雅鲁藏布江西段东波超镁铁岩体经历了俯冲带流体的改造：来自铂族元素的证据

提要：东波超镁铁岩体位于雅鲁藏布江缝合带的西段,在中国是一个不多见的面积超过400 km2的大型超镁铁岩体。已有的岩石学和矿物学特征表明,该岩体与同一带中含有大型铬铁矿的罗布莎岩体可以对比,是一个寻找铬铁矿床的远景区。本文开展了东波超镁铁岩的主要组成岩石类型——方辉橄榄岩的铂族元素（PGE）研究,并结合主量和稀土元素（REE）组成,探讨岩体的成因。东波超镁铁岩中方辉橄榄岩具有相当高的Os含量（3.52×10-9~4.36×10-9）,亏损的主量元素组成和低于原始地幔的稀土元素含量（0.89×10-6~1.37×10-6）,指示东波超镁铁岩为经历过部分熔融和熔体抽取的亏损残余地幔岩石。东波超镁铁岩的PGE总含量为23.97×10-9~31.98×10-9,高于原始地幔的含量;PGE配分型式为左倾的正斜率型,相对Ir亚组铂族元素（IPGE）亏损钯亚组铂族元素（PPGE）,Pd/Ir=1.49~2.65;REE配分型式为中稀土亏损的“V”型或“U”型,原始地幔标准化元素比值（La/Sm）m 为 1.05~3.37,（Gd/Yb）m=0.28~0.64;这些数据揭示东波超镁铁岩经历过交代作用,交代物质应富集不相容元素,高PGE含量,相对IPGE富集PPGE;较低的Cu/Pd比值（1226~3448）要求交代物质还应富含硫化物;推测交代物质可能来源于俯冲带构造环境下所产生岩浆熔离出的富硫化物熔体/流体。     

新疆色尔特能地区超镁铁岩岩石地球化学特征及构造环境分析

通过对出露在康古尔韧性剪切带西段的色尔特能超镁铁岩的野外地质调查和岩石学、岩石地球化学方面的分析研究工作,结果显示：色尔特能超镁铁岩发生了强烈蛇纹石化,基本蚀变成蛇纹岩;岩石主量元素具高Mg （w（MgO）=36.15%~37.96%）、高Cr （w（Cr₂O₃）=0.32%~0.36%）、高Ni （w（NiO）=0.17%~0.21%）、低Si （w（SiO₂）=40.50%~41.92%）、贫Al （w（Al₂O₃）=1.19%~1.77%）、低Fe （w（TFeO）=6.98%~7.87%）特征,Mg^#值为94.71~97.73,m/f值为8.03~9.42,属于典型镁质超镁铁岩,推测原岩为斜方辉石橄榄岩;稀土元素总量w（ΣREE）=1.44×10^-6~2.92×10^-6,配分模式为轻稀土微弱富集近平坦型,w（La）_N/w（Yb）_N=3.09~5.49,具一定程度的负Eu异常（δEu=0.48~1.09）和负Ce异常（δCe=0.53~0.60）;微量元素富集Ba、U、Ta,亏损Nb、Ti。色尔特能超镁铁岩属变质橄榄岩,是SSZ型蛇绿岩的底部组成单元,由原始地幔经2%~10%部分熔融形成的亏损地幔岩,其形成于俯冲带环境中的洋内弧后盆地。     

南祁连大道尔吉早古生代弧后盆地型蛇绿岩的年代学、地球化学特征及意义

大道尔吉蛇绿岩是中祁连地块和南祁连褶皱带之间蛇绿混杂岩带的重要组成部分。出露的岩石单元包括地幔橄榄岩、镁铁–超镁铁质堆晶杂岩和玄武安山岩。其中镁铁–超镁铁质堆晶杂岩包括三个堆晶旋回,单个堆晶旋回底部为含铬尖晶石纯橄岩,向上逐渐变为透辉石岩(辉石橄榄岩)→辉长岩等。堆晶杂岩中辉石橄榄岩Sm-Nd同位素等时线年龄为441±58 Ma,为加里东中期岩浆活动的产物。地球化学特征显示:地幔橄榄岩MgO(40.41%~40.96%)、Cr(3590×10~(–6)~7340×10~(–6))、Ni(1480×10~(–6)~1710×10~(–6))含量高,而Al_2O_3(0.35%~0.59%)、TiO_2(0.03%~0.04%)和∑REE(0.81×10~(–6)~1.84×10~(–6))含量低,具亏损地幔岩的特征;镁铁–超镁铁质堆晶杂岩的主量元素变化大,重稀土元素富集,正Eu异常(δEu=1.22~2.15);玄武安山岩SiO_2为54.90%~57.76%,MgO为3.50%~5.45%,TiO_2为0.72%~1.12%,Na_2O/K_2O1,∑REE为24.9×10~(–6)~53.4×10~(–6),LaN/YbN=1.0~1.7,具平坦稀土配分模式,与E-MORB相似,同时富集Ba、Rb、Th等大离子亲石元素,亏损Nb、Ta、Zr、Ti等高场强元素,具弧后盆地火山岩地球化学特征。综合区域地质、岩石组合和地球化学特征,认为大道尔吉蛇绿岩属构造肢解的蛇绿岩残片,具有俯冲带(SSZ)型蛇绿岩的特征,形成于弧后盆地环境,为奥陶纪柴北缘洋向中祁连地块俯冲,引起弧后扩张形成。     

