Grain growth in quartz aggregates is traditionally understood as a surface energy driven process, where larger grains grow at the expense of smaller ones in order to reduce the total grain surface area. However, most studies that contributed to this concept used relatively homogeneous, fine-grained quartz aggregates, which may not precisely reflect natural samples. Here, we performed an isotropic hot-pressing experiment using a coarser-grained quartz powder with grain sizes between 64 and 125 μm. The experiment was carried out using a Griggs-type solid-medium apparatus at controlled conditions of 1 GPa, ∼950 °C, and hot-pressing duration of ∼8 h. A thermal gradient across the sample produced progressive microstructural variations, reflecting differing intensities of recovery overprint interpreted as distinct evolutionary stages. EBSD analysis revealed that relatively smaller grains with low internal misorientation (i.e., low dislocation density), grew at the expense of both smaller and larger grains with higher misorientation (i.e., higher dislocation density). Grain boundary density remained constant throughout the microstructural evolution, suggesting that the stored strain energy of the system was reduced without reducing surface energy. Interestingly, the strain energy driving force was sufficient to mobilize—and ultimately eliminate—typically more stable low-angle boundaries between growing and consumed small grains. These findings challenge the conventional grain growth models, demonstrating that local strain energy differences can dominate microstructural evolution under static conditions, overriding surface energy as the primary driving force. This has implications for interpreting annealed quartz microstructures in natural rocks and raises caution for direct use of recrystallized grain size as a paleo-stress proxy in rocks that underwent static recovery after deformation. • Strain energy gradient can override the surface energy-driven grain growth in quartz. • Small strain-free grains grow at the expense of larger, strained ones. • Total grain surface remains constant during the strain energy equilibration. • Typically more stable low-angle boundaries can migrate due to strain energy gradient. • Interpretations of static grain growth and linking grain size to stress are debated.

We analyze ∼7000 tectonic tremors recorded between 2012 and 2022 across five clusters along Taiwan's mountain belt at depths of 30–50 km, providing new insights into slow fault slip within an active continental collision zone. All clusters occur above the Moho, exhibit thrust-dominant focal mechanisms, and are distinct from crustal seismicity. Tidal sensitivity varies spatially, with Clusters 2–5, located in zones of active collision and subduction termination, showing strong modulation (α = 0.53–0.75), while Cluster 1, situated in a post-collisional extensional environment near the Okinawa Trough, exhibits weaker sensitivity (α ≈ 0.3). These variations correlate with differences in tidal stress amplitude and tectonic regime. Moment tensor inversions reveal consistent thrusting styles, but principal stress orientations vary with depth, with σ₁ rotating from vertical in the upper crust to horizontal at tremor depths. This supports a two-layer deformation model shaped by orogenic collapse and lower crustal convergence-parallel shear. Our findings demonstrate that tremor generation in Taiwan reflects evolving stress regimes, fluid-assisted weakening, and structural heterogeneity associated with the interplay of collision, subduction, and back-arc extension. Tremors thus serve as sensitive indicators of deep-seated tectonic processes in dynamically evolving mountain belts. • Tremors in Taiwan lower crust show thrust mechanisms and high tidal sensitivity. • Stress field rotates from vertical to horizontal with depth in collision zone. • Five tremor clusters reflect collision, subduction, and back-arc processes.

Most of Sabah in northern Borneo is covered with Paleogene to Lower Miocene deep marine turbidite sequences that were deposited along the southern side of the Proto-South China Sea (PSCS). They include the Sapulut and Trusmadi formations of central-south Sabah, the Labang and Kulapis formations of eastern Sabah, the Kudat Formation of NW Sabah and the Crocker Formation of western Sabah. Sandstone petrography, heavy mineral analysis and detrital zircon U-Pb geochronology reveals changing sources associated with the evolution of the PSCS. Volcanic lithic fragments in some Labang Formation samples and Middle Eocene zircons in a lower Crocker Formation sample, as well as unstable heavy minerals such as apatite and epidote indicate input from contemporaneous volcanism, likely derived from the PSCS subduction arc to the north. By contrast, abundant ultra-stable heavy minerals and Mesozoic zircons indicate multi-recycling from southern sources. Changes in provenance are seen across key stratigraphies. The lower part of the Crocker Formation has similar provenance as the Rajang Group in Sarawak and is interpreted as a more distal equivalent. While the upper Crocker Formation has a similar provenance as the Nyalau Formation in Sarawak and is interpreted as its deeper marine continuation. Parts of the Labang and Kulapis formations suggest an extension of this depositional system into eastern Sabah. In the Early Miocene the Palawan microcontinental fragment collided with the Cagayan Arc, resulting in uplift of a forearc high and formation of mélanges in eastern Sabah. The uplifted forearc was most likely the provenance source for the Temburong Formation in western Sabah. • Turbidites in Sabah show a mix of multi-recycled and fresh volcanic sources. • Middle Eocene zircons show volcanic activity related to Proto-South China Sea (PSCS) subduction. • PSCS subduction initiated at least in the E. to M. Eocene and continued until the E. Miocene. • Unstable heavy minerals indicate input from contemporaneous active arc volcanism. • Drainage shifts were related to tectonic evolution of PSCS and uplift phases in Borneo.