The relationship between lineaments and cave passages in unfaulted gently-folded strata, Snail Shell Cave, central Tennessee, USA

A novel method to map and quantitatively describe very gentle folds (limb dip <5°) at cratonic cave sites was evaluated at Snail Shell and Nanna caves, central Tennessee, USA. Elevations from the global SRTM digital terrain model (DTM) were assigned to points on late Ordovician geologic contacts, and the elevations of the points were used to interpolate 28 m cell size natural neighbor digital elevation models (DEM’s) of the contacts. The global Forest Canopy Height Dataset was subtracted from the global 28 m cell size AW3D30 digital surface model (DSM) to create a DTM, and that DTM was applied in the same way. Comparison of mean and modal strikes of the interpolated surfaces with mean and modal cave passage trend shows that many passages are sub-parallel to the trend of an anticline. WithiSn 500 m of the caves, the SRTM- and AW3D30-based interpolated surfaces have mean strikes within 8° of the mean strike of an interpolated reference surface created with a high resolution (~0.76 m cell size and 10 cm RMSE) Tennessee, USA LiDAR DTM. This evaluation shows that the SRTM- and AW3D30-based method has the potential to reveal a relationship between the trend of a fold, on one hand, and cave passages, on the other, at sites where a geologic contact varies in elevation by >35 m within an area of <12.4 km2 and the mean dip of bedding is >0.9°.

The Kinta Valley karst landscape is characterised by residual limestone hills scattered all over the valley. The aim of this study is to ascertain the link between lineament and cave passage orientations, and to identify the main fracture controlling the karst features. To achieve that, standard cave surveying and direct lineament extraction techniques, from a 2.5m resolution spot image, were employed. Six trends of lineaments were obtained from the remnant limestone hills, and their main orientation appears to be in the NNW-SSE. Similarly, various caves were surveyed and mapped; their passage orientation analyses reveal that NNW-SSE is the prominent direction. The similarity of the lineaments orientation and caves passage trend attests that the karst formation is controlled by the geological structures. Such a similar trend observed in all hills enabled to infer the orientation of the primary structure responsible for the formation of the extant karst features. The multi-fracturing episodes rendered the Kinta Valley to be structurally complex and the karst features unravelled this effect, as evidenced by features such as circular and sinuous cave passage morphology, which developed ensuing fractures oriented in different directions.

Ordovician karst reservoir is the target for oil exploration and production in Lungu area of Tarim Basin. Well‐Driven‐Seismic data reprocessing has improved the seismic images on various karst features, such as caves, cave passages, dolines or sinkholes, and eroded valleys and hills of different scales. Detailed seismic description of karst topography and caves are the two basic tasks for drilling success. The seismic interpretation was guided by seismic attribute maps as quality control. The results exhibit complex karst topography and unevenly distributed caves in various sizes and shapes. Delineation of the cave systems helps understanding complex relationship between topography and cave development and evaluating caves for drilling.

Among the several techniques that allow the estimation of mean depths from airborne geophysical magnetic data, the Euler deconvolution became popular due to the high level of reliability in the generated data. With the use of this tool, it is possible to study structures remotely at different crustal levels that may or may not contain mineralization, consequently being able to determine potential targets for mineral exploration or to study better its relation with the structural background. With the analysis of the magnetic susceptibility of subsurface and the inversion profiles of the magnetic data (Euler deconvolution 2D) were interpolate a 3D model of the region, that allowed to generate a descriptive suggestion of the geometry of the Pari syncline, located in the Cuiabá Group, in the northwestern portion of the Paraguay belt. It has a strong structural control in the context of the Pari River basin and a great auriferous potential, as evidenced by updated research and exploration data. The data applied in this paper were extract from the Cuiabá aerogeophysical project and previous mappings and have their mean depths correlated with the Cuiabá group.

The Belle Fourche arch, a subtle northeast-trending paleoarch, extends across the central part of the Powder River basin, Wyoming, to the Black Hills uplift. The arch is the result of differential vertical uplift, primarily during Cretaceous time, on numerous northeast-trending structural lineaments. Lineament trends are identified from structural offsets in the Black Hills monocline, offsets in well-defined linear topographic escarpments, and by linear drainages which connect trends between the monocline and the escarpments. Underlying basement zones of weakness are thought to be shear zones of Precambrian age analogous to the Mullen Creek-Nash Fork shear zone of southeast Wyoming. Stratigraphic evidence suggests that the structural lineaments which form the Belle Fourch arch have rejuvenated periodically throughout the Phanerozoic. Subtle movements along the lineaments have affected depositional environments and hydrocarbon accumulation in virtually all significant reservoirs in the northern two-thirds of the basin. Evidence includes: (1) localization of Minnelusa Formation (Permian) hydrocarbon production along the crest of the arch; (2) localization of Dakota Formation (Cretaceous) alluvial point-bar production on the crest of the arch; (3) localization of lower Muddy Formation (Cretaceous) channel deposits parallel with, and on the downthrown sides of, lineament trends; (4) abrupt change in depositional strike of upper Muddy Formation (Cretaceous) marine bars close to the arch; (5) superposition of Turner sandstone (Cretaceous) channel deposits alon the trends of Muddy channels; and (6) localization of virtually all significant Upper Cretaceous Shannon and Sussex sandstone offshore marine-bar production along the crest of the arch. Subtle uplift along the arch was persistent during at least lower Muddy through Sussex deposition, a period of about 35 m.y.

