The Basque-Cantabrian basin is located in northern Spain in the westernmost part of the Pyrenees. It is a Mesozoic rift, inverted during the Tertiary. In this basin, a subsiding deep-water depocenter, called the Basque Trough formed during the Early Cretaceous, in response to the opening of the Bay of Biscay. In the Basque-Cantabrian basin, the Triassic salt-bearing red clays are exposed in several diapirs that display discordant contacts with the Mesozoic and the Tertiary successions, suggesting a long-lasting halokinetic growth at regional scale. The synthesis of previously published works, together with the analysis of the geological maps from the Spanish geological survey (IGME) as well as the building of new structural cross-sections, allows reviewing the history of halokinesis in the basin. At least four distinct areas may be defined according to the paleogeographical locations of the diapirs: the northern and southern margins of the Basque Trough, and the southern and eastern areas of the Basque-Cantabrian basin. In the northern margin of the Basque Trough, the Bakio and Gernika diapirs mainly recorded an Aptian-Albian growth history, although older and younger growth cannot be ruled out. These diapirs were growing in relatively deep-water environments and created some paleo-highs where isolated carbonate platforms developped. In the southern margin of the Basque Trough, the Villasana de Mena, Orduña, Murguía diapirs recorded an Early Cretaceous to Late Turonian growth evolution. These diapirs were growing in relatively shallow-water environments at the shelf of the southern margin. In the southern area of the Basque-Cantabrian basin, the Salinas de Rosío and Salinas de Añana diapirs recorded a Cretaceous salt growth in a shallow-marine to continental environment and the Tertiary reactivation during the inversion of the basin. The Salinas de Rosío diapir shows a salt glacier overlying the adjacent Tertiary Villarcayo Syncline that displays a mini-basin shape with a strong thinning of the Tertiary succession toward its margins. In the eastern area of the Basque-Cantabrian basin, five diapirs (Estella, Alloz, Salinas de Oro, Ollo and Anoz) are aligned along the Pamplona fault, that represent a Cretaceous transverse fault bounding the Basque Trough to the east. The Tertiary succession covers the older units masking the possible Cretaceous salt growth evolution. However, strong thinning of the Tertiary succession toward these diapirs together with the lateral facies changes highlights the Tertiary reactivation of these structures during the basin inversion. The compilation of all these data allows creating a geological chart that depicts the evolution of the salt structures through time and in the different areas of the Basque-Cantabrian basin.

The Ziway-Shala Lakes Basin is a structural depression found in the Main Ethiopian rift being associated with Cenozoic volcanism, faulting and sedimentation activities. The Aluto-Langano volcanic complex is one of the geothermal prospect sites found in this basin and is currently being exploited for geothermal power production. Although it contradicts with the previous research results, recent observations using magneto-telluric method reveal nonexistence of a heat source beneath the Aluto volcano. Instead existence of a strong conductor possibly a magmatic heat sources claimed to occur beneath the Silti Debre Zeyet Fault Zone that lays far NW of the Aluto volcanic complex. In this study, ground based magnetic survey is carried out to map magnetic anomaly patterns and structural features associated with the Aluto-Langano. The volcano-tectonic features are extracted from the differentially pole reduced total magnetic field anomaly map and its derivative maps compiled by applying upward continuation, first vertical derivative and tilt derivative filters. Interpretation of the complied anomaly maps reveal existence of a heat conduction structural path along a traverse running from the Aluto-Langano geothermal to the Silti Debre Zeyte Fault zone and laying between 1.5 km and 3 km depths. This result could be taken to prove the most likely heat source feeding the Aluto-Langano geothermal field is found at about the locality of the Silti Debre Zeyte Fault Zone. The research work also identified magnetic lineaments most of which oriented in the direction of pre-existing Mesozoic structures and in the direction of thermally altered structures.

Water retention in soil exhibits diverse phenomena, including suction-saturation hysteresis, non-unique air entrapment at zero suction and negative suction under partial saturations. The constancy of suction after a long rest can be broken by relatively minor mechanical or hydraulic agitations such as low-amplitude wetting cycles -- this fact is here being related to metastable states that differ from the true equilibrium. The complete suction-saturation relationships are thus being recovered using non-equilibrium Landau's hydrodynamic theory and Onsager's reciprocity principles. Equilibrium suction does not pertain to hysteresis, yet can be approached through small amplitude agitations over long duration. Conditions for rate independence are being described, while rate-dependency are also accommodated and illustrated. Finally, it is shown that the new non-equilibrium theory retains the rigorously derived equilibrium result of the effective stress of partially saturated soils.

