- School of Earth, Atmosphere and Environment
Monash University
Clayton, VIC 3800
Australia
Stefan A. Vollgger
Monash University, School of Earth, Atmosphere and Environment, Graduate Student
- 3D Geological Modelling, Geostatistics and GIS, Structural Geology, Economic Geology, Mineral Deposits geology, Geology, Photogrammetry, and 19 moreEarthquakes, Gold Mineralization, Vms Deposits, Orogenic Gold Systems, Lode Gold Deposits, 3D Implicit Modelling, Leapfrog Mining, Damara Belt, Geophysics, Tectonics, Geodynamics, Extensional Tectonics, Earth Sciences, Australia, Folding (Structural Geology), UAV and Aircraft control, Image Processing, Remote Sensing, and Geographic Information Systems (GIS)edit
- Implicit 3D geological modelling in structurally complex environmentsedit
In den interdisziplinär betriebenen Geowissenschaften besteht die Notwendigkeit, zur Erkennung übergeordneter Zusammenhänge sowie zur Entscheidungsfindung, umfassend auf alle verfügbaren geologischen Daten zugreifen zu können. Die für... more
In den interdisziplinär betriebenen Geowissenschaften besteht die Notwendigkeit, zur Erkennung übergeordneter Zusammenhänge sowie zur Entscheidungsfindung, umfassend auf alle verfügbaren geologischen Daten zugreifen zu können. Die für unterschiedlichste Zwecke erhobenen Daten bilden häufig eine inhomogene Datengrundlage, was zu deren Isolation führen kann. Das Ziel der Arbeit bestand darin, alle für den Eisenglimmerbergbau Waldenstein (Kärnten) verfügbaren geologischen Informationen zu erheben, durch gezielte Gelände- und Laboruntersuchungen zu ergänzen und in einer neu entwickelten zentralen Datenbank (Microsoft Access Datenbankanwendung namens GEOrganizer) abzulegen respektive damit zu verknüpfen. Die Schaffung dieser Datenbank vermeidet Datenverluste und gewährleistet einen vereinfachten Zugriff sowie Dokumentation aller geologischen Informationen. Diese Daten bilden die Grundlage für die Erstellung eines geologischen 3d-Lagerstättenmodells mit der Bergbauplanungssoftware Surpac Vision. Damit können sämtliche Hammerbohrdaten, Kernbohrdaten sowie Gefügedaten aus der zentralen Datenbank GEOrganizer ausgelesen und zusammen mit dem Modell und Grubengebäude dreidimensional dargestellt und analysiert werden. Daraus resultieren im Vergleich zur bisherigen 2d-Darstellung mittels Scheibenkarten erhebliche Visualisierungsvorteile. Durch die Implementierung des GEOrganizers sowie die 3d- Modellierung wurden sämtliche geologische Daten der Lagerstätte gesichert und die Möglichkeit geschaffen, diese bei zukünftigen Bearbeitungen abzurufen. Damit wird eine jederzeit erweiterbare Informationsbasis zur Beantwortung unterschiedlichster Fragestellungen im Bergbau und der Lagerstättenkunde zur Verfügung gestellt.
Unmanned aerial vehicles (UAVs), commonly referred to as drones, are opening new and low cost possibilities to acquire high-resolution aerial images and digital surface models (DSM) for applications in structural geology. UAVs can be... more
Unmanned aerial vehicles (UAVs), commonly referred to as drones, are opening new and low cost possibilities
to acquire high-resolution aerial images and digital surface models (DSM) for applications in structural geology.
