Delamination Events Research Articles

Lithosphere structure and its implications for the metallogenesis of the Nanling Range, South China: Constraints from 3-D magnetotelluric imaging

We have obtained a lithospheric electrical resistivity model of the Nanling Range through 3-D inversion of magnetotelluric data from 118 sites comprising an array covering this important metallogenic belt. Approximately divided by longitude 114°E, the western and eastern parts of this area show significantly different lithospheric electrical features, spatially coincident with its west-east differential Jurassic metallogeny. The lithosphere beneath western Nanling is mainly characterized by high-resistivity, but with an approximately north–south trending, lithosphere-scale, nearly upright, high-conductivity zone that occurs beneath the Qin-Hang magmatic belt. We interpret this high-conductively zone to be a long-lived lithospheric weak zone being located on an ancient plate-boundary that experienced multiple reactivations. The zone controlled Jurassic mafic magmatic events, e.g., 174–176 Ma Daoxian and 150–154 Ma Ningyuan, and also acted as a narrow pathway for the rapid upwelling of hot and volatile-rich asthenosphere-derived materials during the Middle-Late Jurassic Cu-Mo/Pb-Zn mineralization. In contrast, to the east of longitude 114° E, a nearly 80 km deep, clear and continuous electrical lithosphere-asthenosphere boundary is imaged, which could result from a major lithospheric delamination event, probably caused by the early Paleozoic Wuyi-Yunkai orogeny and subsequent post-orogenic collapse, or the subduction and rollback of the Pacific slab after the Triassic. The eastern Nanling region with its thinned lithosphere is suggested as allowing broader zones of upwelling asthenospheric during the intensive Jurassic W-Sn metallogenesis, causing slow upwelling and lateral spreading of asthenosphere-derived materials and subsequent strong extension of the crust and also the mixing and assimilation with melts. Consequently, metallic elements were extensively extracted from the crust, eventually giving rise to the world-class W-Sn deposits in the eastern Nanling region.

Epithelial Cells Recover Substrate Adhesion Through Retraction Fiber-Guided Lamellipodia

The integrity of epithelial tissues is constantly challenged during developmental, mitotic, and pathological processes. Here, we used acute chemical and mechanical perturbations to examine how epithelial cells respond to partial delamination events that threaten tissue integrity. We saw that detached cells remained tethered to the substrate via long membrane tubules, termed retraction fibers, that could extend multiple cell lengths in seconds. Cells then extended lamellipodia between adjacent retraction fibers to rapidly and efficiently reestablish substrate adhesion. Although retraction fibers had been observed to guide readhesion following cell division, their general role facilitating seconds-scale cellular reattachment had, to our knowledge, been overlooked. We suggest that retraction fiber-templated respreading may represent a general mechanism to reestablish tissue integrity in the face of acute disruption, both during normal tissue homeostasis as well as in a number of pathological scenarios.

Mineralogy Constraints on Magmatic Processes Controlling Adakitic Features of Early Permian High-magnesium Diorites in the Western Tianshan Orogenic Belt

AbstractWhole-rock geochemistry, usually changed by magmatic processes, might provide misleading information on the petrogenesis of adakites. The Heishantou porphyritic diorites in Nileke, Western Tianshan orogenic belt record complex magma chamber processes, such as magma replenishment, fractional crystallization and crustal contamination, and thus, provide ideal samples for tracing the magmatic processes that generate the typically high Sr and La contents and Sr/Y and La/Yb ratios of adakites. In situ clinopyroxene and amphibole compositions of Heishantou porphyritic diorites (271 ± 2 Ma) are characterized by low Yb and Y content with high Sr/Y and La/Yb ratios, from which calculated early magmas resemble typical adakites derived from partial melting of a subducted slab. But whole-rock composition shows low MgO, Ni and Cr, thus, the Heishantou diorites were previously regarded as the result of partial melting of thickened lower crust. Plagioclase phenocrysts exhibit complex compositional zoning due to magma replenishment, and the rims have higher 87Sr/86Sr ratio and Sr content than the cores, indicating crustal assimilation. The cores of zoned clinopyroxene phenocrysts have high Mg#, Cr and Ni but low Yb and Y with high Sr/Y and La/Yb ratios, which are consistent with the high Mg# of primary adakitic magmas. Magmatic processes have significantly changed the primary adakitic features of Yb, Y and Sr content, Sr/Y and La/Yb ratios, in addition to Mg# values. The Heishantou primitive high-Mg# adakite was derived from partial melting of a delaminated lower crust followed by storage, recharge, and assimilation in a crustal magma chamber. The Western Tianshan orogenic belt experienced a succession of lower crust delamination events in the Early Permian that involved melting of thickened lower crust, subsequent lithospheric detachment and asthenospheric upwelling.