The evolution of the climate and hydrochemistry of Mars is still a mystery but it must have been at least occasionally warm and wet to have formed the ancient fluvial and lacustrine landforms observed today. Terrestrial examples and geochemical modeling under proposed early Mars conditions show that zeolite minerals are likely to have formed under alkaline (pH > 8) conditions with low water/rock ratio and surface temperatures below 150 °C. The identification and spatial association of zeolites on the surface of Mars could thus be used to reconstruct the paleoclimate, paleohydrochemistry, and geological evolution of some locations on Mars. Previous studies identified the zeolite analcime and discuss the difficulties of identifying other zeolite species on the surface of Mars using orbital spectroscopy. We used published global mineralogical, geological, geomorphological, hydrological, physical, and elemental abundance maps and the locations of hydrous minerals detected and mapped using orbital data to create a map that delineates favorable areas to look for zeolites on Mars. We used the data-driven fuzzy-based weights-of-evidence method to identify and map favorable areas for zeolites on the surface of Mars up to ± 40° latitudes towards the poles. The final map shows that the eastern and western Arabia deposits, some sites in the Medusae Fossae formation, and some areas within and near Valles Marineris, Mawrth Vallis, highlands north of Hellas, and the Terra Cimmeria and Terra Sirenum regions would be favorable areas to look for zeolites using targeted orbital spectral analysis or future in situ observations.

Although positive buoyancy of young lithosphere near spreading centers does not favor subduction, subduction initiation near ridges may occur upon forced compression due to their intrinsic rheological weakness. It has been repeatedly proposed that detachment faults may directly control the nucleation of new subduction zones. However, recent 3D numerical experiments suggested that direct inversion of a single detachment fault does not occur. Here, we further investigate numerically this controversy by focussing on the influence of brittle-ductile damage on the dynamics of near-ridge subduction initiation. We model self-consistently the inversion of inherited long-term spreading patterns using 3D high-resolution thermomechanical numerical models combining strain weakening of faults with grain size evolution in lithospheric mantle. Numerical results show that development and evolution of detachment faults are strongly affected by the brittle-ductile damage coupling. Forced compression predominantly thickens the weakest near-ridge region of oceanic lithosphere, and reactivates inherited extensional faults. This results in rotation of blocks along reactivated faults leading to their subsequent locking. As the result, the development of a new megathrust zone occurs, which accommodates further shortening and subduction initiation. Strain weakening has a key impact on the collapse of thickening mid-ocean ridge region and the occurrence of near-ridge subduction initiation. In contrast, grain size evolution of mantle plays a subordinate role in these processes by slightly modifying the localization of shear zones near brittle-ductile transition. Through comparing with the geological record, our numerical results provide new helpful insights into natural near-ridge subduction initiation processes recorded by the Mirdita ophiolite of Albani.

Cosmogenic exposure data can be used to calculate time-varying fault slip rates on normal faults with exposed bedrock scarps. However, the method relies on assumptions related to how the scarp is preserved, which should be consistent at multiple locations along the same fault. Previous work commonly relied on cosmogenic data from a single sample locality to determine the slip rate of a fault. Here we show that by applying strict sampling criteria and using geologically informed modelling parameters in a Bayesian-inference Markov chain Monte Carlo method, similar patterns of slip rate changes can be modelled at multiple sites on the same fault. Consequently, cosmogenic data can be used to resolve along-strike fault activity. We present cosmogenic 36Cl concentrations from seven sites on two faults in the Italian Apennines. The average slip rate varies between sites on the Campo Felice Fault (0.84 0.23 to 1.61 0.27 mm yr ^-1), and all sites experienced a period of higher than average slip rate between 0.5 and 2 ky and a period of lower than average slip rate before 3 ky. On the Roccapreturo fault, slip rate in the centre of the fault is 0.550.11 and 0.350.05 mm yr ^-1 at the fault tip near a relay. The estimated time since the last earthquake is the same at each site along the same fault. These results highlight the potential for cosmogenic exposure data to reveal the detailed millennial history of earthquake slip on active normal faults.

