Miocene-Pliocene strata in the Pacific Northwest preserve a rich record of landscape evolution and coincident faunal shifts. Considerable research efforts in the past century have been aimed at understanding major drainage reorganization and its relation to tectonics, volcanism, climate change, and aquatic biota. Many studies have focused on fish fossils, which show that Miocene fish diversity, particularly salmonoids, displays great adaptive plasticity. However, the details and mechanisms for river reorganization are still debated. Here we present new and recent detrital zircon provenance results from modern and ancestral river sands collected throughout Oregon, Washington, and Idaho. We synthesize our new results and interpretations with existing paleontological evidence for basin isolation and drainage capture. Detrital zircons from the Columbia Basin (CB) consistently show populations derived from the Snake River Plain (SRP) throughout late Miocene-Pliocene time. However, comparisons of Miocene-Pliocene detrital zircons from the CB to modern major rivers and tributaries in the CB and SPR show that the upstream eastern SRP is a major contributor. CB strata do not require zircons sourced from the western SRP, where Pliocene Lake Idaho existed in a large, deep, and occasionally internally drained basin. Based on the age and provenance results, we suggest that the transiting Yellowstone Hotspot divided the modern SRP into two basins: the western basin was isolated and possibly closed, while the eastern basin drained northward into the modern Clark Fork and Columbia Rivers. This scenario is consistent with fish, mollusk, and rodent fossil evidence from the SRP and CB. In addition, the detrital zircon data indicate a Miocene confluence of the Columbia and Clearwater rivers south of the Saddle Mountains anticline, but north of the current Columbia-Snake River confluence. We also find that the Salmon River may have been captured by the Clearwater River sometime between 4.6 and 8.5 Ma. Prior to this time, the Salmon River likely drained into the SRP. Lastly, we find that faunal localities in southern Oregon suggested to contain evidence for fluvial connection between the western SRP and California are ~2.5 Ma, younger than the incision of Hells Canyon.

Meteotsunamis triggered by atmospheric disturbances of Lamb waves due to the 2022 Hunga Tonga volcanic eruption were observed in coastal areas surrounding the Pacific Ocean. However, the spatio-temporal evolution of the meteotsunami wavefield remain elusive due to the lack of geophysical observations in the ocean. Here, we show a detailed distribution of the propagation velocities and directions of the meteotsunamis in the bathymetric slope area between the Japan Trench and nearshore, using 150 absolute pressure gauges deployed at water depths of 100--8000 m. We also illuminate the generation of free waves, i.e., tsunamis, which occur when the meteotsunamis propagate at the slope area. Large amplitudes of the meteotsunamis are produced in the southern part of the slope area, which is caused by the relationship between the incoming direction and the gradient of the bathymetry. Our findings establish a link between seafloor pressure measurements and the Lamb wave-excited wavefields.

Capability of TEC ’s CoRrelation Analysis (CRA) (Iwata and Umeno, 2016) for detecting preseismic anomaly is explained from the view point of the increase in signal-to-noise ratio to {\it amplify} preseismic TEC’s small anomaly signals with multiple sensor data synchronization and correlation to respond to all the criticisms proposed recently by Ikuta et al. 2021. Furthermore, deceleration at propagation velocities of MSTID before the 2016 Kumamoto earthquake firstly observed by CRA as velocity reduction of MSTID propagation in the F Layer of the ionosphere is then elucidated as a candidate of preseismic anomalies. This paper presents three models to explain its physical relationship with preseismic anomalies before large earthquakes. In particular, Model 1 predicts that the 35 m/s change in MSTID propagation velocities estimated by TEC’s CRA requires 0.58*10^{-3} V/m electric field change in the F Layer ionosphere, which is almost consistent with the estimation (Kelley et. al. 2017) in that the E*B/B^2 rift of 12 m/s for dislocations of electrons requires 0.5*10^{-3} V/m electric field in the E Layer to explain Heki’s finding of TEC anomaly behavior before the Tohoku-Oki earthquake. The \(10000\) times amplified effect of weak signals such as 0.58 mV/m in electrical field to affect MSTID propagation velocity change as is firstly observed by Iwata and Umeno, 2017 by CRA which has significant amplified capability. Contrary to the claim by Ikuta et al. 2021, TEC’s correlation anomalies detected (Iwata and Umeno 2016 and 2017) already provided supporting evidences that physical preseismic anomalies really exist.

