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F, Cl, S and P were determined, using electron microprobe, in magmatic inclusions trapped within minerals and glass mesostasis
from Wudalianchi volcanic rocks. The initial volcanic magma from Wudalianchi corresponds to the basanitic magma crystallized
near the surface ( pressure < 91 Mpa ). The potential H2O content of this magma is in the range 2 — 4 wt. %. The initial composition of volcanic magmas varies regularly from early
to late volcanic events. From the Middle Pleistocene to the recent eruptions (1719 – 1721 yr.), the basicity of volcanic magma
tends to increase, as reflected by an increase in MgO and CaO contents and by a progressive decrease in SiO2 and K2O contents. Meanwhile. from early (Q2 ) to late (Q3) episodic eruptions of the Middle Pleistocene, the initial concentrations of chlorine in volcanic magmas range from 1430
– 1930 ppm to 1700 ppm and decrease to 700 — 970 ppm for the first episodic eruption during the Holocene (Q
4
1
). The chlorine concentrations of volcanic magmas of recent eruption (Q
4
2
) are increased again to 2600 – 2870 ppm. A parallel evolution trend for phosphorus and chlorine concentrations in magmas
has been certified: 1500 – 5970 ppm (Q2)→ 3500 – 4210 ppm (Q3)→ 1100– 3500 ppm (Q
4
1
)→ 6800– 7900 ppm (Q
4
2
). The fluorine contents of volcanic magmas, from early to late volcanic events, show the same trend: 770 – 2470 ppm → 200–700
ppm → 700 – 800 ppm.
During the crystallization-evolution of volcanic magmas, fluorine and phosphorus tend to be enriched in residual magmas as
a result of crystal-melt differentiation. for example. the fluorine contents reach 5000– 6800 ppm and the phosphorus contents,
2.93wt.% in residual magmas. An appreciable amount of chlorine may be lost from water rich volcanic magmas prior to eruption
as a result of degassing. Apparently, water serves as a gas carrier for the chlorine. The chlorine contents of residual magmas
may decrease to 100 – 300 ppm.
The volcanic magmas from Wudalianchi are poor in sulfur, normally ranging from 200 to 400ppm. On account of the behavior of
sulfur in magmas and the strontium and oxygen isotopic analyses ((87Sr /86Sr)i=0.70503– 0.70589; δ18O = + 5.50 – + 6.89 ‰ ), it can be considered that the basanitic magmas in the Wudalianchi volcanic area came from the upper
mantle and have not yet been contaminated probably by continental crust materials. 相似文献
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Antonin Richard David A. Banks Marie-Christine Boiron Michel Cathelineau 《Geochimica et cosmochimica acta》2011,75(10):2792-2810
Analyses of halogen concentration and stable chlorine isotope composition of fluid inclusions from hydrothermal quartz and carbonate veins spatially and temporally associated with giant unconformity-related uranium deposits from the Paleoproterozoic Athabasca Basin (Canada) were performed in order to determine the origin of chloride in the ore-forming brines. Microthermometric analyses show that samples contain variable amounts of a NaCl-rich brine (Cl concentration between 120,000 and 180,000 ppm) and a CaCl2-rich brine (Cl concentration between 160,000 and 220,000 ppm). Molar Cl/Br ratios of fluid inclusion leachates range from ∼100 to ∼900, with most values between 150 and 350. Cl/Br ratios below 650 (seawater value) indicate that the high salinities were acquired by evaporation of seawater. Most δ37Cl values are between −0.6‰ and 0‰ (seawater value) which is also compatible with a common evaporated seawater origin for both NaCl- and CaCl2-rich brines.Slight discrepancies between the Cl concentration, Cl/Br, δ37Cl data and seawater evaporation trends, indicate that the evaporated seawater underwent secondary minor modification of its composition by: (i) mixing with a minor amount of halite-dissolution brine or re-equilibration with halite during burial; (ii) dilution in a maximum of 30% of connate and/or formation waters during its migration towards the base of the Athabasca sandstones; (iii) leaching of chloride from biotites within basement rocks and (iv) water loss by hydration reactions in alteration haloes linked to uranium deposition.The chloride in uranium ore-forming brines of the Athabasca Basin has an unambiguous dominantly marine origin and has required large-scale seawater evaporation and evaporite deposition. Although the direct evidence for evaporative environments in the Athabasca Basin are lacking due to the erosion of ∼80% of the sedimentary pile, Cl/Br ratios and δ37Cl values of brines have behaved conservatively at the basin scale and throughout basin history. 