关于风沙土的一些雏议

本文论述了土壤形成过程中应具有的一些质的特征,从而证明了流动砂丘并非属于土壤,而只是地质作用的非土形成物或成土母质。在此基础上,对流动砂丘上土壤的形成发育演变方向以及在土壤分类中的地位和命名等问题进行了探讨。     

Effects of Different Diets on the Dietary Attractability and Selectivity of Chinese Shrimp, Fenneropenaeus chinensis

Attractabilities of different diets and dietary selectivity of Chinese shrimp, Fenneropenaeus chinensis were studied through behavior observation and feeding experiment, respectively. The five diets used in the experiment are: Fish Flesh (FF), Shrimp Flesh (SF), Clam Foot (CF), Polychaete Worm (PW), and Formulated Diet (FD). No significant differences of attractability exist between any two different diets when every two natural diets or all five diets are provided simultaneously. On the other hand, significant differences of attractability exist between FD and every single natural diet when they are provided simultaneously. Results of behavioral observation indicate that natural diets are more attractive than FD. In feeding experiment, Chinese shrimp has distinct selectivity on different diets. It positively selects CF and PW, negatively selects FF and SF, and excludes FD absolutely. The results of the present studies indicate that the dietary selectivity of shrimp was based not only on the attractabilities of the diets, but also on the responses such as growth and food conversion.     

The equilibrium configuration of rapid rotating compact stars and some gravitational effects

In this paper, the equilibrium configurations of rapid rotating compact stars and some gravitational effects are studied within the general relativity by use of the Harrison-Wheeler equation of state and by the self-consistent field method. Numerical calculations show that the equilibrium configuration of a rotating star is a spheroid. For large spin velocities, say, ω > 3.0 × 10² sec⁻¹ the eccentricity and mass increase very rapidly as the angular velocity increases, for the critical angular velocity of the rotating star, the eccentricity is about 0.7, the increase in mass is about 10–35%. The difference of the gravitational redshifts at the surface of the star caused by rotation, and the difference of the light bending when the beam moves in the direction of rotation or in the opposite direction are obvious.     

A possible mechanism of formation of faculae

We propose a new heating mechanism of faculae. We think that the formation of faculae is a result of the Joule dissipation of the Hall current generated by the interaction of the convection field of granules in an active region and the inter-granular magnetic field. For a region to generate effectively Hall current, its characteristic length must be such that the magnetic Reynolds number is less than 1. The equation of energy balance in the facula region is

$\text{16σT}{}^3{}_{\mathrm{p}}\text{(T}{}_{\mathrm{l}}\text{? T}{}_{\mathrm{p}}\text{)}{}^{\mathrm{n}}\text{HP}{}_{\mathrm{s}}{}^{\mathrm{a}}\text{H}{}^{\mathrm{?}}\text{=}\text{Qn}{}_{\mathrm{s}}\text{m}{}_{\mathrm{i}}\text{u}{}_{\mathrm{x}}{}^2\text{(τ}{}^2{}_{\mathrm{in}}\text{ω}{}_{\mathrm{i}}\text{)}$

.For five observational models of faculae, we calculated the corresponding velocity fields, and the results are in basic agreement with the observed fields. The present mechanism explains the dependence of the facula brightness on the magnetic and velocity fields, the apparent distribution of the faculae on the solar disk and suggest a possible interpretation of the five structures of faculae.     

Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slab-derived melts in the mantle wedge

New chronological, geochemical, and isotopic data are reported for Triassic (219–236 Ma) adakite-magnesian andesite-Nb-enriched basaltic rock associations from the Tuotuohe area, central Qiangtang terrane. The adakites and magnesian andesites are characterized by high Sr/Y (25–45), La/Yb (14–42) and Na₂O/K₂O (12–49) ratios, high Al₂O₃ (15.34–18.28 wt%) and moderate to high Sr concentrations (220–498 ppm) and ε_ND (t) (+0.86 to +1.21) values. Low enrichments of Th, Rb relative to Nb, and subequal normalized Nb and La contents, and enrichments of light rare earth elements combine to distinguish a group of Nb-enriched basaltic rocks (NEBs). They have positive ε_ND (t) (+2.57 to +5.16) values. Positive correlations between Th, La and Nb and an absence of negative Nb anomalies on mantle normalized plots indicate the NEBs are products of a mantle source metasomatized by a slab melt rather than by hydrous fluids. A continuous compositional variation between adakites and magnesian andesites confirms slab melt interaction with mantle peridotite. The spatial association of the NEBs with adakites and magnesian andesites define an “adakitic metasomatic volcanic series” recognized in many demonstrably subduction-related environments (e.g., Mindanao arc, Philippines; Kamchatka arc, Russia; and southern Baja California arc, Mexico). The age of the Touhuohe suite, and its correlation with Triassic NEB to the north indicates that volcanism derived from subduction-modified mantle was abundant prior to 220 Ma in the central Qiangtang terrane.     

The age of the Nantuo Formation and Nantuo glaciation in South China

A U–Pb sensitive high‐resolution ion microprobe (SHRIMP) age of 654.5 ± 3.8 Ma from an ash bed immediately below the Nantuo Formation in South China provides the lowest age constraint for the Nantuo glaciation, which has been correlated with the global ‘Marinoan’ glaciation. A U–Pb SHRIMP age of 636.3 ± 4.9 Ma from a fallout tuff within the basal layer of the Nantuo Formation, along with the existing age of 635.2 ± 0.6 Ma from its overlying Doushantuo cap carbonate, suggests that the traditionally defined Nantuo Formation may have been deposited in a short time period at the end of the Nantuo glaciation. In combination with available ages globally, the data support a relatively short duration and rapid termination of ‘Marinoan’ glaciations.     

