Margin Of Zone Research Articles

Imaging crustal melt beneath northeast Japan with Ps receiver functions

To investigate crustal structures related to melt storage, Ps converted waves were used to image crustal velocity discontinuities across the Tohoku region of northeast Japan. Ps receiver functions from 127 permanent seismic stations were migrated to depth, accounting for variations in crustal velocity structure. In the 5-15 km depth range, negative Ps phases indicative of velocity decreases with depth are prevalent in central and western Tohoku, where Holocene volcanoes occur and surface wave tomography indicates low crustal velocities. Large negative Ps phases are largely absent in the crust of the old mountain terranes in eastern Tohoku where crustal velocities are higher. In central and western Tohoku, velocity gradients inferred from Ps phases and shear velocity anomalies are consistent with models for crustal melt storage that involve trans-crustal zones of crystal-melt mush where the highest concentrations of melt are localized at the top of the mush column. Negative Ps phases are concentrated at depths of 5-10 km, and many correlate with the upper margins of localized low velocity zones beneath volcanoes. These correlated features are consistent with the roofs of high melt fraction layers. At depths of 10-30 km, positive Ps phases are consistent with gradual velocity positive gradients that correspond to decreasing melt fraction with depth in the mush column, although some groups of deeper negative Ps phases at depths of 10-20 km may reflect local maxima in melt fraction. The amplitudes of the negative Ps phases at 5-10 km depth vary significantly. In a higher amplitude example, waveform modeling of Ps receiver functions from a station near Hijori volcano indicates a 16% ± 5% Vs drop at 10 km depth, implying melt fractions of 10% ± 3% if Gassmann's equations are assumed, above a velocity increase from 10 to 20 km that indicates decreasing melt fractions with depth. However, modeling of lower amplitude Ps phases in the 5-10 km depth range indicates a 7% ± 3% velocity drop and a maximum melt fraction of 5% ± 2%. The geographic distribution of apparent melt fraction at 5-10 km depth suggests that in some cases the same upper crustal source can supply multiple volcanoes, and in others high melt fraction zones are significantly laterally offset from the nearest volcano.

The tetrad effect in REE distribution patterns: A quantitative approach to genetic issues of argillic and propylitic alteration zones of epithermal Cu-Pb-Fe deposits related to andesitic magmatism (Khan Kandi District, NW Iran)

The impact of the tetrad effect on the accumulation of REE during base metal mineralization can be deduced from four segments of the normalized REE distribution patterns. Quantifying this effect in each part of the REE graph has proven to be a powerful tool when it comes to the investigation of the origin of ore deposits. In the current research, a mathematical method using a logarithmic scale has been designed to calculate each individual tetrad segment in the samples and tested for the alteration zone of the andesite-related epithermal base metal deposits in the Khan Kandi District, NW Iran. In contrast to previous approaches, the current method achieves a higher accuracy for normalized REE patterns of samples from the argillic and propylitic alteration zones of base metal deposits. Using the calculation technique presented here reveals that the values obtained for third and fourth tetrad effects follow different trends in argillic and propylitic samples. In conclusion, mineralizing fluids of low pH accountable for the development of argillic alterations are characterized by larger σ3 (third tetrad) values in fault zones. They decrease toward the margins of the fault zones where argillic alteration is predominant whereas in the propylitic alteration zones the trend is reversed. The tetrad effect in these alteration zones is controlled pH, temperature changes and the fluid-rock interaction, conducive to the decomposition of minerals in host and wall rocks. The behavior of geochemical pairs such as Y/Ho, Zr/Hf and Nb/Ta displays a non-CHARAC behavior highlighted by non-linear and parallel trends in the chondrite-normalized REE curves. The occurrence of conjugate convex and concave tetrad effects in the REE patterns are accounted for by the mixing of meteoric waters and hydrothermal fluids. The correlation between σ3 values and geochemical couples are indicative of a mineralogy that formed under a regime of strong fluid-rock interaction. The data obtained from samples in the central parts of the fault zones document this zone as the pathways for hydrothermal solutions.

