苏北盆地粘土矿物转化模式与古地温

以苏北盆地为例,系统研究了火成岩发育区粘土矿物组合特征及其控制因素;建立了粘土矿物转化模式;根据粘土矿物成岩演化特点,进行古地温分析。研究表明,苏北地区粘土矿物的分布主要受埋藏成岩作用、岩浆侵入、母质来源三种因素的影响,发育四种类型的粘土矿物组合和三种粘土矿物转化模式;火山碎屑岩母岩区和基性岩浆侵入区具有特殊的粘土矿物组合和成岩演化模式,前者以富含蒙皂石矿物为特点;后者出现高岭石与伊/蒙有序间层矿物共生组合,并具有不连续的演化序列;苏北盆地短有序I/S矿物出现于镜质组反射率 0.5 %～ 0.5 5 %的深度,伊/蒙间层矿物转变成伊利石在镜质组反射率 0.75 %～ 0.8%,可以用于热成熟度和古地温的估算;而蒙皂石消失的界面则不具有指标意义     

大气中O3和CO2增加对大豆复合影响的试验研究

利用OTC-1型开顶式气室,对大豆"中黄14"进行了长时期不同O3和CO2处理的接触试验,模拟研究CO2和O3浓度倍增及其交互作用对大豆发育期、黄叶率和绿叶率、根瘤、生物量及其分配、产量结构、籽粒品质及叶片膜保护系统的影响,结果表明:单独O3浓度倍增,发育期明显提前;生物量最多可减少近一半,产量最多减产60%以上;粗蛋白含量增加6.2%,粗脂肪含量降低7.6%;叶片脂膜过氧化加剧.单独CO2浓度倍增,开花后发育期有所延迟;对生物量及产量有明显的正效应,成熟时总生物量和籽粒产量分别比T5增加21.0%和20.3%;粗蛋白和粗脂肪含量分别下降3.3%和1.6%;结荚前叶片脂膜过氧化反应减轻.CO2和O3持续倍增和逐渐达到倍增交互作用处理,在生物量、产量方面表现为CO2的影响大于O3,在叶片膜保护系统方面表现为O3的影响大于CO2,粗蛋白含量下降,粗脂肪含量上升,叶片脂质过氧化加剧.熏气处理均可造成:黄叶率上升,绿叶率下降,凋落物增加,且单独O3浓度倍增的处理最明显,通气仅10天黄叶率就高于50%;超氧化物歧化酶活性增强;气孔阻力增加,蒸腾速率下降,且单独CO2浓度倍增的处理最明显,尤其在高湿阴天,气孔阻力和蒸腾速率变化最高分别可达增加234.0%和下降58.5%.     

Comparison of rhyolites from continental rift,continental arc and oceanic island arc: Implication for the mechanism of silicic magma generation

We discuss the chemical compositions of rhyolites from three distinct tectonic settings: (i) the continental rift from Ethiopia (both Oligocene–Miocene and Quaternary rhyolites); (ii) the early Miocene continental arc of Japan (the Mt Wasso rhyolites related to the rifting of the Japan Sea); and (iii) the oceanic Izu–Bonin Island Arc. The comparison reveals that the oceanic island arc rhyolites have high contents of CaO, Al₂O₃, and Sr, and extremely low abundance of trace elements including K₂O. In contrast, the Ethiopian continental rift rhyolites are characterized by low contents of CaO, Al₂O₃, and Sr, and high contents of K₂O, and are enriched in the whole range of trace elements. The continental arc Mt Wasso rhyolites are apparently low in Nb content, although they display similar chemical trends to those of the Ethiopian rhyolites. This obvious difference in the chemical signatures of the rhyolites from the three tectonic settings is the consequence of their derivation from different sources. The implication of this result is that fractional crystallization processes were dominant in the rift‐related rhyolites both from continental rift and continental arc regardless of the prevailing tectonic setting and the nature of the crust (age, thickness, composition), whereas the oceanic island arc rhyolites may form through partial melting of young, mafic crust.     