Late Miocene Deformation Kinematics Along the NW Zagros Fold‐Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U‐Th)/He Thermochronometry and Balanced Cross Sections

AbstractApatite (U‐Th)/He (AHe) thermochronometric results are integrated with geologic cross sections, structural relationships, and stratigraphic data to reconstruct the growth of the NW Zagros orogenic belt in the Kurdistan region of Iraq. Prolonged exhumation is documented across the belt with deformation advances and retreats from ~14 Ma onward. After in‐sequence propagation of deformation during middle to late Miocene times, preserved growth strata and AHe data show a deformation retreat by latest Miocene time (~5 Ma). In the NW Zagros, the Phanerozoic succession contains two principal décollements in Lower Triassic and middle Miocene units. The Triassic strata are interpreted as the main décollement for a thin‐skinned system that was dominant during most of the Cenozoic. By ~8–5 Ma, the fold‐thrust belt shifted to basement‐involved deformation in association with growth of the mountain front flexure and reactivation of frontal structures. The shift from thin‐skinned to a hybrid thin‐ and thick‐skinned mode of shortening may reflect variations in the mechanical behavior of the upper crust and the presence of inherited basement discontinuities. On the basis of two NE‐SW balanced cross sections spanning the NW Zagros, the estimated total minimum horizontal shortening is ~18.2 km (6%) in the central and ~16 km (7%) in the southern sectors of the Kurdistan region of Iraq. These findings suggest that the evolution of the NW Zagros orogenic belt was likely driven by the mechanical stratigraphy of the sedimentary cover, inherited basement discontinuities, and the dynamic and thermomechanical effects of potential slab breakoff and lithospheric mantle delamination events.

Peridynamic modeling of delaminations in laminated composite beams using refined zigzag theory

This study aims to model delaminations in laminated composite beams by using the PeriDynamic Differential Operator (PDDO) and Refined Zigzag Theory (RZT). A cohesive zone model is employed to monitor the delamination evolvement in laminated composite beams by embedding an interfacial resin layer between two potentially separable material layers. PDDO calculates the local derivatives in their nonlocal forms and produces highly accurate predictions for the solution of differential equations. RZT eliminates the consideration of shear correction factors and paves the way for modeling both thin and thick laminates. RZT enables computationally efficient analyses since it considers a constant number of kinematic variables regardless of the number of layers in the beam. The principle of virtual work is employed to derive the governing equations and boundary conditions of the RZT. The calculation of transverse normal and shear stresses at critical locations plays an important role in the delamination event. Therefore, this approach is promising for the delamination analysis of laminated composite beams. The present approach performs the nonlocal integration for the approximation of the local derivatives; hence, it reduces the undesirable localized stress peaks. It was demonstrated that the present approach successfully captured the deformation and stress fields as well as the delamination onset and evolvement of the laminated beams.

Mechanical forces drive ordered patterning of hair cells in the mammalian inner ear

Periodic organization of cells is required for the function of many organs and tissues. The development of such periodic patterns is typically associated with mechanisms based on intercellular signaling such as lateral inhibition and Turing patterning. Here we show that the transition from disordered to ordered checkerboard-like pattern of hair cells and supporting cells in the mammalian hearing organ, the organ of Corti, is likely based on mechanical forces rather than signaling events. Using time-lapse imaging of mouse cochlear explants, we show that hair cells rearrange gradually into a checkerboard-like pattern through a tissue-wide shear motion that coordinates intercalation and delamination events. Using mechanical models of the tissue, we show that global shear and local repulsion forces on hair cells are sufficient to drive the transition from disordered to ordered cellular pattern. Our findings suggest that mechanical forces drive ordered hair cell patterning in a process strikingly analogous to the process of shear-induced crystallization in polymer and granular physics.