IDN Penelitian ini dilakukan dengan tujuan untuk memetakan pola aliran air tanah di sekitar Kali Sumpil di wilayah Kota Malang. Lokasi penelitian ini adalah di segmen Kali Sumpil sepanjang 5,6 km yang mengalir mulai dari Kecamatan Lowokwaru hingga ke pertemuan antara Kali Sumpil dan Kali Sari di Kecamatan Blimbing, Kota Malang. Pola aliran air tanah di lokasi penelitian dipetakan berdasarkan elevasi muka air tanah yang diukur dari 43 lokasi sumur gali milik warga yang tersebar di sepanjang aliran Kali Sumpil tersebut. Elevasi muka air tanah pada sumur gali warga di lokasi penelitian berkisar antara +493,88 m dpl di bagian hulu hingga +436,70 m dpl di bagian hilir. Elevasi muka air tanah tertinggi berada pada sumur gali SG-26 yang berada di sebelah kanan aliran bagian hulu Kali Sumpil, sedangkan elevasi muka air tanah terendah berada pada sumur gali SG-25 di sebelah kiri aliran bagian hilir Kali Sumpil. Secara umum, aliran air tanah di lokasi penelitian mengalir dari arah Barat Laut menuju ke arah Tenggara bersesuaian dengan arah aliran Kali Sumpil. Hubungan antara air tanah dan air permukaan adalah air tanah mengisi air permukaan Kali Sumpil. EN The objective of this study is to mapping the groundwater flow patterns around Sumpil River in Malang City. The location of this study is in one of the segments of Sumpil River along the 5.6 km which flows from Lowokwaru District to the confluence of Sumpil River and Sari River in Blimbing District, Malang City. The groundwater flow pattern in the area of the study was mapped based on the groundwater level measured from 43 resident’s dug wells scattered along Sumpil River. The groundwater level in the area of the study ranges from +493,88 m asl in the upstream area to +436,70 m asl in the downstream area. The highest groundwater level is in the SG-26 which is located to the right of the upstream flow of the Sumpil River, while the lowest groundwater level is in the SG-25 to the left of the downstream flow of the Sumpil River. In general, groundwater flow in the area of study flows from the Northwest to the Southeast in accordance with the direction of the Sumpil River flow. The interaction between groundwater and surface water is the groundwater flows to Sumpil River (gaining stream).

The current approaches have known limitations to understanding the coupling of terrestrial ecosystem evapotranspiration (ET) and photosynthesis (referred to as gross primary productivity, GPP). To better characterize the relationship between ET and GPP, we developed a novel remote sensing (RS)-driven approach (RCEEP) based on the underlying water use efficiency (uWUE). RCEEP partitions transpiration (T) from ET using a RS vegetation index (VI)-derived ratio of T to ET (VI-fT) and then links T and GPP via RS VI-derived Gc (VI-Gc) rather than leaf-to-air vapor pressure difference. RCEEP and other two uWUE versions (VI-T or VI-G), which only incorporate VI-fT or VI-Gc , were evaluated and compared with the original uWUE model in terms of their performances (Nash-Sutcliffe efficiency, NSE) in estimating GPP from ET over 180 flux sites covering 11 biome types over the globe. Results revealed better performances of VI-T and VI-G compared to the original uWUE, implying remarkable contributions of VI-fT and VI-Gc to a more meaningful relationship between ET and GPP. RCEEP yielded the best performances with a reasonable mean NSE value of 0.70 (0.76) on a daily (monthly) scale and across all biome types. Further comparisons of RCEEP and approaches modified from recent studies revealed consistently better performances of RCEEP and thus, positive implications of introducing VI-fT and VI-Gc in bridging ecosystem ET and GPP. These results are promising in view of improving or developing algorithms on coupled estimates of ecosystem ET and GPP and understanding the GPP dynamics concerning ET on a global scale.

