Location Of Deposits Research Articles

Head and neck amyloidosis – a report on five cases

BACKGROUND: Amyloidosis is a group of diseases caused by extracellular accumulation of insoluble fibers referred to as amyloid fibers in tissues and organs. Amyloid fibers have a secondary beta-sheet structure which makes them resistant to proteolysis. In histological examination, amyloid deposits stain with Congo red and show apple-green birefringence in polarized light. Amyloid deposits disturb the function of organs and cause clinical symptoms. Their formation or accumulation within the system may be acquired or inherited. Due to the location of amyloid deposits, one may distinguish systemic and localized amyloidosis with the formation of tumors (usually composed of immunoglobulin light chains). CASE REPORTS: Five cases of amyloidosis in the head and neck region are presented in this paper. Locations of the amyloid deposits were as follows: larynx, nasopharynx, sublingual and submandibular gland and the tongue. The initial clinical presentation correlated with the location of amyloid tumour in our patients. Two patients had a history of local recurrence of the disease. Surgical resection and histopathological examination were performed. Sections stained with Congo red confirmed the diagnosis of amyloidosis. Three patients had potential conditions that predisposed them to amyloidosis, including previous radiotherapy, chronic inflammation due to hepatitis C virus infection and graft versus host disease. CONCLUSION: Amyloidosis should be considered as a possible cause of pathological symptoms in the head and neck region. The diagnosis requires a histopathological examination. The systemic form of the disease must be ruled out in all patients with head and neck amyloidosis. In localized amyloidosis, surgical resection of lesions is the procedure of choice; however, maintenance of organ's functionality should be taken into account.

Analysis of Lunar Terrain Altitudes and Correlation Links between the Terrain and Gravitational Field; Preliminary Conclusions on the Global Density Inhomogeneities of the Lunar Crust

The harmonic and statistical analysis of lunar terrain altitudes has been performed based on the procedure developed by the authors. The explanations for the displacements of the Moon's figure relative to the center of mass and for the shift of the major equatorial axis relative to the earthward direction have been given. The maps have been plotted for the density anomalies in the near-surface layers of the Moon that correspond to mascons (with negative correlation between the field and terrain mainly for N= 10, 11) and other variants of links between the gravitational field and terrain (with positive correlation between the field and terrain). It has been shown that the harmonics of the degree N= 5–9 mainly correspond to the isostatic compensation of the terrain in the near-surface layers of the crust; the low harmonics (N 11 may indicate the presence of tension in the crust generated by small structures of the terrain. Based on the maps, possible locations of deposits of volatile elements (mainly on the far side of the Moon and in the northern cir-cumpolar region) and other natural resources have been determined.

Extensional fault and fold growth: Impact on accommodation evolution and sedimentary infill

AbstractExtensional faults and folds exert a fundamental control on the location, thickness and partitioning of sedimentary deposits on rift basins. The connection between the mode of extensional fault reactivation, resulting fault shape and extensional fold growth is well‐established. The impact of folding on accommodation evolution and growth package architecture, however, has received little attention; particularly the role‐played by fault‐perpendicular (transverse) folding. We study a multiphase rift basin with km‐scale fault displacements using a large high‐quality 3D seismic data set from the Fingerdjupet Subbasin in the southwestern Barents Sea. We link growth package architecture to timing and mode of fault reactivation. Dip linkage of deep and shallow fault segments resulted in ramp‐flat‐ramp fault geometry, above which fault‐parallel fault‐bend folds developed. The folds limited the accommodation near their causal faults, leading to deposition within a fault‐bend synclinal growth basin further into the hangingwall. Continued fold growth led to truncation of strata near the crest of the fault‐bend anticline before shortcut faulting bypassed the ramp‐flat‐ramp structure and ended folding. Accommodation along the fault‐parallel axis is controlled by the transverse folds, the location and size of which depends on the degree of linkage in the fault network and the accumulated displacement on causal faults. We construct transverse fold trajectories by tracing transverse fold hinges through space and time to highlight the positions of maximum and minimum accommodation and potential sediment entry points to hangingwall growth basins. The length and shape of the constructed trajectories relate to the displacement on their parent faults, duration of fault activity, timing of transverse basin infill, fault linkage and strain localization. We emphasize that the considerable wavelength, amplitudes and potential periclinal geometry of extensional folds make them viable targets for CO2 storage or hydrocarbon exploration in rift basins.