3:18 PM Abstract No. 129 Effect of background liver cirrhosis on performance of a 915-MHz synchronous phased array microwave ablation device: 3D imaging assessment of ablation zone volume and morphology

Evaluate impact of liver cirrhosis on synchronous-phased array microwave heating patterns in vivo, and determine if this technology overcomes known limitations of conventional asynchronous MWA devices used for tumor ablation in cirrhotic livers Retrospective, HIPAA-compliant, IRB-approved. Institution records from Jan 1, 2015 thru Aug 31, 2019 revealed total of 100 liver tumor ablations eligible for inclusion. Cirrhosis confirmed by biopsy or elastography. All treatments performed with CT-guidance and consisted of a single application (burn) using 1 or multiple (up to 3) antennae positioned in parallel or cluster array. Antennae positioned under CT-fluoroscopy. Non-contrast volumetric CT documented antennae alignment, spacing, and position immediately before treatment. Treatment parameters obtained from procedural reports. Contrast-enhanced CT obtained immediately posttreatment to define ablation zone margins. 3D imaging software used to postprocess archived volumetric CT data to calculate ablation zone volume, shape and mean margin variance (MMV = expected ablation defect diameter – observed defect diameter) in 3D space. Ablation defect volume and MMV analyzed for identical treatments based on power/duration, antenna type, number and spacing in normal versus cirrhotic liver using generalized mixed modeling (lognormal distribution), and Fishers Exact test. All analyses conducted using SAS 9.4 with PROC GLIMMIX and FREQ (significance P <0.05) There was significant reduction in ablation defect volume and increase in MMV for single-antenna treatments (asynchronous) performed in cirrhotic versus non-cirrhotic liver at same treatment parameters (P = 0.03). No significant difference in defect volume and MMV between cirrhotic versus non-cirrhotic liver when multi-antennae (synchronous-phased emission) ablation performed (P = 0.03). Controlled for antenna number, MMV was significantly larger in cirrhotic liver (P = 0.04) Synchronous-phased array microwave emission performs equally as well in both cirrhotic and non-cirrhotic liver, thereby conferring a more consistent performance advantage of synchronous over conventional asynchronous microwave emission for ablation of tumors in cirrhotic liver.

Abstract No. 490 Three-dimensional assessment of the ablation zone margins with the Neuwave Ablation Confirmation software: a feasibility study

Abstract No. 490 Three-dimensional assessment of the ablation zone margins with the Neuwave Ablation Confirmation software: a feasibility study

The fault outcrop of the boundary fault in the lower Pleistocene around the eastern margin of the Yokote basin fault zone

The fault outcrop of the boundary fault in the lower Pleistocene around the eastern margin of the Yokote basin fault zone

Thermomechanical Analysis of the Effects of Water Distribution on Cracks during Vertical Continuous Casting under Soft Reduction Conditions

In the production process of continuous casting slab, the unreasonable secondary cooling system can lead to serious crack defects. This study focuses on the problem of cracks in nuclear power stainless steel produced by vertical continuous casting under soft reduction conditions. Based on the actual production process parameters, the thermomechanical finite element model was established to investigate the effects of water distribution in the secondary cooling zones on cracks by using ProCAST. The results show that the stress concentration is obvious under the original process, especially the positions of 4 mm below the wide surface and 6 mm below the narrow surface. It is easy to generate cracks, and the area with the highest hot‐tearing index is approximately 26 cm2. In addition, the secondary cooling system is adjusted based on the existing problems of the original process. The temperature of the casting slab rises by about 15°C at the solidification end point, and the length of the liquid core increases by about 0.5 m when the quantity of the water flow decreases in zone 2 and zone 3. The stress concentration is alleviated, and the possibility of cracking is reduced. Especially, it is evident that the proportion of water on the loose side margin increases from 40% to 45%, while the proportion of water on the fixed side margin of zone 3 is adjusted from 56% to 60%.