Despite the importance of turbidity currents in environmental and resource geology, their flow conditions and mechanism are not well understood. To resolve this issue, a new method for the inverse analysis of turbidity current using deep learning neural network (DNN) was proposed. This research aims at verifying and calibrating this method using artificial and flume experiment datasets. The forward model based on the shallow water equation was employed in this study to produce artificial datasets of turbidite deposits. DNN was applied to two hundred artificial datasets and two sets of experiment data. As a result of inversion by DNN, spatial distributions of grain size and thickness of experimental turbidites were reconstructed accurately. With regard to hydraulic conditions, the flow heights were reasonably estimated, and sediment concentrations reconstructed were reasonable except for regions where the values measured in experiments were extremely low. Flow duration also showed reasonable reconstructed values. In contrast to the other values, there was a large discrepancy between the measured and reconstructed values of flow velocity. The reason for this discrepancy in velocity may be attributed to inaccuracy in closure functions employed in the forward model. Future application to actual data of natural scale turbidite is anticipated.

Abstract The repetitive narrative that, “Tsunami waves and receded coastal water initiated by an earthquake are closely related,” is analyzed through the sequential events that followed the earthquake; a mechanism based on the interaction of receded water with magma is suggested to explain the amplification of Tsunami wave deep beneath the ocean floor (Fig.1), where earthquake occurred under the seabed’s or in coastline; the mechanism explained how the water is amplified into steam in the magma chamber, as its volume increased 1,700 times, the transformed water encompass the tremendous force that uplifted the ocean water endowed it with such destructive force; the mechanism explained characteristics related to Tsunami wave, including relation with earthquake and volcano, receding costal water, the foams, inundation, runup, the nature of the great force of Tsunami, ideas to calculate the magnitude of Tsunami force and energy, volume of receded water, volume of tsunami wave, the repetition of its wave; these and related issues are stated; the idea is derived based on the continual flow of lava from earth’s interior and the existence of magma reservoir bellow earth’s surface in places like Yellowstone in USA and hotspot beneath Hawaii, such magma chamber when existed under seabed, if opened by crack during earthquake, can easily lead to an interaction between receded water and the magma, resulted in the suggested mechanism, all is based on logical analyses and deep thinking to attained the Tsunami Mechanism in response to 2004 and 2011 human tragedies; thus understanding this mechanism will help laying measures to counter the phenomenon, which will reflect positively in saving lives and mitigate its destructive force and reduce consequences of its impact on local societies and above all to understand its true mechanism.

Parental melt compositions of poikilitic shergottites exhibit similar compositions to that of olivine-phyric shergottites, possibly linking them.

Rock fractures play a fundamental role in fluid migration through the crust, rendering them important in geoenergy applications. Although often modelled as smooth parallel plates, fracture surfaces are rough, and roughness impacts transport properties. Despite their importance, there remains a paucity of data related to what controls fracture roughness and, consequently, how this affects fluid flow. Here, we examine how fracture orientation affects fracture roughness in Nash Point Shale, using laboratory-and synchrotron-based µ-CT, and optical microscopy methods, and consequently how fracture orientation and roughness affect fluid flow through a series of core flooding experiments. We show that there is a strong correlation between fracture orientation, fracture roughness and surface area, for fractures between the Short-transverse and Arrester orientations. Fractures in the Divider orientation have both a larger surface area and higher roughness than fractures in all other orientations, which we relate to fundamental differences in the fracture mechanics in this orientation. We also measured the permeability of samples containing mated fractures of different orientations to bedding but discovered no systematic differences between them.

Volcanic eruptions progress by co-evolving fluid and solid systems. The fluid mechanics can be observed through the plumes and ejecta produced, but how does the solid system evolve? When does the conduit open? When does it close? Seismology can potentially tell us about these processes by measuring the failure of the solid rock. Such inferences require the detection of earthquakes during an explosive eruption. Standard earthquake detection methods often fail during this time as the eruption itself produces seismic waves that obscures the earthquake signals. We address this problem by applying supervised and unsupervised search techniques to the existing catalog of the 2008 Okmok eruption to find brittle failure signals during the continuous eruptive sequence. The interaction between fluid pathways and seismicity is reinforced by high precision earthquake relocations that highlight a ring-fault structure, which may be acting as a conduit for fluids to the surface. The timing of the earthquakes during the eruption reveal that the seismicity gradually increases during the vent-opening stage (July 12-July 24), peaks during the vent-widening stage (July 24-August 1) which culminates in a large burst of earthquakes, and then gradually decrease until the end of the eruptive period. Seismic bursts during the eruption are not synchronized with the exhalation of large ash and steam plumes. In other words, when the system is closed, the rock breaks. We call this scenario clog and crack.

