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The opening of the Arctic oceanic basins in the Mesozoic and Cenozoic proceeded in steps, with episodes of magmatism and sedimentation marking specific stages in this development. In addition to the stratigraphic record provided by sediments and fossils, the intrusive and extrusive rocks yield important information on this evolution. This study has determined the ages of mafic sills and a felsic tuff in Svalbard and Franz Josef Land using the isotope dilution thermal ionization mass spectrometry (ID-TIMS) U–Pb method on zircon, baddeleyite, titanite and rutile. The results indicate crystallization of the Diabasodden sill at 124.5 ± 0.2 Ma and the Linnévatn sill at 124.7 ± 0.3 Ma, the latter also containing slightly younger secondary titanite with an age of 123.9 ± 0.3 Ma. A bentonite in the Helvetiafjellet Formation, also on Svalbard, has an age of 123.3 ± 0.2 Ma. Zircon in mafic sills intersected by drill cores in Franz Josef Land indicate an age of 122.7 Ma for a thick sill on Severnaya Island and a single grain age of ≥122.2 ± 1.1 Ma for a thinner sill on Nagurskaya Island. These data emphasize the importance and relatively short-lived nature of the Cretaceous magmatic event in the region.

This is the first book to focus on the solo residential work of the visionary interior decorator Stephen Sills. Simultaneously classical and modern, Stephen Sills's design work is a dialogue between past and present. Filled with luxurious fabrics, furnishings from across centuries, and unusual finishes, his work is polished, seemingly effortless, and quietly rich, with a muted color palette that serves as a brilliant foil for modern art.

Igneous sill intrusions are common features in volcanic basins worldwide, constituting important components of basin‐scale magma plumbing systems. While sills exhibiting simple geometries, such as saucer‐shaped sills, are commonly linked to distinct mechanical processes, emplacement mechanisms for sills exhibiting more complex geometries are debated. To better understand the emplacement of complex sills, this study aims to constrain the formation mechanisms associated with the Infinity Sill, a 237 km2 elongated sill located in the SW Vøring Basin. Detailed seismic interpretation and attribute analysis of an industry‐standard 15,000 km2 3D seismic data set reveal that the 36 km long and 4–8 km wide Infinity Sill intruded mud‐dominated Late Cretaceous strata. The thickness of the sill has been estimated to be dominantly 50–150 m, with a volume of ∼20 km3 (ranging between 7.9 and 25.5 km3). The shape of the sill and geometry of the sill elements suggest that the sill propagated as a large, magma‐filled fracture exploiting a pre‐existing polygonal fault network during propagation. The sill originated at a source in the SW, and the asymmetric propagation away from the source facilitated a 36 km lateral elongation of the sill, contrasting along‐axis dike models for elongated intrusion geometries. Local deformation around the sill initially facilitated continuous transgression, but with increasing sill length, forced folding of the overburden triggered abrupt transgression of the sill margins, resulting in a lateral change in geometry. The Infinity Sill, with its distinct geometrical features and changing cross‐sectional geometry, demonstrates that complex sill geometries are formed by a combination of emplacement mechanisms.

The Early Cenozoic igneous activity of the North Atlantic Igneous Province that generated widespread sill complexes in sedimentary basins at the NW European margins also generated various intrusive systems in the contemporaneous basaltic lava pile of the Faroe Islands. The Faroe Island Basalt Group comprises seven formations with a total thickness of about 6.5 km, of which four major formations are built up of tholeiitic lava flows, each being several hundred metres thick, and three thinner formations are mostly built up of volcaniclastic lithologies, each being a few metres to a few tens of metres thick. The largest sills are exposed as partly saucer-shaped bodies in the three uppermost formations, where inner gently dipping basal sill sections gradually give way to more steeply inclined discordant outer rims that commonly cut several hundred metres into overlying lava flows. Numerous subvertical and moderately inclined dykes ranging in thickness from c. 0.5 to c. 4.0 m intersect the areas affected by sill intrusion, but only inclined dykes or sheets have been positively identified as sill feeders. Locally controlled rotations of least principal stress axes σ3 during initial sill intrusion or propagation may have been an important contributing factor in determining the overall geometry of the investigated intrusions.

