chalcopyrite, bornite, and chalcocite in breccia and stockwork veins. Diagrams correlating geochemistry to lithology show that the bulk of Cu mineralization is hosted in the breccia. An anomalous concentration of Co occurs with Cu in breccia, but the two metals do not show similar enrichment and depletion behaviors. The Cu‐rich orebody forms in hematite‐dominated breccia domain, whereas Co‐rich orebody forms in siderite‐dominated breccia units in the transition domain. In addition to Cu and Co, geochemical data show significant enrichment of Fe, P, Ba, Mo, Pb, W, U, V, and light rare earth elements in the breccia. Sulfur isotopic values of sulfide minerals show lighter δ34S values between 5 and 9‰ in the breccia and heavy δ34S signatures of approximately 17–28‰ in the siltstone. The δ34S values measured from sulfides in the breccia were comparable to the values obtained from the Kitumba deposit, which is located at the center of the hydrothermal system. We propose a magmatic‐hydrothermal origin for the Cu‐ and Co‐rich orebodies in the breccia at Target H. Breccia was the conduit for iron‐oxide‐rich metal‐bearing fluids that originated from the Kitumba deposit. Cooling and reaction of the fluids with dolomite‐rich siltstone triggered a redox reaction that deposited Cu sulfide minerals and an anomalous concentration of Co.