On 20 March 2012, a Mw 7.5 thrust earthquake started a series of large events up to magnitude Mw 8.2 (2017) that struck central Mexico during a period of nine years. Before this event, the Mexican subduction zone did not experience subduction earthquakes (Mw > 7.0) for at least 12 years. Most of the events during this highly active period (2012-) occurred in the plate interface, resulting in a significantly larger interplate slip rate in the states of Oaxaca and Guerrero. In this study, we explore how the aseismic slip transient caused by the 2012 Mw 7.5 earthquake affected the region and whether this earthquake had a causal relationship with a nearby similar magnitude event that occurred in 2018 (Mw 7.2). To this end, we identified and analyzed characteristic repeating earthquakes along the Mexican subduction zone for assessing the plate interface slip history and found a notably increase in the aseismic slip rate inferred from repeating earthquake activity following the 2012 mainshock, which suggests a long-standing slip perturbation in Oaxaca near the trench that continued until the 2018 Mw 7.2 Pinotepa Nacional earthquake.

Gas hydrate dynamics and the fluid flow systems from two active pockmarks along Vestnesa Ridge (offshore west Svalbard) were investigated through the pore fluid geochemistry obtained during the 2016 MARUM-MeBo 70 drilling cruise. Based on the pore water chloride concentration profiles from Lunde and Lomvi pockmarks, we estimated up to 47% pore space occupied by gas hydrate in the sediments shallower than 11.5 mbsf. These gas hydrates were formed during periods of gaseous methane seepage, but are now in a state of dynamic equilibrium sustained by a relatively low methane supply at present. We detect a saline formation pore fluid around nine meters below seafloor from one of the seepage sites in Lunde pockmark. This formation pore fluid has elevated dissolved chloride concentrations and B/Cl ratios, higher δO and δD isotopic signatures of water and lower δB signatures, which collectively hint to a high temperature modification of this fluid at great depths. By integrating our findings with the previous work from Vestnesa Ridge, we show that the variable fluid phases (gaseous vs. aqueous fluid) and migration pathways are controlled by the sediment properties, such as buried carbonate crusts, and the state of fluid reservoirs.

Large thermospheric neutral density enhancements in the cusp region have been examined for many years. The CHAMP satellite for example has enabled many observations of the perturbation, showing that it is mesoscale in size and exists on statistical timescales. Further studies examining the relationship with magnetospheric energy input have shown that fine-scale Poynting fluxes are associated with the density perturbations on a case-by-case basis, whilst others have found that mesoscale downward fluxes also exist in the cusp region statistically. In this study, we use nearly 8 years of the overlapping SuperDARN and AMPERE datasets to generate global-scale patterns of the high-latitude and height-integrated Poynting flux into the ionosphere, with a time resolution of two minutes. From these, average patterns are generated based on the IMF orientation. We show the cusp is indeed an important feature in the Poynting flux maps, but the magnitude does not correlate well with statistical neutral mass density perturbations observed by the CHAMP satellite on similar spatial scales. Mesoscale height-integrated Poynting fluxes thus cannot fully account for the cusp neutral mass density enhancement, meaning energy deposition in the F-region or on fine-scales, which is not captured by our analysis, could be the primary driver.

We use continuous and survey GNSS data to image the spatial and temporal evolution of afterslip during the two-months following the Mw8.3 Illapel earthquake. Our approach solves for the incremental daily slip on the subduction interface using non-negative least-squares and spatial/temporal minimum Laplacian constraints. We find that afterslip developed at three specific areas at the megathrust, surrounding the coseismic rupture. The largest patch takes place at shallow depth north of the coseismic rupture. Smaller patches occur at greater depth north and south of the rupture, but no afterslip is found downdip. In addition, well resolved afterslip also occurs within the coseismic area that experienced 3-5 meters of seismic slip. Our afterslip model shows striking correlations with the spatial distribution of aftershocks and repeating earthquakes. A Mw6.8 aftershock occur on November 7 at the deep patch of enhanced afterslip and our inversion captures the triggered afterslip. Two Mw6.9 events occurred 100 km north of the rupture 55 days after the mainshock. The enhanced shallow afterslip developing northward possibly triggered these remote and delayed events. Enhanced afterslip spatially correlates with areas having experienced regular seismic swarms observed during the years prior to the Illapel earthquake. This correlation supports the view of localized fluid high-pore pressure areas behaving aseismically and surrounding a highly locked asperity, preventing the seismic rupture to propagate into them. The similarity with the behavior observed for the Mw7.8 2016 Ecuador and Mw7.6 2012 Costa Rica, suggests a common behaviour for heterogeneous subduction interfaces.