THE TECHNOLOGY OF HYDRO-SAND BLASTING PERFORATION IN WELLS WITH ABNORMALLY HIGH RESERVOIR PRESSURE USING COILED TUBING

Areas of application of coil tubing or columns of flexible pipes are quite diverse. During the underground repair of wells carry out current and major repairs, impact on the reservoir and margin zone. The use of the flexible pipe column has made a positive change in the practice of drilling oil and gas wells, especially at their completion, as well as works on hydropower perforation. The article suggests the technology of hydro sandblasting perforation in wells with abnormally high formation pressures with the use of coiled tubing with pressure drawdown and overbalance, which will help to familiarize oil and gas industry specialists with the advanced technology of stimulated completion of productive horizons. Schemes of wellhead equipment and process equipment for hydro sandblasting perforation using coiled tubing in wells with abnormally high reservoir pressures have been developed and their operating principles have been described in detail. The proposed schemes are recommended to be used as typical for hydro sandblasting perforation with pressure drawdown and overbalance of the productive horizon. Conclusions are made concerning expediency of carrying out works on the technology described in the article with the purpose of prevention of sealing and swelling of the bottomhole zone rock in case of ingress of the sand-carrier fluid during the process of perforation.

Scientific drilling of Lake Chalco, Basin of Mexico (MexiDrill)

Abstract. The primary scientific objective of MexiDrill, the Basin of Mexico Drilling Program, is development of a continuous, high-resolution ∼400 kyr lacustrine record of tropical North American environmental change. The field location, in the densely populated, water-stressed Mexico City region gives this record particular societal relevance. A detailed paleoclimate reconstruction from central Mexico will enhance our understanding of long-term natural climate variability in the North American tropics and its relationship with changes at higher latitudes. The site lies at the northern margin of the Intertropical Convergence Zone (ITCZ), where modern precipitation amounts are influenced by sea surface temperatures in the Pacific and Atlantic basins. During the Last Glacial Maximum (LGM), more winter precipitation at the site is hypothesized to have been a consequence of a southward displacement of the mid-latitude westerlies. It thus represents a key spatial node for understanding large-scale hydrological variability of tropical and subtropical North America and is at an altitude (2240 m a.s.l.), typical of much of western North America. In addition, its sediments contain a rich record of pre-Holocene volcanic history; knowledge of the magnitude and frequency relationships of the area's explosive volcanic eruptions will improve capacity for risk assessment of future activity. Explosive eruption deposits will also be used to provide the backbone of a robust chronology necessary for full exploitation of the paleoclimate record. Here we report initial results from, and outreach activities of, the 2016 coring campaign.

ОЩУТИМЫЕ в МОЛДОВЕ в 2013 г. ЗЕМЛЕТРЯСЕНИЯ: 11 августа с КР=11.8, 6 октябряс КР=14.1, 15 октября с КР=12.3 (Румыния–Молдова)

The article presents instrumental and macroseismic data on earthquakes of the Carpathian region in 2013, felt on the territory of the Republic of Moldova. Three earthquakes, with an intermediate focal depth, occurred in the Vrancea zone: August 11 with h=93 km, КР=11.8; October 6 with h=140 km, КР=14.1; Octo-ber 15 with h=144 km, КР=12.3. Also in 2013, a swarm of small earthquakes was recorded, near Galati (Ro-mania) and Giurgiulesti (Moldova). The swarm arose September 23, its shocks were recorded for two months. More than 370 seismic events happened, of which three had КР  11 (September 29, 30, and Octo-ber 4 with КР=11.2, 10.9, 10.6). The intensity of shaking reached 5. For earthquakes, September 29, 30 and October 4 regional solutions for the focal mechanism from the Mostryukov and Petrov catalog (GO "Borok" IPE RAS) were received. The event of August 11, 2013, with КР=11.8, occurred at a depth of 93 km on the northeastern margin of the focal zone of Vrancea, felt at the epicenter with intensity I=4. In Chisinau, only some people felt weak shocks (I=2). The two largest earthquakes of 2013 occurred on October 6 at 01h 37m (КР=14.2, mb=5.3, I0=6) and on October 15 at 19h 33m (КР=12.3, mb=4.8), in the central part of the focal zone Vrancea. Between these events, three more earthquakes were noted with ML=3–3.5. However, the most extensive macroseismic manifestations arose from the main shock – October 6, which caused shaking in the territory of four states – in Romania, in the north of Bulgaria, in the south-west of Ukraine, and in Moldova. The reason for such a significant spread of tremors lies in a large focal depth of 140 km. But for the same reason, the intensity of the macroseismic impact did not exceed I=5 in Romania and I=4–5 in Moldova and Ukraine. As a result, a map of the intensity distribution of the October 6 earthquake is given, built on the basis of data processing in 104 locations. Various solutions for the focal mechanisms of intermediate earthquakes in 2013 are presented. The consistent manifestation of a swarm of crustal earthquakes and a number of earthquakes of intermediate depth confirms the unity of tectonic processes in the Carpathian region. The accumulated seismic stresses were preliminarily realized in the form of crustal shocks, then powerful discharge occurred in the Vrancea region, which interrupted a series of events associated with Sfintul-Gheorghe and Peceneaga–Camena faults.

