LiDAR and photogrammetry technology and its application in paleovolcanic reconstructions of pillow lavas. A case study from Western Srednogorie, Bulgaria.

Terrestrial laser scanning (LiDAR) and photogrammetry are a recent innovation in spatial information data acquisition, which allows geological outcrops to be digitally captured with unprecedented resolution and accuracy. With point precisions and spacing of the order of a few centimetres, an enhanced quantitative element can now be added to geological fieldwork and analysis, opening up new lines of investigation at a variety of scales in all areas of field-based geology. Integration with metric imagery allows 3D photorealistic models to be created for interpretation, visualization and education.

The studied pillow lavas belong to the Middle Volcano-Sedimentary Formation in Western Srednogorie magmatic region. More than ten lava flows of this type have been identified.

3D models provide the opportunity to draw conclusions about the conditions of formation of aqueous flows. One of the factors controlling the growth of the pillow lavas is cooling rate. This can be determined through the analysis and measurements of the thickness and distinctiveness of the quenched (peripheral) rims of every individual lava lobes. Well-defined and distinct rims indicate relatively rapid cooling rates. The morphology and size of separate pillows largely depend on the basins slope angle on which the lava flowed. Their morphology is also influenced by the effusion rate and lava viscosity. The formation of large and rounded pillow obes is typical for moderate slope angles.

The application of terrestrial laser scanning (LiDAR) and photogrammetry enables the precise and detailed digital capture of geological outcrops, significantly enhancing field-based geological studies. In the case of pillow lavas from the Middle Volcano-Sedimentary Formation in the western Srednogorie magmatic region, these technologies allow for the creation of 3D photorealistic models, which aid in interpreting the conditions under which the lavas formed. Key factors influencing the growth and morphology of pillow lavas include cooling rates, slope angles, effusion rates, and viscosity. Rapid cooling produces well-defined quenched rims, while moderate slopes favor the development of large, rounded pillow lobes. These insights provide a deeper understanding of the dynamics of subaqueous lava flows and their formation processes.