Lithospheric Delamination Beneath the Southern Puna Plateau Resolved by Local Earthquake Tomography

AbstractWe present a local earthquake tomography to illuminate the crustal and uppermost mantle structure beneath the southern Puna plateau and to test the delamination hypothesis. Vp and Vp/Vs ratios were obtained using travel time variations recorded by 75 temporary seismic stations between 2007 and 2009. In the upper crust, prominent low Vp anomalies are found beneath the main volcanic centers, indicating the presence of magma and melt beneath the southern Puna plateau. Beneath the Moho at around 90‐km depth, a strong high Vp anomaly is detected just west of the giant backarc Cerro Galan ignimbrite caldera. This high Vp anomaly is only resolved if earthquakes with an azimuthal gap up to 300° are included in the inversion. However, we show through data subset and synthetic tests that the anomaly is robust due to our specific station‐event geometry and interpret it as a delaminated block of lower crust and uppermost mantle lithosphere under the southern Puna plateau. The low velocities in the crust are interpreted as a product of the delamination event that triggered the rise of fluids and melts into the crust and induced the high topography in this part of the plateau. The tomography also reveals the existence of low‐velocity anomalies that link arc magmatism at the Ojos del Salado volcanic center with slab seismicity clusters at depths of about 100 and 150 km and support fluid transport in the mantle wedge due to dehydration reaction within the subducted slab.

Damage monitoring of surface treated steel under severe rolling contact loading conditions

The aim of this study has been to investigate the rolling contact behaviour of plasma nitrided and duplex treated (plasma nitrided and diamond-like carbon (DLC)) EN40B steel under overloading and intermittent lubricating conditions using the acoustic emission technique (AE). The signal amplitude and energy were monitored and related to cracking and delamination events observed from scanning electron micrographs. AE technique was found to be capable of detecting cracking and delamination on both surface treatments, proving to be a useful tool for monitoring rotating machinery condition effectively.

Transient Contact Opening Forces in a MEMS Switch Using Au/MWCNT Composite

Most failures in micro electromechanical system (MEMS) switches can be attributed to the degradation of contact surfaces and sticking contacts. A wear-tolerant composite contact material, composed of a Au film supported by multi walled carbon nanotubes (Au/MWCNT), has been engineered to provide wear resistance and enhanced switching lifetime with conductive properties close to pure Au. Switching lifetimes of billions of cycles have been demonstrated, representing greatly increased performance over thin film Au. Below the arcing threshold (~12 V) the wear mechanism has been shown to be a combination of the fine transfer of contact material by the molten metal bridge (MMB) phenomenon and a delamination of the Au. In this study, the composite contact is hot switched at low current DC conditions (4 V DC and 20 mA) while the contact force is measured at the micro Newton scale in nanosecond resolution. The characteristic voltage waveform associated with the MMB is observed with forces detected as the contact softens, melts, and separates. The presence of a delamination event (DE) is also observed, where the contact opens abruptly with no MMB phenomenon apparent. The DE contact openings are associated with a transient peak force of 21.6 ± 2.3 µN while the MMBs are linked to a lower peak force of 18.1 ± 2.5 µN.

Geochemical variations of the Late Mesozoic granitoids in the southern margin of North China Craton: A possible link to the tectonic transformation from compression to extension