Classification of ground points is a critical step in producing digital elevation models of the Earth’s surface for studying landscape processes and geomorphic or ecological change. This paper describes a new algorithm for ground point classification and assesses the relative accuracy of the resulting ground surface in filtered light detection and ranging (lidar) and structure-from-motion (SFM) datasets. This color-enhanced multiscale curvature classification algorithm (MCCRGB) extends a popular lidar classification method (MCC) by introducing classification updates that distinguish vegetation and ground points by color. Multispectral lidar and SFM data imaging a subalpine volcanic tree kill are used to evaluate both methods. We find that color-based classification updates remove tree fall, low canopy, and brush, often requiring fewer iterations on large, ultra-high-density datasets. SFM data capture rills, small channels, and tree fall not visible in the lidar data. “Bare-earth” datasets from each method are internally consistent (mean vertical differences: -0.01 to 0.08 m) and validation at a set of 165 checkpoints shows a mean vertical difference of 0.46 m (standard deviation: 2.21 m) with the SFM ground points. The methods produce consistent topographic derivatives from each data source, including digital elevation models, slope, and profile curvature. While SFM derivatives are more variable and less continuous, the filtered products may be useful for geomorphic mapping and analysis, including mapping of microtopography or measuring landscape change in challenging, forested settings.

The intermontane Tarom Basin of NW Iran (Arabia-Eurasia collision zone) is located at the transition between the Iranian Plateau (IP) to the SW and the Alborz Mountains to the NE. This basin was filled by Late Cenozoic synorogenic red beds that retain first-order information on the erosional history of adjacent topography, the vertical growth of the plateau margin and its lateral (orogen perpendicular) expansion. Here, we perform a multidisciplinary study including magnetostratigraphy, sedimentology, geochronology and sandstone petrography on these red beds. Our data show that widespread Eocene arc volcanism in NW Iran terminated at ~ 38-36 Ma, while intrabasinal synorogenic sedimentation occurred between ~ 16.5 and < 7.6 Ma, implying that the red beds are stratigraphically equivalent to the Upper Red Formation. After 7.6 Ma, the basin experienced intrabasinal deformation, uplift and erosion in association with the establishment of external drainage. Fluvial connectivity with the Caspian Sea, however, was interrupted by at least four episodes of basin aggradation. During endorheic conditions the basin fill did not reach the elevation of the plateau interior and hence the Tarom Basin was never integrated into the plateau realm. Furthermore, our provenance data indicate that the northern margin of the basin experienced a greater magnitude of deformation and exhumation than the southern one (IP margin). This agrees with recent Moho depth estimates, suggesting that crustal shortening and thickening cannot be responsible for the vertical growth of the northern margin of the IP, and hence surface uplift must have been driven by deep-seated processes.

Water soluble organic carbon (WSOC) makes up a large fraction of organic carbon, which attracted great attention due to its light absorption properties and human health effects. Sources and light absorption properties of WSOC in 10 cities across China were studied by dual carbon isotope analysis and UV−visible spectrophotometer, respectively. Despite the dominate contribution of non-fossil sources, the fossil sources contribution of WSOC in China was higher than other regions across the world. The average MAE365 and fossil sources contribution of WSOC was 1.13 ± 0.37 m2/gC and 39.9 ± 9.4%, both of which were higher in Northern China. The non-fossil sources contribution of WSOC and MAE365, WSOC exhibited significant seasonal variations with highest values during cold seasons, which was likely associated with corn residues burning. Compared to warm seasons, the MAE365, WSOC showed a positive relationship with relative contribution of fossil sources and with higher values during cold seasons, indicating the fossil derived WSOC had higher light absorption capacity and enhance the overall color of WSOC during cold seasons. To constraining the regional climate and health impact of WSOC, this study suggests that mitigation strategy should consider the spatiotemporal variations in the sources, formation pathways and light absorption properties of WSOC.

