云南兰坪盆地喜马拉雅期碱性岩^40Ar／^39Ar年龄及地质意义

对侵位于云南兰坪中新生代红层盆地中的碱性岩进行了Ar_Ar同位素定年 ,获得永平卓潘碱性杂岩体的侵入年龄为 36 .70Ma,巍山莲花山碱性石英二长斑岩的侵入年龄为 38.81Ma。兰坪盆地的构造演化受控于古特提斯的闭合及印度与亚洲大陆碰撞的造山作用 ,盆地经历了陆内裂谷、拗陷盆地和走滑盆地 3个阶段的发育过程。喜马拉雅期盆地处于走滑拉分阶段 ,可分为 4个构造幕 ,碱性岩主要在第 1构造幕期间侵入。盆地中的碱性岩体是青藏高原东缘总体呈NW走向的金沙江红河巨型富碱侵入岩带的组成部分。金沙江红河断裂带经历由转换压扭变形(42～ 2 4Ma)到转换张扭变形 (2 4～ 16Ma)、再到东西向伸展 (<16Ma)的过程 ,兰坪盆地的碱性岩发育于转换压扭变形期间。认为兰坪盆地碱性斑岩的侵入和盆地的喜马拉雅期构造演化主要受控于古特提斯扬子地块向西的俯冲板片遗迹引发的地幔上隆和部分熔融     

Geologic relationships and mineralization of peralkaline/alkaline granite-syenite of the Zargat Na＇ am ring complex, Southeastern Desert, Egypt

The Zargat Na’ am ring complex crops out 90 km NW of Shalatin City in the Southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. It is cut by two sets of joints and faults which strike predominantly NNW-SSE and E-W, and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. It consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills. The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFSM), such as Zr and Nb. The highest concentrations (1.5 wt% Zr, 0.25 wt% Nb, 0.6 wt% Σ REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartzhosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750 ￠ 10⁻⁶), Zr (2500 × 10⁻⁶) and REEs (1450 × 10⁻⁶). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions.     

Factors Controlling the Hydrothermal Sulphur Ore Deposition in Keciborlu Mine Area (SW Turkey)

Abstract. Replacement-type subsurface sulphur ores of Keciborlu are situated in fault controlled and metasomatically altered fragmental ophiolite media between alkaline Pliocene volcanics of Isparta and Afyon regions, SW Turkey. Subsurface volcanic sulphur-mineralising fluids and gases were brought up along the sulphur-hosting oblique slip fault zone into the oxidising meteoric water-saturated media and the sulphur-ore bodies were developed at more porous, cross-fault locations.
Chemically the sulphotaric alteration of the parent rock and sulphur ore formation is characterised by outward volcanic gas and sulphuric acid leaching and oxidation to sulphur from the crushed porous centres. Consequently, concentric pyritiferous, opaline and argillaceous zones developed adjacent to the sulphur ores. The inner alteration zones progressed and widened toward the outer zones through time and the central sulphur ore developed during a single, continuous phase of mineralisation in the water saturation zone such that the alteration zones do not cross each other.     

Improvement of kerogen structural interpretations based on oxidation products isolated from aqueous solutions

A detailed investigation of kerogen oxidation products remaining in aqueous solutions after the usual isolation of degradation products by extraction with ether or precipitation, was carried out for the first time in kerogen structural studies. Three shale samples were investigated: Green River shale (type I kerogen), Toarcian shale, Paris Basin (type II), and Mannville shale, Canada (type III). The yields of acids from aqueous solutions were noticeable: 12.98, 15.32 and 22.32%, respectively, based on initial kerogens. Qualitative and quantitative capillary GC/MS analysis showed that the ratios of different kinds of identified acids depended much on the type of precursor kerogen. Some of the acids identified in aqueous solutions have not been found earlier among the degradation products of the same kerogen samples, or were obtained in different ranges and yields. Consequently, slight modifications were suggested of the image on the nature of various types of kerogens based on examination of ether-soluble acids only. Namely, slightly higher proportions of aromatic and alkane-polycarboxylic acids in the total oxidation products of both type I and type II kerogens indicated larger participation of aromatic and alicyclic and/or heterocyclic structures in these two kerogens. On the other hand, for type III Mannville shale kerogen, a somewhat larger share of aliphatic type structures was demonstrated.     

