Retrograde fluid infiltration in the high-grade Modum Complex South Norway: evidence for age,source and REE mobility

The high-grade metamorphic basement of the Modum Complex, South Norway,exhibits retrogradation and alteration due to late stage fluid infiltration.Extensive alteration zones of albite-and calcite-rich veining occur especiallywithin and around numerous metagabbros. The gabbros, intruded at 1224±15Ma, are now partly altered to amphibolites due to the subsequent high-grade metamorphism.Two generations of albite-rich rocks have been recognized: (1) a fine-grained, foliated type;(2) a coarse-grained, crosscutting type. Both types show a typical greenschist facies mineralassemblage; albite ± actinolite ± chlorite ± talc. The calcite veins/dykesrepresent a younger generation of veins than both albite-rich types. U–Pb data for spheneof type (1) yielded an age of 1080±3 Ma, determining a point on the retrogradeP-T-t path of the Modum Complex. Increasing albitisation of themetagabbros leads to a decrease in(¹⁴³ND/¹⁴⁴Nd)_oand an increase in (⁸⁷Sr/⁸⁶)_o.Albite- and calcite-rich samples show negative _Nd and positive _Sr, suggesting that fluids which interacted with the metagabbros originated from a crustal reservoir. The Nd and Sr isotopic data show disequilibrium at the microscale as well as at the macroscale. Negative Sm–Nd model ages of the albite-rich rocks demonstrate that rare-earth elements (REEs) were mobile and fractionated during albitisation.     

Particle acceleration and the decay of soft X-ray non-thermal line broadening in solar flares

The relationship between the production of -ray emitting particles and non-thermal soft X-ray line broadening is investigated. A model of particle acceleration via the stochastic interaction with MHD turbulence is assumed and the time development of the wave energy density derived under the condition of energy conservation between waves and particles. The inferred numbers and energy distribution of accelerated protons for four -ray flares are used to define the wave energy density and its temporal development. The presence of Alfvén wave turbulence is considered as the source of the non-thermal motions in the ambient plasma. These motions are observed as excess widths in the soft X-ray line emission from these events. The decay of the waves via the particle acceleration process is compared with the observed decays of this non-thermal line broadening. Our results show that both the -ray emission and excess soft X-ray line widths in these flares can be explained by the single physical phenomenon of Alfvén wave turbulence.     

Fe-Cu-Zn-Mo同位素示踪氧化还原过程

非传统稳定同位素（Fe-Cu-Zn-Mo）理论与数据相结合提高了科研工作者对地质体系氧化还原过程的理解。本文对这一相对较新的领域进行了综述,包括与氧化还原过程相关的同位素分馏理论和实验约束、时空尺度下的氧逸度以及同位素示踪氧化还原过程。稳定同位素理论预测,Fe-Cu-Zn-Mo同位素应该对氧化还原状态的变化能够做出响应。结果表明,Fe同位素作为岩浆过程、表生过程、俯冲带流体性质"氧逸度计"应用前景广阔;Cu同位素在岩浆、热液、陆地系统可以很好地示踪氧化还原过程;Zn同位素由于络合过程分馏已经被用在许多不同环境中作为含硫/碳流体迁移的敏感示踪剂;Mo同位素作为古氧逸度计可有效重建古海洋-大气氧化还原状态。     

Provenance of Conglomerate and Sandstone from Early Permian Shoushangou Formation in Xi Ujimqin, Inner Mongolia: Implications for Understanding Paleo-Asian Ocean Subduction