Geological conditions of natural gas accumulation and new exploration areas in the Mesoproterozoic to Lower Paleozoic of Ordos Basin, NW China

Based on field outcrop investigation, interpretation and analysis of drilling and seismic data, and consulting on a large number of previous research results, the characteristics of ancient marine hydrocarbon source rocks, favorable reservoir facies belts, hydrocarbon migration direction and reservoir-forming law in the Ordos Basin have been studied from the viewpoints of North China Craton breakup and Qilian-Qinling oceanic basin opening and closing. Four main results are obtained: (1) Controlled by deep-water shelf-rift, there are three suites of source rocks in the Ordos Basin and its periphery: Mesoproterozoic, Lower Cambrian and Middle-Upper Ordovician. (2) Controlled by littoral environment, paleo-uplift and platform margin, four types of reservoirs are developed in the area: Mesoproterozoic– Lower Cambrian littoral shallow sea quartz sandstone, Middle-Upper Cambrian–Ordovician weathering crust and dolomitized reservoir, and Ordovician L-shape platform margin reef and beach bodies. (3) Reservoir-forming assemblages vary greatly in the study area, with “upper generation and lower storage” as the main pattern in the platform, followed by “self-generation and self-storage”. There are both “upper generation and lower storage” and “self-generation and self-storage” in the platform margin zone. In addition, in the case of communication between deep-large faults and the Changchengian system paleo-rift trough, there may also exist a “lower generation and upper reservoir” combination between the platform and the margin. (4) There are four new exploration fields including Qingyang paleo-uplift pre-Carboniferous weathering crust, L-shape platform margin zone in southwestern margin of the basin, Ordovician subsalt assemblage in central and eastern parts of the basin, and Mesoproterozoic–Cambrian. Among them, pre-Carboniferous weathering crust and L-shape platform margin facies zone are more realistic replacement areas, and Ordovician subsalt assemblage and the Proterozoic-Cambrian have certain potential and are worth exploring.

Transition from shallow to steep foliation in the Early Neoproterozoic Gangpur accretionary orogen (Eastern India): Mechanics, significance of mid-crustal deformation, and case for subduction polarity reversal?

The ENE-trending Gangpur Schist Belt (GSB) comprising foreland sediments and distended screens of mafic/ultramafic rocks is sandwiched between the Meso/Neoarchean Singhbhum Craton (SC) in the south, and the Early Neoproterozoic granitoids of the Chottanagpur Gneiss Complex (CGC). These meta-sediments are thrust (D2 deformation) northward along a shallow-dipping decollement in the CGC granitoids. The shallow foliations with orogen-parallel stretching lineation in granitoids are coaxial with axes of D2 recumbent folds in the meta-sediments; locally-developed orogen-normal extensional shears and en echelon quartz vein are associated with this deformation phase. The shallow-D2 structures are dissected by two orogen-parallel south-dipping shear zones (D3) with steep stretching lineations. Sinistral-normal kinematics dominates the shear zones, but the northern margins of the shear zones exhibit dextral and north-down kinematics. Analyses of NCKFMASH P-T pseudosections constructed for the meta-sediments suggest the pre/post-D2 stage was characterized by mid-crustal amphibolite facies near-isothermal loading punctuated by prograde heating. Th-U-Pb (total) ages of metamorphic monazite grains in the schists (1080–940 Ma) and the magmato-metamorphic ages of CGC granitoids (1020–940 Ma from previous studies) overlap with each other, but monazite (>1050 Ma) inclusion trails in the core of pre-S2 garnets predate the magmato-metamorphic ages in the granitoids.The D2 Early Neoproterozoic deformation in the GSB involved top-to-the-north translation of the foreland sediments along a mid-crustal decollement in the CGC, followed by transpressional deformation that caused inclined extrusion and lateral escape along orogen-parallel hinterland vergent shear zones. However, the initiation of SC-CGC accretion (>1050 Ma) possibly involved northward subduction (pre-D2 near isothermal loading) of the GSB foreland sediments that ultimately was linked to the emplacement of granitoids in the over-riding CGC plate. Cessation of the subduction and continued N-S shortening caused CGC to evolve as the overridden basement.