相似文献
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High PT experiments were performed in the range 2.5–19 GPa and 800–1,500°C using a synthetic peridotite doped with trace elements
and OH-apatite or with Cl-apatite + phlogopite. The aim of the study was (1) to investigate the stability and phase relations
of apatite and its high PT breakdown products, (2) to study the compositional evolution with P and T of phosphate and coexisting
silicate phases and (3) to measure the Cl-OH partitioning between apatite and coexisting calcic amphibole, phlogopite and
K-richterite. Apatite is stable in a garnet-lherzolite assemblage in the range 2.5–8.7 GPa and 800–1,100°C. The high-P breakdown
product of apatite is tuite γ-Ca3 (PO4)2, which is stable in the range 8–15 GPa and 1,100–1,300°C. Coexisting apatite and tuite were observed at 8 GPa/1,050°C and
8.7 GPa/1,000°C. MgO in apatite increases with P from 0.8 wt% at 2.5 GPa to 3.2 wt% at 8.7 GPa. Both apatite and tuite may
contain significant Na, Sr and REE with a correlation indicating 2 Ca2+=Na+ + REE3+. Tuite has always higher Sr and REE and lower Fe and Mg than apatite. Phosphorus in the peridotite phases decreases in the
order Pmelt ≫ Pgrt ≫ PMg2SiO4 > Pcpx > Popx. The phosphate-saturated P2O5 content of garnet increases from 0.07 wt% at 2.5 GPa to 1.5 wt% at 12.8 GPa. Due to the low bulk Na content of the peridotite,
[8]Na[4]P[8]M2+
−1
[4]Si−1 only plays a minor role in controlling the phosphorus content of garnet. Instead, element correlations indicate a major contribution
of [6]M2+[4]P[6]M3+
−1
[4]Si−1. Pyroxenes contain ~200–500 ppm P and olivine has 0.14–0.23 wt% P2O5 in the P range 4–8.7 GPa without correlation with P, T or XMg. At ≥12.7 GPa, all Mg2SiO4 polymorphs have <200 ppm P. Coexisting olivine and wadsleyite show an equal preference for phosphorus. In case of coexisting
wadsleyite and ringwoodite, the latter fractionates phosphorus. Although garnet shows by far the highest phosphorus concentrations
of any peridotite silicate phase, olivine is no less important as phosphorus carrier and could store the entire bulk phosphorus
budget of primitive mantle. In the Cl-apatite + phlogopite-doped peridotite, apatite contains 0.65–1.35 wt% Cl in the PT range
2.5–8.7 GPa/800–1,000°C. Apatite coexists with calcic amphibole at 2.5 GPa, phlogopite at 2.5–5 GPa and K-richterite at 7 GPa,
and all silicates contain between 0.2 and 0.6 wt% Cl. No solid potassic phase is stable between 5 and 8.7 GPa. Cl strongly
increases the solubility of K in hydrous fluids. This may lead to the breakdown of phlogopite and give rise to the local presence
in the mantle of fluids strongly enriched in K, Cl, P and incompatible trace elements. Such fluids may get trapped as micro-inclusions
in diamonds and provide bulk compositions suitable for the formation of unusual phases such as KCl or hypersilicic Cl-rich
mica. 相似文献
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河北平原第四系地下水^36Cl年龄研究 总被引：6，自引：3，他引：6
本文报道了河北平原第四系地下水~(36)Cl研究的样品采集、制备,加速器质谱计(AMS)测定及地下水~(36)Cl年龄的计算原理和结果。 相似文献
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河北沧州地区第四纪地下水36Cl示踪 总被引：3，自引：0，他引：3
通过对华北平原沧州地区第四纪地下水中宇宙成因核素36CI进行的测定,其浅层咸水的36Cl/Cl值为57×10-15,证实了该区浅层地下水的盐化成因主要是蒸发浓缩所造成.该区深层地下水中大气成因的36Cl所占的份额为33%～30%,系由上覆咸水下移所致. 相似文献
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河北平原第四系深层地下水36Cl同位素年龄的研究 总被引：10，自引：0，他引：10