SUN-346 Diffusion Weighted Imaging (DWI) Highlights SDHB-Related Tumours: A Radiation Free Alternative for Surveillance Imaging

Background There is general consensus that asymptomatic carriers of SDHB mutations should undergo periodic surveillance imaging. It is established that 68Ga-DOTATATE PET/CT is superior for localisation of primary head & neck paragangliomas and SDHB-associated metastatic phaeochromocytoma and paragangliomas (PPGLs). For surveillance, MRI has the major advantage of avoiding radiation exposure. Its sensitivity and specificity for detecting PPGL will be dependent on sequences obtained and expertise of the reporting radiologist. For MRI diffusion weighted imaging (DWI) sequences to compete with PET in terms of sensitivity and specificity, they need to be able to identify small PPGLs at all the possible body sites in which they can occur and ideally metastatic deposits. Method Our SDHB surveillance screening scans include DWI sequences. We reviewed 18 patients with 28 SDHB-related tumours. All these scans had already been comprehensively double reported. We presented the scans to a radiologist, expert in reporting PPGL screening scans, without specifying the location of the tumour (if present) and asked them to use DWI sequences to guide a more focused review. If DWI identified an area of interest, this was then compared with the standard MRI sequences. The site and size of the tumour was recorded, as well as the b values and ADC values for the sequences obtained. Results The DWI sequence identified all 28 tumours. Many false positive areas of focus were noted and excluded. The tumours detected by DWI ranged in size from 5-52mm. Primaries were identified on DWI in the abdomen (n=13), adrenal gland (n=1), thorax (n=3), neck (n=2), and bladder (n=2). Additionally one SDHB-related GIST and two SDH-related RCCs were also highlighted by DWI, as were metastatic deposits in the liver and bone. The smallest metastatic deposits visualised were 5mm. In addition we will present examples of MR images that demonstrate the value of DWI sequences. Conclusion We would recommend, for units not already adding DWI sequences to their MRI screening scans, that these sequences are considered so that a wider experience can be reported on the sensitivity and specificity of the size and location of tumours and metastatic deposits that can be identified. If the sensitivity is confirmed in a larger series and for all SDH subunits, this will provide added reassurance about identifying small SDH-related tumours, without the consequences of exposing the patients to radiation based imaging techniques.

Boosting for Mineral Prospectivity Modeling: A New GIS Toolbox

With an increasing demand for raw materials, predictive models that support successful mineral exploration targeting are of great importance. We evaluated different machine learning techniques with an emphasis on boosting algorithms and implemented them in an ArcGIS toolbox. Performance was tested on an exploration dataset from the Iberian Pyrite Belt (IPB) with respect to accuracy, performance, stability, and robustness. Boosting algorithms are ensemble methods used in supervised learning for regression and classification. They combine weak classifiers, i.e., classifiers that perform slightly better than random guessing to obtain robust classifiers. Each time a weak learner is added; the learning set is reweighted to give more importance to misclassified samples. Our test area, the IPB, is one of the oldest mining districts in the world and hosts giant volcanic-hosted massive sulfide (VMS) deposits. The spatial density of ore deposits, as well as the size and tonnage, makes the area unique, and due to the high data availability and number of known deposits, well-suited for testing machine learning algorithms. We combined several geophysical datasets, as well as layers derived from geological maps as predictors of the presence or absence of VMS deposits. Boosting algorithms such as BrownBoost and Adaboost were tested and compared to Logistic Regression (LR), Random Forests (RF) and Support Vector machines (SVM) in several experiments. We found performance results relatively similar, especially to BrownBoost, which slightly outperformed LR and SVM with respective accuracies of 0.96 compared to 0.89 and 0.93. Data augmentation by perturbing deposit location led to a 7% improvement in results. Variations in the split ratio of training and test data led to a reduction in the accuracy of the prediction result with relative stability occurring at a critical point at around 26 training samples out of 130 total samples. When lower numbers of training data were introduced accuracy dropped significantly. In comparison with other machine learning methods, Adaboost is user-friendly due to relatively short training and prediction times, the low likelihood of overfitting and the reduced number of hyperparameters for optimization. Boosting algorithms gave high predictive accuracies, making them a potential data-driven alternative for regional scale and/or brownfields mineral exploration.