Subduction and collision processes between the North China and South China blocks constrained by the geochronology and geochemistry of the Wuguan Complex in the Qinling orogen, China

ABSTRACT The Qinling orogen is a key area for understanding the processes of subduction and collision between the South China Block (SCB) and North China Block (NCB). The Wuguan Complex, distributed along the southern margin of the Shangdan suture zone, can provide important constraints on the age of collision between NCB and SCB and the tectonic evolution of the Qinling orogen in Late Paleozoic. Detrital zircons from meta-sedimentary rocks of the Wuguan Complex in the Danfeng-Shangnan area have an age spectrum with two main peaks at ~448 Ma and ~819 Ma, and two subordinate peaks at ~938 and ~1440 Ma, respectively, and are interpreted to have been derived from the North Qinling terrane (NQT). The petrographic and geochemical characteristics of the meta-sedimentary rocks indicate that they were deposited in a fore-arc basin along the southern margin of the NQT. The youngest detrital zircons yield a weighted mean age of 378 ± 3 Ma, indicating that the fore-arc deposition was continuing at least to this time, which implies that the Paleo-Qinling Ocean between the NCB and SCB was not finally closed until at least the late Devonian. In combination with regional data, we propose that sedimentary rocks of the Wuguan Complex might once have been a sequence of late Ordovician to late Devonian strata with intercalated mafic rocks, which has been dismembered by the later tectonic activity. It was metamorphosed during northward subduction of the Paleo-Qinling Ocean at ca. 320 Ma, and slowly cooled through ca. 350°C at ca. 247 Ma (muscovite 40Ar/39Ar age). It has recorded the detailed processes of subduction and collision between the NCB and SCB.

Rectal wall saline displacement for improved margin during MRI-guided cryoablation of primary and recurrent prostate cancer.

To describe safety, efficacy, and added oncologic margin of saline displacement of the rectal wall during MRI-guided cryoablation of primary and recurrent prostate cancer. A retrospective review was conducted for patients who underwent MRI-guided cryoablation with saline displacement of the rectal wall for treatment of primary and recurrent prostate cancer over a 2-year period. Saline displacement was used when the distance from the edge of the ablation area to the rectal wall was insufficient to provide at least a 5-mm treatment margin. Pre- and post-ablation rectal wall displacement distances as well as ablative zone margins were assessed with MRI. Saline displacement distance was measured from the rectal wall to the edge of the lesion for focal lesion ablation and from the edge of the prostate for hemi-gland ablation. Immediate and intermediate-term complications were assessed. Saline displacement was used in 25 patients undergoing MRI-guided cryoablation. Twenty-one patients underwent salvage cryoablation, while four patients had it as primary treatment for prostate cancer. Median pre- and post- saline displacement rectal wall displacement distances were 6.0 and 11.2mm, respectively (P < 0.0001). Median-added oncologic margin achieved by saline displacement was 4.6mm (range 0.6-26.5). Median follow-up was 14months (range 5-29). There were no intra-procedural complications and 3 patients experienced minor (Clavien-Dindo grade I) complications. One rectal complication occurred in a patient undergoing salvage cryotherapy with a history of extensive pelvic surgery and radiation. Saline infusion at the time of MRI- guided cryoablation for prostate cancer resulted in increased distances between the target lesion and rectum. This is a useful technique in providing an added oncologic margin when treating lesions close to the rectal wall.