A subtle northeast-trending paleoarch extends across the central part of the Powder River basin, Wyoming, from the Salt Creek-Meadow Creek structural province to the Black Hills uplift. The Belle Fourche arch is the result of differential vertical uplift, primarily during Cretaceous time, on numerous northeast-trending structural lineaments. Lineament trends are identified from structural offsets in the Black Hills monocline, offsets in well-defined linear topographic escarpments, and by linear drainages which connect trends between the monocline and the escarpments. Underlying basement zones of weakness are thought to be Precambrian age shear zones analogous to the Mullen Creek-Nash Fork shear zone of southeast Wyoming. Stratigraphic evidence suggests that the structural lineaments which form the Belle Fourche arch have been rejuvenated periodically throughout the Phanerozoic. Subtle movements along the lineaments have affected depositional environments and hydrocarbon accumulation in virtually all significant reservoirs in the northern two-thirds of the basin. Evidence includes: (1) localization of Minnelusa Formation (Permian) hydrocarbon production along the crest of the arch; (2) localization of Dakota Formation (Cretaceous) alluvial point-bar production on the crest of the arch; (3) localization of lower Muddy Formation (Cretaceous) channel deposits parallel with, and on the downthrown side of, lineament trends; (4) abrupt change in depositional strike of upper Muddy Formation (Cretaceous) marine bars close to the arch; (5) superposition of Turner S ndstone (Cretaceous) channel deposits along exactly the same trends as those of Muddy channels; and (6) localization of virtually all significant Upper Cretaceous Shannon and Sussex Formation offshore marine-bar production along the crest of the arch. Subtle uplift along the arch has been persistent from at least lower Muddy through Sussex deposition, a period of about 35 m.y. End_of_Article - Last_Page 569------------

Linear anomalies are important in the interpretation of gravity data because they indicate some important structural features. Gravity anomalies obtained from horizontal derivatives generally reflect lineaments and faults or compositional changes which can describe structural trends of a region. This study involves the delineation of the Gongola basin structural trend based on the convolution between the Fourier kernel obtained from the second horizontal derivative (SHD) of the truncated horizontal plate model (THPM) and the gravity anomaly. The Fourier kernel for the second horizontal derivative was obtained through the application of Fourier transform over the expression of a Bouguer slab with exponential density contrast variation. The weighting density distribution is obtained through the determination of the mean depth perturbed by interfaces. The edges were identified by the closed maximum in the SHD gravity map. The results show that the region’s Bouguer gravity is characterized by elongated SE-NE negative gravity anomaly corresponding to a collapsed structure associated with a granitic intrusion beneath the region, limited by the fault systems. This was clearly evident on an isostatic residual gravity map. The horizontal gradients of the Bouguer gravity anomaly data from the basin defined the edges, lineaments and faults structures very clearly. Major and minor lineaments derived from the SHD map were transposed on the isostatic residual map. These features led to the production of the structural map of the study area. The NE-SE and E-W trending lineaments were interpreted as fault (strike-slip wrench) systems. The steep gradients evident in the gradient maps are reflection of sharp discontinuities or interfaces between basement blocks of contrasting properties, such as: fault, basement shear zones and intrusive contacts. The tectonic information brought about by the distribution of the lineaments was corroborated by the 2D gravity model of the basin. These models and fault map will complement the selection of the promising areas for detailed hydrocarbon mapping.