During the Late Carboniferous to Early Permian, a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean (PAO) subduction in the Xi Ujimqin area. Nevertheless, the closure time of the PAO is still under debate. Thus, to identify the origin of the PAO, the geochemistry and U-Pb age of zircons were analyzed for the extra-large deep marine, polymict clastic boulders and sandstones in the Shoushangou Formation within the basin. The analyses revealed magmatic activity and tectonic evolution. The conglomerates include megaclasts of granite (298.8 ± 9.1?Ma) and granodiorite porphyry (297.1 ± 3.1?Ma), which were deposited by muddy debris flow. Results of this study demonstrated that the boulders of granitoids have the geochemistry of typical I-type granite, characterized by low Zr + Nb + Ce + Y and low Ga/Al values. The granitoid boulders were formed in island arc setting, indicating the presence of arc magmatism in the area that is composed of the Late Carboniferous to Early Permian subduction-related granitoid in southern Xi Ujimqin. Multiple diagrams for determining sedimentary provenance using major and trace elements indicate that Shoushangou sediments originated from continental island arc-related felsic rocks. Detrital zircon U-Pb age cluster of 330–280?Ma was obtained, indicating input from granite, ophiolite, Xilin Gol complex, and Carboniferous sources to the south. The basin was geographically developed behind the arc during the Early Permian period because the outcropped intrusive rocks in the Late Carboniferous to Early Permian form a volcanic arc. The comprehensive analyses of source areas suggest that Shoushangou sediments developed in a backarc basin in response to the northward subduction of the PAO. The backarc basin and intrusive rocks, in addition to previously published Late Carboniferous to Early Permian magmatic rocks of arc unit in Xilin Gol, confirm the presence of an Early Permian trench-arc-basin system in the region, represented by the Baolidao arc and Xi Ujimqin backarc basin. This study highlights the importance and potential of combined geochemical and geochronological studies of conglomerates and sandstone for reconstructing the geodynamic setting of a basin.     

自拟通窍祛瘀汤治疗外伤性气滞血瘀型脑内血肿51例

目的：观察自拟通窍祛瘀汤治疗外伤性气滞血瘀型脑内血肿的临床疗效。方法：选取外伤性气滞血瘀型脑内血肿患者100例,将其随机分为治疗组（51例）和对照组（49例）。2组均予以基础治疗,对照组在基础治疗上加用西医常规治疗,治疗组在对照组基础上加用自拟通窍祛瘀汤口服治疗。治疗2周后观察2组中医证候疗效,治疗前、治疗1周后、治疗2周后观察2组血肿吸收、水肿吸收、神经功能缺失（NIHSS）评分、中医证候积分情况。结果：总有效率治疗组为94.11%（48/51）,明显高于对照组的75.51%（37/49）,2组比较,差异有统计学意义（P＜0.05）。治疗后2组血肿体积、水肿体积、NIHSS评分、中医证候积分均较治疗前减少,且治疗组与对照组治疗后同时间节点比较,差异均有统计学意义（P＜0.05或P＜0.01)。结论：外伤性气滞血瘀型脑内血肿患者在常规治疗的基础上使用自拟通窍祛瘀汤治疗可以促进神经功能恢复,改善中医证候,促进血肿和水肿吸收。     

卫矛醇对C6胶质瘤细胞体外抗癌活性及机制探讨

目的:研究卫矛醇对C6胶质瘤细胞株的体外增殖及凋亡的影响。方法：将C6大鼠胶质瘤细胞随机分为对照组、卫矛醇干预组、卫矛醇+雷帕霉素组、卫矛醇+3-MA组,各组予不同药物孵育,采用MTT法检测卫矛醇对C6细胞的体外增殖抑制率,筛选出抑制率相对较高且生长状态良好的细胞;应用Hoechest 33342染色透射电镜观察细胞凋亡亚显微结构的改变,采用免疫荧光和Western Blot技术检测与凋亡和自噬相关蛋白的表达水平。结果:卫矛醇对C6胶质瘤细胞增殖有明显的抑制作用,并呈现出良好的浓度-效应相关性,与对照组比较,随着浓度的增加,细胞的增殖抑制率上升(P＜0.01);Hoechst染色结果显示,与对照组相比,共同孵育卫矛醇24 h后的C6细胞出现明显的核固缩现象,证明有大量的细胞出现凋亡;Western Blot结果显示,与对照组相比,促凋亡基因Bax表达上调,抗凋亡基因Bcl-2表达下调。结论:卫矛醇能够抑制C6细胞的增殖,并诱导其凋亡,其作用机制可能与上调Bax、下调Bcl-2有关。     

Mechanisms of shrubland expansion: land use,climate or CO2?