UAVs can be programmed to fly autonomously along a user defined grid to systematically capture high-resolution
photographs, even in difficult to access areas. The photographs are subsequently processed using software that
employ SIFT (scale invariant feature transform) and SFM (structure from motion) algorithms. These photogrammetric
routines allow the extraction of spatial information (3D point clouds, digital elevation models, 3D meshes,
orthophotos) from 2D images. Depending on flight altitude and camera setup, sub-centimeter spatial resolutions
can be achieved. By “digitally mapping” georeferenced 3D models and images, orientation data can be extracted
directly and used to analyse the structural framework of the mapped object or area.We present UAV assisted aerial
mapping results from a coastal platform near Cape Liptrap (Victoria, Australia), where deformed metasediments
of the Palaeozoic Lachlan Fold Belt are exposed. We also show how orientation and spatial information of brittle
and ductile structures extracted from the photogrammetric model can be linked to the progressive development
of folds and faults in the region. Even though there are both technical and legislative limitations, which might
prohibit the use of UAVs without prior commercial licensing and training, the benefits that arise from the resulting
high-resolution, photorealistic models can substantially contribute to the collection of new data and insights for
applications in structural geology.
to acquire high-resolution aerial images and digital surface models (DSM) for applications in structural geology.
UAVs can be programmed to fly autonomously along a user defined grid to systematically capture high-resolution
photographs, even in difficult to access areas. The photographs are subsequently processed using software that
employ SIFT (scale invariant feature transform) and SFM (structure from motion) algorithms. These photogrammetric
routines allow the extraction of spatial information (3D point clouds, digital elevation models, 3D meshes,
orthophotos) from 2D images. Depending on flight altitude and camera setup, sub-centimeter spatial resolutions
can be achieved. By “digitally mapping” georeferenced 3D models and images, orientation data can be extracted
directly and used to analyse the structural framework of the mapped object or area.We present UAV assisted aerial
mapping results from a coastal platform near Cape Liptrap (Victoria, Australia), where deformed metasediments
of the Palaeozoic Lachlan Fold Belt are exposed. We also show how orientation and spatial information of brittle
and ductile structures extracted from the photogrammetric model can be linked to the progressive development
of folds and faults in the region. Even though there are both technical and legislative limitations, which might
prohibit the use of UAVs without prior commercial licensing and training, the benefits that arise from the resulting
high-resolution, photorealistic models can substantially contribute to the collection of new data and insights for
applications in structural geology.
Research Interests:
Structurally controlled mineralisation commonly shows distinctive geometries, orientations and spatial distributions that derive from associated structures. These structures have the ability to effectively transport, trap and focus... more
Structurally controlled mineralisation commonly shows distinctive geometries, orientations and spatial distributions
that derive from associated structures. These structures have the ability to effectively transport, trap and focus
fluids. Moreover, structures such as faults and shear zones can offset, truncate and spatially redistribute earlier
mineralisation. We present a workflow that combines structural fieldwork with state-of-the-art 3D modelling to
assess the structural framework of an ore deposit. Traditional 3D models of ore deposits rely on manual digitisation
of cross sections and their subsequent linkage to form 3D objects. Consequently, the geological interpretation
associated with each section will be reflected in the resulting 3D models. Such models are therefore biased and
should be viewed and interpreted with caution. Conversely, 3D implicit modelling minimises the modelling bias
by using an implicit function that is fitted to spatial data such as drillhole data. This function defines a scalar
field, from which 3D isosurfaces can be extracted. Assay data can be visualised as 3D grade shells at various
threshold grade values and used to analyse and measure the shape, distribution and orientation of mineralisation.
Additionally, lithology codes from drillholes can be used to extract lithological boundaries in 3D without the need
for manual digitisation.
In our case study at the Palaeozoic Currawong Pb-Zn-Cu deposit (Victoria, Australia), orientations extracted
from ore bodies within a 3D implicit model have been compared to structural field data collected around the
deposit. The data and model suggest that Currawong’s massive sulfide lenses have been structurally modified.
Mineralisation trends are parallel to a dominant NW dipping foliation mapped in the field. This foliation
overprints earlier bedding in the host metasediments that has been deformed into upright folds. Several sets
of steep faults further increase the structural complexity of the deposit and offset mineralisation. Previously
suggested conceptual models for Currawong do not adequately explain the spatial geometry and distribution
of the mineralisation that is apparent in the 3D implicit model. We present a new structural history for the
Currawong deposit, which explains the structural evolution (folding & faulting) of the massive sulfide lenses in 3D.