In this paper, Landsat images are used in the mapping of transverse fault lineaments in Zagros, Iran, and the origin of the fault lineaments as the result of basement reactivation faults is examined using geomagnetic maps. The area under investigation is located in the SE part of the Zagros Fold Belt (ZFB) and was affected by influence of concealed faults, or fault lineaments, during the late Alpine Zagros orogeny. Image interpretation of geological structures such as curvilinear geometry of fold hinges, en echelon pattern of surficial lineaments and younger folds, and breached salt plugs, has been used to map the fault lineaments. Two sets of strike‐lateral transverse fault lineaments have been detected. The first set, NW‐trending, was identified by right lateral curved geometry of the main fold hinges, generation of younger folds, and en echelon pattern of surficial lineaments. The second set, NE‐trending, was verified based on left lateral displacement of the structures and alignment of salt plugs pierced anticline hinges. The placement of Upper Proterozoic salt plugs on the surface along the fault lineaments, together with their correlation with the magnetic‐driven lineaments, implies that the fault lineaments have a basement origin. The trend of these fault lineaments can be correlated with the trend of basement faults in the northern margin of the Arabian plate. The key result of this study is that the fault lineaments identified by integration of remotely sensed data and geomagnetic maps are generated as first order wrench faults by reactivation of the N–S‐trending basement faults. The thick Hormoz Salt formations overlaying the basement do not allow the fault lineaments to emerge at the surface. Therefore, they can be mapped through regional remote sensing and their basement origin can only be recognized by their correlation with magnetic faults. It is also concluded that satellite imagery can greatly contribute to the structural mapping of the ZFB and is therefore a valuable aid for oil and gas exploration in analogous tectonic environments.

Menopausal changes expose an individual towards risk of various pathologies during midlife transition. This study aimed to investigate the possible association of bone mineral density (BMD) with periodontal parameters in early postmenopausal Indian women. In 78 dentate postmenopausal female patients periodontal examination was performed including clinical attachment loss, pocket depth, plaque index and sulcular bleeding index. Alveolar crestal height was measured on proximal surfaces of all posterior teeth except third molars with the help of bitewing radiographs. Patient's BMD was assessed with dual energy X-ray absorptiometry. Statistical analysis was performed to assess the correlation between BMD and periodontal parameters. Pocket depth, clinical attachment loss and alveolar crestal height were found to have negative and statistically significant (P=-0.000 each) correlation with T-score, with the value of Pearson's correlation coefficient being -0.474, -0.426, and -0.419 respectively. Number of teeth lost due to periodontitis was not significantly correlated with T-score (P>0.05). Results of anova and the post-hoc Tukey test revealed a statistically significant difference of mean clinical attachment loss, pocket depth and alveolar crestal height for the osteoporotic versus osteopenic group and the osteoporotic versus normal group. However, between the osteopenic and normal group, the differences of mean were statistically nonsignificant (P>0.05). Body mass index was found to have a weakly positive (r=0.376) and statistically significant (P=0.001) correlation with T-score. Bone mineral density is an important risk indicator for periodontitis in postmenopausal women. Number of teeth lost due to periodontitis is not significantly affected by the BMD of the early postmenopausal phase.

Both Airborne Magnetic and Radiometric datasets were employed to interpret the geology and geological structures that serve as host to gold and associated minerals within the Bida and Zungeru, Niger State, Nigeria. An area of 55 by 110km2, contained within the cretaceous sediments of Bida Basin and the meta-sediments of Zungeru-sarkin-pawa schist belt. Data interpretation involve the application of a mathematical algorithm for data enhancing such as, Reduce to the Equator, Analytical signal, First Vertical Derivative, and Centre for Exploration Targeting (CET) to the magnetic data, and Ternary imaging to the radiometric data, with a sole aim of mapping geological structures such as faults fracture folds joints and geological boundaries and possible gold mineralization veins that arise from hydrothermally altered zones. Two major geological units inhibit the study area, the cretaceous sediment, and the meta-sediments, major feature identifies within the Cretaceous sediment are the folds majority of which are located within the contacts. The result of the 1VD display is the vivid picture of the observed structural features such as faults fractures folds’ contacts labeled F1 to F8 both within the high region of magnetic susceptibility (in red) and low regions (in blue) geology contacts (yellow), folds (bold yellow) all across the field. Prominently at the North-Western corner of the study area are sets of linear structure that trend NE-SW, located within the contacts between the mylonites and the amphibolites and the belt-type meta-sediments located around Katakwo, Gindei, Kwange, Gabas and Akusu villages. Equallyworth mentioning are sets of lineament (in blue) trend E-W all across the mid-region of the study area, precisely at the Eastern corner within and below the Federal University of Technology Minna around Kata-eregi, Sabon-Dagan, Kakaki down Minkwoigi, Sunbwagi, Kakagi, Sabon dagga, and Bobo-shiri towns, where the majority of volcanic activities must have been recorded. The airborne radiometric show mobilization of the immobile thorium Th, concentration, and this also indicated hydrothermally altered zones. The increase in potassium concentration and decrease in K/Th relation observed from radiometric interpretation are very pinpointing of hydrothermal activities within the study area. The gold mineralisations are found within this vein and in the adjacent, highly deformed host rock located below the Federal University of Technology Minna Campus. The deformation seems to comprise principally of pebbly schist, amphibolites along fine-grained and magnetite.