Tectonic evolution of the hinterland of the Zagros Orogen revealed from the deformation of the Golpaygan Metamorphic Complex, Iran

In the southwestern part of the Central Iran zone, the Golpaygan Metamorphic Complex (GMC) was evolved during the Zagros orogeny. This complex is composed of different metamorphic rocks including schist, marble, slate, gneiss and amphibolite. The metamorphic complex is overlain by a cover sequence including Permian carbonates, Jurassic clastic rocks, Cretaceous carbonates and Eocene clastic rocks. The internal structure of the GMC is characterized by four deformational stages. The first stage (D1) developed contemporaneously with the prograde regional metamorphism and resulted in formation of the first generation folds and prevailing axial plane foliation. The second stage of deformation (D2) was accompanied by deformation partitioning and formation of contractional shear zones. These structures were overprinted by different scale folds of the third stage (D3). The fourth stage of deformation (D4) is characterized by generation of the extensional shear zones which gradually transformed into normal faults. D1 and accompanied metamorphism may have resulted from steep subduction of the Neotethys Ocean beneath the active margin of the Central Iran zone during Jurassic times. D2–D3 structures and retrograde metamorphism may have been formed by a regional shortening and transpression deformation event which resulted in exposure of the metamorphic rocks in shallower levels during Cretaceous flat slab subduction. This condition lasted until Paleocene time when the slab roll-back caused extension and thinning of the overriding Central Iran plate. The subsequent decompression and regional extension resulted in intrusion of magmatic rocks and generation of D4 which formed the GMC and related magmatism in Paleocene-Eocene time.

Transductive Bounds for the Multi-Class Majority Vote Classifier

In this paper, we propose a transductive bound over the risk of the majority vote classifier learned with partially labeled data for the multi-class classification. The bound is obtained by considering the class confusion matrix as an error indicator and it involves the margin distribution of the classifier over each class and a bound over the risk of the associated Gibbs classifier. When this latter bound is tight and, the errors of the majority vote classifier per class are concentrated on a low margin zone; we prove that the bound over the Bayes classifier’ risk is tight. As an application, we extend the self-learning algorithm to the multi-class case. The algorithm iteratively assigns pseudo-labels to a subset of unlabeled training examples that have their associated class margin above a threshold obtained from the proposed transductive bound. Empirical results on different data sets show the effectiveness of our approach compared to the same algorithm where the threshold is fixed manually, to the extension of TSVM to multi-class classification and to a graph-based semi-supervised algorithm.

The structure, depositional style and accumulation characteristics of continental margin with diachronous breakup in the northern South China Sea

ABSTRACT A typical diachronous breakup developed in the South China Sea (SCS); the breakup has been unequivocally identified, and gradually decreases in age from NE to SW. To illustrate the influence of a diachronous breakup on hydrocarbon accumulation, we used seismic profiles from CNOOC, and analysed crustal extension characteristics, sedimentary style and source rock accumulation. The main conclusions are as follows: (1) Because of the diachronous breakup in the SCS, various tectonic units developed in different positions on the northern continental margin with different degrees of extension. The Pearl River Mouth Basin (PRMB) is closer to the central sea basin of the SCS and has been affected by regional tension stress for a longer time. Tectonic units of proximal domain, necking zone, and distal margin types developed, and the crust structure thinned from the land towards the sea. The Qiongdongnan Basin (QB) is closer to the Southwest Sub-basin. There are symmetrical proximal domains on the southern and northern sides of the QB, with a necking zone in the central part. It presents as an abandoned passive continental margin. (2) The PRMB exhibited rifted cells first, followed by canyon type extensional faulting and horizontal axial transportation, and then by a longitudinal shelf-slope sedimentary style. But the QB has only rifted cells and canyon type faulting stages, no longitudinal shelf-slope sedimentary stage. The major source rocks in the northern SCS become younger from east to west, and the sedimentary facies change from lacustrine facies to marine-continental transitional facies. (3) The diachronous breakup process ultimately affecting oil and gas migration and accumulation process. The PRMB is dominated by deep-water shelf break accumulation with deep-water fan reservoir bodies. The QB is dominated by canyon type accumulation with channels.