松南海坨子—大布苏地区泉四段— 姚家组层序地层研究

根据工区内现有的钻井、测井和地震资料,应用以多级次基准面旋回为参照面的高分辨层序地层学理论与研究方法,对松辽盆地南部海坨子—大布苏地区的泉四段—姚家组地层进行了详细的层序地层研究,共识别出5个长期基准面旋回（相当于三级层序）,9个中期基准面旋回（相当于四级层序）,建立了研究区的层序划分方案,在连井剖面的层序地层对比基础上,建立了该区的地层格架,并对层序构成特征进行了分析,研究了储集层在层序格架内的分布规律,揭示出浊积砂体和三角洲前缘相的分流河道形成于基准面上升期,三角洲前缘相的河口坝、远砂坝和席状砂沉积形成于基准面下降期,指出浊积砂体和三角洲前缘相的远砂坝、席状砂沉积是研究区形成岩性油气藏的有利储集体。     

延边东部五道沟岩群的单颗粒锆石SHRIMP U-Pb 年代学及其地质意义

通过对延边地区东部五道沟岩群黑云阳起石片岩的单颗粒锆石SHRIMP U-Pb年龄测定.获得21个单点年龄,其中包括7组谐和年龄和1组不谐和年龄.谐和年龄分别为1347.8 Ma、844.8 Ma、340.2～313.7 Ma(平均值为323±23 Ma,N=4,MSWD=0.23,置信度=0.88)、292.9～288.3 Ma(平均值=291±25 Ma,N=3,MSWD=0.031.置信度=0.86)、279.2～266.2 Ma(平均值为279±28 Ma,N=4,MSWD=0.031,置信度=0.86)、127.4～124.2 Ma(206Pb/208U年龄平均值为126.5±3.7 Ma,N=5,MSWD=0.12;置信度=O.97)、116.1～106.3 Ma(平均值为115±39 Ma,N=2,MSWD=1.2置信度=0.27),不谐和年龄的下交点年龄为(451±120)Ma、上交点年龄为(1811±400)Ma(MSWD=7.2);这一结果表明:阳起石片岩的原岩主要是来自中元古代、新元古代和早古生代的碎屑物,指示五道沟群的沉积成岩作用发生在石炭世(323±23 Ma),变质作用发生在晚二叠世(291±25 Ma),之后在279.2～266.2 Ma、126.5～106.3 Ma先后受两次岩浆用和蚀变作用的改造.     

川西前陆盆地中—新生代沉积迁移与构造转换

川西前陆盆地中—新生代各构造层的残余厚度展布和沉积特征分析发现,四川克拉通周缘的前陆盆地在晚三叠世时期发育于龙门山山前,明显属于龙门山褶皱逆冲构造载荷所形成的前渊凹陷;侏罗纪早期的沉积地层呈面状分布,没有表现出显著的挠曲沉降,指示了一个构造相对平静的阶段;中侏罗世早期前渊凹陷迁移至龙门山北段和米仓山山前,前渊沉积从晚三叠世的北东向转换为近东西向,广泛的湖泊相沉积预示了前陆盆地的欠充填状态;中侏罗世中晚期,川西盆地沉降中心又迁移到大巴山山前,相应的挠曲变形又从近东西向转化为北西向,构成了大巴山的前渊凹陷;晚侏罗世—早白垩世时期,沉降中心再次回到米仓山山前,巨厚的前渊凹陷沉积指示了米仓山冲断带的主要活动时期;白垩纪末—古近纪的前渊凹陷则跃迁至雅安—名山地区。川西前陆盆地的同造山沉降中心以四川盆地中心为核心在西部和北部呈弧形迁移,沉积序列不断更替和叠加。中生界各构造层底界构造图显示现今的构造低部位位于川西北地区和川西南地区,在川西北地区均有东西走向的等值线分布,而川西南地区等值线走向则为北东-南西向。因此分析认为,晚侏罗世至早白垩世的构造变形可能控制了川西盆地现今的地层变形,形成了川西北地区的南北向构造挤压结构,而晚期的新生代构造变形则主要体现在川西盆地的西南部,形成北东-南西向的地层展布特征。     

阿尔金南缘构造带西段辉绿岩墙群的地球化学特征及构造环境

对阿尔金南缘构造带西段辉绿岩墙群的岩石学和地球化学的详细研究表明,该区辉绿岩墙群为拉斑系列岩石,其主量元素以中等TiO2(1.19%～1.59%)、高MgO(5.51%～7.88%)、贫K2O(0.04%～0.84%)和P2O5(0.10%～0.20%)、Na2OK2O为特征;高场强元素(HFSE)丰度特征显示其为E-MORB型或过渡型玄武岩质岩石;稀土元素总量相对较高,轻重稀土元素分馏不显著[(La/Yb)N=1.93～3.61,LREE/HREE=3.01～4.10],在球粒陨石标准化配分模式图上呈略富集型.结合玄武岩构造环境判别图解综合分析推测,它们可能形成于一种裂谷向MORB环境过渡的构造环境,即初始小洋盆构造环境.