A predictive algorithm for wetlands in deep time paleoclimate models

Abstract. Methane is a powerful greenhouse gas produced in wetland environments via microbial action in anaerobic conditions. If the location and extent of wetlands are unknown, such as for the Earth many millions of years in the past, a model of wetland fraction is required in order to calculate methane emissions and thus help reduce uncertainty in the understanding of past warm greenhouse climates. Here we present an algorithm for predicting inundated wetland fraction for use in calculating wetland methane emission fluxes in deep-time paleoclimate simulations. For each grid cell in a given paleoclimate simulation, the algorithm determines the wetland fraction predicted by a nearest-neighbour search of modern-day data in a space described by a set of environmental, climate and vegetation variables. To explore this approach, we first test it for a modern-day climate with variables obtained from observations and then for an Eocene climate with variables derived from a fully coupled global climate model (HadCM3BL-M2.2; Valdes et al., 2017). Two independent dynamic vegetation models were used to provide two sets of equivalent vegetation variables which yielded two different wetland predictions. As a first test, the method, using both vegetation models, satisfactorily reproduces modern day wetland fraction at a course grid resolution, similar to those used in paleoclimate simulations. We then applied the method to an early Eocene climate, testing its outputs against the locations of Eocene coal deposits. We predict global mean monthly wetland fraction area for the early Eocene of 8×106 to 10×106 km2 with a corresponding total annual methane flux of 656 to 909 Tg CH4 yr−1, depending on which of the two different dynamic global vegetation models are used to model wetland fraction and methane emission rates. Both values are significantly higher than estimates for the modern day of 4×106 km2 and around 190 Tg CH4 yr−1 (Poulter et al., 2017; Melton et al., 2013).

Enrollment and participation in a universal child savings program: Evidence from the rollout of Israel's National Program

Child Development Accounts (CDAs) are savings or investment accounts typically opened at birth or during a child's early years with the aim of promoting savings and asset accumulation for child development purposes, such as post-secondary education or homeownership. Beginning in January of 2017, the Israeli government established a universal CDA program called the Saving for Every Child Program (SECP). Under the program, every Israeli child gets a personal investment fund into which the government makes monthly contributions, and parents can further opt to make additional monthly deposits and change the default deposit location for these funds (a savings account versus an investment fund). Using population-level administrative data, this paper examines SECP enrollment and participation patterns for the first six months following the program's inception. We observe generally high rates of program participation among SECP-eligible households. However, we also find that more affluent, better educated, more employed, and ethnic majority households tend to engage with the program at higher rates and in ways that will likely yield higher economic returns in the future. These results indicate that while the SECP, as currently designed, may increase the overall financial security of Israelis, it may also contribute to growing economic inequality.

Ancient deep roots for Mesozoic world-class gold deposits in the north China craton: An integrated genetic perspective

The North China Craton (NCC) hosts some of the world-class gold deposits that formed more than 2 billion years after the major orogenic cycles and cratonization. The diverse models for the genesis of these deposits remain equivocal, and mostly focused on the craton margin examples, although synchronous deposits formed in the interior domains. Here we adopt an integrated geological and geophysical perspective to evaluate the possible factors that contributed to the formation of the major gold deposits in the NCC. In the Archean tectonic framework of the NCC, the locations of the major gold deposits fall within or adjacent to greenstone belts or the margins of micro-continents. In the Paleoproterozoic framework, they are markedly aligned along two major collisional sutures – the Trans North China Orogen and the Jiao-Liao-Ji Belt. Since the Mesozoic intrusions hosting these deposits do not carry adequate signals for the source of gold, we explore the deep roots based on available geophysical data. We show that the gold deposits are preferentially distributed above zones of uplifted MOHO and shallow LAB corresponding to thinned crust and eroded sub-lithospheric mantle, and that the mineralization is located above regions of high heat flow representing mantle upwelling. The NCC was at the center of a multi-convergent regime during the Mesozoic which intensely churned the mantle and significantly enriched it. The geophysical data on Moho and LAB upwarp from the centre towards east of the craton is more consistent with paleo-Pacific slab subduction from the east exerting the dominant control on lithospheric thinning. Based on these results, and together with an evaluation of the geochemical and isotopic features of the Mesozoic magmatic intrusions hosting the gold mineralization, we propose a genetic model that invokes reworking of ancient Au archives preserved in the lower crust and metasomatised upper mantle and which were generated through multiple subduction, underplating and cumulation events associated with cratonization of the NCC as well as the subduction-collision of Yangtze Craton with the NCC. The heat and material input along zones of heterogeneously thinned lithosphere from a rising turbulent mantle triggered by Mesozoic convergent margins surrounding the craton aided in reworking the deep roots of the ancient Au reservoirs, leading to the major gold metallogeny along craton margins as well as in the interior of the NCC.