东乌旗晚石炭世辉石橄榄岩锆石U-Pb年龄及其构造意义

目前关于内蒙古东乌旗晚古生代花岗岩中辉石橄榄包体的精确年代学及其构造意义不清,直接制约了该区晚古生代地幔性质及构造演化的探讨.对东乌旗新发现的辉石橄榄岩进行了岩相学、全岩地球化学和锆石U-Pb定年研究.结果表明,辉石橄榄岩主要由橄榄石、角闪石、斜方辉石及少量斜长石、黑云母、单斜辉石组成;锆石U-Pb年龄为317.8±1.6 Ma,属晚石炭世.地球化学数据显示,岩石SiO₂含量为40.28%~44.50%、MgO含量为23.42%~29.44%、Na₂O+K₂O含量为1.00%~2.12%（小于3.5%）,具有低m/f比值（3.13~3.86）和高FeOT含量（11.18%~14.70%）、高Mg#值（75.60~79.26）,属铁质超镁铁岩和拉斑玄武岩系列.岩石稀土总量较高（∑REE=31.98×10-6~72.60×10-6）,轻稀土（LREE）相对于重稀土（HREE）富集,（La/Yb）_N=3.56~7.72,Eu异常不明显（δEu=0.79~1.65）,球粒陨石标准化稀土元素配分模式表现为右倾型.岩石富集大离子亲石元素Rb、Sr、K等,相对亏损高场强元素Nb、Ta,具明显的Nb、Ta、Ti负异常;其形成于受俯冲流体改造的岩石圈地幔的减薄作用,并且岩浆在演化过程中遭受了地壳物质的同化混染作用.      

内蒙古东乌旗早二叠世超镁铁岩的发现及其构造意义

为研究东乌旗晚古生代地幔性质和造山演化特征,对在东乌旗西部首次发现的超镁铁岩—辉闪橄榄岩进行系统的岩相学和元素地球化学研究。东乌旗辉闪橄榄岩主要由橄榄石、角闪石、斜方辉石及少量斜长石、单斜辉石组成,SiO_2含量介于42.84%~43.96%、MgO(24.10%~26.10%)、Na_2O+K_2O(1.52%~2.32%,小于3.5%),低m/f(3.03~3.54)比值和高FeO~T(12.67%~14.33%)的含量、高Mg~#(76.42~79.20),属铁质超镁铁岩和拉斑玄武岩系列。岩石稀土总量较高(∑REE=39.57×10~(-6)~83.32×10~(-6)),轻稀土(LREE)相对于重稀土(HREE)明显富集[(La/Yb)_N=4.04~7.66],Eu异常不明显(δEu=0.90~0.95),稀土元素球粒陨石标准化配分模式表现为轻稀土相对富集的右倾型。岩石富集大离子亲石元素(LILE)Cs、Rb、Ba、Sr、K等,相对亏损高场强元素(HFSE)Nb、Ta,具明显的Nb、Ta、Ti负异常,而又有别于强烈Nb、Ta亏损的岛弧岩浆岩;相容元素Cr(769×10~(-6)~2480×10~(-6))、Ni(454×10~(-6)~901×10~(-6))含量较高;低Th/U(2.54~3.03)、Nb/U(3.40~12.85)比值和高La/Nb(2.60~3.63)、Ba/Nb(43.11~72.52)、Zr/Y(5.45~7.83)比值。综上,结合区域最新研究成果,我们认为辉闪橄榄岩来源于受俯冲流体交代的尖晶石相地幔橄榄岩部分熔融,上升过程中受地壳物质不同程度的混染,形成于早二叠世板内伸展构造体制,与古亚洲洋闭合之后板内非造山作用有关。这一认识填补了早二叠世幔源岩浆事件和非造山阶段超镁铁质岩石记录的空白。     

