M4 Stage Research Articles

Study on the Structural Characteristics of Mesh Filter Cake in Drip Irrigation: Based on the Growth Stage of Filter Cake

Mesh filters are frequently employed in water-saving irrigation fields. Studies addressing the method of cake formation and the characteristics of the cake during the mesh filter’s growing phase are still missing. One-way and orthogonal experiments were carried out using mesh filters with 220 μm and 320 μm aperture sizes as the research objects, taking particle concentrations, inlet flow, and growth phases as experimental factors. According to the variation rule of seed pressure drop in the formation process of filter cake, the growth process of filter cake is divided into four stages, which are as follows: slow blockage first and second stages (M1, M2), fast blockage stage (M3), and filter cake filtration stage (M4). Moreover, the size distribution, porosity (ε), pore-to-particle ratio (KP), and median size (d50) of the filter cake were used to represent the structural characteristics. The results show that the growth of filter cake was a process that started with the filling of mesh pores by intercepted particles and progressed to the filling of large-particle skeleton pores by subsequently filtered particles. During this process, the proportion of intercepted particles gradually decreased, while the proportion of filtered particles increased incrementally, and the median size (d50) and porosity (ε) decreased. Meanwhile, the smaller the aperture size of the screen, the smaller the filter cake’s median size (d50) was, but the larger the pore-to-particle ratio (KP) was. As the flow rate increased, the porosity (ε) was augmented in the M1 and M2 stages; however, it decreased in the M3 and M4 stages. The concentration had a minor influence on the filter cake’s porosity. Lastly, the regression model for filter cake porosity under two aperture size conditions was established, based on factors such as flow rate, concentration, and growth stage. The coefficients of determination, R2, for the model were 90.33% and 80.73%, indicating a good fit.

New P-T path of Huwan high-pressure unit from Hong'an orogen, Central China Orogenic Belt: Implications for oceanic to continental subduction and exhumation in the subduction zones

Oceanic to continental subduction is a pivotal process in plate tectonics, yet characterizing this tectonic transition and subsequent exhumation remains a challenging task. This study integrates our novel pressure-temperature (P-T) estimates on a metabasite lens and its hosting metasedimentary rock in the Xiongdian area of the Huwan high-pressure unit of the Hong'an orogen, Central China Orogenic Belt, with existing geochronological data from the same and neighboring outcrops. Our preliminary but comprehensive findings reveal the evolution of this subduction transition process. After the opening at ca. 430–400 Ma the Paleotethyan ocean subducted northward and formed a warm oceanic subduction zone at ca. 400–385 Ma, marked by relatively low P and high T conditions (∼610–740 °C and ∼1.5–1.8 GPa; M1 stage). Subsequently, the Paleotethyan oceanic plate continued its subduction and cooled the overlying mantle until its final closure during ca. 385–300 Ma. This phase led to the subduction of South China Block (SCB) and the formation of a cold continental subduction zone at ca. 300–270 Ma, featured by relatively high P and low T conditions (∼570–610 °C and ∼2.1–2.7 GPa; M2 stage). Following the delamination from the subducted SCB continental lithospheric mantle, the detached high-pressure rocks experienced a two-stage accelerated exhumation process, i.e., early slow exhumation (∼0.7 ± 0.4 mm/a) to shallower mantle depth (∼610–730 °C and ∼1.5–2.1 GPa; M3 stage) at ca. 270–243 Ma and later rapid exhumation (>2.5 ± 0.9 mm/a) to approximately the Moho depth (∼550–600 °C and ∼0.8–1.3 GPa; M4 stage) at ca. 243–233? Ma. To facilitate the buoyancy-driven exhumation of eclogite blocks from their maximum depth (M2 stage), a minimum of ∼16–25 vol% of low-density metasedimentary rock is required. The increasing buoyancy caused by decreasing densities of the high-pressure rocks with exhumation (from M2 to M4 stage), slab break-off induced rebound forces, and other tectonic factors may jointly explain the accelerated exhumation pattern. Our density results also emphasize that, partly owing to a stronger contribution from a buoyancy-driven mechanism, the high-pressure rocks would be preferentially exhumed in warm to extremely warm oceanic subduction zones compared to their intermediate to cold counterparts.

Gamma rays induced enhancement in the phytonutrient capacities of tomato (Solanum Lycopersicum L.)

One of the most important problems for the field-grown Ayaş tomato (Solanum lycopersicum Ayas population), which is preferred for consumption in Central Anatolia because of its aromatic taste, is that the shelf life is short because of insufficient fruit firmness. Therefore, a study was initiated to develop high-quality lines and variety candidates through mutation breeding in the current Ayaş population. In this study, the effective mutation dose (EMD50) was found to be 150 Gy for seeds using a Cobalt-60 gamma ray source. The main mutant population was generated by applying EMD50. During the study, mutant lines selected by following the classical mutation breeding stages were evaluated in terms of yield and quality traits (antioxidant content, total soluble solid amount, fruit firmness, Brix, etc.) starting from the M4 stage. One of our aims was to determine and improve the phytonutrient content of field-grown tomatoes. The fruits of selected lines at the M4 stage were extracted by liquid-liquid partition and accelerated solvent extraction techniques and analyzed by High Performance Liquid Chromatography (HPLC) in this study. It was found that 28 of the 29 mutant lines were significantly different from the control and mutant lines. Mutant lines 9-22, 8-90, 8-135, and 8-127 were determined to be the most promising for commercialization.