On the relation between the rare-earth — rare-metal and gold ore mineralization and fault-block tectonics of the Ukrainian Shield. 1

The paper, which is the first of a series of articles on the relation of metallogeny and fault-block tectonics of the Ukrainian Shield (USh), summarizes data on the chemical-mineralogical composition and the exact location of deposits, ore occurrences and points of increased rare-earth — rare-metal and gold mineralization, which are combined into eight groups: TR, U and Th, W and Mo, Be and Sn, Ta, Nb and other rare metals, zir-con and monazite (Zr), Au, F. They are compared with the scheme of the fault-block structure of the shield constructed from the results of tectonophysical studies. A detailed description of the fault zones of the USh has been given and many of them are shown to be composed of packets of a budinized and cataclasized varicoloured complex: metamorphosed basites and ultrabasites, calciphyres, quartzites, gneisses, micas, skarns, plagioclasites, quartz-feldspar rocks and silicification zones. The formation of such packages of the varicoloured complexes is associated with shear processes in wide (from 7 to 20 km) fault zones, accompanied by tectonic stratification of the basement rocks, dynamometamorphism, diaphthoresis, metasomatism, etc. The age of the fault zones of the USh and correlation with the formation of ore mineralization are considered in this article. It is emphasized that the rock complexes of the Precambrian faults are brought to the surface from considerable depths and are determined by the conditions of deep stress metamorphism and granitization during shifts, therefore they cannot be compared with complexes of modern faults. However, the structural parageneses of Precambrian faults in their geometric relationships are close to those obtained from the results of physical experiments on brittle-plastic and plastic materials. This makes possible to determine the nature of the stress-strain state of the Earth’s crust during the process of fault formation and the parameters of the stress fields. It is established that 94 % of all deposits and ore occurrences are located within fault zones, the area of which occupies about 22 % of the USh area. The obtained data refine the known metallogenic maps of the USh and allow reducing the priority areas in four to five times when planning future mapping and prospecting works for the groups of deposits under consideration.

Axillary Lymph Node Dissection Extension in Breast Cancer Between Under and Overtreatment Analysis of a series of cases and literature review

The surgical management of breast cancer tumors depends not only on knowing the right histological type of tumor, but also on identifying the grade of axillary node invasion and the presence of metastases. Unfortunately, due to a lack of general understanding of how these tumors actually spread and their path towards axillary lymph nodes, there is a tendency of over or undertreating patients in the surgical environment. Even though we now have the Sentinel Ganglion method to help us, we haven�t decided on a universally accepted algorithm in the management of this disease. Many studies are still needed in order to fully clarify the most appropriate surgical management for each type of tumor and the level of axillary node dissection. Multiple factors should be taken into account when managing the case of a patient suffering from breast cancer and faced with the need of an axillary lymph node dissection (ALND). We have tried to identify some of these factors based on the experience of our clinic and available literature. The factors identified are the positive SLN (Sentinel Lymphatic Node) aspect, the differentiation between micro and macrometastases, the use of the S classification of SLN and microanatomic location of SLN metastases and the microanatomic location (MAL) of the tumor deposit in the sentinel ganglion.

Fine particle retention and deposition in regions of cyclonic tidal current rotation

Benthic sediments in continental shelf seas control a variety of biogeochemical processes, yet their composition, especially that of fine sediment, remains difficult to predict. Mechanisms for mud or fine sediment deposition and retention are not fully understood. Using sediment data and a hydrodynamic model of the Northwest European shelf seas, a relationship is shown to exist between fine benthic sediment composition and regions of cyclonic tidal current rotation. The reduced thickness of cyclonic tidal benthic boundary layers compared with the anticyclonic case promotes deposition of fine sediment and trapping of resuspended material. Adding the effects of the benthic boundary layer thickness, as influenced by ellipticity or not, sheds some light on the limitations of approaches only focusing on bed shear stress and sediment pathways to predict the location of mud deposits. A tidal boundary layer predictor that includes ellipticity alongside tidal current magnitude and depth was shown to spatially agree with maps of mud deposits.