Over recent decades, the Southern Ocean (SO) has experienced multi-decadal surface cooling despite global warming. Earlier studies have proposed that recent SO cooling has been caused by the strengthening of surface westerlies associated with a positive trend of the Southern Annular Mode (SAM) forced by ozone depletion. Here we revisit this hypothesis by examining the relationships between the SAM, zonal winds and SO sea-surface temperature (SST). Using a low-frequency component analysis, we show that while positive SAM anomalies can induce SST cooling as previously found, this seasonal-to-interannual modulation makes only a small contribution to the observed long-term SO cooling. Global climate models well capture the observed interannual SAM-SST relationship, and yet generally fail to simulate the observed multi-decadal SO cooling. The forced SAM trend in recent decades is thus unlikely the main cause of the observed SO cooling, pointing to a limited role of the Antarctic ozone hole.

Most previous efforts to characterize the size and composition of the upper mantle, the source of mid-ocean ridge basalts (MORBs), have assumed that this MORB source is the residue of continental crust extraction. The use of Nd isotopes to model this process led to the near-consensus that the “depleted MORB reservoir” is more-or-less confined to the upper mantle (above 670 km, ~30% of the mantle), with a severe degree of depletion of incompatible elements, leaving the lower mantle in a more primitive state. Here, we reassess the mass and composition of the mantle reservoir depleted by continental crust extraction. We initially apply simple mass balance considerations, using alternatively ε(Nd) and “canonical” (Nb,Ta)/U tracers, to a conventional three-reservoir silicate Earth consisting of primitive mantle, continental crust, and depleted mantle. The (Nb,Ta)/U tracer yields a ‘depleted reservoir’ exceeding 60% by mass of the total mantle (X(DM) > 0.6) with average ε(Nd) ≤ 3, whereas the ε(Nd)-based mass balance, using ε(Nd) = 8.5, yields a “depleted reservoir” of X(DM) ≤ 0.3. This discrepancy requires additional processes/reservoirs that impact the fractionation of Sm/Nd in the depleted mantle. Simple segregation of enriched OIB sources is shown to be insufficient. Permanent sequestration of a fourth, early-enriched, mafic reservoir (EER), leaving behind an early-depleted reservoir (EDR) can resolve the dilemma. Segregation of the present-day continental crust from EDR generates a moderately depleted, “residual-mantle” reservoir (RM), which occupies 80-98% of the total mantle (X(RM) = 0.8-0.98). This leads to concordant results for the two crust-mantle mass balances.

The Danakil depression in Ethiopia, at the end of the southern Red Sea, has been the locus of volcanic crises in 2004-10, with emplacement of 15 dykes: one, non-emergent, in Lake Asale next to Black Mountain and south of the Dallol dome during fall 2004, the others in the Dabbahu-Manda Hararo rift segment between September 2005 and May 2010. We report on a hydrothermal crisis that opened a 4.5 km long fissure in the ground, at the same time the Black Mountain dyke was intruding the crust 2 km away and parallel to it. The fissure, located north and south of Yellow Lake (Gaet’ale) and trending NNW-SSE, is still active. Its morphology is remarkably diversified, but surface evidence of the structural deformation has been lost over the years. Its formation is coeval with the intrusion of the Black Mountain dyke intrusion. It is suggested that after its documented propagation, the Black Mountain dyke propagated aseismically eastward as a sill, disrupting the stress equilibrium in the long-living Yellow Lake hydrothermal environment. The stress field was brought to rupture by the increased deviatoric stress, triggering the nucleation of a tensile fracture that propagated to the surface and released the far-field stress already released at depth by the emplacement of the dyke. This study documents the delicate intermingling of magmatic, tectonic, and hydrothermal processes at the ultimate step of continental rifting prior to the earliest stage of oceanic spreading.