Molecular response and developmental speculations in metamorphosis of the veined rapa whelk, Rapana venosa.

Metamorphosis is the short developmental stage characterized by dramatic ontogenetic changes that occurs in most animals. However, this important process remains largely unclear in marine invertebrates. In this study, we performed the sequential RNA sequencing of a representative mollusk, the rapa whelk (Rapana venosa), that is undergoing metamorphosis and conducted differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) to investigate the overall and dynamic transcriptome responses. The results revealed that the expression of cytochrome P450 2A and 3A were upregulated during metamorphosis, while the expression of H/ACA ribonucleoproteins increased 4 h after metamorphosis induction (M4 stage), indicating that R. venosa mainly responded to the pelagobenthic changes. At the M24 stage, the enrichment of V-type proton ATPase and insulin indicated the complete development of secretory organs and initiation of hormone secretion. Furthermore, at the M48 stage, the enrichment of zinc metalloproteinase and conotoxin indicated a well-developed predation system that requires exogenous nutrition. Finally, during the PL stage, the genes associated with growth control were highly enriched, implying that R. venosa had completed metamorphosis and has entered the period of rapid growth. Therefore, our study provides useful transcriptomic resources for R. venosa and contributes new insights that may assist in elucidating the mechanisms underlying metamorphosis in marine invertebrates.

Continuous activation of the IL-17F driven inflammatory pathway in acute and chronic digital dermatitis lesions in dairy cattle

Objectives of the present study were to get a deeper insight into the course of the inflammatory pathways of digital dermatitis lesions in dairy cattle by investigating the gene expression patterns throughout the different clinical stages (M0 to M4.1) of the disease. Normal skin samples (M0) were used as a reference for comparing the gene expression levels in the other M-stages through RNA Seq-technology. Principal component analysis revealed a distinct gene expression pattern associated with digital dermatitis lesions in comparison to healthy skin with a further clustering of the acute M1, M2 and M4.1 stages versus the chronic M3 and M4 stages. The majority of the up-and downregulated genes in the acute and chronic stages can be placed into a common ‘core’ set of genes involved in inflammation, such as A2ML1, PI3, CCL11 and elafin-like protein, whereas the most downregulated genes included keratins and anti-inflammatory molecules such as SCGB1D and MGC151921. Pathway analysis indicated the activation of the pro-inflammatory IL-17 signaling pathway in all the M stages through the upregulation of IL-17F. These results indicate that digital dermatitis is associated with an excessive inflammatory immune response concomitant with a disrupted skin barrier and impaired wound repair mechanism. Importantly, despite their macroscopically healed appearance, a significant inflammatory response (Padj < 0.05) was still measurable in the M3 and M4 lesions, potentially explaining the frequent re-activation of such lesions.

Effects of Some Mutagens and Priming Applications on M4 Generation in Bean Mutation Breeding

In this study, it was carried out to determine some vegetative characteristics and yield characteristics of 30 lines of M4 plants to which different mutagens were applied. As a mutagen, 120 Gy gamma rays and 30 and 40 Mm Ethyl Methane Sulfonate (EMS), humidification and neem oil applications were among the trial subjects. Features such as pod length and width, pod weight, plant height, stem diameter, number of pods, number of grains per plant and grain weight were investigated in mutant plants that have reached the M4 stage. The pod length of the examined lines is 13.50-16.29 cm, pod width 12.24-17.82 mm, pod weight 10.03-13.73 gr, plant height 46.00-74.17 cm, stem diameter 6.35-11.44 mm, number of pods 21.27-45.43, number of grains 56.88-131.72 and the grain weight was found to be between 16.40-40.91 gr. It was observed that the pod length, which is one of the yield factors, increased by 214% compared to the control group of H2E1, the weight of NH3E2 pod increased by 37% compared to the control group, the number of NHG1 grains increased by 232% compared to the control group, and the weight of NHG1 grains increased by 246% compared to the control group. When the lines of all applications were examined, it was seen that humidification and humidification applications with neem oil reached the highest average values, while the control group reached the lowest average values.

M-score and wound healing assessment of 2 nonantibiotic topical gel treatments of active digital dermatitis lesions in dairy cattle