Substrate geology controlling different morphology, sedimentology, diagenesis and geochemistry of adjacent travertine bodies: A case study from the Sanandaj-Sirjan zone (western Iran)

A travertine fissure ridge and travertine mound are situated ~800 m from each other at the western margin of the active tectono-volcanic Sanandaj-Sirjan zone (western Iran). Despite their close proximity, the two geobodies show a difference in morphology, lithofacies, lithotypes, diagenesis and geochemistry. Petrographic analysis of the fissure ridge carbonates revealed homogeneous sparitic fabrics with dendritic structures reflecting precipitation under fast-flowing conditions from calcite supersaturated spring water. The mound carbonates are much more heterogeneous and display dominantly micritic fabrics with (mainly volcanic) clasts reflecting a lower energy flow regime and lower calcite saturation. In contrast to the limited diagenetic overprint of the fissure ridge carbonates, the more porous mound carbonates are affected by dissolution, cementation, and formation of Mn/Fe-oxide/hydroxides, attesting of a strong control on porosity by early diagenetic processes. The widespread bright luminescent calcite phases especially in sparitic fabrics within both geobodies display high Mn concentrations in calcite indicating suboxic precipitation conditions.The overlapping 87Sr/86Sr signatures and δ13C signatures point to a mixture of CO2 that dominantly originated from dissolution of the marine carbonate Qom Formation (Oligo-Miocene). The different δ18O signatures, indicate different upwelling systems caused by different substrate settings. The fissure ridge formed on a hard and brittle limestone substrate with precipitation from dominantly subsurface-sourced fluids. The mound travertine formed on top of fairly unconsolidated and fractured volcanic strata. The depleted δ18O signatures and impure micrite-dominated fabrics of the mound travertine reflect precipitation from thermal water that mixed with surrounding groundwater. This difference is also reflected in a different calculated precipitation temperature that varies between 4 and 21 °C for the mound versus 25–50 °C for the fissure ridge.Our findings show that subsurface geology exerts a major control on precipitation processes resulting in differences in travertine morphology, sedimentology, diagenesis, and geochemistry, despite that the travertine bodies occur adjacent to each other.

Carboniferous\u2013Permian magmatism and Mo\u2013Cu (W) mineralization in the contact zone between the Ma\u0142opolska and Upper Silesia Blocks (south Poland): an echo of the Baltica\u2013Gondwana collision

The Kraków–Lubliniec tectonic zone (KLFZ) in southern Poland, which divides the Małopolska Block (MB) from the Upper Silesia Block (USB), is a portion of the SW margin of the Trans-European Suture Zone. Zircon U–Pb dating of a variety of igneous rocks (granodiorites, dacites, lamprophyre and diabase) from the subsurface Kraków–Lubliniec igneous belt along the KLFZ shows that magmatism spanned within a narrow time period (ca. 10 Ma) between 303.8 ± 2.2 and 292.7 ± 4.9 Ma. The earlier magmatism (303.8 ± 2.2–294.7 ± 2.3 Ma) was felsic calc-alkaline, and the contemporaneous or/and slightly later alkaline volcanism (294.4 ± 4.9–292.7 ± 4.9 Ma) was of mafic–intermediate composition. The felsic rocks (granitoids and dacitoids) are weakly peraluminous, medium to high K, moderate Mg# (0.39–0.46), weakly evolved and I-type rocks. Due to the intensive development of hydrothermal alteration, these rocks are commonly strongly altered and locally mineralized by porphyry and other types of Mo–Cu (W) ores that are closely related to the felsic magmatism in space and time. The zircon U–Pb dating yielded ages which are similar to the previously measured Re–Os ages of molybdenites from the KLFZ. Felsic magmatism at the Myszków Mo–Cu–W deposit yielded ages in the range 301.0 ± 2.1–295.9 ± 2.9 Ma. The youngest rocks dated are from the Mysłów area in the USB—volcanic alkaline rocks (lamprophyre and diabase) of shoshonitic character, with low Mg# (0.49 and 0.69, respectively) and Ni contents (< 62 ppm), indicative of a relatively juvenile magma composition. Inherited zircon cores, remnant detrital zircon from a sediment component in the source rocks, were dated to be ranging from ca. 2775 to 575 Ma. Inheritance of ca. 600 Ma (Cadomian basement) and ca. 1.40 Ga (Mesoproterozoic) is common in the rocks from both blocks, but those from the MB contain additional inheritance with dates of 2.78–2.67 and 2.05–1.92 Ga, both ages characteristic of zircon from the Svecofennian of northern Europe (Baltica). The inherited zircon from the youngest alkaline rocks provided evidence for Mesoproterozoic (ca. 1.55–1.44 and 1.09 Ga) and Palaeoproterozoic (1.96 Ga) thermal events in the USB, and its possible affinity to Avalonian cratonic crust as a source for its igneous protolith. U–Pb isotopic studies of zircons from KL igneous belt indicate its inherited signatures from the crustal sources and magma emplacements during the KLFZ wrenching which allowed channels and room for magma emplacement along the MB and USB in upper Carboniferous–lower Permian on SW margin of the East-European Craton. Mo–Cu (W) ore mineralization, associated with the ~ 300 Ma felsic magmatism, represents rather the product of decompression melting induced in the areas of decreased pressure, undergone in the regional wrench fault zones than the classic Mo–Cu porphyry-style mineralization.