The emplacement of dikes and sills plays a crucial role in crustal mechanics. The parameter used to describe their resistance to propagation, fracture energy, remains controversial. Here, we show how different stress biaxiality levels experienced by dikes can directly affect the micromechanisms of crack propagation in rocks, consequently impacting fracture energy. We performed controlled tensile crack propagation experiments under opposite stress biaxialities. We connect fracture energy variations monitored through a compliance‐based method to crack microstructures observed on post‐mortem specimens. Microscopy techniques showed that biaxial tension generates intricate microstructures driven by topological instabilities, such as deflections and branches, to circumnavigate tougher grains. This yields a higher fracture energy, that we attribute to front roughening and bridging mechanisms due to front fragmentation. Bridging toughening is gradual and increase with crack size. This hints at the existence of a scale dependency of fracture energy of dikes also experiencing biaxial tension. Plain Language Summary Dikes and sills play a key role in volcanic systems by storing and helping magma move beneath the Earth's surface, affecting volcanic eruptions and the formation of igneous rocks. However, the resistance of rocks to the propagation of these cracks, known as fracture energy, varies widely and is not well understood. This study investigates how stress conditions, specifically stress biaxiality, influence crack growth in rocks and their overall resistance. We conducted lab experiments under two opposite stress conditions: tension in both principal directions and a mix of compression parallel and tension perpendicularly to the crack, mimicking the stresses that dikes experience. Using advanced imaging techniques, we discovered that under biaxial tension, cracks form intricate patterns, like zigzags and branches, to bypass stronger grains. This surprisingly increases the energy required to break the rocks. This is due to the creation of larger surfaces and to the fragmentation of the crack front trapping intact rock patches called bridges, which resist crack opening. As their number increases with crack size, fracture energy gradually increases. This finding suggests that the fracture energy of dikes under biaxial tension may also depend on the length of the crack, providing new insights into volcanic processes. Key Points Biaxial tension enhances crack deflections, branching, and bridging formation around tougher grains Despite circumnavigating tougher grains, tests under biaxial tension yields higher fracture energy, predominantly attributed to bridges In geological settings, bridging occurrence coincides with scale‐dependent toughness of fluid‐driven cracks experiencing biaxial tension

Interpretation of the seismic reflection profiles associated with borehole data from the petroleum industry offers a novel way to study sill emplacement in sedimentary basins. This study uses this approach to reveal the intrusive part of the Tarim Large Igneous Province (LIP) within the basin, which has not been systematically reported. A large number of igneous intrusions (sills) are identified in the sedimentary layers of the Central Tarim Basin. The burial depth of the sills is 6–8 km, and they are mainly located within the upper Ordovician strata. According to their seismic facies and drilling data, it is inferred that they are dolerite sills. Based on the uplift of the overlying strata above the intrusions, it is concluded that the sills were mainly formed during the depositional period of the middle Permian Kupukuziman Formation and Kaipailezike Formation (early stage), with a few formed during the depositional period of the upper Permian strata (late stage). It is likely that these two stages of sill intrusion correspond to the main basaltic eruptions within the basin and the mafic dike emplacement in the Bachu area of the Tarim LIP, respectively. The study suggests that that the dolerite sills reported in this study are also an important component of the Permian Tarim LIP.

Understanding the relationship between mineral occurrences and host granitic rocks can be controversial. The Zaozigou Au-Sb deposit (118 t Au, 0.12 Mt Sb), hosted in metasedimentary rocks and dacitic to granodioritic sills and dikes, is one such example of a large gold deposit argued to have formed from either magmatic or metamorphic hydrothermal processes. Two populations of monazite are identified within a mineralized dacite located along a major shear zone. Magmatic monazite commonly occurs within magmatic biotite and quartz phenocrysts and is characterized by uniform and high Th concentrations. It has a crystallization age of 238.3 ± 2.6 Ma, consistent with the zircon U-Pb age of 238.0 ± 1.8 Ma from the same dacite. Hydrothermal monazite is associated with sulfides and sericite, and has a 207Pb-corrected 206Pb/238U age of 211.1 ± 3.0 Ma. The amount of Th in hydrothermal monazite is widely variable. The low Th content of some monazite grains reflects direct precipitation from a metamorphic hydrothermal fluid. Furthermore, the elevated Th content in other hydrothermal monazite grains is likely due to the release of Th (and U) into hydrothermal fluids by dissolution of pre-existing Th-rich minerals in the country rock during ore-related alteration events. The magmatism, which overlaps Middle-Late Triassic terrane subduction-accretion in the West Qinling orogen, thus pre-dates the ore-forming event by about 30 m.y. The δ34S values of pyrite, arsenopyrite, stibnite, marcasite, and chalcopyrite from disseminated- and vein-type ores range from − 12.0 to − 5.5‰. Such negative values are distinct from those measured for other deposits in the northwestern part of the orogen that are genetically related to Triassic magmatism, including the Xiekeng-Jiangligou-Shuangpengxi Cu-Au-Fe-Mo skarn, Laodou reduced intrusion-related Au, and Gangcha epithermal Au ores. The Zaozigou deposit is best classified as an epizonal orogenic Au-Sb deposit. Our results demonstrate the usefulness of high-precision in situ geochronology on monazite for deciphering age relationships in ore deposits that have spatial associations with granitic rocks, thus aiding in the testing of the veracity of ore formation models.