This open-label, randomized clinical trial with positive control compared the treatment of active digital dermatitis (DD) lesions (stages M1, M2, and M4.1) on dairy cattle hind feet with an enzyme alginogel or a copper and zinc chelate gel (coppergel). Upon recruitment (d 0), active DD lesions were cleaned, photographed, treated, and bandaged. This procedure was repeated on d 3 and d 7, with treatment and bandaging discontinued for those lesions that had transitioned to the M0, M3, or M4 stage on d 7. Day 10 was considered the end of the treatment trial, and all recruited feet were cleaned and photographed. Treatment effect of the 2 products was assessed not only using the M-score but also using general wound healing progress criteria. Improvement of M-score was defined as transition to M0, M3, or M4 stages, or to lesions with a smaller ulcerative area (e.g., M2 stage to M1 stage). Lesions with improved wound healing had at least one of the following criteria when compared with the previous observation: decreased defect size, healthier granulation tissue color (pink-red instead of purple-grayish), more regular aspect of granulation tissue surface, wound contraction, or epithelization starting from the surrounding skin. Both primary outcomes were assessed using a multivariable logistic regression analysis. Lesions treated with the enzyme alginogel had a decreased adjusted odds ratio for M-score improvement (aOR: 0.04; 95% confidence interval: 0.01-0.11). Lesions treated with the coppergel mostly transitioned to chronic lesions, whereas lesions treated with the enzyme alginogel mostly remained active lesions. The wound healing progress of almost 70% of the lesions treated with coppergel could not be scored, for the greater part due to the presence of crust materials. With these unscorable lesions classified as "improved," there was no treatment effect on wound healing progress (aOR: 0.99; 95% confidence interval: 0.34-3.05), whereas with unscorable lesions classified as "not improved," the enzyme alginogel outperformed the coppergel with regard to wound healing progress (aOR: 2.48; 95% confidence interval: 1.07-5.79). None of the products used in our study achieved high cure rates (transition to the M0 stage) for active DD lesions. Low cure rates of topical treatment of DD, together with the important role of chronic lesions in the epidemiology of DD, indicate that future research should investigate how to achieve successful wound management of DD lesions, thereby mitigating pain associated with the lesions and reducing both transmission and prevalence of DD within herds.

The Metamorphism and Its Tectonic Implications of Indosinian High Pressure Granulites from the Badu Complex of the Cathaysia Block, Southwestern Zhejiang Province, South China

AbstractThe Badu Complex is the oldest metamorphic rock in Cathaysia Block which experienced several episodes of metamorphism Especially indosinian metamorphic reworking in the southwestern Zhejiang Province, South China. The degree of indosinian metamorphism reaches granulite facies. However, there is still insufficient understanding of the characteristics of the Indosinian granulite metamorphism in the Cathaysia and many interpretations of its tectonic significance. Therefore, we present detailed petrology, mineral chemistry and LA‐ICP‐MS zircon U‐Pb age in this paper from pelitic granulites of the Badu Complex, which is composed of “sillimanite + garnet + cordierite + spinel + biotite + k‐feldspar” assemblage and garnet pyroxenite with garnet amphibolite which is consists of “garnet + clinopyroxene + orthopyroxene + amphibole + plagioclase”. By comprehensive study we get following new findings: Pelitic granulites record four stages of metamorphic mineral assemblages, including prograde (M1), pressure peak (M2), Peak (M3) and post‐peak decompressional and then cooling (M4) stages. The prograde M1 assemblage consists of garnet1 (core) + staurolite + kyanite + biotite + quartz ± rutile ± chlorite; The pressure peak M2 assemblage consists of garnet1 (mantle) + sudoite + rutile + kyanite + corundum + biotite + quartz; The peak M3 have garnet2 (rim‐mantle) + biotite + sillimanite + quartz ± K‐feldspar ± plagioclase ± ilmenite assemblag; the M4 stage is consist of garnet + cordierite + biotite + sillimanite + quartz + ilmenite ± spine ± K‐feldspar. The garnet pyroxenite and garnet amphibolites have experienced three stages of metamorphic evolution. Peak high‐pressure granulite facies stage M2 consists of garnet + sahlite ± ilmenite ± quartz; Post‐peak near isothermal decompression medium granulite facies stage M3 is characterized by typical decompression reaction textures and assemblage of orthopyroxene + plagioclase (An=90–92); amphibolites facies retrograde metamorphic stage M4 is characterized by amphibole + plagioclase (An=33–35) + ilmenite ± sahlite ± quartz mineral assemblage.By means of phase equilibrium simulation and traditional thermobarometer, P‐T conditions of 785–820 °C and 8.9–9.9 kbar for M3 stage, 780–860 °C and 5.7–6.2 kbar for decompressional M4 stage, 705–720 °C and 4.5–4.7 kbar for cooling M4 stage in pelitic granulites were obtained. And also 11.6–12.5 kbar and 780–840 °C for M2 stage, 7.4–8.2 kbar and 800–880 °C for M3 stage, 6.6–7.5 kbar and 500–560 °C for M4 stage were obtained in garnet pyroxenite and garnet amphibolite. A clockwise P‐T path is confirmed in the two type rocks of the Badu Complex which reflected a near‐isothermal decompressional metamorphic process. The peak metamorphism can reach high‐pressure granulite facies. In addition, the mineral assemblage of garnet + rutile + kyanite + corundum in the peak metamorphic stage of pelitic granulite indicates that it may underwent ultra‐high‐pressure metamorphism, and the acidic plagioclase exsolution of clinopyroxene in garnet pyroxenite also suggests that it may be retrograded eclogites, which indicates that the deeper Cathaysian block may have eclogite metamorphism.Analyses of LA‐ICP‐MS zircon U‐Pb dating indicate that the metamorphic age of pelitic granulite is 233.5 Ma–subduction/collision followed by rapid exhumation and cooling events. The events may relate with the amalgamation of the Indochina Block‐South China Block North China Block in the paleo‐Tethyan domain.

