Coastal zones, particularly those with low-lying areas, are increasingly affected by anthropogenic pressures and climate change. Rocky and cliffed coasts, slow-evolving geomorphic systems, experience erosional processes that pose significant geohazards. Understanding the controls on cliff retreat is critical for predicting coastal evolution, assessing geological risk, and supporting land-use and heritage management. This study integrates 2D orthophoto interpretation with high-resolution 3D unmanned aerial vehicle-based structure-from-motion (UAV-SfM) photogrammetry to link structural geological mapping with quantitative change detection, thereby improving the precision and spatial coverage of cliff-change analysis. Three 3D models of Pakri Cliff, derived from datasets collected in 2015, 2022, and 2024, were used to quantify cliff retreat and characterise key geological features, including strata, joint systems, and coas tal notches. Results indicate a mean retreat rate of 18 cm/year. While erosion rates vary with lithology, their relative distribution remains stable over time, maintaining a distinct vertical profile. Coastal notches are initiated along joints and progressively modified by marine dynamics. These findings highlight that cliff erosion at Pakri is a multi-mechanism process controlled by geological structure, weathering, mass movement, and wave action, all of which exhibit high spatiotem poral variability. Ultimately, this integrated approach demonstrates how coupling structural geology with high-resolution monitoring enhances the detection of geohazards and provides a more comprehensive understanding of long-term cliff evolution mechanisms.
The study aimed to determine the origin of iron mineralisation in the crystalline basement beneath the Jõhvi magnetic anomaly through the trace element geochemistry of magnetite. Magnetite-bearing samples from mineralised intervals were examined petrographically, and the trace element compositions of magnetite grains were characterised using scanning electron microscopy and laser ablation inductively coupled plasma mass spectrometry. The results show that magnetite trace element compositions cluster into distinct groups depending on the host rock. The Jõhvi magnetite ore most likely formed as a banded iron formation deposit. However, its trace element signature has been significantly altered by later metamorphic and hydrothermal processes. These results highlight that magnetite trace element analysis alone cannot reliably determine the origin of iron ore deposits that have undergone strong alteration.
The supplementary material is designed to provide complementary figures and plots enhancing the geochemical distribution patterns described in this research.
The ~1.62 Ga Märjamaa and Kloostri rapakivi intrusions of western Estonia record a tripartite magmatic evolution during the late stages of the Wiborg rapakivi suite, emplaced in a transtensional pull-apart setting related to shear-zone reactivation during Nuna breakup and constructed through piston cauldron-subsidence processes. Whole-rock major-element geochemistry, complemented by CIPW normative phase relations, is used to constrain melt evolution, redox conditions, and crystallization patterns across three magmatic phases. Phase I formed as a deeply rooted intrusion that evolved into a piston cauldron structure through roof collapse and block assimilation, and comprises ferroan granodioritic to quartz-monzonitic compositions with lower silica and alkalis and elevated Ca and FeâTiâP-bearing components, reflecting relatively less evolved melts. Phase II intruded as a concentric granite ring during continued subsidence and represents the most fractionated stage, characterized by higher silica and alkalis, pronounced Ca depletion, and minimal normative FeâTi oxides and apatite. Phase III corresponds to the late Kloostri body emplaced by asymmetric subsidence and represents a Na-rich leucogranitic melt with the highest silica contents and the lowest abundances of Ca-bearing, FeâTi-bearing, and P-bearing components. Progressive differ entiation from Phase I to Phase III is reflected by systematic Fe-Mg trends, whereas redox conditions are more robustly constrained by iron speciation, indicating reduced conditions in Phase II, intermediate values in Phase I, and more oxidized conditions in Phase III. Decreasing normative FeâTi oxides from Phase I to Phase III primarily reflect progressive differentiation rather than solely oxygen-fugacity variations, emphasizing the semi-quantitative nature of redox constraints derived from major-element data. Theoretical thermobarometric estimates indicate mid-crustal crystallization at ~3â5 kbar with progressive cooling from Phase I to Phase III.