Primorskoye epithermal Ag-Au deposit (Northeast of Russia): geologic aspects, mineralogic and geochemical features, and ore formation conditions

As a potentially large Ag-Au epithermal deposit, Primorskoye comprises the following three areas: Kholodny, Spiridonych, and Teply. This deposit is located in the Omsukchan district of the Magadan Region, where similar deposits, including Dukat, Lunnoye, Goltsovoye, Arylakh, Tidit, and Perevalnoye, have developed. The deposit can be attributed to the Kalalagian volcano-tectonic depression and is localized in a flat-lying rock mass in the Late Cretaceous ignimbrites and rhyolites having thicknesses of greater than 700 m, which is cut through by numerous dykes of medium and major composition. According to the drilling data, the solid mass of leucocratic granites is located in deposits at a depth of 400–500 m with outcrops in the northeastern part of the ore field. The presence of Bi-containing galena and matildite, the availability of mid and high temperature facies of metasomatites (epidote and actinolite), and the specific physical and chemical conditions during the formation of the epithermal Ag-Au ores indicate the intrusive position above and the role of granitoids as generators of high temperature magmatic fluids, which introduced Bi and heated the rocks enclosing the mineralization. The geochemical features of the ores are well correlated with their mineral compositions. The high concentrations of Mn and Ag, elevated concentration of Au, low concentrations of Cu, Pb, Zn, Sb, As, Bi, and Te, low sum of REE, and negative Eu- and positive Се-anomalies were observed. The high values of the Te/Se, Sr/Ba, Y/Ho, and U/Th indicators in the ores are associated with the deposit location in the zone of granitoid massif effect. Further, the physical and chemical parameters of ore formation in the Teply area are unusual and are characterized by high temperatures, low concentrations of salts, and fluid density, which are indicative of the typical “dry steam” conditions. The obtained results allow the Primorskoye epithermal deposit to be attributed to the intermediate class. The information present in the article is practically valuable for the regional forecast and metallogenic developments as well as for searching and assessing the epithermal Ag-Au deposits.

Detection of prospective areas for mineralization deposits using image analysis technique of aeromagnetic data around Marsa Alam-Idfu road, Eastern Desert, Egypt

Area around Marsa Alam-Idfu road is considered as one of the most prospective regions for gold and base metals mineralization in Egypt. The total intensity aeromagnetic reduced to northern magnetic pole (RTP) data of such area revealed that a set of parallel continuous linear features taken NNW-SSE trend with variable magnetic amplitudes, which are related to faults, dykes and shear zones. Also, this map showed strong negative and positive magnetic anomalies generated in contact zones, which may be considered with the linear features as prospective areas for mineralization.The application of centre for exploration targeting (CET) grid image analysis technique was applied for the aeromagnetic data of such area for rapidly locating regions perceived to be most favorable for gold and base metals deposits. The technique generated a series of high structural complexity maps which are combined to create an overall prospectively map that defined regions of high potentially for mineral deposits.Integration of the obtained results from the resulted maps and the RTP magnetic map, aided by the geological information revealed that a good correlation between the known gold and base metals locations and the regions of mineralization that are generated by the proposed technique. Besides, additionally locations of gold and base metals deposits were found on the generated map. These new locations are suggestive of where the mineralization may occur. The derived locations of these mineralization are aligned along definite trends, which are arranged according to their magnitude and importance as NNE-SSW, NW-SE, NNW-SSE, E-W and NE-SW directions. Serpentine rocks and their contacts with the surrounding rocks could be considered valuable as gold mineralization zones of economic importance and are considered as significant targets for follow-up and ground investigations.

