辽宁沿海早、中期全新世海进中的一次海退事件探讨

通过分别对辽东半岛东侧大洋河平原中部的D65孔岩心做连续的硅藻分析,以及对辽东半岛西侧的长兴岛八岔沟古泻湖平原B3孔、下辽河平原的机械钻孔X33及手动钻孔X11和X21等钻孔岩心做连续的粘土混浊水电导率测定,得到各岩心的硅藻图谱/或粘土混浊水电导率图谱。显示出在这些海岸平原均有厚度在6m以上的海相层存在。表明全新世海侵时海水达到并长期占据这些海岸平原。同时还显示在这些海相地层的5～7m深处,普遍存在一层陆相或海陆交互相地层,通过对各地点已有的14C年代数据分析,推测这层陆相层或海陆交互相地层应该形成于全新世海面上升的早全新世—中全新世时期。表明全新世海进期当中,辽宁沿海普遍存在一次海退地质事件。从下辽河平原样品的14C测年数据,推测这次海退时期大致在9300～8000aB.P.(校正年)。     

钠离子对于海洋成因10-水锰矿结构稳定性的影响

10-水锰矿是海洋成岩型铁锰结核和很多陆生锰矿的主要矿物,铜、镍等过渡金属元素对于10-水锰矿结构的稳定起着重要的作用,而对于碱金属元素钠离子在其中的地球化学行为则少有涉及.利用取自东太平洋海底的成岩型铁锰结核,借助化学方法,利用矿物学和晶体化学的理论对碱金属元素钠离子在成岩型铁锰结核中的存在状态以及对结核组成矿物10-水锰矿结构的影响进行了研究.结果显示,10-水锰矿中钠离子可以被弱酸析出并且会导致其结构的破坏,使得10-水锰矿转换成7-水锰矿;析出钠离子并且结晶状态变差的10-水锰矿吸附钠离子后,其结晶状态可明显好转并且部分非10相转化为10-水锰矿,但是这种结构的破坏在自然条件下不能完全恢复.因此,钠离子对于10-水锰矿结构的稳定性起着非常重要的作用.     

Tectonic and geomechanical control of dikes and sill-like bodies: Evidence from the northwestern part of the Kola Peninsula

A study of the meticulously documented Paleoproterozoic swarms of basic dikes and sill-like bodies, as well as granite veins crosscutting Archean granite-gneiss country rocks of the Central Kola Geoblock of the Fennoscandian Shield, elucidates the question of geomechanical control of the spatial location of syntectonic sheetlike magmatic bodies intruding into heterogeneous structured geomedium. Based on structural analysis and mapping results, the succession of emplacement of several dike generations has been reconstructed and linked to structural parageneses of the corresponding deformation stages. We evaluate the effect of geomechanical and tectonic factors as well as the structural elements of enclosing strata on the places of dike localization, the character of their spatial distribution, morphology of particular bodies, and patterns of swarm systems. Geomechanical problems on the intrusion of single bodies and their communities are solved taking into account their interaction and the heterogeneity of the medium. The conditions necessary for transition of nearly vertical dikes into sills are discussed.     

U–Pb SHRIMP II age and origin of zircon from lhertzolite of the bug Paleoarchean complex,Ukrainian Shield

Complex study of the U–Pb and Lu–Hf systems of zircon from a lhertzolite lens of Archean gneiss enderbites of the Bug complex, Ukrainian Shield, showed that ultramafic magma was contaminated by the material of the country gneiss enderbites. The age of the zircons of 2.81 ± 0.05 Ga corresponds to the period of ultramafic magmatism within the Bug complex. Previously, this peak of endogenic activity was considered the stage of manifestation of metamorphism and magmatism of mafic composition.     

Mechanism of jet formation in objects of the type of SS 433

Erevan State University; Institute of Applied Physics Problems, Armenian Academy of Sciences. Translated from Astrofizika, Vol. 31, No. 2, pp. 271–279, September–October, 1989.     

Coordinates of the centre of the figure of lunar marginal zone

On the basis of large-scale star-calibrated lunar photographs the rectangular selenoequatorial coordinates of the centre of the figure of lunar marginal zone have been obtained with reference to its mass centre, the position of which has been computed by the ephemerides j = 2 and LURE-2. A new definition method of lunar mass centre coordinates by photographic observation in system j = 2 and LURE-2 is proposed.     

Depth of origin of the gas content in thermal waters

The gas composition of recent thermal waters is in perfect conformity with their geologictectonic positions. The composition of gas-liquid inclusions in the basic-hyperbasic xenoliths of basaltoid lavas depends on the depth from which xenoliths are supplied. (The depth is determined by using the methods of geological thermobarometers). By comparing available data we came to the conchision that the gas compositions of thermal waters reflect the depth of generation of deep fluid which heats them and depends on the penetration depth of the fluid-conducting fissure zones.     

Tectonics of the Caucasus and adjoining regions: implications for the evolution of the Tethys ocean

The evolution of Tethys is analysed on the basis of ophiolitic geology, reconstruction of continental margins, and plate kinematics. The North Anatolian-Minor Caucasian-South Caspian ophiolitic belt is considered to be the major suture of Palaeozoic Tethys, dividing its southern carbonate shelf from the Pontian-Caucasian-Turanian active margin. The Caucasian part of the latter comprises the Transcaucasian island arc, the Great Caucasian small ocean basin, the Great Caucasian island arc and the Precaucasian marginal sea, each characterised by its own magmatic, metamorphic and sedimentary facies association typical of that tectonic environments. The North Anatolian branch of Tethys persisted throughout the Palaeozoic and Mesozoic, whereas eastwards the major oceanic tract shifted south into the Zagros zone.The Northern frame of Mesotethys comprises the Pontain-Caucasian and Nakhichevan-Iranian island arc systems, divided by the Minor Caucasian basin, a relict of Palaeotethys reduced to a narrow northern branch of the Mesozoic ocean. In the late Cretacaous-Palaeogene, the youngest southwestern branch of Tethys separated Taurus-Anatolia from the Arabian shelf. Its ‘old’ northern branches were closed in the Palaeogene. Northward subduction in the South Anatolia-Zagros intracontinental basin triggered Neogene calc-alkaline volcanism in the Pontides, Antolia, Caucasus and Iran.