Metamorphic Petrology of Clinopyroxene Amphibolite from the Xigaze Ophiolite, Southern Tibet: P-T Constraints and Phase Equilibrium Modeling

The clinopyroxene amphibolite from the Bailang terrane is located in the central section of the Yarlung Zangbo suture zone (YZSZ), southern Tibet. The study of it is expected to provide important clues for the subduction of the Neo-Tethyan Ocean below the Asian Plate and thus for better understanding of the development of the India-Asia collision zone. Based on integrated textural, mineral compositional, metamorphic reaction history and geothermobarometric studies of the clinopyroxene amphibolite within a serpentinite melange, four overprinted metamorphic stages are established. They are the first metamorphic record of M1 stage indicated by a relict assemblage of plagioclase+clinopyroxene+amphibole, an early M2 stage characterized by an assemblage of medium-grained clinopyroxene+amphibole+plagioclase+quartz as well as rutile inclusion in titanite, which is formed during burial process, an isobaric cooling M3 stage which is characterized by an assemblage of clinopyroxene+amphibole+plagioclase+titanite, and a decomposing retrograde stage M4, which is represented by the amphibolite+plagioclase symplectite+titanite+ rutile+quartz. By applying the THERMOCALC (versions 6.2 and 6.3) technique in the NCFMASHTO system, the P-T conditions estimated from M1 to M4 stages are ca. 8.6 kbar/880 °C, 10.8-13.4 kbar/800-840 °C, 12.7-13.2 kbar/650-660 °C and <11.2 kbar/640 °C, respectively. The mineral assemblages and their P-T conditions define a counterclockwise P-T path for the clinopyroxene amphibolite of the Xigaze ophiolite, suggesting that the rocks underwent a cooling process during burial from magmatic protolith, and a decompressing stage after the pressure peak metamorphic conditions, which implies that the Bailang terrane of the Xigaze ophiolite may have experienced subduction/collision-related tectonic processes. The peak metamorphism reaches to the transitional P-T conditions among amphibolite facies, granulite facies and eclogite facies with a burial depth of 30–40 km. After exhumation of the ophiolitic unit to the shallow crustal levels, the clinopyroxene amphibolite exposes to a high fO2 condition on the basis of the stable epidotebearing assemblage in the T-MO2 diagrams. A late subgreenschist facies overprinting subsequently occurs, the relevant mineral assemblage is prehnite+albite+chlorite+epidote+quartz.

Petrological and geochronological evidence for Paleoproterozoic granulite-facies metamorphism of the South Liaohe Group in the Jiao-Liao-Ji Belt, North China Craton

To better understand the formation of high-temperature metamorphic rocks, we present a detailed petrological and geochronological study of recently discovered cordierite-bearing granulites of the South Liaohe Group in the Jiao-Liao-Ji Belt, North China Craton. Petrographic observations indicate that four distinct mineral assemblages are present in the granulites: pre-peak amphibolite facies (M1), peak granulite facies (M2), post-peak decompression (M3), and late cooling retrogression (M4). M1 is preserved as fine-grained inclusions in the cores of garnet grains, represented by quartz + plagioclase + biotite + ilmenite. M2 is interpreted to have comprised garnet + sillimanite + plagioclase + quartz + biotite + ilmenite + melt. M3 was characterized by the formation of cordierite + sillimanite symplectites and cordierite + quartz coronas replacing garnet. M4 is indicated by the formation of staurolite, accompanied by the crystallization of melt. A combination of multi-equilibria geothermobarometers and pseudosection modeling constrains the P–T conditions of the M1, M2, M3, and M4 stages to P = 0.66–0.71 GPa and T = 620–650 °C, P = 0.96–1.10 GPa and T = 790–840 °C, P = 0.62–0.65 GPa and T = 725–785 °C, and P = 0.43–0.55 GPa and T = 595–625 °C, respectively. Zircon and monazite U–Pb dating yields three distinct and meaningful ages for the granulites: (1) 2200–2100 Ma for the granulite protoliths, (2) ca. 1945 Ma for the near-peak metamorphism, and (3) 1851–1839 Ma for the post-peak and late retrogressive metamorphism. Thus, a clockwise P–T–t path is determined for the cordierite-bearing granulites of the South Liaohe Group. Petrological and geochronological evidence from regional metamorphic rocks in the Jiao-Liao-Ji Belt suggests that the belt experienced a continuous orogenesis from 1950 to 1800 Ma.