为研究河北平原第四系深层地下水的年龄，应用加速器质谱计对河北平原深层地下水样品的N(^36Cl)/N(Cl)进行了测定，计算了其年龄，并与地下水动力学年龄进行了对比研究。结果表明，河北冲洪积平原山前地带保定市第四系第三和第四含水组的地下水年龄皆很小，为近期补给的地下水。中部地带保定地区东部和沧州地区西部的第三含水组地下水年龄皆小于5万a，第四含水组地下水的年龄可能大于10万a。边缘地带沧州市和青县第三含水组地下水年龄为8－9万a左右，东光县为26万a左右；沧州市第四含水组地下水年龄为33万a左右，东光县为77万a左右。 相似文献
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Yunchao LANG Congqiang LIU Jianghong WU Hiroshi Satake Siliang LI 《中国地球化学学报》2006,25(B08):173-173
A groundwater system in a karstic terrain is easily subject to pollution and its remediation is difficult once contaminated by human activities. The groundwater samples collected in both winter and summer seasons at Guiyang, SW China, show a wide range of variations in chemical composition and dominance of Ca^2＋, Mg^2＋, SO4^2-, and HCO3^- ions. The anthropogenic inputs include Cl^-, NO3^-, SO4^2-, Na^＋, and K^＋, as judged from the relationships between different elemental ratios and sewage samples. Cl^- concentrations of all water samples in the study area vary from 0 to 3.9 mmol/L in winter and are higher than in summer. In most of the samples, SO4^2- concentrations are high, ranging from 0.1 to 11 mmol/U The studies show that the cycling of sulfur plays an important role in controlling water chemistry and fate of contaminants in groundwater. In order to understand the source of SO4^2- and the geochemical cycling of some elements in the karstic groundwater environment, we have carried out a study on the variations of S and Cl isotope compositions, in addition to other isotopic tracers such as ^87Sr/^86Sr and δ^13C studied previously. The δ^37Cl values of the groundwater samples present a seasonal variation, ranging from 0.00‰ to ＋2.03‰ in winter and from -1.46‰ to ＋0.29‰ in summer. The surface water samples show a similar range of variations as observed for groundwater. Two rainwater samples collected at Guiyang have a distinct isotopic signature （mean value is -3‰） compared to the δ^37Cl values reported in literature. These results indicate that ground water is mainly derived from precipitation and suggest a fast recharge of the karst system by surface water. 相似文献
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DU Shaorong ZHENG Mianping Lü Yuanyuan ZHANG Yongsheng ZHANG Xuefei MIAO Zhongying LI Mingming 《《地质学报》英文版》2022,96(6):2028-2039
The Lanping?Simao Basin is located on the southeastern Tibetan Plateau, China, and contains massive evaporites. The origin of evaporites in the basin has been hotly debated because of the strong transformation by tectonic movement. Forty halite samples from borehole MK-3 in the Mengyejing area of the basin were collected and analyzed using XRD, Cl-Sr isotopes and chemical compositions to trace the origin of the evaporites in the basin. The Br × 103/Cl ratios of the halite samples are between 0 and 0.55, most of which are synchronized with the law of seawater evaporation and at the stage of halite precipitation from seawater, indicating that the evaporites are mainly of marine origin. The 87Sr/86Sr ratios range from 0.707489 to 0.711279; after correction, the 87Sr/86Sr 145 Ma ratios range from 0.704721 to 0.707611, equivalent with the 87Sr/86Sr ratios of seawater at 145 Ma, indicating a marine origin. The decay of 87Rb in the evaporite during deposition, change of the depositional environment and the unsealed environment at a later period resulted in the present 87Sr/86Sr ratios of some samples being high. The δ37Cl value compositions range from ?0.38‰ to 0.83‰, which is consistent with the δ37Cl value composition of the world marine halite (?0.6‰ to 0.4‰), further confirming that seawater is the main origin. In addition, the high δ37Cl value of some samples at the boundary of the upper and lower evaporite layers might be related to the influence of δ37Cl-rich brine and the incomplete dissolution of the halite. 相似文献
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To interpret the degassing of F-bearing felsic magmas, the solubilities of H2O, NaCl, and KCl in topaz rhyolite liquids have been investigated experimentally at 2000, 500, and ≈1 bar and 700° to 975 °C.