The composition of the continental crust of the North China Craton (NCC) is more felsic than that of the average bulk crust, which is regarded to be the result of the delamination of the thickened lower crust during Mesozoic. However, whether the thickened continental crust existed and when the delamination event happened along the southern margin of the NCC are still debated. Here, we report geochronological, geochemical and Sr-Nd-Hf-Pb isotopic evidence that granitoids from the Late Jurassic Wuzhangshan pluton and the Early Cretaceous Huashani complex were derived by partial melting of the lower crust with different thickness. Our new data shows that the two lithofacies of the Wuzhangshan pluton were mainly formed between ca. 157 and 156 Ma, whereas the five lithofacies of the Huashani complex were mainly emplaced between ca. 132 and 125 Ma. The Wuzhangshan pluton and the earlier four lithofacies granitoids of the Huashani complex (ca. 160–125 Ma) both display adakitic geochemical features, which are characterized by as high SiO2 (63.26–72.71 wt%), Al2O3 (13.97–16.89 wt%) and Sr (413–1218 ppm) contents, and low Y (6.30–14.98 ppm) and YbN (1.55–4.43), and high Sr/Y (33−112) and (La/Yb)N (11.53–29.72) ratios. They also have high (87Sr/86Sr)i (0.7066–0.7086), and low εNd(t) (−9.9 to −18.8) and εHf(t) (−11 to −26) values, and two-stage Nd and Hf model ages ranging from 2.4 to 1.7 Ga and 2.7 to 1.7 Ga, respectively. In contrast, the late Early Cretaceous (ca. 125–110 Ma) granitoids have higher SiO2 (71.30–76.78 wt%) and lower Sr (64–333 ppm) contents, and lower Sr/Y (17–29) and (La/Yb)N (13.25–18.36) ratios, and similar εNd(t) (−10 to −16) and relatively higher εHf(t) (−10 to −14) values. These geochemical variations suggest that the ca.160–125 Ma granitoids were most probably produced by partial melting of thickened crust (>45 km) with eclogite, garnet amphibolite or amphibolite residues, whereas that the ca. 125–110 Ma granitoids were formed by partial melting of the thinner crust (<33 km). We thus suggest that the NCC likely underwent a synchronous tectonic transformation at ca. 125 Ma from a compressional setting with thickened crust to an intensive extensional setting with thinner crust at ca. 125 Ma, which demonstrates that the lower crust was most likely delaminated.

The top-down solidification of iron asteroids driving dynamo evolution.

The cores of some small planetesimals, such as asteroid (16) Psyche, are thought to have been exposed through collisions during the early solar system that removed their mantles. These small bodies likely solidified from the top down representing a fundamentally different solidification regime to that of Earth's core. Here we derive simplified models of the downwards solidification of the metallic crust, and consider thermal convection and the potential for viscous delamination of the weak, warm base of the crust to provide a buoyancy flux sufficient to drive a dynamo. Thermal buoyancy is very short lived (~1000 years), and therefore cannot be the source of measured paleomagnetic remanence. In contrast, viscous delamination is found to provide a long-lasting buoyancy flux sufficient to generate an intense, multipolar magnetic field, while not greatly affecting the crustal solidification time. Our results suggest that a Psyche-sized (150 km radius) body solidified in roughly 6.7 - 20 Myr, and that delamination produced a strong magnetic field over much of this time. Finally, including light, insoluble impurities, such as sulfur, results in a partially solid mushy zone at the base of the crust. This further weakens the base of the crust and results in smaller scale delamination events. Despite a significant change in the dynamics of delamination, the time to total solidification and the predicted properties of the magnetic field are broadly comparable to the sulfur-free case, though we argue this may result in observable compositional stratification of the body.

A numerical design of experiment approach to understand aortic dissection onset and propagation

Aortic dissection is a sudden and life-threatening delamination event of the aortic wall, with an incidence of 35 cases per 100,000 per year, which requires rapid diagnosis and decision-making. In ...

A combined experimental-numerical lamellar-scale approach of tensile rupture in arterial medial tissue using X-ray tomography

Aortic dissection represents a serious cardio-vascular disease and life-threatening event. Dissection is a sudden delamination event of the wall, possibly leading to rupture within a few hours. Current knowledge and practical criteria to understand and predict this phenomenon lack reliable models and experimental observations of rupture at the lamellar scale. In an attempt to quantify rupture-related parameters, the present study proposes an analytical model that reproduces a uniaxial test on medial arterial samples observed under X-ray tomography. This model is composed of several layers that represent the media of the aortic wall, each having proper elastic and damage properties. Finite element models were created to validate the analytical model using user-defined parameters. Once the model was validated, an inverse analysis was used to fit the model parameters to experimental curves of uniaxial tests from a published study. Because this analytical model did not consider delamination strength between layers, a finite element model that included this phenomenon was also developed to investigate the influence of the delamination on the stress-strain curve through a sensitivity analysis. It was shown that shear delamination strength between layers, i.e. mode II separation, is essential in the rupture process observed experimentally.