Volcanic arcs consist of many distinct vents that are ultimately fueled by the common melting processes in the subduction zone mantle wedge. Seismic imaging of crustal‐scale magmatic systems can provide insight into how melt is organized in the deep crust and eventually focused beneath distinct vents as it ascends and evolves. Here, we investigate the crustal‐scale structure beneath a section of the Cascades arc spanning four major stratovolcanoes: Mt. Hood, Mt. St. Helens (MSH), Mt. Adams (MA), and Mt. Rainier, based on ambient noise data from 234 seismographs. Simultaneous inversion of Rayleigh and Love wave dispersion constrains the isotropic shear velocity (Vs) and identifies radially anisotropic structures. Isotropic Vs shows two sub‐parallel low‐Vs zones (∼3.45–3.55 km/s) at ∼15–30 km depth with one connecting Mt. Rainier to MA, and another connecting MSH to Mt. Hood, which are interpreted as deep crustal magma reservoirs containing up to ∼2.5%–6% melt, assuming near‐equilibrium melt geometry. Negative radial anisotropy, from vertical fractures like dikes, is prevalent in this part of the Cascadia, but is interrupted by positive radial anisotropy, from subhorizontal features like sills, extending vertically beneath MA and Mt. Rainier at ∼10–30 km depth and weaker and west‐dipping positive anisotropy beneath MSH. The positive anisotropy regions are adjacent to rather than co‐located with the isotropic low‐Vs anomalies. Ascending melt that stalled and mostly crystallized in sills with possible compositional differences from the country rock may explain the near‐average Vs and positive radial anisotropy adjacent to the active deep crustal magma reservoirs. Plain Language Summary Volcanic arcs, a common result of subduction processes, comprise a large proportion of active volcanoes in the world and pose significant hazards. Seismic tomography measures variations of seismic wave speed in the subsurface, which can then be used to infer important properties of the volcanic systems, such as the distribution and configuration of active melts in the crust. In this study, we use continuous seismic data from 234 seismography in the Cascades arc and measure the wave speed of two types of surface waves, Rayleigh and Love waves. This allows us to infer not only the averaged shear‐wave speed of the subsurface structures, but also its direction dependence, a seismic property known as seismic anisotropy. Our results show two concentrated and arc parallel low‐velocity anomalies at 15–30 km depth beneath the arc: one connecting Mt. Rainier to Mt. Adams, and another connecting Mt. St. Helens to Mt. Hood. We interpret these low‐velocity zones as deep crustal magma reservoirs with up to ∼2.5%–6% melt. We identify positive radial anisotropy adjacent to the isotropic low‐velocity anomalies at a similar depth range, and interpret them as sill complexes with mostly crystallized magma extracted from laterally offset deep crustal reservoirs. Key Points Anisotropic Rayleigh and Love wave tomography of the Cascades arc reveals two distinct arc parallel magma reservoirs in the mid‐lower crust One connecting Mt. Rainier to Mt. Adams (MA) and another Mt. St. Helens (MSH) to Mt. Hood with ∼50 km offset at the latitudes of MA and MSH Positive anisotropy adjacent to the magma reservoirs may represent and is interpreted as sill complexes with mostly crystallized mafic magma

Nature-based solutions, such as living shorelines, have the potential to restore critical ecosystems, enhance coastal sustainability, and increase resilience to natural disasters; however, their efficacy during storm events compared to traditional hardened shorelines is largely untested. This is a major impediment to their implementation and promotion to policy-makers and homeowners. To address this knowledge gap, we evaluated rock sill living shorelines as compared to natural marshes and hardened shorelines (i.e., bulkheads) in North Carolina, USA for changes in surface elevation, Spartina alterniflora stem density, and structural damage from 2015 to 2017, including before and after Hurricane Matthew (2016). Our results show that living shorelines exhibited better resistance to landward erosion during Hurricane Matthew than bulkheads and natural marshes. Additionally, living shorelines were more resilient than hardened shorelines, as they maintained landward elevation over the two-year study period without requiring any repair. Finally, rock sill living shorelines were able to enhance S. alterniflora stem densities over time when compared to natural marshes. Our results suggest that living shorelines have the potential to improve coastal resilience while supporting important coastal ecosystems.