Chloride solubility in these liquids increases with decreasing H2O activity, increasing pressure, increasing F content of the liquid from 0.2 to 1.2 wt% F, and increasing the molar ratio
of ((Al + Na + Ca + Mg)/Si). Small quantities of Cl− exert a strong influence on the exsolution of magmatic volatile phases (MVPs) from F-bearing topaz rhyolite melts at shallow
crustal pressures. Water- and chloride-bearing volatile phases, such as vapor, brine, or fluid, exsolve from F-enriched silicate
liquids containing as little as 1 wt% H2O and 0.2 to 0.6 wt% Cl at 2000 bar compared with 5 to 6 wt% H2O required for volatile phase exsolution in chloride-free liquids. The maximum solubility of Cl− in H2O-poor silicate liquids at 500 and 2000 bar is not related to the maximum solubility of H2O in chloride-poor liquids by simple linear and negative relationships; there are strong positive deviations from ideality
in the activities of each volatile in both the silicate liquid and the MVP(s). Plots of H2O versus Cl− in rhyolite liquids, for experiments conducted at 500 bar and 910°–930 °C, show a distinct 90° break-in-slope pattern that
is indicative of coexisting vapor and brine under closed-system conditions. The presence of two MVPs buffers the H2O and Cl− concentrations of the silicate liquids. Comparison of these experimentally-determined volatile solubilities with the pre-eruptive
H2O and Cl− concentrations of five North American topaz and tin rhyolite melts, determined from melt inclusion compositions, provides
evidence for the exsolution of MVPs from felsic magmas. One of these, the Cerro el Lobo magma, appears to have exsolved alkali
chloride-bearing vapor plus brine or a single supercritical fluid phase prior to entrapment of the melt inclusions and prior
to eruption.
Received: 6 November 1995 / Accepted: 29 January 1998 相似文献
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用36Cl研究灰岩侵蚀速率的理论与方法 总被引：2，自引：0，他引：2
从理论上研究了方解石中^36Cl 的5种起源：（1）近地表Ca散裂和散裂成因的中子捕获；（2）由Ca产生的负μ介子捕获；（3）负μ介子捕获以后的中子发射；（4）由快μ介子引起的光致蜕变反应产生的中子；（5）由U裂变和（α，n）反应产生的中子。论述^36Cl在灰岩深度剖面上的4个分布特征；（1）^36Cl浓度随深度增加而减少；（2）深度能够自然地区分由不同生成反应形成的^36lμl贡献；（3）为了把测量的N(Ca)/N(Cl)比值的范围；（4）甚至在最干旱条件下，灰岩的浸蚀也是不可避免的，并且在稳定状态下起重要 作用。详细概述了^36Cl的采样方法和AMS分析技术，研究了测定灰岩侵蚀速率的数学模型，并且对一些灰岩表面侵蚀速率作了评价。 相似文献
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介绍了加速器质谱计测定＾３６Ｃｌ的原理和方法以及应用前景,并对沧州地区第四纪地下水的＾３６Ｃｌ进行了测定,利用氯同位素确定了沧州地区的咸水成因,同时根据＾３６Ｃｌ资料计算出该区第四系第三含水组地下水的年龄为２５０ｋａ,第四含水组地下水年龄为３００ｋａ。 相似文献
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通过对华北平原沧州地区第四纪地下水中宇宙成因核素3 6Cl进行的测定 ,其浅层咸水的3 6Cl Cl值为5 7× 10 - 1 5,证实了该区浅层地下水的盐化成因主要是蒸发浓缩所造成。该区深层地下水中大气成因的3 6Cl所占的份额为 33%～ 30 %,系由上覆咸水下移所致。 相似文献
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海相年轻沉积物~(36)Cl定年研究 总被引：1，自引：1，他引：0
提取、纯化海相沉积颗粒表面"诱导吸附"的36Cl(和Cl),制成加速器质谱(AMS)测定放射性比度I(36Cl/Cl)所需的标准样品,即高纯度AgCl;定量计算出沉积颗粒沉积封闭时的放射性比度I0(36Cl/Cl),依据放射性衰败定律I=I0e-λt计算得到沉积年龄t。研究结果表明:年轻的海相沉积物沉积封闭时的36Cl放射性比度I0与地理纬度之间存在一定比例关系,采取具有代表性、无污染的太平洋表面海水(4°18′N,161°09′E),经AMS测出的36Cl放射性比度IL为99.34±10.30,再利用36Cl产率与纬度的关系图,得出"放射性比度-产率"的比例常数μ为23.65238。测定了两个海底沉积物和一个海底锰结核的放射性比度I,计算得到的沉积年龄分别为83.2×104a、74.0×104a、17.6×104a。文章提出的I0定值计算方法具有科学依据,可操作性强,为揭示海洋沉积地层相关关系和沉积年龄精确测定提供技术支撑。 相似文献