浙江沐尘石英二长岩及其镁铁质包体的锆石U-Pb年龄和Hf同位素组成——对岩浆混合作用的示踪

浙江沐尘石英二长岩体中普遍发育形态各异的暗色镁铁质微粒包体.本文运用LA-ICP-MS锆石U-Pb定年技术,对该石英二长岩和其中的暗色镁铁质微粒包体进行了精确的年龄测定,获得的年龄分别为112.1土1.0Ma和112.4士1.2Ma,二者在误差范围内一致,说明它们同时形成,这为指示包体属岩浆混合作用成因提供了关键证据....     

印度尼西亚塔里亚布岛锡铁多金属矿床的地质地球化学特征与成因

印尼塔里亚布岛新近发现大型锡铁多金属矿床,初步探明铁储量超过l亿吨,全铁品位可达50%.塔里亚布岛锡铁多金属矿床以矽卡岩型与矿浆型为主,兼具热液型,构成一个完整的成矿系统.印支期二长花岗岩源自地壳部分熔融产生的岩浆,是矿床的主要成矿物质来源与控矿因素;岩浆经过高度的演化分异过程,生成富铁矿浆贯入充填成矿,主要赋存于花岗...     

Zircon U–Pb and molybdenite Re–Os dating of the Chalukou porphyry Mo deposit in the northern Great Xing’an Range,China and its geological significance

The newly discovered Chalukou giant porphyry Mo deposit, located in the northern Great Xing’an Range, is the biggest Mo deposit in northeast China. The Chalukou Mo deposit occurs in an intermediate-acid complex and Jurassic volcano-sedimentary rocks, of which granite porphyry, quartz porphyry, and fine-grained granite are closely associated with Mo mineralization. However, the ages of the igneous rocks and Mo mineralization are poorly constrained. In this paper, we report precise in situ LA-ICP-MS zircon U–Pb dates for the monzogranite, granite porphyry, quartz porphyry, fine grained granite, rhyolite porphyry, diorite porphyry, and andesite porphyry in the Chalukou deposit, corresponding with ages of 162 ± 2 Ma, 149 ± 5 Ma, 148 ± 2 Ma, 148 ± 1 Ma, 137 ± 3 Ma, 133 ± 2 Ma, and 132 ± 2 Ma, respectively. Analyses of six molybdenite samples yielded a Re–Os isochron age of 148 ± 1 Ma. These data indicate that the sequence of the magmatic activity in the Chalukou deposit ranges from Jurassic volcano-sedimentary rocks and monzogranite, through late Jurassic granite porphyry, quartz porphyry, and fine-grained granite, to early Cretaceous rhyolite porphyry, diorite porphyry, and andesite porphyry. The Chalukou porphyry Mo deposit was formed in the late Jurassic, and occurred in a transitional tectonic setting from compression to extension caused by subduction of the Paleo-Pacific oceanic plate.     

A mafic intrusion of “arc affinity” in a post-orogenic extensional setting: A case study from Ganluogou gabbro in the northern Yidun Arc Belt,eastern Tibetan Plateau