东天山圪塔山口镁铁-超镁铁质岩体地球化学、锆石U-Pb年代学及其对Ni-Cu成矿的指示

新疆新近发现的圪塔山口镍铜硫化物矿床位于东天山康古尔-黄山镍铜硫化物成矿带的东端。矿区包含4个镁铁-超镁铁质岩体,其中Ⅰ、Ⅱ、Ⅲ号岩体均见镍铜硫化物矿化。本文利用SIMS锆石U-Pb法测得Ⅰ号矿化岩体辉长岩年龄为282.6±1.9Ma,不仅与东天山地区其它含Ni-Cu矿化的镁铁-超镁铁质岩体形成时代一致,而且与塔里木玄武岩、镁铁质岩墙及北山地区的镁铁-超镁铁质岩体形成时限相一致。其形成可能与造山后伸展背景下的地幔柱叠加作用有关。地球化学数据表明圪塔山口岩体具有高Mg特征,除2个辉长岩样品m/f值较低外,其余14个样品集中于2.73~5.05之间,属铁质超基性岩。岩石稀土元素配分模式为右倾式,轻、重稀土比2.64~3.39;含长角闪辉橄岩及部分含长角闪橄辉岩和含长橄辉岩δEu具正异常,可能与这3个岩相中存在斜长石的结晶有关。微量元素蛛网图表明岩石富集大离子亲石元素Cs、Rb、Ba、K、Sr,富集高场强元素U、Pb,亏损高场强元素Th、Nb等特征。主量元素SiO₂-（Na₂O+K₂O）与（FeO^T/MgO）-FeO^T图解、微量元素相关图及微量元素比值相关图说明圪塔山口岩体成岩物质为来源于亏损地幔的钙碱性玄武质岩浆,成岩作用以岩浆结晶分异为主导,并受到地壳的混染作用,具有较好的镍铜硫化物矿床成矿潜力。     

大兴安岭温布其地区白音高老组火山岩的形成机制

大兴安岭温布其地区白音高老组火山岩主要由流纹质岩屑晶屑凝灰岩和流纹岩等一系列酸性火山岩构成。LA-ICP-MS锆石U-Pb测年结果显示,研究区流纹岩形成于(131±1.5)Ma,为早白垩世;岩石地球化学研究表明,样品具有高硅SiO_2(72.43%~78.64%)、富铝Al2O3(11.48%~14.24%)、富钾K_2O(4.09%~5.05%)和低镁MgO(0.14%~0.34%)的特点;轻重稀土分馏较明显[(La/Yb)_N=8.22~13.68],Eu负异常明显(δEu=0.39~0.90);微量元素相对富集大离子亲石元素Rb、Ba、K,亏损高场强元素Nb、P、Ti。~(176)Hf/~(177)Hf比值为0.282 830~0.282 983,εHf(t)为6.02~10.19。研究发现,温布其地区白音高老组火山岩岩浆来源于新元古代亏损地幔增生的年轻基性地壳的部分熔融,形成于伸展的构造环境。     

新疆准噶尔北东缘造山后伸展及陆壳生长：来自哈旦逊杂岩体的岩石学及地球化学的证据

哈旦逊岩体位于准噶尔北东缘玛因鄂博断裂以南,受断裂构造控制,呈近三角形。该岩体岩石类型较复杂,主要岩石组合为石英二长岩、二长岩、辉长岩、闪长岩、二长花岗岩、钾长花岗岩等。二长岩中锆石SHRIMP UPb测年结果为289.5±3.6Ma。除个别辉长岩样品为钙碱性系列外,其它所有样品属于碱性系列。辉长岩的稀土总量（∑REE）为43×10-6~88×10-6,Eu异常不明显,轻稀土富集（LaN/YbN=2～6）,微量元素含量变化趋势一致且富集大离子元素,Cr、Ni含量低。中性岩的∑REE大于100×10-6,轻稀土元素表现出不同程度的富集（LaN/YbN=6~20）,具有不明显或是弱的Eu正异常。微量元素含量变化大,但总体变化趋势一致,即表现出大离子亲石元素（LILE）富集而高场强元素（HFSE）亏损。花岗岩的稀土元素组成可以分两类,一类具有中等到弱的Eu负异常（δEu=0.7~1.0）,轻稀土强烈富集（LaN/YbN=12~30）,其微量元素的原始地幔标准化配分模式与中性岩近于一致;另一类具有显著的Eu负异常（δEu=0.1~0.3）,轻重稀土的分异不明显（LaN/YbN=3~8）。在微量元素配分模式中,有显著的Ba、Sr、P、Ti的亏损。不同岩石类型显示出Sr初始值异常低（0.7036~0.7039）和正的εNd(t)初始值（~6.5）。综合野外观察、岩石学及地球化学特征,推测辉长岩部分来自被俯冲带流体交代的亏损岩石圈地幔,而花岗岩部分来自年轻的基性下地壳重熔,熔融发生的深度大约在30~40km,使其中的部分酸性岩浆出现典型的高BaSr花岗岩的特征。基性岩浆和酸性岩浆在上升过程中发生混合,闪长岩及二长岩可能是它们混合的产物。哈旦逊岩体形成于造山后伸展构造背景,壳幔岩浆的混合可能是造成新生陆壳生长的一种重要方式。     

