俄罗斯贝加尔裂谷带中呼兰霍博克火山岩岩石学及地球化学研究

位于贝加尔裂谷带通京盆地中的呼兰霍博克火山火山锥由火山弹、火山灰等火山碎屑岩和基性熔岩(橄榄玄武岩)组成.橄榄玄武岩中橄榄石可分为具有较高Mg#值的捕虏晶和Mg#值相对较低的斑晶.部分斜长石斑晶具有核.幔.边结构,且幔部发生减压分解,一些单斜辉石晶体(俘虏晶)边部发生了减压分解.根据岩石的化学成分,该玄武岩属于橄榄粗玄岩系列,轻稀土强烈富集,重稀土相对亏损,轻重稀土之间分异较大,具有与OIB相似的微量元素和同位素地球化学特征.岩石学和元素地球化学研究表明,该橄榄玄武岩的源区和岩浆的形成可能与地幔柱活动有关;岩浆演化经历了压力骤减的过程,在岩浆快速上升过程中,深部形成的矿物(可能是地幔矿物的俘虏晶)减压分解.快速上升的岩浆几乎未受大陆地壳的混染,仅捕获了少量流纹质熔体.     

贝加尔裂谷带通京盆地新生代火山岩石学与地球化学特征及其构造意义

位于贝加尔裂谷带西南端通京盆地的尚加泰火山玄武岩由高拉长石—中长石、贵橄榄石、次透辉石、火山玻璃组成,据对S iO2与全碱(N a2O K2O)的关系判断,均为碱性橄榄玄武岩,微量元素、稀土元素分布型式与板内碱性玄武岩一致,推测原始岩浆来源于上地幔距地表200 km~250 km深度处,在距地表约40 km处即莫霍面附近开始冷却结晶,该火山活动区可能成因于异常地幔凸起中的物质-能量流沿着断裂在通京盆地内的上升。     

贝加尔裂谷下的软流圈底辟：岩石学约束条件

地壳底部部分熔融物质的存在是对贝加尔裂谷带深部构造所提出的模型的主要依据之一，可以把这种上地幔异常解释为不连续的０－５０ｋｍ的 厚层，这种厚层是通过狭窄的通道与软流层连接的（流体，张性破裂模型），或解释为与地壳基底相接触的２００－３００ｋｍ宽的软流圈隆起（地幔柱模型）。来自于新生代玄武岩的地幔捕虏体的岩石学数据与热软流圈物质引起的壳下岩石圈的完全机构交代简单模式不一致，来源于４５－７５ｋｍ深处的尖     

所谓的贝加尔裂谷实际为水平挤压带

贝加尔带并不是一个裂谷带,而是一个水平挤压带。为证实这一假设我们业已分析了地质、地球物理和地貌方面的资料。分析是依据板块与旋转理论进行的。获得的模式涉及各种内动力作用,如运动学、构造学、火山活动、地震活动和这些作用在构造和地形上的表现形式。该模式如下: 在中新生代北东欧亚板块的岩石圈运功到西南部。上杨斯克褶皱带超伏在西伯利亚台地之上。并且后者挤压它的南部格架。在贝加尔带的东北部发生了地块相撞。这就导致了斯塔诺夫高地的形成。沿着该带北东翼的盆地,产生了恰拉-北贝加尔位移。然而,这个左行移动带包括一个走向延伸至蒙古-鄂霍次克带的宽阔地块。在该区,出现     

贝加尔裂谷带中部的新构造特征及其成因分析

位于贝加尔裂谷带中部的滨奥里洪地区主要包括3个大地构造单元:西部滨海山脉、滨奥里洪高原和小海地堑.笔者着重对该地区中新世以来的新构造活动特征,特别是对第四纪夷平面的变化、断层的发育、河流的变迁、河流阶地的发育等进行了研究,表明该地区在中新世以来具有强烈的拉张运动与升降运动特征,是贝加尔裂谷带新构造运动表现最强烈的地区.新生代贝加尔裂谷带的发育受印度板块-欧亚板块碰撞、西太平洋俯冲引起弧后扩张作用的影响;中部滨奥里洪地区受到NW-SE向拉张作用,发育了强烈的新构造.     