Generally, arc-related or subduction-related mafic magmas are formed during or slightly postdate subduction, and characterized by depletion in high field strength elements (HFSEs) relative to the large ion lithophile elements (LILEs) and light rare-earth elements (LREEs). Combining with mineral chemistry and Sr–Nd isotopes, these geochemical characteristics were usually used to define an arc setting, especially for some ancient arcs that had been strongly modified by later tectonic activities. However, we report an exceptional case from the northern part of the Triassic Yidun Arc Belt, eastern Tibetan Plateau. The Ganluogou gabbro (∼152 Ma) occurs as several intrusive bodies. Its mineral assemblage is olivine (chrysolite), plagioclase (anorthite), clinopyroxene (diopside), amphibole (edenite and pargasite) and phlogopite. Whole rock geochemistry shows low SiO₂ (42.87–46.99 wt.%), total rear earth elements (ΣREE = 22.8–28.4 ppm), Na₂O + K₂O (0.92–1.34 wt.%), and high Al₂O₃, MgO and FeO contents. It has small variations of initial ⁸⁷Sr/⁸⁶Sr ((⁸⁷Sr/⁸⁶Sr)_i = 0.7053–0.7055) and ε_Nd(t) values (−4.8 to −1.8). All the samples exhibit enrichment in LILEs including Th and U, but strongly depleted in HFSEs, including Nb, Ta, Zr and Hf. For the mineral chemistry, there are two type amphiboles. Amp(I) show higher V, Sc, Cr, Sr, Nb and Zr contents, but lower Th and U contents than those of Amp(II). Their REE patterns range from convex shape without Eu anomaly to LREE-enriched pattern with weak positive Eu anomaly. We suggest that Amp(I) was crystallized from a liquid that was mainly buffered by olivine, clinopyroxene and plagioclase, while Amp(II) crystallized from later melt that was mainly buffered by olivine. Based on clinopyroxene chemistry, compositions of coexisting olivine and plagioclase, and whole rock Sr–Nd isotopes, the parental magma of the Ganluogou gabbro is interpreted as a tholeiitic arc-affinity magma, which might be derived from an N-MORB mantle that had been metasomatised by slab-derived melts in the late Triassic (237–206 Ma). Thus, the Ganluogou gabbro provides an example that magmas exhibiting arc-affinity could in fact be formed in a post-orogenic extensional setting.     

云南宁洱-通关火山区最上地壳地热场:构造和岩浆活动意义

思茅中生代红层盆地中央的宁洱和通关两地在第四纪均发生过小规模的玄武岩浆喷发,喷发渣锥至今清晰可见,而同属于该盆地中央的思茅-普洱地震区百年来6级地震密集发生。思茅盆地中央断裂发育,新构造隆升显著,壳幔速度和电性结构意味着该地区现今仍有可能存在着岩浆活动。然而,对宁洱-通关火山区目前到底有无壳内岩浆房和岩浆活动,以及岩浆活动与思普地震带地震活动的关系仍知之甚少。利用该地区的温泉资料和水化学分析数据,我们对宁洱-通关火山区及邻区范围内的36个温泉的热储温度进行了估算,得到了36个点的热储温度数据,通过克里金插值方法获得了宁洱-通关火山区的热储温度空间分布。结果发现:在宁洱火山和通关火山附近存在2个热储温度在220℃以上的温度场高值异常区。综合考虑我们的地热场结果、前人的速度和电性结构等深部探测资料,我们认为:宁洱-通关火山区现今仍存在2个岩浆房,第1个岩浆房位于宁洱县城一带,第2个岩浆房位于墨江通关火山区附近;但宁洱火山和通关火山已不在现今岩浆房的正上方,各反向错开约18km,由此推断把边江断裂(F2)为右旋错动,其中更新世以来的右旋错动速率为18mm/y;宁洱地区频繁而密集的中强地震活动与深部岩浆活动及其产生的深源流体活动密切相关。岩浆的存在使上部地壳与下伏地壳充分解耦并产生应力集中,深源流体活动则有利于断层发生错动。     

双消浪室局部开孔沉箱防波堤反射特性的理论与试验研究

双消浪室局部开孔沉箱防波堤具有低反射、结构受力小、适宜较大水深和工程造价低等优点。为明确双消浪室局部开孔沉箱水动力特性的主要影响因素,采用理论分析和物理模型试验相结合的方法,对规则波和不规则波作用下双消浪室局部开孔沉箱防波堤的反射特性进行研究。基于势流理论,建立规则波和不规则波对局部开孔沉箱防波堤作用的三维解析解,采用二次压力损失边界条件考虑沉箱开孔墙对波浪运动的影响,利用周期性边界条件考虑防波堤结构沿长度方向的周期性变化。开展相应规则波和不规则波物理模型试验,验证理论模型的合理性。通过算例分析,研究不同波浪要素和结构参数对防波堤反射特性的影响。研究表明:双消浪室局部开孔沉箱相对消浪室宽度取值为0.08~0.20,沉箱前墙开孔率大于后墙开孔率时,防波堤在较大波浪频率范围内消波效果显著;当前后墙的开孔率相等时,防波堤反射系数的最小值随着开孔率增大而减小。