Buoyant trench sediment generates an isostatic restoring force, which opposes the slab pull of subducting plates, but the influence of this force on subduction dynamics is poorly understood. Here, we performed 3D free subduction simulations adopting a variety of sediment distributions along a trench to investigate the correlation between trench kinematics and heterogeneous buoyant force. Two endmembers, sediment-rich and sediment-starved centers, induced convex and concave trenches, respectively. The trench curvatures obtained from natural subduction zones are well constrained by our models over wide magnitudes (1-9 km) and wavelengths (100-400 km) of deficient and excess sediment. Conversely, uniform sediment distribution leads to an extremely narrow range of trench curvature. These results imply that trench sediment contributes to the diversity of trench shapes. Finally, we observed stress localization in slab hinges beneath abundant sedimentation, thereby clarifying the relationship between sediment thickness and subduction earthquakes.

Basaltic melts are produced when convection adiabatically brings deep and hot mantle to lower pressures. Such primary melts were extracted from the mantle of Mars, crystallized near the surface and progressively built the Martian crust. This process displaced a large fraction of the heat producing elements from the mantle to the crust and created an insulating layer that slowed down further cooling of the mantle. The complex crust-mantle system controlled many aspects of the geologic history of Mars, including the development of an atmosphere and whether conditions favorable to life could have existed. Our knowledge of the mineralogy, chemical composition and physical properties of the crust of Mars is rapidly expanding. Global geodynamical models can be used to interpret the available data and constrain the processes of crust-mantle differentiation. However, existing models still treat melting in a simplified way. For example, the degree of melting is often assumed to increase linearly above the solidus temperature, while the density of the residue is assumed to decrease linearly. Calculating the density of the residual mantle more accurately is critical because the compositional buoyancy that develops during partial melting fundamentally modifies mantle dynamics. Here, we present an improved parametrization of partial melting of the Martian mantle, which will be combined with the convection code Gaia. We created a new empirical model of melting that calculates the composition of the extracted melts and, when combined to thermodynamic models (e.g., Perple_X), the density of the corresponding residual mantle. Another advantage of the new melting parametrization is that the major-element composition of partial melts can be tracked and used to constrain the petrogenesis of surface rocks. Preliminary results will be compared to available Martian rocks believed to represent primary mantle melts or melts affected by minor fractional crystallization.

An approximately 40-km long high-resolution reflection seismic profile (P3) was acquired in the metropolitan area of Seoul in South Korea for the purpose of fault system imaging in a highly noisy and challenging urban environment. Two 12t seismic vibrators (mini-vibs) were used as the seismic source. Data were recorded using a dual element seismic spread; 20 m spaced 421 wireless seismic recorders connected to 10 Hz geophones and 20 micro-electro-mechanical (MEMS-based) landstreamer sensors (2 m sensor spacing) attached to one of the vibrators. The purpose of the dual spread employed was to delineate both near-surface and deep structures. The processing results show good quality and the processing work was complemented by different analysis to further constraints the geological interpretation. The survey results provide evidence for the 3D geometry of three fault systems, including Chugaryeong, Pocheon and Wangsukcheon faults. A gently westerly-dipping set of reflectivity underlying a domed-shaped package of reflectivity is interpreted as a fault, and could project to the known surface position of the Pocheon fault. The domed-shaped reflectivity is interpreted as folded and faulted dyke or sill systems. Downward continuation of the interpreted fault intersects the sub-vertical Chugaryeong fault in a zone where the current seismicity is observed, suggesting that these two major fault systems may have jointly evolved in the form of splay faults. Reflections from the Wangsukcheon fault are also present in the data and interpreted to dip approximately 60 degrees to the east, in an opposite direction to the two other faults.