内蒙古阿拉善右旗吊井子一带镁铁质—超镁铁质岩石地球化学特征及成因分析

内蒙古自治区西部阿拉善右旗吊井子一带发育有3处镁铁质—超镁铁质岩体,位于华北板块之巴丹吉林坳陷西缘,其主要岩石类型为角闪石岩及橄榄岩。相对比与北大山镁铁质—超镁铁质岩体,本文研究区内角闪石岩分异明显,具有低钾、高钛、高铝、低磷等特征;大离子亲石元素富集,高场强元素亏损,稀土元素分异不明显,La/Sm、La/Ce、La/Yb较低,为亏损地幔来源的(N-MORB)洋中脊玄武岩的特点;橄榄岩富镁贫铁,具有镁质超基性岩的特点,岩浆未发生明显分异,微量元素中Cu、Ni、Co、Cr、V等地幔来源的元素强烈富集,不相容元素富集,稀土元素分异明显,稀土曲线右倾,具有弱Eu异常,La/Sm、La/Ce、La/Yb值较高,岩浆源于富集地幔物质的部分熔融。两种岩石地球化学成分及特征差异较大,不具备同源性特征。     

四川力马河镁铁-超镁铁质岩体的地球化学特征及成岩成矿分析

四川会理力马河镍矿是峨眉山大火成岩省最重要的岩浆硫化物矿床之一,成矿岩体为一小型锾铁-超镁铁岩侵入体,由含斜长石的超镁铁岩(包括舍长辉石橄榄岩和斜长橄榄辉石岩)和辉长岩类的镬铁质岩组成.矿床富含硫化物,成矿元素组合为铜、镍,铂族元素含量很低,没有铂族元素的工业富集,是蛾眉山大火成岩省中富铜镍贫铂族元素的代表性岩浆硫化物矿床.本文对力马河镍矿成矿岩体的镁铁、超镁铁岩及矿床中各种硫化物矿石进行了主量元素、微量元素及铂族元素含量分析.分析结果表明,力马河岩体的镁铁、超镁铁岩属拉斑玄武岩成因系列,岩石特征微量元素比值大致与高钛的峨眉山玄武岩相当、与低钛的峨眉山玄武岩有明显区分,但估计原始岩浆强不相容微量元素绝对含量大大低于高钛玄武岩,因此,其成矿岩体不是与一般的低钛或高钛峨眉山玄武岩(不包括苦橄岩在内)直接对应的深成相.岩体超镁铁岩及矿石铂族元素组成特征表现为无钌亏损的型式,钯/铱比值较小、在5左右,也显著不同于一般的峨眉山玄武岩,而类似于峨眉山大火成岩省苦橄岩的铂族元素组成.运用岩石地球化学研究方法计算,原始岩浆为苦橄质成分:MgO含量约17%、SiO2含量约48%.估计原始岩浆形成于130公里左右的深度,由类似于洋岛玄武岩岩浆源区成分的地幔经19%左右的部分熔融形成.超镁铁岩及硫化物矿石铂族元素含量一般在10-9～10-8暑级,铂族元素相对铜镍强烈亏损,铜/钯比值高于原始地幔10～100倍,铜镍铂族元素组成的原始地幔标准化曲线呈铂族元素显著亏损的“U“型.模式分析说明,导致铂族元素亏损的原因是岩浆成矿演化过程中多阶段硫化物熔离作用造成的,早期熔离出来的硫化物被丢失并造成岩浆中铂族元素亏损,其铂族元素亏损后的岩浆(第)二次硫化物熔离富集形成铂族元素亏损的矿石.     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

某高速公路下伏煤矿采空区稳定性分析

在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。      

塘口水电站坝基岩体透水性和渗漏问题分析

塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。     

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

Calculation of the Inverse of the Covariance

In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

Artemia in the Salt Lakes of Russia:the Productivity of Populations,the Reserves of the Cysts and the Fisheries

正Artemia cysts are an extremely important component of aquaculture diets.It is well established that the cultivation of fish and shellfish derive substantial health and growth advantages when Artemia are included in the diets of the