四川攀西裂谷带峨眉玄武岩的岩石学及其成因研究

峨眉玄武岩属典型的大陆拉斑玄武岩。该玄武岩是在特定的温度、压力、氧逸度条件及裂谷的构造背景下形成的。它同时遭受分离结晶作用和地壳的同化混染作用。且可以用Depaolo AFC模型描述之。通过计算所获得的图解表现了C_L~i/C_（o,L）~i,F和r之间的相互关系（i为不相容的微量元素）。用B_（13）层玄武岩数据计算的C_（o,L）~（La）值为6.15ppm,F为0.75,r为0.75。     

汾渭与贝加尔裂谷系相似性的统计分析

在野外观测与遥感综合解译的基础上,充分利用区内已积累的地质与地球物理资料,应用统计分析方法,从7个方面分别计算分析了汾渭与贝加尔裂谷系的相似性系数。显著性统计检验表明,两裂谷系在几何形态、三维构造格局、历史与现今活动性各方面都存在显著的相似性。
结合空间测量与两裂谷系现今构造应力场的实测资料分析,推断汾渭与贝加尔裂谷系高度相似性产生的动力学机制与东亚大陆这一地带南、北块体间不等速西向运动所造成的大规模S形张裂作用存在成因联系。      

大兴安岭北部伊列克得组玄武岩的地球化学特征

大兴安岭北部伊列克得组玄岩类具有富碱（Ｋ２Ｏ＋Ｎａ２Ｏ〉６．３７％）、高Ｋ２Ｏ（２．６２％～３．１１％）,高Ｋ２Ｏ／Ｎａ２Ｏ比值（０．７～０．８）和Ｔｈ／Ｔａ、Ｃｅ／Ｎｂ、Ｔａ／Ｎｂ比值,以及强烈富集大离子亲石元素（ＬＩＬＥ）和轻稀土元素（ＬＲＥＥ）的特征,属于钾玄质系列,低Ｓｒ／Ｎｄ比值（１３～１７．５）的特征类似于洋岛玄武岩,但其Ｔａ／Ｈｆ,Ｔｈ／Ｔａ比值特征及与Ａ型花岗岩共生等特征表明,钾玄     

Slavin Yar: a new Upper Cenozoic reference section in the Tunka rift valley (Southwestern Baikal region)

The biostratigraphic study of a new Upper Cenozoic reference section in the Tunka rift valley (southwestern Baikal region) accompanied by radiocarbon measurements made it possible to date its lithological units. It is established that the section is largely composed of Upper Pleistocene fluvial sediments resting with distinct angular unconformity uapon Pliocene conglomerates. The revealed structural features of the section confirm the views that the directed development of the Tunka depressions was complicated by local inversions, when the sedimentation area became reduced. The main sedimentation features during the Late Cenozoic and its stages are reconstructed for the studied area.     

Morphotectonics of lacustrine basins: The Baikal rift zone as an example

Formation mechanisms and development of numerous and morphologically diverse lacustrine basins of the Baikal rift zone are considered in terms of morphotectonics. All the representative lake species are characterized, and their regional morphotectonic classification is suggested.     

Heat transport by groundwater flow during the Baikal rift evolution

A two-dimensional modelling study of sedimentation, fluid flow, and heat flow in the Baikal rift basin undergoing flank uplift and basin subsidence has been performed in order to understand the impact of these processes on the surface heat flow signal. Heat flow anomalies of different scales and magnitudes have been observed at the sediment surface of the lake Baikal basin, and the presence of a hydrothermal vent suggests that fluids play an important role in the regional distribution of heat flow. The BASIN-code applied for this study allows to simulate topographically and compaction-driven hydrodynamical fluid flow and coupled heat transfer.The flank uplift history provides the basis for a regional groundwater circulation towards the central basin area, with predicted Darcy velocities at present-day situation in the basement varying between 1 and 100 cm/year. Within the basin, the presence of aquifers and the pinch-out layering has a major control on the flow field, and compaction-driven flow velocities are strongly altered when combined with topography-driven flow. When velocities in the basement are larger than several centimeters per year, the regional fluid circulation is an effective mechanism of heat redistribution. Heat is brought from the flanks towards the basin area, with largest heat transported at a depth of 1–2 km at both sides. During the flank uplift, heat advection increases, with secondary variation related to the deposition of sedimentary layers. The heat flow is increased over the basin and reduced in the flanks, with a total heat output balance always positive. The extra heat output over the modelled transection is 2–10% of the initial heat output. The maximum computed heat fluxes are smaller than measured in the heat flow anomalies of the lake Baikal basin. Nevertheless, the model suggests that flow in the sedimentary basin combined with a topographically driven heat advection in the surrounding basement is a sufficient mechanism to account for the increased heat flow over the basin and the main features of the heat flow distribution.     