Drought Tolerance in Irradiated Wheat Mutants Studied by Genetic and Biochemical Markers

Mutation breeding is an alternative method for developing agriculturally important crops. A large set of Sagittario bread wheat seeds (Triticum aestivum L. cv.) were exposed to gamma ray irradiation (200 Gy) to obtain drought-tolerant mutant lines. To study drought tolerance, polyethylene glycol (PEG) 6000 was applied to the M2 and M3 individuals under in vitro conditions. Except in well-watered (100%) control plants, drought stress was triggered by a 50% decrease in the irrigation water applied to M3 and M4 plants in a greenhouse. Afterwards, 11 candidate drought-tolerant lines were obtained at the M4 stage and subjected to molecular analysis. The highest percentage of polymorphisms (72.4%) was detected with Retrotransposons Microsatellite Amplified Polymorphism (REMAP) markers followed by Inter-Simple Sequence Repeat (ISSR; 62.07%) and Inter-Retrotransposon Amplified Polymorphism (IRAP) markers (52.94%). A dendrogram tree and a principal coordinate analysis (PCoA) plot classified the experimental samples into three distinctive groups. Additionally, the activities of several antioxidant enzymes were evaluated in both vegetative and flowering stages, and mutant lines showing the highest biochemical performance under stress were detected in the same group through phylogenetic analysis. Gamma ray irradiation was used to improve drought-tolerant wheat lines for forward/reverse genomic studies and marker-assisted selection in crops.

High-pressure pelitic granulites from the Helanshan Complex in the Khondalite Belt, North China Craton: Metamorphic P-t path and tectonic implications

This paper presents petrographic and mineral chemistry data and an inferred P-T path for the high-pressure pelitic granulites from the Helanshan Complex in the Khondalite Belt, a Palaeoproterozoic collisional belt along which the Yinshan and Ordos blocks joined to form the Western Block in the North China Craton. Petrographic observation indicates that these high-pressure pelitic granulites experienced four metamorphic stages: the early prograde (M1), peak high-pressure (M2), post-peak decompression (M3) and late retrograde (M4) stages. The early prograde assemblage (M1) is preserved as mineral inclusions within the cores of garnet, represented by plagioclase + biotite + quartz + muscovite + kyanite + ilmenite. The peak high-pressure assemblage (M2) is garnet + kyanite + biotite + K-feldspar + plagioclase + quartz + ilmenite in the matrix. The post-peak decompressional stage (M3) is represented by sillimanite replacing kyanite and formation of cordierite + sillimanite symplectites (M3-1) and cordierite ± spinel coronas replacing garnet porphyroblasts (M3-2). The late retrograde stage (M4) is indicated by the formation of staurolite + chlorite in the matrix. Pseudosection modeling for a representative sample in the NCKFMASHTO system constrains the P-T conditions of M1, M2, M3-1, M3-2 and M4 stages at 9.3-9.7 kbar/656-674 °C, 10.2-11.2 kbar/792-805 °C, 5.5-5.7 kbar/810-820 °C, 4.5-5.0 kbar/780-785 °C and 3.4-4.4 kbar/580-610 °C, respectively. These mineral assemblages and their P-T conditions define a clockwise P-T path involving isothermal decompression and isobaric cooling following the peak high-pressure metamorphism, suggesting that the high-pressure pelitic granulites underwent initial crustal thickening (M1-M2), followed by isothermal exhumation (M3) and final retrogression and cooling (M4). Such a clockwise P-T path involving near-isothermal decompression is in accord with the P-T paths reconstructed for other complexes in the Khondalite Belt, and, combined with available geochronological data, is considered to record a continent-continent collisional event that led to the amalgamation of the Yinshan and Ordos Blocks to form the Western Block of the North China Craton at ∼1.95 Ga. This is coincident with these global-scale collisional events (2.1–1.8 Ga) leading to the assembly of the Palaeo-Mesoproterozoic supercontinent, further supporting an early proposal that the North China Craton was one of the components of the Palaeo-Mesoproterozoic Columbia (or Nuna) supercontinent.

Digital dermatitis in cattle is associated with an excessive innate immune response triggered by the keratinocytes

BackgroundDigital Dermatitis (DD) is a common disease of dairy cows, the pathogenesis of which is still not clear. This study examined some host responses associated with the typical lesions, in an attempt to further elucidate the pathogenesis of the disease. Twenty four samples representing the 5 different clinical stages of DD (M0-M4) were collected from slaughtered cattle for histopathological and immunological analyses.ResultsSignificant increases in total epidermal thickness were found in M2, M3, and M4 when compared with M0 and M1. M3 samples, when compared with M0 and M1, were characterized by a significant increase in the thickness of the keratin layer. Counts of both eosinophils and neutrophils were at a maximum in the M2 stage and decreased in the M3 and M4 stage. A significant increase in IL8 expression was observed in the M2-M3 stages of the disease and immunohistochemical staining showed the source as keratinocytes, suggesting an important role for keratinocyte-derived IL8 in the pathogenesis of DD.ConclusionResults of the present study point to a strong stimulation of the innate immune response at the level of the keratinocytes throughout most of the clinical stages, and a delayed response of the adaptive immune reaction.