Highly responsive nature of porous coordination polymer surfaces imaged by in situ atomic force microscopy.

The ability of porous coordination polymers to undergo reversible structural transformations in response to the presence of guest molecules has been intensively investigated for applications such as molecular separation, storage, sensing and signalling processes. Here we report on the direct observation of the highly guest-responsive nature of the surface of a single-crystalline porous coordination polymer, which consists of paddlewheel zinc clusters and two types of ligand, by in situ liquid-phase atomic force microscopy. Observations were carried out in solution at constant temperature (28 °C) by high-speed atomic force microscopy with lattice resolution. A sharp and reversible response to the presence or absence of biphenyl guest molecules was observed, under conditions that can scarcely induce the transformation of the bulk crystal. Additionally, by modulating the surface coordination equilibrium, layer-by-layer delamination events were captured in real time at every ~13 s per frame.

Topographic inversion and changes in the sediment routing systems in the Variscan orogenic belt as revealed by detrital zircon and monazite U[sbnd]Pb geochronology in post-collisional continental basins

The basal alluvial and fluvial siliciclastic successions within the late Carboniferous intracontinental basins of the west-central Bohemian Massif provide an intriguing sedimentary record of changes in paleotopography and paleodrainage systems during and after orogenic collapse. We analyze this record using the UPb laser ablation ICP-MS detrital zircon and monazite geochronology. Five distinct age groups have been identified across the examined stratigraphic succession: (I) Archean/Paleoproterozoic, (II) late Neoproterozoic, (III) Cambro–Ordovician, (IV) Late Devonian, and (V) mid- to late-Carboniferous. These age groups indicate mixing of both local and distal, extra-basinal sources and also point to a two-stage post-convergent geodynamic evolution of the Variscan belt. The first stage followed collapse of the central ‛Bohemian’ orogenic plateau at around 346–337 Ma and involved rapid cooling at ca. 340–320 Ma and removal of ca. 2–3 km of sedimentary overburden from the top of the plateau. No sedimentary record of this erosional event suggests that the river systems transported detritus radially outwards from the inner part of the orogen to its forelands. A paleorelief inversion and thus major reorganization of the sediment routing systems were then associated with uplift in the southerly and southwesterly peripheral domains of the orogen at ca. 330–310 Ma. In turn, these uplifted domains, occupied by rapidly unroofed voluminous granite plutons, shed detritus into the ‛Bohemian’ sink. This was represented by the former plateau, collapsed to relatively low elevations, but still with significant internal paleorelief dominated by a system of tens of kilometers long ~NNE–SSW-trending paleovalleys. Some of the material was further transported in extensive river systems crossing the former plateau to the northerly Variscan foreland basin. Thus, the radial sediment routing system changed into axial (unidirectional). Finally, we suggest that these major inversions of paleorelief and changes in the surface processes and paleodrainage systems may have been linked to distinct late-orogenic lithospheric-mantle delamination events. First-stage delamination occurred beneath the center of the Bohemian Massif to cause the plateau collapse, denudation, and radial sediment transport, whereas the second-stage delamination occurred along its periphery to cause uplift sourcing the intracontinental basins and unidirectional sediment transport. End of deposition and magmatic shutdown at around 305 Ma may then define the very cessation of late-orogenic vertical movements and the transition to a post-orogenic, intra-plate setting.

Biomechanical Analysis of Porcine Cartilage Elasticity.