The tool of phase-field modeling for the prediction of chemical as well as microstructural evolution during crystallization from a melt in a mineralogical system has been developed in this work. We provide a compact theoretical background and introduce new aspects such as the treatment of anisotropic surface energies that are essential for modeling mineralogical systems. These are then applied to two simple model systems - the binary olivine-melt and plagioclase-melt systems - to illustrate the application of the developed tools. In one case crystallization is modeled at a constant temperature and undercooling while in the other the process of crystallization is tracked for a constant cooling rate. These two examples serve to illustrate the capabilities of the modeling tool. The results are analyzed in terms of crystal size distributions (CSD) and with a view toward applications in diffusion chronometry; future possibilities are discussed. The modeling results demonstrate that growth at constant rates may be expected only for limited extents of crystallization, that breaks in slopes of CSD-plots should be common, and that the lifetime of a given crystal of a phase is different from the lifetime of this phase in a magmatic system. The last aspect imposes an inherent limit to timescales that may be accessed by diffusion chronometry. Most significantly, this tool provides a bridge between CSD analysis and diffusion chronometry - two common tools that are used to study timescales of magmatic processes.

The bottom topography of ridged sea ice differs largely from that of other sea ice types. The form drag on ridge keels plays an important role affecting sea ice drift and deformation. We have carried out laboratory experiments and numerical simulations for a ridge model in a flume in order to better understand the characteristics of the form drag. The experimental setup covered both laminar and turbulent conditions. The local form drag coefficient of a keel, Cd, varied with the keel depth h and slope angle α in the turbulent regime. The numerical model extended the experimental results to independence of the water depth in order to achieve an analogy for ocean conditions. The results showed Cd= 0.68ln(α/7.8),R2= 0.998, 10˚ ≤ α≤ 90˚, Cd ranging from 0.14 to 1.66, when keel depth is much smaller than mixed layer depth. In the Arctic Ocean, keel slope angles are within the range of 10˚–50˚ where Cd increases monotonously and becomes the dominant part of the total ice-water drag coefficient when α ≥ 20˚. When h/Lr (the ratio of keel depth to spacing) was high (h/Lr>0.01), the ratio of air-ice to ice-water drag coefficient first decreased and then increased with α and reached the minimum at α ≈ 30˚. The variation of Cd with α (10˚–50˚) affects the momentum transfer of drifting sea ice, and we suggest that Cd under ridged sea ice to be tuned to 0.14–1.26 in multi-category sea ice models.

The mining sector generates a substantial quantity of stone waste and tailings, which constitutes an environmental risk. The most prevalent method for disposing of this industrial waste is dumping, which contributes to soil deterioration and water contamination while acquiring precious land. It can be recycled using a number of processes, such as the promising geopolymerization technique, which transforms waste into value. This study reviews current developments in the manufacturing of mine tailings-based geopolymer composites from industrial waste as a possible sustainable building material. This paper also gives in-depth studies on the characteristics and behaviors of mine tailings composites used in geopolymer manufacturing, including physical and mechanical properties. This review also identifies knowledge gaps that must be filled in order to advance mine tailings composites for geopolymers.

A document by Qian Liu. Click on the document to view its contents.

Shipping activities are a major source of air pollution in port cities with the expected high population of port workers and related workforce being chronically exposed to air pollutants such as carbon monoxide (CO) and suspended particulate matters (SPM: PM 10). These two priority air pollutants in addition to relative humidity (RH) and wind speed were monitored every month over a period of four years at Tin Can, Apapa Lagos, being the location of the busiest port in Nigeria. Results indicate that the highest monthly mean concentrations recorded throughout the study were 3.31 ppm and 258.6 µg/m 3 for CO and PM 10 respectively. While the value of CO was within the recommended threshold limits by the World Health Organization (WHO) and the Federal Ministry of Environment (FMEnv), the PM 10 exceeded the WHO specified limit of 50 µg/m 3 for a-24 h period of exposure. The ambient concentrations of the two air pollutants were higher in the dry season than their concentrations in rainy season. However, a significant seasonal variation was observed in the ambient concentrations of PM 10. Regression analysis shows that wind speed contributes significantly (p<0.05) to the detectable concentration of CO while RH had no significant influence on CO availability in the study area. Conversely, RH significantly influenced the concentration of PM 10 with a direct positive correlation between the climatic index and particulate matter while wind speed had no significant influence on suspended particles. The study established that there is no risk of acute human exposure to the air pollutants in the ports area. In spite of the low ambient concentrations recorded during the study, chronic exposure of workers or residents in port areas has its long-term health implications. Further study is required to monitor the indoor concentrations of these pollutants, which were possibly dispersed by wind from the lagoon and the ocean.