Metamorphic P–T path and tectonic implications of medium-pressure pelitic granulites from the Jiaobei massif in the Jiao-Liao-Ji Belt, North China Craton

Both medium- and high-pressure pelitic granulites were found in the Jiaobei massif in the southern segment of the Jiao-Liao-Ji Belt, which is a Paleoproterozoic tectonic belt in the Eastern Block of the North China Craton. Studies on mineral assemblages and metamorphic reaction textures reveal that the medium-pressure pelitic granulites from the Jiaobei massif underwent four metamorphic stages: (1) the prograde stage (M1) represented by mineral inclusions within the core of garnet grains; (2) the peak stage (M2) indicated by the formation of sillimanite+K-feldspar and the growth of inclusion-free garnet mantle, (3) the decompression stage (M3) characterized by the cordierite+sillimanite symplectite, and (4) the decompression-cooling stage (M4) forming cordierite coronas. An integrated study of mineral reaction textures, mineral chemistry and pseudosection modelling in the NCFKMASHTO system with the THERMOCALC technique constrains the P–T conditions of 9.4–10kbar and 870–900°C for the M2 stage, 6.3–6.6kbar and 840–900°C for the M3 stage, and 4–5.2kbar and 815–830°C for the M4 stage. The P–T conditions of the early prograde (M1) assemblage cannot be estimated due to reworking at later metamorphic stages (M2–M4). The mineral assemblages of the M2–M4 stages and their P–T conditions define a clockwise P–T path involving isothermal decompression (ITD) and subsequent decompression-cooling for the medium-pressure pelitic granulites, which are consistent with a continent–continent collision environment. This suggests that the Jiao-Liao-Ji Belt was not formed simply by the closure of a Paleoproterozoic rift basin as conventionally considered, but the tectonic evolution of its southern segment must have been involved in subduction and/or continent–continent collisional processes. Based on this study and previous data, we propose that the Jiao-Liao-Ji Belt represented a Paleoproterozoic rifting- and collision-belt along which the Langgang and Langrim Blocks amalgamated to form the Eastern Block of the North China Craton.

A simple method to score digital dermatitis in dairy cows in the milking parlor

The diagnosis of digital dermatitis (DD) in cows is crucial for researchers to evaluate the effectiveness of control measures. The objective of this study was to evaluate intra- and inter-observer agreement and accuracy of a simple method to score DD lesions that is based on the inspection of cleaned feet in the milking parlor with a swiveling mirror and a powerful headlamp. The hind feet of 242 Holstein cows from 4 farms were inspected concurrently by 5 observers (to assess inter-observer agreement) during 2 consecutive milkings (to assess intra-observer agreement). This inspection was followed by an inspection of the feet in a trimming chute, considered to be the gold standard test, to test for accuracy. The reliability of the method was assessed using both the 5 M-stages scoring system (M0 to M4, M standing for Mortellaro) and a simplified M-stages scoring system in which the M3 and M4 stages are merged. As most disagreements concerned the M3 and M4 stages, performance was improved with the simplified M-stages scoring system. With this simplified system, the method had good intra-observer agreement [percent of overall raw agreement (PA)=80%, weighted kappa (κw)=0.71, and good inter-observer agreement (PA=77%, κw=0.66)]. The agreement with the gold standard test was moderate (PA=69%, κw=0.58). Considering absence versus presence of a DD lesion on a foot, the method had good sensitivity (0.90) and specificity (0.80). The time spent for inspection varied from 30 to 60s per cow. Inspection of cleaned feet with a swiveling mirror and a powerful headlamp in the milking parlor is a reliable, cost- and time-friendly method, which may be useful for both farmers and researchers, especially when the DD status of many dairy cows has to be evaluated concomitantly. The reliability of this method might be improved by using more precise descriptive criteria for the discrimination of each M-stage.

P–T evolution of eclogite-facies metabasite from NE Sardinia, Italy: Insights into the prograde evolution of Variscan eclogites

A petrological study of the Punta Orvili metabasite in NE Sardinia has been carried out, integrating quantitative pseudosection modelling with reaction balancing, with the aim of reconstructing the metamorphic evolution and P–T path.The Punta Orvili metabasite preserves microstructural evidence of: (i) a pre-symplectite polyphase and prograde stage (M1) indicated by the occurrence of amphibole inclusions in garnet, by Na-rich diopside and by compositional zoning in garnet, clinopyroxene and amphibole; (ii) a symplectite stage (M2) represented by the occurrence of Cpx2+Pl1 symplectite; (iii) a corona stage (M3) documented by the formation of micrometre-thick Pl2±Am3±Ilm coronas around garnet; and (iv) a late stage (M4), documented by the growth of epidote and albite and by the replacement of biotite and clinopyroxene by chlorite. The M1 pre-symplectite stage has been modelled by P–T pseudosections calculated in the NCKFMASTH model system at a(H2O)=1 (for a(H2O)=0.5 temperature values are ~50°C lower). Mg and Ca zoning in garnet and Na zoning in clinopyroxene testify to a progressive increase in temperature and pressure during garnet and clinopyroxene growth from 610<T<630°C, 1.7<P <1.8GPa up to 620<T<650°C, 1.9<P<2.1GPa, allowing to reconstruct a prograde segment of the P–T path. Peak pressure conditions were reached in the amphibole–eclogite-facies field. Destabilization of clinopyroxene led to the formation of Cpx2+Pl1 symplectite (M2 stage) at P–T conditions of 760<T<800°C, 0.9<P<1.0GPa.The corona stage (M3) was modelled in the NCFMASTH model system using the bulk composition of the effectively reacting microdomain, calculated from mineral compositions and stoichiometric coefficients of the corona-forming reaction. T=610–670°C and P~0.7GPa have been determined for this stage. Presumed P–T conditions of the latest re-equilibration stage (M4 stage) are around 300–400°C and 0.2–0.3GPa.The prograde evolution of the Punta Orvili metabasite took place under a geothermal gradient of ~10°C/km, compatible with a relatively hot subduction of a small, young marginal basin. Subsequent increase of the geothermal gradient up to 20–30°C/km suggests that subduction was followed by the Variscan continental collision.The P–T path of the Punta Orvili metabasite has significant analogies with that of the retrogressed eclogite of Golfo Aranci, NE Sardinia, and with other eclogites from the Migmatite Complex of NE Sardinia.