Моніторинг та картографування територій нелегального видобутку бурштину за даними ДЗЗ (на прикладі Житомирського Полісся)

The article presents the distribution of current locations of amber deposits on the territory of Ukraine using cartographic data. The preconditions and the scale of the problem are indicated. The list of areas where the activity of amber extraction is currently the largest is given. The main possible ecological, economic and social consequences of illegal extraction of amber for natural ecosystems are determined, and the specifics of damage are described. The study investigates the possibility of detecting areas damaged by amber mining through multi-zonal satellite images Sentinel-2 that are available in a free access and have a high resolution. Composite images have been selected and the best identified composites for areas of illegal amber extraction have been chosen. Classifications of land covers of the area have been studied in the context of the last two years and qualitative changes in the structure of land use were detected. It has been shown that data of space surveys in the monitoring mode allow to indicate and map the illegal extraction of amber, as well as to detect the scale of negative impact on the environment for implementation of a system of reclamation methods for damaged territories. This methodology can be used in monitoring compliance with environmental legislation in open mining areas of other minerals.

To the theory of determining the location of hydrate deposits in gas pipelines by acoustic sounding

Evolution of pressure perturbations propagating in pipeline filled with gas-and-drop medium representing “wet” methane at temperature below dew point and having damaged section, in form of extended narrowing of channel due to hydrate plug, is investigated. Hydrate formation is due to the presence of water (or its vapours) and gas, the components of which dissolve in water under certain conditions form a solid phase. Hydrate deposits help to reduce the cross-country capacity of gas pipelines and therefore their detection is a pressing task. It is proposed to solve the problem using acoustic methods. For this purpose mathematical model of propagation of acoustic waves in long-wave range in gas-and-droplet medium is considered. The horizontal pipeline appears semi-pointed, the solution is sought in the form of a harmonic wave. Wave is one-dimensional, having small amplitude of oscillations. Based on dispersion equations, dependence of phase velocity and attenuation coefficient on frequency of acoustic wave disturbance and on volume content of suspended phase (water droplets) are built. In the high frequency region, the attenuation coefficient increases with the volume content. The formulas for reflection and passage coefficients are derived taking into account pipeline narrowing due to hydrate deposits. The results of numerical calculations illustrating the dynamics of pulse signals depending on the thickness of the gas hydrate on the inner wall of the pipeline are presented. Calculations are based on forward and backward Fourier transformations and the use of software. It is established that the greater the hydrate deposit on the wall in thickness, the greater the amplitude of the returned reflected signal.

The Zn-Pb Mineralization of Florida Canyon, an Evaporite-Related Mississippi Valley-Type Deposit in the Bongará District, Northern Peru

AbstractThe Florida Canyon evaporite-related Zn-Pb sulfide deposit, in northern Peru, is one of the largest Mississippi Valley-type deposits in South America. Triassic carbonate and former evaporite-bearing rocks of the Pucará Group host the orebodies that constitute two different styles: (1) predominantly stratabound ore associated with hydrocarbon-rich porous dolostones and evaporite dissolution breccias and (2) high-grade ore associated with evaporite breccias representing diapiric injections along faults. A dome structure that controls the location of the ore deposit was defined by drill hole spatial data; the dome likely resulted from halokinetic processes during Andean deformation. NNE-trending, steeply dipping secondary faults linked to major northwest structures appear to control the distribution of ore grades in the deposit. Mineralization postdated hydrocarbon migration and accumulation. Strontium, carbon, and oxygen data isotope signatures allow distinction between pre- and synmineralization carbonate stages. The sulfur isotope composition of sulfides in the deposit suggests they precipitated as the result of mixing of a metal-rich fluid with resident hydrogen sulfide in the dome. Local thermochemical sulfate reduction may have contributed to the reduced sulfur budget during mineralization.

Norms Formation: The Gold Rush and Women's Roles

Does the mining-driven scarcity of women affect gender norms? Do gender norms persist over time? We explore the Gold Rush in Western United States in the late19th-century as a natural experiment to answer these questions. We use a geographic difference-in-difference methodology, exploiting the location and discovery of the gold deposits and its influence on sex ratios, to understand short term and persistent changes in women’s labor market participation and marriage market opportunities. Gold mining, through the oversupply of marriageable men with income, increased (decreased) marriage rates among women (men). Women married older men with higher prestige occupations. In parallel, the Gold Rush created a market based service sector economy, potentially catering to men with money but poor marriage prospects. Using all subsequent censuses up until 1940, we show that the effects persist over time.