浙江建德新生代玄武岩源区特征及其成因

中国东南部浙江境内分布有大量新生代板内玄武岩，这些玄武岩的分布受到三条北东—南西向的断裂控制，将浙江玄武岩分为西部、中部、东部三个区域。其中，出露于浙江西部江山-绍兴断裂带的建德玄武岩是浙江境内最古老的新生代玄武岩（约40 Ma）。为进一步认识浙江境内新生代岩浆作用的本质，测定了建德玄武岩的元素组成和Sr、Nd、Hf、Pb同位素组成，并在与浙江境内其它新生代玄武岩对比的基础上，探讨它们之间的成因联系。建德玄武岩为碧玄岩，与浙江西部其它新生代玄武岩一样，碱性程度明显高于浙江中部和东部的新生代玄武岩（以弱碱性的碱性橄榄玄武岩和拉斑玄武岩为主）。这些玄武岩具有较低的SiO₂ (41.3~42.3 wt%）和Al₂O₃（9.70~12.6 wt%）含量，较高的MgO（8.90~15.6 wt%）、CaO（8.92~12.1 wt%）、TiO₂（2.78~3.18 wt%）和Fe₂O₃^T（14.1~16.2 wt%）含量以及较高的Ca/Al（1.02~1.16）比值。不相容微量元素组成上与火成碳酸岩具有亲缘性，即蛛网图上表现为明显的K、Zr、Hf、Ti的负异常（Hf/Hf*=0.74~0.77, Ti/Ti*=0.70~0.74），同时具有高的Zr/Hf比值（48.5~50.1），表明其地幔源区含有碳酸盐组分。建德玄武岩具有亏损的Sr-Nd-Hf同位素组成（⁸⁷Sr/⁸⁶Sr=0.7032~0.7034, εNd=5.85~5.95, εHf=7.78~8.56）和较高的²⁰⁶Pb/²⁰⁴Pb（18.491~18.554）、²⁰⁷Pb/²⁰⁴Pb（15.488~15.518）和²⁰⁸Pb/²⁰⁴Pb（38.387~38.523）比值。相比浙江中部和东部玄武岩，浙江西部玄武岩及建德玄武岩具有更高的碱含量、不相容微量元素含量、La/Yb比值和更明显的K、Zr、Hf、Ti负异常，表明浙江西部玄武岩是碳酸盐化地幔低程度熔融的产物。浙江新生代玄武岩的Ti/Ti*与Ba/Th、K/La比值之间较好的正相关性表明其源区存在两端元混合的特征。其中，以浙江西部玄武岩（包括建德玄武岩）为代表的地幔端元是由含碳酸盐的再循环洋壳熔融产生的碳酸盐熔体与亏损地幔反应形成的碳酸盐化地幔，以较低的Ba/Th、K/La和Ti/Ti*比值为特征。以浙江东部玄武岩为代表的地幔端元具有和碳酸盐化地幔端元互补的、较高的Ba/Th、K/La和Ti/Ti*比值，代表熔融残余的再循环洋壳。因此，浙江新生代玄武岩的地幔源区是不均一的，这种不均一性主要是由具有成因联系的两种端元组分所控制。     

舟山海域一株产碱性蛋白酶海洋放线菌的鉴定、选育及发酵条件的初步研究

从舟山海域潮间带海泥筛选到产碱性蛋白酶的海洋放线菌,利用Folin-酚法进行酶活测定,选取酶活最高的菌株进行鉴定,绘制系统进化树。再通过紫外线和DES诱变从而得到高产碱性蛋白酶的海洋放线菌菌株,并进行初步的发酵条件研究。结果表明:分离筛选得到2株菌株,在脱脂奶筛选平板上能产生较大的水解透明圈,通过Folin-酚法进行酶活测定,挑选出酶活较高的菌株A20(初始酶活为104.7U/mL),生理生化试验和16S rDNA试验结果显示该菌株为Streptomyces roseus。对菌株A20进行紫外线和硫酸二乙酯(DES)诱变,最终得到高产碱性蛋白酶的菌株,酶活为227.5U/mL,酶活提高117.3%,传代试验显示该菌株具有较好的遗传稳定性。单因素试验显示最适发酵温度为50°C、pH值为9.0、培养时间为72h。     

不同形态磷源对具槽帕拉藻(Paralia sulcata)生长和磷酸酶活性的影响

分别采用磷酸二氢钾(KH2PO4)、β-甘油磷酸钠(Sodium-β-glycerophosphate,β-G-P)、葡萄糖-6-磷酸(Glucose-6-phosphate,G-6-P)、卵磷脂(Lecithin,LEC)和三磷酸腺苷二钠(Adenosine disodium triphosphate,ATP)作为f/2培养基的磷源,探讨了不同形态磷源对具槽帕拉藻(Paralia sulcata)生长及磷酸酶活性的影响。结果发现,具槽帕拉藻能够有效利用上述五种磷源,且溶解有机磷(Dissolved organic phosphorus,DOP)比KH2PO4更有利于具槽帕拉藻的生长;对碱性磷酸酶(Alkaline phosphatase,AP)活性分析发现,大分子DOP(LEC)可能需要通过磷酸酶的水解作用才能被吸收利用。在胞外磷充足的情况下,具槽帕拉藻能够在胞内储存磷源,而在磷限制时则可利用胞内储存的磷源来维持藻细胞的生长。     