The thermal and geodynamic evolution of the Lapland granulite belt: Implications for thermal structure of the lower crust during granulite-facies metamorphism

The tectono-thermal history of the Lapland Granulite belt is considered within the framework of a combined superplume-plate tectonic model on the basis of new geochronological and petrological data. The high-grade metamorphic events were linked with plume-related extensional episodes at ∼ 2.44 Ga (M0), ∼ 2.0–1.95 Ga (M1), ∼ 1.95–1.92 Ga (M2) and 1.92–1.91 Ga (M3). The last (M4) high-grade event at ∼ 1.89–1.87 Ga corresponds to the final collision. P– T parameters of metamorphism during M1 event ranged from 960 to 860 °C and from 14.0 to 10.3 kbar. They decreased from the lower to the upper part of the belt during the M2 event from 860 °C at 12.4 kbar and to 800 °C at 5.8 kbar, during the M3 event from 770 °C at 10.7 kbar to 640 °C at 4.8 kbar, and during the M4 event from 650 °C at 8.4 kbar to 550 °C at 4.5 kbar. Upward displacement of a hot tectonic slice during the M4 stage caused inverted metamorphic zoning in the autochthonous rocks and a clockwise P– T evolution within the mélange zone at the base of LGB 1 1 Lapland Granulite Belt. . The internal thermal gradient within the lower crust during events M2 and M3 was 1.8–2.3 °C/km, and during the M4 event it fell to 4–5 °C/km. The agreement of thickness estimates of the granulite ensemble obtained from seismic and petrological data attests to the lithostatic nature of metamorphic pressures. The average thickness of the Lapland granulite slice was initially ∼ 21–23 km.

Mesoproterozoic Reworking of Palaeoproterozoic Ultrahigh-temperature Granulites in the Central Indian Tectonic Zone and its Implications

In the southern periphery of the Sausar Mobile Belt (SMB), the southern component of the Central Indian Tectonic Zone (CITZ), a suite of felsic and aluminous granulites, intruded by gabbro, noritic gabbro, norite and orthopyroxenite, records the polymetamorphic evolution of the CITZ. Using sequences of prograde, peak and retrograde reaction textures, mineral chemistry, geothermobarometric results and petrogenetic grid considerations from the felsic and the aluminous granulites and applying metamorphosed mafic dyke markers and geochronological constraints, two temporally unrelated granulite-facies tectonothermal events of Pre-Grenvillian age have been established. The first event caused Ultrahigh-temperature (UHT) metamorphism (M1) (T ∼950°C) at relatively deeper crustal levels (P ∼9 kbar) and a subsequent post-peak near-isobaric cooling P–T history (M2). M1 caused pervasive biotite-dehydration melting, producing garnet–orthopyroxene and garnet–rutile and sapphirine–spinel-bearing incongruent solid assemblages in felsic and aluminous granulites, respectively. During M2, garnet–corundum and later spinel–sillimanite–biotite assemblages were produced by reacting sapphirine–spinel–sillimanite and rehydration of garnet–corundum assemblages, respectively. Applying Electron Microprobe (EMP) dating techniques to monazites included in M1 garnet or occurring in low-strain domains in the felsic granulites, the UHT metamorphism is dated at 2040–2090 Ma. Based on the deep crustal heating–cooling P–T trajectory, the authors infer an overall counterclockwise P–T path for this UHT event. During the second granulite event, the Palaeoproterozoic granulites experienced crustal attenuation to ∼6•4 kbar at T ∼675°C during M3 and subsequent near-isothermal loading to ∼8 kbar during M4. In the felsic granulites, the former is marked by decomposition of M1 garnet to orthopyroxene–plagioclase symplectites. During M4, there was renewed growth of garnet–quartz symplectites in the felsic granulites, replacing the M3 mineral assemblage and also the appearance of coronal garnet–quartz–clinopyroxene assemblages in metamorphosed mafic dykes. Using monazites from metamorphic overgrowths and metamorphic recrystallization domains from the felsic granulite, the M4 metamorphism is dated at 1525–1450 Ma. Using geochronological and metamorphic constraints, the authors interpret the M3–M4 stages to be part of the same Mesoproterozoic tectonothermal event. The result provides the first documentation of UHT metamorphism and Palaeo- and Mesoproterozoic metamorphic processes in the CITZ. On a broader scale, the findings are also consistent with the current prediction that isobarically cooled granulites require a separate orogeny for their exhumation.