Seismicity at the Northern Hikurangi Margin, New Zealand, and Investigation of the Potential Spatial and Temporal Relationships With a Shallow Slow Slip Event

AbstractIn 2014–2015, the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip experiment deployed seafloor absolute pressure gauges and ocean bottom seismometers directly above a large slow slip event, allowing examination of the relationship between slow slip and earthquakes in detail. Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip data were combined with nearby existing land stations to create a catalog of microseismicity consisting of 2,300 earthquakes ranging in magnitude between 0.5 and 4.7 that is complete to magnitude 1.5, yielding almost twice as many events as detected by the onshore networks alone. This greatly improves the seismicity catalog for this active subduction zone margin, especially in the offshore portion that was difficult to study using only the inland permanent seismic network. The new locations for the events within the footprint of the offshore network show that earthquakes near the trench are systematically shallower than and NW (landward) of their locations using only land‐based stations. Our results indicate that Hikurangi seismicity is concentrated in two NE‐SW bands, one offshore beneath the outer forearc wedge, one onshore beneath the eastern Raukumara Peninsula, and the majority of earthquakes are within the subducting Pacific plate with a smaller percent at the plate interface. We find a 20‐km wide northeast trending gap in microseismicity between the two bands and beneath the inner forearc wedge and this gap in seismicity borders the downdip edge of a slow slip patch.

Optimizing a soil gas monitoring network layout across faults based on a seismogenic model

We undertake a sturdy body seismogenic model study along the northern margin of the West Qinling fault zone, China, to address some existing problems of neglecting scientific layout based on certain prediction theory and observation facts surrounding underground fluid monitoring networks across faults. A combination of high-density underground fluid measurements and vertical crustal deformation and seismological observations were used to elucidate the interplay between fluid dynamics, crustal deformation, and seismic activity and to comprehensively analyze the fault segment characteristics along the fault zone. We found correspondence between these parameters along the northern margin of the West Qinling fault zone. All parameters showed higher values in the Wu Shan (WS) segment than in the western Xia He–Huang Xiang Gou–Zhang Xian (XH-HXG-ZX) segment and eastern Tian Shui (TS) area. The 222Rn concentration reached 5.0942 at BZC, and the Hg concentration reached 3.4398 at LJG in WS. Similarly, the vertical crustal deformation and seismic activity in this area were both stronger than those in the western XH–HXG–ZX and TS area. Based on the sturdy body seismogenic model, we found that the ZX and TS segments exhibited weaker activity than the surrounding areas and may be in a deep locked state under the corresponding regional stress. Compared with existing monitoring network for background value detection and comprehensive research results, we propose a technical underground flow monitoring network prototype that includes two grade I and five grade II survey sites along the northern margin of the West Qinling fault zone based on the sturdy body seismogenic model. This prototype will provide a more reliable basis for earthquake prediction, tracking and mitigation, and disaster risk reduction. The presented scheme can be used as a guideline for deploying fault soil gas monitoring networks in China.