The characterization of the geochemical reservoirs Earth's continental crust, including determination representative upper and lower crustal compositions, underpins our understanding evolution. classic I- S-type granite classification has often been invoked to distinguish between melts derived from igneous protoliths those melting a sedimentary source. Recent studies suggest that most granites, even cited as typical examples ‘S-type’, show evidence for mixture mantle sources, thereby...

Rare granulitized eclogites exposed in the eastern Himalaya provide insight into conditions and processes deep within orogen. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb, Ti, rare earth element (REE) data from zircons mafic located upper structural levels of Greater Himalayan Sequence Bhutan show that zircon was crystallized under eclogite-facies metamorphic between 15.3 ± 0.3 14.4 Ma, a couple million years later granulite-facies overprint. In conjunction with pressure estimates...

In the Himalayan region of Sikkim, well-developed inverted metamorphic sequence Main Central Thrust (MCT) zone is folded, thus exposing several transects through structure that reached similar grades at different times. In-situ LA-ICP-MS U–Th–Pb monazite ages, linked to pressure–temperature conditions via trace-element reaction fingerprints, allow key aspects evolution thrust be understood for first time. The ages show peak were earliest in structurally highest part sequence, Greater...

Abstract. The formation and exhumation of high ultra-high-pressure, (U)HP, rocks crustal origin appears to be ubiquitous during Phanerozoic plate subduction continental collision events. Exhumation (U)HP material has been shown in some orogens have occurred only once, a single short-lived event; other cases multiple discrete times or single, long-lived, protracted event. It is becoming increasingly clear that no mechanism dominates any particular tectonic environment, the may change time...

Geochemical and geochronological analyses provide quantitative evidence about the origin, development motion along ductile faults, where kinematic structures have been overprinted. The Main Central Thrust is a key structure in Himalaya that accommodated substantial amounts of India–Asia convergence. This juxtaposes two isotopically distinct rock packages across zone deformation. Structural analysis, whole-rock Nd isotopes, U–Pb zircon geochronology reveal hanging wall characterized by...

Abstract Metals such as Li, Be, V, Co, Nb, In, Cs, Sn, Ta, and W are considered resources that critical for modern economies. They can be significantly enriched in granites pegmatites, but the mechanisms of enrichment remain poorly understood. Many metal-enriched granitic magmas form through mica dehydration reactions during high-grade metamorphism. The preferential incorporation these metals into micas provides a mechanism concentration mobilization crustal melting. Comprehensive data sets...

UHP rocks commonly form and exhume during the transition from oceanic subduction to continental collision. Their exhumation in channels depends on balance between down‐channel shear traction up‐channel buoyancy. Thermal‐mechanical upper‐mantle‐scale numerical models are used investigate how variations material properties of subducting margin affect this balance. Changes leading crustal decoupling/detachment investigated by varying onset strain weakening, thermal parameters, convergence...

Abstract The South Tibetan detachment system (STDS) in the Himalayan orogen is an example of normal‐sense displacement on orogen‐parallel shear zone during lithospheric contraction. Here, situ monazite U(–Th)–Pb geochronology combined with metamorphic pressure and temperature estimates to constrain pressure–temperature–time ( P–T–t ) paths for both hangingwall footwall rocks a Miocene ductile component STDS (outer STDS) now exposed eastern Himalaya. outer located south younger,...

Rocks metamorphosed to high temperatures and/or pressures are rare across the Himalayan orogen, where peak metamorphic conditions recorded in exposed core, Greater Sequence (GHS), generally at middle upper amphibolite facies. However, mafic garnet‐clinopyroxene assemblages highest structural levels Bhutan, eastern Himalaya, preserve patchy textural evidence for early eclogite‐facies conditions, overprinted by granulite‐facies conditions. Monazite hosted within leucosome of neighboring...

Abstract The deformation of the middle to lower crust in collisional settings occurs via mechanisms that vary with rock composition, fluid content, pressure, and temperature. These are responsible for accommodation large tectonic transport distances during nappe stacking exhumation. Here, we show fracturing flow triggered coupled dissolution–precipitation creep processes, which were formation a mylonitic microstructure amphibolites. This fabric is developed over crustal thickness >500 m...

The exhumation of crustal ultra‐high‐pressure (UHP) material depends on temporal and spatial variations in its detachment within the subduction channel. This dependence is investigated using numerical models with variable initial strengths, representing a range compositions, parameterized strain weakening, processes that reduce effective viscosity during deformation. Competition between down‐channel shear traction, favoring subduction, up‐channel buoyancy, exhumation, expressed as number, E...

Abstract Eclogites and garnet‐blueschists exposed at the deepest structural levels of Oman Mountains in north‐eastern Saih Hatat, Oman, indicate that Arabian continental margin was subducted subsequently exhumed. The peak metamorphic pressure has been a matter debate for over decade, with initial thermobarometric estimates, based on garnet–clinopyroxene–phengite barometry presence radial cracks around quartz inclusions garnet, yielding values excess 20 kbar; these estimates have questioned...

Numerical models offer powerful insights into tectonic processes, especially when their validity can be tested against geological and geophysical observations from natural orogenic belts. Here we explain some of the criteria for success in integrating with data, using examples Grenville Orogen. Model designs must simplified by comparison nature to illuminate first-order processes that control evolution, which limits extent model results reproduce observations. For western Orogen, observed...

Quantitative constraints on the rates of tectonic processes underpin our understanding mechanisms that form mountains.In Sikkim Himalaya, late structural doming has revealed time-transgressive evidence metamorphism and thrusting permit calculation minimum rate movement a major ductile fault zone, Main Central Thrust (MCT), by novel methodology.U-Th-Pb monazite ages, compositions, metamorphic pressure-temperature determinations from rocks directly beneath MCT reveal samples ~50 km along...

The Zimithang Thrust juxtaposes two lithotectonic units of the Greater Himalayan Sequence in Arunachal Pradesh, NE India. Monazite U–Pb, muscovite 40Ar/39Ar and thermobarometric data from rocks hanging footwall constrain timing conditions their juxtaposition across structure, subsequent cooling. grains biotite–sillimanite gneiss wall yield LA-ICP-MS U–Pb ages 16 ± 0.2 to 12.7 0.4 Ma. A schistose within high strain zone yields overlapping-to-younger monazite 14.9 0.3 11.5...

Abstract The chemical compositions of magmatic zircon growth zones provide powerful insight into evolving magma due to their ability record both time and the local environment. In situ U-Pb Hf isotope analyses rims from Oligocene–Miocene leucogranites Bhutan Himalaya reveal, for first time, an evolution in melt composition between 32 12 Ma. data indicate a uniform source Ma 17 Ma, progressive addition older component at least ca. Age-corrected ɛHf ratios decrease −10 −15 down values as low...

Lithium has been receiving increased attention due to its relevance the green energy transition and increasing demand. One of main sources Li is peraluminous granitoids pegmatites. Current models for genesis such enriched lithologies include fractional crystallisation melts derived from sedimentary protoliths (e.g., Linnen et al., 2012); low-volume melting Li-rich Shaw 2016); subsequent re-melting S-type orthogneisses (Ballouard 2024; Koopmans 2024). Hence, understanding behaviour during...