Grafting of tissue-engineered cartilage to joints with osteoarthritis has the potential to supersede arthroplasty as the standard of care. However, in order to support the development of functional tissue engineering methods, the subfailure biomechanics of the individual cartilage types that comprise joints must be determined. Current methods for analyzing tissues are based on imaging and are therefore unable to profile the strain dependence of mechanical behaviors within different cartilage types. Recently, an analysis technique based on Optical Fiber Polarimetric Elastography (OFPE) has overcome these challenges. OFPE has been used to characterize the different mechanical behaviors of a range of unprocessed biomaterials and tissues. In the present work, this technique is used to characterize the biomechanics of both articular cartilage and meniscal fibrocartilage within a porcine knee. OFPE testing of the tissue is conducted over a range of physiological loading and unloading values. These results demonstrate the distinctive mechanics of each cartilage type. Due to their different locations within the knee, each cartilage type exhibits distinctly unique biomechanical behavior. Based on the results of OFPE, we correlate the specific buckling, delamination, and bridging events to maxima and minima along the loading and unloading curves. This provides unprecedented detail with regard to the subfailure biomechanics. This information is integral to the design of the next generation of tissue-engineered constructs. Therefore, OFPE will be used across multiple disciplines to rapidly determine the mechanical behavior of tissue-engineered constructs to support functional tissue engineering efforts.

Different response to middle-Palaeozoic magmatism during intracontinental orogenic processes: evidence from southeastern South China Block

ABSTRACTIntracontinental orogens are major sites to better understand tectonic regime of plate interior. However, deep response to those processes remains poorly constrained due to the rare exposure of magmatic rocks. Middle-Palaeozoic magmatic rocks from the eastern Yangtze Block (EYB) and Cathaysia Block (CB) of the southeastern South China Block (SCB) have markedly unimodal age distribution with peaks at ~424 and ~438 Ma, respectively. The zircon saturation temperatures (T–Zr) range from 699 to 920°C, and increase in granitic rocks of younger age in the CB; however, most of the granitic T–Zr values in EYB are low and relatively uniform (643–855°C, most of them lower than 800°C). In CB, the Nd-Hf isotopic ratios of the granitic rocks (εNd(t) = – 13.2 to + 1.0; magmatic zircon εHf(t) = – 36 to + 12) are variable, nonetheless they clearly show the presence of a juvenile component. On the contrary, Nd isotopic ratios (εNd(t) = – 7.8 to + 1.6) of mafic rocks in EYB abruptly increase in rocks of younger age. Within the long-lived intracontinental orogenic processes of EYB and CB, consistent age peaks between metamorphism and magmatism and the abrupt increase in contributions of juvenile materials suggest that the thickened lithospheric roots were delaminated into asthenospheric mantle as many independent parts below the metamorphic domes in CB. The data suggest that the deep response to the intracontinental orogenic processes was strong non-uniform between EYB and CB in terms of magmatic period and contribution of mantle derived material to granitic magmas (related to the crustal reworking). We deduced that the combined influence of far-field stress transmission (derived from the convergence of Australia and the SCB), local delamination event in CB and different degree of reworking of the crustal sources, is the main reason to the different responses between EYB and CB.

Novel self-healing CFRP composites with high glass transition temperatures

Carbon fiber reinforced polymer (CFRP) composites were fabricated using a novel intrinsically healable isocyanurate-oxazolidone (ISOX) thermosetting matrix. After multiple delamination events, repeatable strength recovery of the composites has been demonstrated with a first healing efficiency up to 85% after thermal treatment. The healing mechanism results from transformation of the isocyanurate with epoxide groups to yield new oxazolidone rings at the fracture surface. This novel ISOX polymer utilizes commercial diglycidyl ether of bisphenol F (DGEBF) and toluene diisocyanate to produce a high cross-link density thermoset with a glass transition temperature (Tg) up to 285 °C, and 99.5% of the composite weight remains at 300 °C. The strength and stiffness of the composites are comparable with an engineering grade polymer matrix composite typically used in aerospace applications and the thermal stability places the materials in the polybismaleimide performance region although with greater toughness. This polymer exhibits the highest Tg of any self-healing material reported and is composed of low cost reactants, which gives the polymer great potential to function as a major component of an advanced structural composite for extreme environments.