In their study, Dong and Ochsner (2018) used an extensive dataset of 18 cosmic-ray neutron rover surveys to assess the influence of precipitation and soil texture on mesoscale soil moisture patterns. Based on their analysis, they concluded that soil texture, represented by sand content, often exerts a stronger influence on mesoscale soil moisture variability than precipitation, represented by the antecedent precipitation index. However, we consider that Dong and Ochsner (2018) made a mistake in their calculation of volumetric soil moisture, such that their analysis on the influence of soil texture on soil moisture is not valid. This result does however not bring into question the paper’s conclusion on the influence of soil texture on mesoscale soil moisture patterns.

Geologically, Eastern Indonesia is a 180o orocline created by the dynamic interaction of three opposing tectonic plates. Additional complexity resulted from the sporadic breakup of Gondwana that fragmented the northern margin of New Guinea-Australia (NGA) and caused crustal blocks to collide with SE Asia before the Pliocene arc-continent collision with Australia. One consequence is that protoliths of two distinct metamorphic associations on Timor have mixed Gondwanan and SE Asian affinities. This article presents a reclassification of the metamorphic rocks of Timor that links their formation and radiometric ages to tectonic provenance and key events that occurred as NeoTethys was consumed by subduction. Four periods of metamorphism are recognised, plus radiometric dating evidence of peak and cooling P-T conditions and the tectonic settings that caused metamorphism and deformation of different complexes on the island. Key conclusions are: [1] a basement complex accreted to the Sunda margin from Gondwana in the Cretaceous. [2] Oceanic crust and pelagic sediment of Jurassic to Early Cretaceous age form a tectono-metamorphic complex comprised of volcanic greenstones, greenschists, mn-rich sediments, and radiolarian cherts metamorphosed in the pre-collision Sunda forearc. [3] Eocene back arc spreading led to injection of gabbro and peridotite, and a metamorphic episode that peaked at 45Ma. [4] The metamorphosed Permo-Triassic Aileu Complex originated on Gondwana but includes Sunda upper plate peridotite that became attached during subduction and extrusion at the close of the Miocene.

Early observations from the Perseverance rover suggested a deltaic origin for the western fan of Jezero crater only from images of the Kodiak butte. Here, we use images from the SuperCam Remote Micro-Imager and the Mastcam-Z camera to analyze the western fan front along the rover traverse, and further assess its depositional origin. Outcrops in the middle to lower half of hillslopes are composed of planar, inclined beds of sandstone that are interpreted as foresets of deltaic deposits. Foresets are locally structured in ~20-25 m thick, ~80-100 m long, antiformal structures interpreted as deltaic mouth bars. Above these foresets are observed interbedded sandstones and boulder conglomerates, interpreted as fluvial topset beds. One well-preserved lens of boulder conglomerate displays rounded clasts within well-sorted sediment deposited in fining upward beds. We interpret these deposits as resulting from lateral accretion within fluvial channels. Estimations of peak discharge rates give a range between ~100 and ~500 m3.s-1 consistent with moderate to high floods. By contrast, boulder conglomerates exposed in the uppermost part of hillslopes are poorly sorted and truncate underlying beds. The presence of these boulder deposits suggests that intense, sediment-laden flood episodes occurred after the deltaic foreset and topset beds were deposited, although the origin, timing, and relationship of these boulder deposits to the ancient lake that once filled Jezero crater remains undetermined. Overall, these observations confirm the deltaic nature of the fan front, and suggest a highly variable fluvial input.