Drones in carbonate geology: opportunities and challenges, and application in diagenetic dolomite geobody mapping

Unmanned aerial vehicles (UAVs) or drones have become widely available for use in a broad range of disciplines. Despite the decreased cost and technological developments of platforms, sensors and software, the use of drones in carbonate geology has yet to be exploited. Nevertheless, drones offer multiple advantages over traditional field work or high-altitude remote sensing techniques, in that they enable the reconstruction of three dimensional models of inaccessible or unsafe outcrops, and can bridge the spatial scale gap in mapping between manual field techniques and airborne, high-altitude remote sensing methods. In this contribution, we present our methodology of structure from motion photogrammetry on drone-captured images and highlight opportunities and challenges of using drones in carbonate geological studies. Moreover, we apply this method to document the spatial distribution and dimensions of diagenetic dolomite geobodies in Carboniferous limestone host rock of the Picos de Europa, northern Spain. The results of our study indicate that dolomite geobodies occur preferentially near to strike-slip faults, rather than thrust faults or specific types of limestone host rock lithology, in the study area. The geobody dimensions appear to be related to the strain magnitude of the strike-slip faults. We propose that these identified links and controls are applicable to structurally-controlled dolomitization on a more general basis. Our study has demonstrated the potential for using drones in carbonate geological studies

Soil Contamination Interpretation by the Use of Monitoring Data Analysis

The presented study deals with the interpretation of soil quality monitoring data using hierarchical cluster analysis (HCA) and principal components analysis (PCA). Both statistical methods contributed to the correct data classification and projection of the surface (0–20 cm) and subsurface (20–40 cm) soil layers of 36 sampling sites in the region of Burgas, Bulgaria. Clustering of the variables led to formation of four significant clusters corresponding to possible sources defining the soil quality like agricultural activity, industrial impact, fertilizing, etc. Two major clusters were found to explain the sampling site locations according to soil composition—one cluster for coastal and mountain sites and another—for typical rural and industrial sites. Analogous results were obtained by the use of PCA. The advantage of the latter was the opportunity to offer more quantitative interpretation of the role of identified soil quality sources by the level of explained total variance. The score plots and the dendrogram of the sampling sites indicated a relative spatial homogeneity according to geographical location and soil layer depth. The high-risk areas and pollution profiles were detected and visualized using surface maps based on Kriging algorithm

Diagenesis of phosphatic hardgrounds in the Monterey Formation: A perspective from bulk and clumped isotope geochemistry

Understanding the authigenesis of carbonate fluorapatite through isotopic geochemistry can yield important information on fundamental geologic processes occurring on continental margins around the world. This is particularly true for phosphatic hardgrounds, which are often found in regions of upwelling, but of which questions remain about the initial formation and subsequent diagenesis. Here, we apply standard isotopes (δ13C, δ18O) alongside the novel clumped isotope (Δ47) used in this study for the first time to reconstruct the temperature of formation of carbonate ions within the lattice of sedimentary carbonate fluorapatite. We investigated phosphatic hardgrounds of Miocene age (12.7–10.8 Ma) sampled at El Capitan State Beach in the Monterey Formation. The range of isotopic signatures observed is between +1.5‰ and +8.0‰ for δ13C relative to the Vienna Peedee belemnite (VPDB) standard and –9.5‰ and –6.0‰ VPDB for δ18O, and values range between 0.599‰ and 0.615‰ for Δ47. The enriched δ13C and depleted δ18O signatures are suggestive of recrystallization within the methanogenic zone. Clumped isotope geochemistry further constrains this transformation as having taken place at a temperature of 61–66 °C ± 5 °C, in line with previous estimates for maximum burial of the Monterey Formation based on the silica phase transition. The calculated δ18O for the connate fluid shows an expected range for seawater composition for the Miocene, suggesting only minor contribution of silica-derived oxygen to the δ18O of carbonate fluorapatite. The combined conventional and clumped isotope data set also points out that methanogenesis took place deeper within the sediment in the middle Miocene than at present day within the Santa Barbara Basin. This study furthers our understanding of phosphogenesis and potential links to burial processes in the Monterey Formation, and it shows for the first time that the clumped isotope paleothermometer could be used to understand fundamental geochemical processes in authigenic sedimentary phosphates

Data for: Effect of salinity on the kinetics of pyrite dissolution in oxygenated fluids at 60 ºC and implications for hydraulic fracturing

Batch and mixed flow reactor data from pyrite oxidative dissolution experimentsTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Genesis of zebra dolomites (Cathedral Formation: Canadian Cordillera Fold and Thrust Belt, British Columbia)

The late diagenetic zebra dolomites (Middle Cambrian Cathedral Formation: British Columbia, Canada) formed from focalised fluid flow of hot saline fluids (T-h maximum= 180-200 degreesC, T-m = - 18 to - 20 degreesC). delta(18)O values vary around - 18.0 parts per thousand (VPDB) and delta(13)C around - 1.35 parts per thousand. Sr-87/Sr-86 values for the grey (a) replacive dolomite laminae (0.70958 to 0.70970) and for the white, partially replacive laminae and dolomite cement (0.71187 to 0.71228), support involvement of radiogenic fluids which interacted with siliciclastics. Zebra dolomitisation post dates cleavage and is controlled by normal faults. Syn-fracturing dolomitisation in an overpressured regime is invoked for the zebra dolomites formation while the associated coarse crystalline beige dolomites reflect the more passive influx of the dolomitising fluids replacing the host rocks. Overpressuring relates to the fluids that became expulsed during Fold and Thrust Belt development along the paleo-structural Kicking Horse Rim, which defines an area where major pateogeographical changes occurred in the Middle Cambrian. However, the exact age of the dolomites is still uncertain. The fact that MVT mineralisations (Kicking Horse and Monarch deposits), which post-dates zebra formation, occur within a similar structural setting adjacent to the zebra dolomites, suggests that similar fluid flow pathways where re-used several times