夏季长江口不同粒级浮游植物碱性磷酸酶活性

碱性磷酸酶活性(alkaline phosphatase activity, APA)是海洋研究中用于反映浮游植物磷限制状态的重要指标。在长江口等“氮过剩”海域,磷是控制海域初级生产力水平的主要因子,然而,磷限制的范围常常难以界定,当前对不同粒级浮游植物的磷限制效应所知甚少。该文根据2020年夏季长江口航次资料,给出了海洋表层各粒级浮游植物(Net:≥20 μm;Nano:2~20 μm;Pico:0.8~2 μm)APA、浮游细菌APA(0.2~0.8 μm)和溶解态APA(<0.2 μm)的空间分布特征,并分析了APA与环境要素间的相关性。结果显示,各粒级浮游植物APA均与无机磷酸盐浓度(dissolved inorganic phosphate, DIP)呈显著负相关,这表明DIP浓度是影响浮游植物APA分布的主要因素。在平面分布上,各粒级浮游植物APA在近口门的光限制区均较低,且呈现自口门向外逐渐升高的趋势,与DIP的分布特征相反。Net和Nano级APA[平均值分别为 (40.28±32.35) nmol/(L·h)和(52.38±34.78) nmol/(L·h)]显著高于Pico级APA[平均值为(28.43±20.23) nmol/(L·h)],这表明大粒级浮游植物可能更易受DIP下降的影响。该研究中,诱导浮游植物APA快速升高的DIP浓度为0.159 μmol/L,与近岸区磷限制经验阈值相接近。该研究揭示了夏季不同粒级浮游植物对长江口磷分布的响应特征,有助于理解长江口初级生产过程的环境调控机制。     

钙碱性火成岩的角闪石全铝压力计 ——回顾、评价和应用实例

定量地获得岩体结晶时的压力,对于探讨其剥蚀深度及了解造山带的构造热演化史等方面有重要意义。对于钙碱性侵入岩而言,可以应用角闪石全铝压力计对钙碱性火成岩结晶压力进行估计。对于不同角闪石压力计公式的选择,前提是满足它们各自的适用条件,否则所得结果没有意义。角闪石全铝压力计不能用于估算A型花岗岩的结晶压力,更不能用于计算变质岩的变质压力。对于结晶温度低于750℃的钙碱性中酸性岩体而言,Anderson和Smith(1995)的温度校正意义不大。Ridolfi等(2010)提出的指数关系角闪石压力计公式适用于钙碱性火山岩中角闪石斑晶的结晶压力估算。Uchida等(2007)的黑云母全铝压力计缺乏理论和实验基础,不建议使用。应用角闪石全铝压力计所得到薛家石梁—黑山寨复式岩体侵位深度的区域变化,指示了云蒙山变质核杂岩下盘的掀斜;低角度正断层(拆离断层)可以通过高角度正断层的掀斜旋转而形成。     

山西临县紫金山碱性杂岩体SHRIMP锆石U-Pb年龄、地球化学和Sr-Nd-Hf同位素研究

山西临县紫金山碱性杂岩体位于华北克拉通内鄂尔多斯盆地东缘,为汾河富碱侵入岩带中最典型的碱性岩体。岩体主要岩石类型为二长岩、辉石正长岩、霓霞钛辉岩、暗霞正长岩、霞石正长岩、假白榴石斑岩和粗面斑岩。依据SHRIMP锆石U-Pb定年结果,结合前人的测年数据,确定岩体形成于138.7~125.0 Ma,系早白垩世碱性岩浆事件的产物。该套岩石高钾、富碱、贫钙和镁,属于碱性岩石系列。稀土元素总量高,轻、重稀土元素分馏明显,Eu异常不显著。微量元素富集LREE和Rb、Ba、K、Sr等大离子亲石元素,亏损HREE和Th、U、Nb、Ta、Ti等高场强元素。同位素分析结果显示全岩ISr为0.704 228~0.706 313,εNd(t)变化于-12.3~-0.5之间。锆石的εHf(t)为-20.2~-16.4,二阶段模式年龄tDM2为2.22~2.46 Ga。推测紫金山碱性杂岩体形成于华北克拉通中生代构造体制转折后的伸展背景下,因构造体制转换产生的强大应力作用导致吕梁地区软流圈多次上涌,随后软流圈、岩石圈地幔和下地壳物质部分熔融产生的岩浆发生多次不同比例的混合,所形成的各期混合岩浆分批上侵定位在地壳浅部环境,从而形成紫金山碱性杂岩体。汾河富碱侵入岩带形成时间集中于138.7~125.0 Ma,是华北克拉通中西部岩石圈破坏事件的岩浆活动证据,其与华北克拉通东部地区几乎同时发生岩石圈减薄作用。因构造体制转换产生强大应力作用导致构造薄弱地区软流圈上涌,进而引起大规模的壳-幔岩浆相互作用,可能为华北克拉通中西部地区中生代破坏的主要原因,并且由北至南壳幔岩浆相互作用中幔源岩浆逐渐减少。