Analysis and integration of geological/metallogenic data and digitally processed gravimetric/aeromagnetic data to the oriental Saharan Atlas domain were carried out to understand the spatial distribution and structural control on Pb-Zn (Ba) deposits of the oriental Saharan Atlas. The use of this combined technique suggests that most of mineral deposits appear to be regionally controlled by structural trends (subparallel NE-SW-trending) along margins of subsiding sedimentary basins. Mineralization occurs along or near major NE-SW-trending faults, locally intersected by NW-SE-trending faults. In addition, mineral deposits are usually either inside anticlinal hinge zones (example, Merouana, Ichmoul and Ain Mimoum ore deposits) or on the flanks of anticlinal structures (example, Ain Bougda ore deposit). In “diapiric zone”, mineral deposits are generally located on diapiric structures borders (peridiapiric concentrations), related to NE-SW/NE-SW and E-W-trending faults. Other mineral concentrations occurs along the margins of tectonic troughs zones (example, Morsott trough) resulting probably by NW-SE-trending deep faults movement. In summary, our research suggested that regional parameters, such as NE-SW/NW-SE-trending lineaments, intersections of these lineament zones and margins of subsiding sedimentary basins/diapiric structures, serve as significant indicators and provides a valuable framework for guiding the early stages of Pb-Zn (Ba) mineral exploration; other considerations must then be applied in this region, like integration of surficial geochemical anomalies that allows better delineation of targets for further mineral exploration.

Origin, characteristics and significance of collapsed-paleocave systems in Sinian to Permian carbonate strata in Central Sichuan Basin, SW China

Identification of potential mineral exploration targets from the interpretation of aeromagnetic data covering the Sirwa region (Central Anti-Atlas, Morocco)

Abuja and environs usually experiences water shortage during the dry season as a result of rapid population growth, due to the fact that the water from Lower Usuma Dam used for domestic and industrial purposes are no longer sufficient to cater for its teeming population. The shortage can be minimized through better understanding of lineament configurations of the area. Regional groundwater studies using high-resolution aeromagnetic data in Abuja and environs, North-Central Nigeria were carried out to address water shortages in Abuja and its surroundings. The aim of the study was to identify groundwater targets/potential zones for the purpose of providing sufficient water to the communities in the area. The study area is situated in the North-Central part of Nigeria and lies between latitudes 8° 00’- 9°30’ N and longitudes 6°30’- 8°00’ E. First vertical derivative (1VD) technique was applied to the residual magnetic data of the study area using Oasis Montaj software version 8.3 and thereafter extracted lineaments from 1VD map using ArcGIS software version 10.4.1. Result of 1VD technique indicates that polyphase deformation was pervasive throughout the area as joints, fractures, faults, as well as folds in the map. Major lineament trends identified in the study area are NNE-SSW 27.47%, NE-SW 25.54%, ENE-WSW 18% and N-S 9.57%, the magnitudes and orientations of the lineaments are essential for groundwater movement. The study indicates that Dogon-Kurmi, Gitata, Rafin, Gurku, Karshi, Keffi, Paiko, Farindoki, Takuti, Lambata, Izom, Tudun Wada, Safon Lapai, Mayaki, Gwagwalada, Gidan Ali, Takura, Dafa, Dangara, Abaji, Kwali, Zuba, Madalla, Gauraka, Suleja, Kuje, Abuja, Bwari, Udegi, Zango-Daji, eastern part of Katakwa, Gadabuke, Buga, Koton-Karfe, Bibirako, Kworaki, Toto, Dagoshi and Umaisha have good groundwater prospect. Fieldwork conducted in the area confirmed the existence of lineaments/fractures in the area and as such are targets for groundwater exploration.

Middle Proterozoic age iron, light rare-earth apatite, copper deposits are exposed in the St. Francois Mountains in a larger alkalic granite and rhyolite terrane that is favorable for the occurrence of world-class deposits of the Olympic Dam type. The Precambrian age structural network of lineaments cut the Proterozoic rocks above where movement has been revived in post-Precambrian time including both Paleozoic and Mesozoic age rocks. The Mississippi Valley-type of deposits in Paleozoic-age rocks are located at the crests of domes (Central Kentucky and Central Tennessee districts), or faulted collapsed domes (Illinois-Kentucky) on half-domes (Upper Mississippi Valley and Tri-State districts), or they surround Precambrian islands in an open oval in fault zones and facies changes where shales, carbonate rocks and sandstones pinch out (Southeast Missouri). Some ores were deposited as veins in faults, as replacements in adjacent permeable beds, in cryptovolcanic breccia (part of Illinois-Kentucky), or in fault zones adjacent to and above Precambrian rift valleys (eastern northern Arkansas and parts of the Illinois-Kentucky districts). In the Central States major structures of repeated uplift and subsidence are crossed by a complex system of intersecting structural lineaments that form a cratonic network across the large domes, basins and rift valleys. The lineaments trend northwest, northeast, east and north. Some are curved and many have a strike-slip component of movement