Encroachment of trees and shrubs into grasslands and the thicketization of savannas has occurred worldwide over the past century. These changes in vegetation structure are potentially relevant to climatic change as they may be indicative of historical shifts in climate and as they may influence biophysical aspects of land surface-atmosphere interactions and alter carbon and nitrogen cycles. Traditional explanations offered to account for the historic displacement of grasses by woody plants in many arid and semi-arid ecosystems have centered around changes in climatic, livestock grazing and fire regimes. More recently, it has been suggested that the increase in atmospheric CO₂ since the industrial revolution has been the driving force. In this paper we evaluate the CO₂ enrichment hypotheses and argue that historic, positive correlations between woody plant expansion and atmospheric CO₂ are not cause and effect.Please direct all correspondence to the senior author.     

Transmission electron microscopy of subsolidus oxidation and weathering of olivine

Olivine crystals in basaltic andesites which crop out in the Abert Rim, south-central Oregon have been studied by high-resolution and analytical transmission electron microscopy. The observations reveal three distinct assemblages of alteration products that seem to correspond to three episodes of olivine oxidation. The olivine crystals contain rare, dense arrays of coherently intergrown Ti-free magnetite and inclusions of a phase inferred to be amorphous silica. We interpret this first assemblage to be the product of an early subsolidus oxidation event in the lava. The second olivine alteration assemblage contains complex ordered intergrowths on (001) of forsterite-rich olivine and laihunite (distorted olivine structure with Fe³⁺ charge balanced by vacancies). Based on experimental results for laihunite synthesis (Kondoh et al. 1985), these intergrowths probably formed by olivine oxidation between 400 and 800°C. The third episode of alteration involves the destruction of olivine by low-temperature hydrothermal alteration and weathering. Elongate etch-pits and channels in the margins of fresh olivine crystals contain semi-oriented bands of smectite. Olivine weathers to smectite and hematite, and subsequently to arrays of oriented hematite crystals. The textures resemble those reported by Eggleton (1984) and Smith et al. (1987). We find no evidence for a metastable phase intermediate between olivine and smectite (M — Eggleton 1984). The presence of laihunite exerts a strong control on the geometry of olivine weathering. Single laihunite layers and laihunite-forsteritic olivine intergrowths increase the resistance of crystals to weathering. Preferential development of channels between laihunite layers occurs where growth of laihunite produced compositional variations in olivine, rather than where coherency-strain is associated with laihunite-olivine interfaces.     

Genesis of monazite and Y zoning in garnet from the Black Hills, South Dakota

The paragenesis of monazite in metapelitic rocks from the contact aureole of the Harney Peak Granite, Black Hills, South Dakota, was investigated using zoning patterns of monazite and garnet, electron microprobe dating of monazite, bulk-rock compositions, and major phase mineral equilibria. The area is characterized by low-pressure and high-temperature metamorphism with metamorphic zones ranging from garnet to sillimanite zones. Garnet porphyroblasts containing euhedral Y annuli are observed from the garnet to sillimanite zones. Although major phase mineral equilibria predict resorption of garnet at the staurolite isograd and regrowth at the andalusite isograd, textural and mass balance analyses suggest that the formation of the Y annuli is not related to the resorption-and-regrowth of garnet having formed instead during garnet growth in the garnet zone. Monazite grains in Black Hills pelites were divided into two generations on the basis of zoning patterns of Y and U: monazite 1 with low-Y and -U and monazite 2 with high-Y and -U. Monazite 1 occurs in the garnet zone and persists into the sillimanite zone as cores shielded by monazite 2 which starts to form in the andalusite zone. Pelites containing garnet porphyroblasts with Y annuli and monazite 1 with patchy Th zoning are more calcic than those with garnet with no Y annuli and monazite with concentric Th zoning. Monazite 1 is attributed to breakdown of allanite in the garnet zone, additionally giving rise to the Y annuli observed in garnet. Monazite 2 grows in the andalusite zone, probably at the expense of garnet and monazite 1 in the andalusite and sillimanite zones. The ages of the two different generations of monazite are within the precision of chemical dating of electron microprobe. The electron microprobe ages of all monazites from the Black Hills show a single ca. 1713 Ma population, close to the intrusion age of the Harney Peak Granite (1715 Ma). This study demonstrates that Y zoning in garnet and monazite are critical to the interpretation of monazite petrogenesis and therefore monazite ages.