Many communities along the East and Gulf coasts of the United States are experiencing moderate to severe erosion. Decadal shoreline erosion rates determined by the North Carolina Division of Coastal Management indicate that >65% of the NC shoreline is eroding, with 20% losing shore at ~1 m per year. Chronic long-term erosion and episodic rapid impacts from storms have encouraged most coastal NC communities to conduct beach nourishments for mitigation. One concern is that there is limited knowledge of how offshore sand shoals – often sources for nourishments – are evolving in response to storm conditions and dredging activity. In September 2018, Hurricane Florence impacted southern NC and northern SC, and many communities experienced enhanced erosion. Future offshore sand removal for beach nourishment is inevitable here and elsewhere along the East Coast. A borrow area on the continental shelf seaward of Bogue Inlet (NC) offers an opportunity to see how the seabed is changing as a result of anthropogenic and oceanographic processes. Hurricane Florence made landfall as a Category 1 near Wilmington, NC on the morning of September 14, 2018. Prior to making landfall the storm was a powerful Category 2 hurricane, down from Category 4 status days prior. Hurricane-force winds were experienced over a large region, yielding powerful storm surge and waves over 8 m near the study area. Given the water depths of the ODMDS, seabed reworking was anticipated. The project collected geophysical data and sediment samples over a portion of the ODMDS offshore of Bogue Banks, NC in February 2019. Multibeam bathymetry, backscatter and seismic reflection data were obtained along with 24 sediment samples. These data add to previously collected data over the same area in 2013 and 2018. Grain-size analysis has been completed on all collected samples. Preliminary analysis of the post-hurricane data in comparison to earlier results indicate that the seabed has been reshaped since the last survey in March 2018, likely in response to Hurricane Florence. The broad dome-shape of the ODMDS remains, however, there is conspicuous morphological change. In shallower areas large sand waves (crests oriented roughly N-S, wavelength 20-30 m) differ from earlier mapping. Despite notable reworking, the anthropic signature of dredging in 2013 remains on the seascape.

To date, actively flowing lava has only been observed on Earth and on Jupiter’s moon Io. This lack of observation means that for the vast majority of volcanic systems in the Solar System, solidified lava-flow morphologies are used to infer important information about eruption and emplacement parameters. These include: lava supply rate, lava composition, lava rheology, and determination of laminar or turbulent emplacement regimes. Commonly used models that relate simple lava flow morphologic properties (e.g., width, thickness, length) to emplacement characteristics are based on assumptions that are readily misinterpreted. For example, the simplifying assumption of fully turbulent lava flow allows for a thermally mixed flow interior, but ignores the lava properties that naturally work to suppress full turbulence (such as thermal boundary layers encasing active lava flows, and a temperature-dependent lava rheology). However, full turbulence in silicate lava flows erupted into environments that have temperatures lower than the lava solidification temperature requires a rare combination of characteristics. We model Bingham Plastic, Newtonian, and Herschel-Bulkley fluids in rectangular channels, tubes, and sheets with computational fluid dynamics (COMSOL) software to obtain flow solutions and general flow rate equations and compare them to field measurements of volcanic velocity and flow rates. We present these as more realistic alternatives to older simpler rate-from-morphology models. We find that several lava rheology properties work together to delay the onset of turbulence as compared to isothermal Newtonian materials, and that while turbulent lavas flows certainly exist, they are not as prevalent as the published literature might indicate. Results obtained from models that assume full turbulence in silicate flows on the terrestrial planets should therefore be interpreted cautiously.

In the 2011 Tohoku-Oki earthquake, the rupture in the subduction megathrust reached the trench axis and triggered a large tsunami. The shallow portion of the subduction megathrust fault was regarded as an aseismic stable zone. The frictional properties along the shallow subduction plate boundary are an important foundation for understanding the cause of the dynamic fault rupture in the earthquake near the trench. The critical taper model of a sedimentary wedge best describes the first-order mechanics of a subduction zone wedge. The tapered wedge geometry (slope angle α and basal dip angle β) is responsible for the strength of a shallow megathrust. However, to apply the critical taper model for the investigation of spatial heterogeneity, we need to improve handling β, since β is derived from the subsurface structure and its value depends on the number of accurately depth-converted seismic profiles. Here, the effect of décollement dip angle β in the critical taper model of a sedimentary wedge is examined. The effect is negligible for a high pore fluid pressure ratio, allowing the frictional variation to be obtained with only bathymetry data. We applied the model to the Japan Trench. The frictional variation indicates that a smaller frictional area corresponds to an area with a larger coseismic shallow rupture during the 2011 earthquake than those of the southern and northern areas. The method can be applied to other trenches to predict seismic potential.