The metamorphic evolution of the high pressure mafic granulites of the Bacariza Formation (Cabo Ortegal Complex, Hercynian belt, NW Spain) ☆

The high pressure mafic granulites of the Bacariza Formation outcrop in the two uppermost structural units of the Cabo Ortegal Complex (La Capelada unit and Cedeira unit) were separated by a Variscan thrust. In both cases, they appear as heterogeneous metabasites in normal contact between ultramafic rocks and other more homogeneous and less differentiated metabasic rocks, also affected by catazonal metamorphism. The main difference between the mafic granulites in the two units is the degree of deformation, which is higher in the underlying Cedeira unit. Petrologie and mineralogical data indicate that the high-pressure (HP) granulites (Gt-Cpx ± Amp-Pl ± Qtz ± Scp-Rt ± Ilm-Czo) are already retrograde (M2 Stage), post-dating an earlier eclogite facies metamorphism (Ml Stage) characterised by the mineral associations: Gt-Cpx ± Amp ± Ky ± Qtz-Rt and Gt-Cpx ± Amp ± Qtz ± Zo-Rt. The main structure relatted to the exhumation processes is the development of a general mylonitic foliation that, although initiated in granulite facies conditions, was mainly equilibrated in amphibolite facies (M3 Stage). This foliation was affected by isoclinal folds, which led to the formation of the Variscan thrusts responsible for the present stacking position. Thrust conditions were transitional between amphibolite and greenschist facies (M4 Stage). Thermobarometric data point to different P—T exhumation paths in the two units. Estimated P—T conditions were higher in La Capelada unit during Ml (P ≥ 13 kbar; 860 °C) and M2 (15 kbar; 800 °C) than in the Cedeira unit (Ml: P ≥ 11 kbar, 770 °C; M2: 12 kbar; 750 °C). Temperatures for the M3 stage were comparable (720 °C) in both units but rocks from the Cedeira unit show a much bigger drop in pressure. This resulted in an isothermal decompression type path for the Cedeira unit, while both P and T decreased more steadily in La Capelada rocks. These were always located at deeper level than the Cedeira rocks before the Variscan stacking. The difference in the two paths is related to different exhumation rates; higher in rocks from the Cedeira unit than in those from La Capelada. Exhumation processes coeval with underthrusting, and a different location of the rocks with respect to the main shear zone responsible for the exhumation would account for the distinct paths.

Multi-stage fluid incursion in the Palaeozoic basement-hosted Saint-Salvy ore deposit (NW Montagne Noire, southern France)

The Saint-Salvy vein-hosted Zn (+Ge) deposit occurs in an E–W fault system which flanks the southern margin of the late Variscan Sidobre granite, and cross-cuts Cambrian black shales of the Palaeozoic basement. Comprehensive mineralogical and geochemical studies of vein samples have revealed four mineralizing events (M1–M4) related to late and post-Variscan tectonic events. A further late-stage event may be related to weathering. M1 (=skarn deposits) and M2 (=patchily mineralized quartz veinlets) are associated with granite emplacement. Quartz contains low salinity, H 2O CO 2 (NaCl)-dominated fluids (⩽6wt% NaCl equiv.) of relatively high temperature (300–580°C), trapped under moderate to high pressure. Estimated M1 fluid δD and calculated fluid δ 18O plot within the metamorphic water field. There appears to be no involvement of magmatic fluids. By contrast, M3 (= barren quartz) and M4 (= zinciferous economic mineralization) stages have H 2O CO 2 NaCl CaCl 2 fluid inclusions with high salinities (23–25 wt% NaCl equiv.) and low temperatures (∼ 80–140°C), which were trapped under low-pressure conditions. The high salinity and NaCl + CaCl 2 content of both M3 and M4 indicates that their parent fluids leached evaporitic salts. M3 fluids are meteoric water dominated, falling close to the meteoric water line (δD and δ 18O averaging −64 and −8‰, respectively). M4 fluids have highly distinctive δD averaging −101‰, and calculated fluid δ 18O varying from −1.2to+7.1‰. The unusually low δD composition of M4 suggests the involvement of “organic” fluids, in which H is derived directly or indirectly from organic matter. The relatively high δ 18O of M4 fluids indicates that considerable isotopic exchange with sedimentary material took place, displacing the δ 18O from the meteoric water line. The data imply interaction of meteoric waters with evaporite and hydrocarbon-bearing sedimentary sequences, most probably the adjacent Aquitain Basin. The main economic mineralization (M4 stage) took place during a tensional event, probably coincident with the Lias-Dogger transition. Calculated δ 34S H 2S of M4 sulphide (+5.4to+8.2‰) is almost identical to δ 34S of local Cambrian sulphides (+4.7to+9.4‰) suggesting a genetic link. Abundant siderite associated with M4 sphalerite has δ 13C ranging from −2.6to−4.4‰ indicating that carbon was sourced from sedimentary carbonate mobilized by, or equilibrated with the hydrothermal fluid. Late-stage sulphides exhibit extraordinary and highly distinctive δ 34S . Sphalerite has extremely low δ 34S (−42.5to−50.5‰), whereas pyrite has an extraordinary large range from −33.2‰to+74.3‰. Closed system sulphate reduction is held to be responsible for the extremely high δ 34S : whereas more open system reduction produces the very low values. The coincidence of isotopically low δ 13C(−7.6to−11.9‰) for co-genetic calcite suggests the involvement of organic matter in the reduction process.