Hydrogen-assisted failure in a bimodal twinning-induced plasticity steel: Delamination events and damage evolution

The effect of the bimodal grain size distribution on the hydrogen susceptibility of a high-Mn fully austenitic twinning-induced plasticity (TWIP) steel was investigated by tensile testing under ongoing electrochemical hydrogen charging. Observation of the surface microstructure of the hydrogen-charged specimen yielded a correlation between the microstructure, crack initiation sites, and crack propagation path. The observed embrittlement arose from crack initiation/propagation along the grain and twin boundaries and delamination governed crack growth. In the present bimodal TWIP steel, the fine grained regions mostly showed intergranular cracking along the grain boundaries between the fine and coarse grains. By contrast, the coarse grained region exhibited transgranular cracking along the twin boundaries. The delamination cracking phenomena is rationalized by the evident nucleation, growth, and coalescence of microvoids in the tensile direction. The results reveal that the bimodal grain size distribution of TWIP steel plays a major role in hydrogen-assisted cracking and the evolution of delamination-related damage.

Mesozoic to Cenozoic magmatic history of the Pamir

New geochronologic, geochemical, and isotopic data for Mesozoic to Cenozoic igneous rocks and detrital minerals from the Pamir Mountains help to distinguish major regional magmatic episodes and constrain the tectonic evolution of the Pamir orogenic system. After final accretion of the Central and South Pamir terranes during the Late Triassic to Early Jurassic, the Pamir was largely amagmatic until the emplacement of the intermediate (SiO2>60 wt.%), calc-alkaline, and isotopically evolved (−13 to −5 zircon εHf(t)) South Pamir batholith between 120–100 Ma, which is the most volumetrically significant magmatic complex in the Pamir and includes a high flux magmatic event at ∼105 Ma. The South Pamir batholith is interpreted as the northern (inboard) equivalent of the Cretaceous Karakoram batholith and the along-strike equivalent of an Early Cretaceous magmatic belt in the northern Lhasa terrane in Tibet. The northern Lhasa terrane is characterized by a similar high-flux event at ∼110 Ma. Migration of continental arc magmatism into the South Pamir terrane during the mid-Cretaceous is interpreted to reflect northward directed, low-angle to flat-slab subduction of the Neo-Tethyan oceanic lithosphere. Late Cretaceous magmatism (80–70 Ma) in the Pamir is scarce, but concentrated in the Central and northern South Pamir terranes where it is comparatively more mafic (SiO2<60 wt.%), alkaline, and isotopically juvenile (−2 to +2 zircon εHf(t)) than the South Pamir batholith. Late Cretaceous magmatism in the Pamir is interpreted here to be the result of extension associated with roll-back of the Neotethyan oceanic slab, which is consistent with similarly aged extension-related magmatism in the Karakoram terrane and Kohistan.There is an additional pulse of magmatism in the Pamir at 42–36 Ma that is geographically restricted (∼150 km diameter ellipsoidal area) and referred to as the Vanj magmatic complex. The Vanj complex comprises metaluminous, high-K calc-alkaline to shoshonitic monzonite, syenite, and granite that is adakitic (La/YbN = 13 to 57) with low Mg# (35–41). The Vanj complex displays a range of SiO2 (54–75 wt.%) and isotopic compositions (−7 to −3 εNd(i), 0.706 to 0.710 87Sr/86Sr(i), −3 to +1 zircon εHf(i), 6.0 to 7.6‰ zircon δ18OVSMOW), which reflects some juvenile mantle input and subsequent assimilation or mixing with the Central/South Pamir terrane lower crust. The Vanj complex is speculatively interpreted to be the consequence of a mantle drip or small delamination event that was induced by India–Asia collision. The age, geochemistry, outcrop pattern, and tectonic position of the Vanj magmatic complex suggest that it is part of a series of magmatic complexes that extend for >2500 km across the Pamir and northern Qiangtang terrane in Tibet. All of these complexes are located directly south of the Tanymas–Jinsha suture zone, an important lithospheric and rheological boundary that focused mantle lithosphere deformation after India–Asia collision. Miocene magmatism (20–10 Ma) in the Pamir includes: 1) isotopically evolved migmatite and leucogranite related to crustal anataxis and decompression melting within extensional gneiss domes, and; 2) localized intra-continental magmatism in the Dunkeldik/Taxkorgan complex.