Monazite fission-track presents itself as a novel, low-temperature thermochronometer with annealing studies placing its closure temperature between ~45 and 25 °C. Previously, monazite has been unsuitable for fission-track dating due to high abundance of gadolinium and insufficient investigation of the etching protocol. Gadolinium causes self-shielding via thermal neutron capture and substantial associated nuclear heating during irradiation which prevented robust monazite fission-track dating using the traditional external detector method. Further, early etching studies were found to be extremely corrosive to monazite grains. However, developments in LA-ICP-MS fission-track analysis allow for measurement of 238U and improvements in monazite fission-track etching protocols mean that dating monazite through the fission-track method is now viable. In this study, we present monazite fission-track data from an elevation profile (2260 m, 2000 m, 1600 m, and 1200 m) from the Catalina metamorphic core complex (Catalina MCC), in southern AZ, USA. We follow the etching protocol described in Jones et al. (2019), etching the monazites in 6 M HCl for 90 minutes at 90 °C. We measure the 238U concentration via LA-ICP-MS and compare the dates to other multi-method thermochronology from the same rocks. Traditional low-temperature thermochronology (apatite and zircon fission-track, apatite and zircon (U-Th-Sm)/He) from the Catalina MCC reveals cooling at 25-20 Ma and 18-10 Ma. Preliminary monazite fission-track analysis yields a date of 6.1 ± 0.4 Ma, far younger than all the traditional thermochronometric data, in-line its far lower closure temperature. The 6 Ma monazite fission-track date is consistent with the youngest phase of hematite (U-Th)/He dates observed in the nearby Rincon metamorphic core complex and suggest that these dates correspond to the latest phase of exhumation in response to Basin and Range extension and/or climate enhanced erosion. These preliminary results show that monazite fission-track can reveal shallow crustal processes and contribute to constraining thermal histories below ~60 oC, which are traditionally difficult to resolve.

Reconstructing thermal histories in thrust belts using thermochronometry is a widely used method to infer the age and rates of thrusting, a precondition to understanding the driving mechanisms of orogenesis. Along a thrust sheet, the time and temperature conditions at the switch between heating and cooling retrieved from thermal modeling are commonly interpreted as the onset of thrust-induced exhumation associated with thrustbelt development. In subduction orogens such as the Andes, this interpretation can be challenged by the intrinsic changes in basal heat flow imposed by changes in subduction regimes. We document a case in the northwestern Sierras Pampeanas in the Argentinean Central Andes in which independent constraints on the onset late Cenozoic thrusting derived from structural cross-cutting relationships allow us to explore alternative causes for Cenozoic cooling signals. Located at ~31°S Lat, the Villa Unión-Ischigualasto basin hosts a composite stratigraphic record associated with Triassic rifting developed onto the Paleozoic substratum of western Gondwana and the overlying Meso-Cenozoic foreland basin record. A multi-method approach including apatite fission-track, apatite and zircon (U-Th)/He analyses, vitrinite reflectance and clay mineralogy carried out along three stratigraphic profiles, and inverse thermal modeling reveals the thermal history patterns and allows inferring its triggering mechanisms. Despite an up to 5 km-thick Cenozoic overburden and unlike previously thought, the thermal peak in the basin is not due to Cenozoic burial but occurred in the Triassic, associated with an abnormally high heat flow of up to 90 mWm-2 and less than 2 km of burial, which heated the base of the Triassic strata to ~160°C. Following exhumation, attested by the development of an unconformity between the Triassic and Late-Cretaceous-Cenozoic sequences, Cenozoic re-burial increased the temperature to ~110°C at the base of the Triassic section and only ~50°C 4 km upsection, suggesting a dramatic decrease in the thermal gradient. The onset of Cenozoic cooling from those conditions occurred between ~10 and 8 Ma, approximately 5 My before the onset of thrusting that has been independently documented by exceptionally well preserved stratigraphic-cross-cutting relationships. We argue that the onset of cooling is associated with lithospheric refrigeration following a decrease in the angle of subduction of the Nazca slab, leading to the eastward displacement of the asthenospheric wedge beneath the South American plate. Our study places time and temperature constraints on an idea that has been previously discussed in the region and calls for a careful interpretation of exhumation signals in thrustbelts inferred from thermochronology only.