Cobar Deposits - Structural control

The Cobar Superbasin is located in the Central Subprovince of the Lachlan Orogen in the central part of New South Wales, about 700km northwest of Sydney. The Cobar Superbasin is the most mineralised Palaeozoic sedimentary basin in Lachlan Orogen. It has an estimated pre‐mining resource of 202 t of Au, 4.597 t Ag, 2.5 Mt Cu, 4.8 Mt Zn and 2.8 Mt Pb metals. The term ‘Cobar Superbasin’ is introduced to refer to a series of deep-water troughs/basins, inferred to have formed as half graben and shallow water shelfs. Its northern portion is dominated with siliciclastic sedimentary sequences whilst the southern portion comprises sediments, volcaniclastics, volcanic rocks, granites and minor limestone. The basin formed in the Early Devonian by NE-SW transtension and was closed by NW transpression in Late and Middle Carboniferous. The overall inversion structural style is NW-SE folding, overprinted by NE-SW trending and NNW-trending eastwards oblique left-lateral reverse faulting, in a combined thick- and thin-skinned tectonic environment. The Cobar Style mineralisation is a common name for mineral deposits hosted in the Cobar Superbasin and includes massive sulphides (VMS), clastic hosted Pb-Zn mineralisation and epithermal gold. In the Cobar Superbasin, the primary location of mineral deposits is controlled by basement architecture and then overprinted and modified with secondary controlling factors of inversion tectonics. Primary control is related to the location of mineral deposits within basin architecture and directly depends om major basement structures such as: - basin marginal growth fault; - intersection of growth and transform/transfer faults; and - intersection transform/transfer faults. Secondary control is related to deposit geometry and is direct consequence of invasion tectonic such as: - intersection termination and deflection of strike-slip faults; - overlap of en-echelon strike-slip; and - junction of major faults. Cobar Style mineralisation occurs in form of sheeted veins characterised by narrow width (5m - 10m), short strike (50m – 10m) and a significant depth extension (> 2000m). The deposits occur as a group of lenses in an en-echelon array with a steep plunge

Identifying Lithospheric Boundaries and Their Importance for Mineral Discovery

Major lithospheric boundaries under cover have commonly been recognised through tracing of potential field anomalies, such as extensive magnetic boundaries representing margins of upper crustal packages in conjunction with density contrast. Here, we extend the investigation of domain mapping to include isotope geochemistry and deep-probing magnetotelluric data, which are able to map the deeper crustal and mantle lithosphere. We demonstrate with examples across the Kalinjala Shear Zone, South Australia, and the Eastern Gawler Craton, that major lithospheric domain boundaries exert a primary control on the location of mineral deposits near the surface. We show examples of correlating magnetotelluric models derived from the Australian Lithospheric Magnetotelluric Project (AusLAMP) and higher density broadband magnetotelluric deployments along profiles with isotope geochemistry across major lithospheric boundaries in South Australia. As one example, the Kalinjala Shear Zone in the southern Gawler Craton can be better constrained using the additional geochemical and magnetotelluric data sets and solve a long-standing debate about the northern extension of the Kalinjala Shear Zone towards the prospective Olympic Province, which hosts, major IOCG deposits. These insights have led to the development of future exploration programs which focus on in-fill broadband deployments for MT and isotope mapping to trace major lithosphere boundaries to the surface, reducing risk for mineral exploration.

Imprints of tectonic processes imaged with magnetotellurics and seismic reflection

Co-located seismic and magnetotelluric (MT) profiles provide fundamental geophysical data sets to image the crust of Australia. Despite their overlapping nature, the data are processed and interpreted separately based on legacy workflows. We qualitatively compare 2D resistivity inversion models derived from MT and uninterpreted seismic reflection profiles across Proterozoic Australia to address the long-standing cross-cutting nature of interpreted seismic faults and low resistivity zones derived from MT. We find that a good correlation exists between high/low reflectivity in seismic sections and low resistivity in MT sections. These relationships elucidate signatures of past magmatic and fluid-related events and constrain zones of weakened rheology in the crust. Depending on their characteristics, these signatures may signify fossil melting of the crust due to underplating or magmatic invasion into the crust or reworking associated with redistribution of fluids along newly developed faults. These findings have implications for constraining mineral deposit genesis and location.