DOI: 10.1306/10231414089 Published on May 2015, First Published on May 04, 2015
Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200E, B-3001 Leuven, Belgium; present address: Department of Earth Science and Engineering, Imperial College London, Exhibition Road, SW7 2AZ London, United Kingdom; email@example.com
Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200E, B-3001 Leuven, Belgium; Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussels, Belgium; Marijke.Huysmans@vub.ac.be
(A) Overview of the Latemar and neighboring Ladinian carbonate platforms and Upper Ladinian intrusions of the Dolomites. (B) East–west dike-perpendicular cross section across the Latemar platform (modified from Preto et al., 2011). The platform is subdivided into different lithozones (Egenhoff et al., 1999). Figure modified from Jacquemyn et al. (2014, and used with permission of Elsevier).
Overview of the digital outcrop model (DOM). The part of the DOM obtained by helicopter LIDAR scanning is indicated by solid black lines. It is subdivided into four zones that are smaller and easier to manipulate. The rest of the DOM is acquired from the digital terrain model (DTM). The outlines of the reservoir model are indicated by the dashed line. Sample sections are marked by their section number.
Northern half of the digital outcrop model (DOM). The textured part of the DOM is acquired by LIDAR scanning, whereas the white part is obtained from the digital terrain model. The traces of the mafic dikes are shown in yellow. The volcanic breccia pipes are marked in red. A color version of this figure is available in the online version of this paper.
(A and B) Example of a photograph that is projected on the digital outcrop model on the northern flank of the Valsorda valley. A large dolomite body is located in the upper right corner of the photograph and model. Dolomite and limestone can be distinguished based on differences in rock color. (C and D) Two examples, at different scales, of clear dolomite versus limestone division are enlarged. Dolomite has an orange or brown patina, whereas limestone is mostly gray to white colored. The very high resolution of the photographs allows lithology distinction at meter scale (C).
Variogram grid of the complete lithology point cloud with a resolution of 5 m. Analogous to variogram maps, the center of the grid represents the starting point of all semivariograms. The semivariogram in a specific direction is then represented by a line crosscutting the variogram grid that starts in the center and follows this specific direction.
The orientation of all dikes is calculated by fitting a plane to the dike traces. (A) Equal angle lower hemisphere stereographic projections of all dikes. (B) Bi-directional rose diagram of the strike of all dikes. The main strike direction is approximately 325°.
Vertical proportion curve of lithology. Only the carbonate fraction is considered in this plot, and the magmatic bodies are disregarded. The Contrin Formation is almost completely dolomitized, and the UCF and UTF are basically free from replacement dolomite. The lower part of the LPF shows a strong decrease in dolomite–limestone ratio and stagnates around 23%. This value is maintained up to the top of the LCF. In the MTF, the dolomite percentage drops to zero.
Experimental omnidirectional semivariograms of the complete limestone–dolomite dataset (circles) and the complete dataset except the points belonging to the Contrin Formation (triangles). Their curves are relatively similar up to 400 m (1312 ft), at larger distances an average difference of 0.015 exists between both curves. Nested semivariogram models are fit to both experimental semivariograms (solid lines).
Three-dimensional contour surfaces at 0.09 of the variogram grids for the entire dataset and every zone separately. Orientation of all boxes is identical. The gray plane represents the best fit plane to the contour at 0.09 of all data. The subvertical and subhorizontal anisotropy is clearly visible for all data combined. For the separate zones, outcrop orientation has an important control on the contours. For example, the contour of the Plateau zone lacks the subvertical anisotropy. This can be explained by the fact that the topography of this zone is rather flat, and thus, very few vertically oriented point pairs are available. In every grid, it can be observed that anisotropy contours occur along the fitted plane.
Contour surface (green) of a large-scale variogram grid at 0.18 semivariance. The best-fit plane to the contour surface is marked in blue and is slightly dipping to the northeast. The anisotropy orientation is equal to bedding. The small-scale anisotropy contour surface is added in red for comparison (center of the picture). A color version of this figure can be seen in the online version of this paper.
Horizontal cross section through the reservoir model at the top of LPF after carbonate lithology kriging and emplacement of igneous rocks, showing the limestone and dolomite distribution. The outline of the Valsorda valley is indicated by a white dashed line. The mafic dikes are marked by light gray lines. The lack of dikes in the middle of the model is the result of the lack of information on the dike traces in the Valsorda.
Dike-perpendicular (A–C) and dike-parallel (D–F) vertical cross sections through the reservoir model. The Contrin Formation, at the base of the model, is completely dolomitized. Similarly, the top of the model consists of 100% limestone, based on field observations, which are not interpolated. This results in sharp upper boundaries of the dolomite bodies. (A) Vertical dolomite chimneys can be observed that rise up from the Contrin Formation. (B) Not all dolomite bodies are connected directly vertically to the Contrin Formation but have a horizontal connection to a dolomite pipe. Isolated dolomite bodies only account for 10% of the total dolomite volume. (C) Not only do vertical dolomite pipe rise up high into the Latemar Formation, wide triangular dolomite bodies also exist. (D and E) Parallel to the dikes, dolomite pipes are not always vertical, but large dolomite pipes are always rooted in the Contrin Formation. (F) Sub-vertical dolomite pipe with horizontal dolomite bodies.
Rose diagram of the dike orientation data (black) compared to the common plane of both small-scale anisotropy orientations (white arrow). The difference between the main dike orientation and the shared anisotropy plane is less than 3°.
↵* The surface area of exposed scree slopes is approximately 50%, where no lithology could be determined. The remaining amount of the outcrop model is categorized into limestone and dolomite based on outcrop color. The resolution of the point cloud is on average . DOM = digital outcrop model.
↵* Scan lines are horizontal and perpendicular to the average dike strike.
Anisotropy Directions and Corresponding Parameters of Modeled Directional Semivariograms*
Fract. of Sill
↵* In order to include all detected anisotropies, a high degree of nesting is required. These anisotropy orientations correspond to the orientation of dolomite bodies at different scales. The anisotropy ranges describe the distribution structure (elongated, flattened, etc.).