that derive from associated structures. These structures have the ability to effectively transport, trap and focus
fluids. Moreover, structures such as faults and shear zones can offset, truncate and spatially redistribute earlier
mineralisation. We present a workflow that combines structural fieldwork with state-of-the-art 3D modelling to
assess the structural framework of an ore deposit. Traditional 3D models of ore deposits rely on manual digitisation
of cross sections and their subsequent linkage to form 3D objects. Consequently, the geological interpretation
associated with each section will be reflected in the resulting 3D models. Such models are therefore biased and
should be viewed and interpreted with caution. Conversely, 3D implicit modelling minimises the modelling bias
by using an implicit function that is fitted to spatial data such as drillhole data. This function defines a scalar
field, from which 3D isosurfaces can be extracted. Assay data can be visualised as 3D grade shells at various
threshold grade values and used to analyse and measure the shape, distribution and orientation of mineralisation.
Additionally, lithology codes from drillholes can be used to extract lithological boundaries in 3D without the need
for manual digitisation.
In our case study at the Palaeozoic Currawong Pb-Zn-Cu deposit (Victoria, Australia), orientations extracted
from ore bodies within a 3D implicit model have been compared to structural field data collected around the
deposit. The data and model suggest that Currawong’s massive sulfide lenses have been structurally modified.
Mineralisation trends are parallel to a dominant NW dipping foliation mapped in the field. This foliation
overprints earlier bedding in the host metasediments that has been deformed into upright folds. Several sets
of steep faults further increase the structural complexity of the deposit and offset mineralisation. Previously
suggested conceptual models for Currawong do not adequately explain the spatial geometry and distribution
of the mineralisation that is apparent in the 3D implicit model. We present a new structural history for the
Currawong deposit, which explains the structural evolution (folding & faulting) of the massive sulfide lenses in 3D.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
"Tectonic processes and the resulting deformation of Earth’s crust are well known to control and influence the location and shape of ore bodies. Furthermore, ore body geometries and their associated spatial relationships provide... more
"Tectonic processes and the resulting deformation of Earth’s crust are well known to control and influence the location and shape of ore bodies. Furthermore, ore body geometries and their associated spatial relationships provide fundamental clues to the genesis of ore deposits. It is therefore important to establish accurate 3D geological models to visualise and analyse ore delineation in order to understand the controls on mineralisation processes.
Implicit modelling is capable of generating internally consistent and bias-free 3D geological models directly from drill-hole data; hence it can be used for objective structural interpretations. Instead of manual linkage of hand-digitised 2D cross-sections, mathematical interpolation functions are used to generate 3D isosurfaces, which can represent ore grade shells, lithological boundaries or structural trends. These isosurfaces can also be used to define ore bodies and obtain their geometries, grade continuity direction(s) and their spatial relationship to lithological boundaries and major structures. Subsequently, working hypotheses based on the geometrical analysis of the initial 3D model are tested in the field.
We present the workflow and preliminary results from a case study at the Navachab gold deposit (Namibia), where ore body geometries obtained from a 3D implicit model were linked to field observations. The results suggest a strong structural control on mineralisation during the growth and lock-up stage of a regional scale dome.
Implicit modelling combined with selective fieldwork allows us to improve the understanding of structural controls on the genesis of mineral deposits. "
Implicit modelling is capable of generating internally consistent and bias-free 3D geological models directly from drill-hole data; hence it can be used for objective structural interpretations. Instead of manual linkage of hand-digitised 2D cross-sections, mathematical interpolation functions are used to generate 3D isosurfaces, which can represent ore grade shells, lithological boundaries or structural trends. These isosurfaces can also be used to define ore bodies and obtain their geometries, grade continuity direction(s) and their spatial relationship to lithological boundaries and major structures. Subsequently, working hypotheses based on the geometrical analysis of the initial 3D model are tested in the field.
We present the workflow and preliminary results from a case study at the Navachab gold deposit (Namibia), where ore body geometries obtained from a 3D implicit model were linked to field observations. The results suggest a strong structural control on mineralisation during the growth and lock-up stage of a regional scale dome.
Implicit modelling combined with selective fieldwork allows us to improve the understanding of structural controls on the genesis of mineral deposits. "