新疆和田玉和俄罗斯贝加尔湖地区软玉的岩石学特征研究

通过对新疆和田玉以及俄罗斯贝加尔湖地区软玉的化学成分、矿物组成、结构构造等方面的研究和对比,从岩石学的角度较系统地总结了两者的异同点,指出两者主要成分和主要矿物组成是近似的,但主要结构有区别,因而在外观上也有一定的差别,这对于两者的开发和利用有重要的实际意义.     

Absence of a regional surface thermal high in the Baikal rift; new insights from detailed contouring of heat flow anomalies

Heat flow in active tectonic zones as the Baikal rift is a crucial parameter for evaluating deep anomalous structures and lithosphere evolution. Based on the interpretation of the existing datasets, the Baikal rift has been characterized in the past by either high heat flow, or moderately elevated heat flow, or even lacking a surface heat flow anomaly. We made an attempt to better constrain the geothermal picture by a detailed offshore contouring survey of known anomalies, and to estimate the importance of observed heat flow anomalies within the regional surface heat output. A total of about 200 new and close-spaced heat flow measurements were obtained in several selected study areas in the North Baikal Basin. With an outrigged and a violin-bow designed thermoprobe of 2–3-m length, both the sediment temperature and thermal conductivity were measured. The new data show at all investigated sites that the large heat flow highs are limited to local heat flow anomalies. The maximum measured heat flow reaches values of 300–35000 mW/m², but the extent of the anomalies is not larger than 2 to 4 km in diameter. Aside of these local anomalies, heat flow variations are restricted to near background values of 50–70 mW/m², except in the uplifted Academician zone. The extent of the local anomalies excludes a conductive source, and therefore heat transport by fluids must be considered. In a conceptual model where all bottom floor heat flow anomalies are the result of upflowing fluids along a conduit, an extra heat output of 20 MW (including advection) is estimated for all known anomalies in the North Baikal Basin. Relative to a basal heat flow of 55–65 mW/m², these estimations suggest an extra heat output in the northern Lake Baikal of only 5%, corresponding to a regional heat flow increase of 3 mW/m². The source of this heat can be fully attributed to a regional heat redistribution by topographically driven ground water flow. Thus, the surface heat flow is not expected to bear a signal of deeper lithospheric thermal anomalies that can be separated from heat flow typical for orogenically altered crust (40–70 mW/m²). The new insights on the geothermal signature in the Baikal rift once more show that continental rifting is not by default characterized by high heat flow.     

远震数据显示贝加尔裂谷带北穆伊斯克(Severomuysk)段地壳和上地幔的精细结构

通过贝加尔裂谷系统北穆伊斯克(Severomuysk)段的密集地震台站线性网络获得的远距离强震记录,并利用P波接收函数技术,揭示了地壳和上地幔顶部的复杂分层块状结构。横波速度的分布表明构成北穆伊斯克地壳的地块具有不同性质。这些地块的西部聚散和地壳下部的分层证实了该地区隆起的堆积-碰撞起源。位于西伯利亚克拉通变薄的倾斜边缘上的北穆伊斯克段解释了该地区地壳碰撞效应的强度。2015年地震的震中深度与Muyakan 凹陷地壳上部的明显速度差异存在令人信服的相关性。     

东昆仑中段万宝沟群玄武岩的形成时代和构造意义

万宝沟群位于柴达木地块南缘、东昆仑造山带中段,主要由溢流相玄武岩、火山和陆源碎屑岩以及灰岩组成。万宝沟玄武岩可以分为两类:高Ti碱性玄武岩和低Ti拉斑玄武岩,前者具有高的Ti/Y(502~660)、Nb/Y(0.8~1.6)值和Ti O2含量(2.76%~4.97%),与OIB类似;后者具有相对低的Ti/Y(383~439)、Nb/Y(0.3~0.4)值和Ti O2含量(1.80%~2.49%),与E-MORB类似。SIMS锆石年代学结果表明万宝沟玄武岩形成于新元古代(762±2 Ma)。野外地层和地球化学特征显示万宝沟玄武岩可能形成于大陆裂谷或者初始洋盆环境,代表Rodinia超大陆裂解的峰期阶段。     

Active faults, seismicity and recent fracturing in the lithosphere of the Baikal rift system

A map of major active faults has been constructed for the Baikal rift system (BRS). Recent active faults are identified using seismological data. The BRS seismicity of the past 40 years is statistically analyzed. Areas of a “stable” concentration of epicenters are revealed. On this basis, a zone of recent fracturing of the lithosphere is identified and its relation to active and developing faults of the BRS is analyzed. The zone of the lithosphere fracturing is a major tectonic structure, which controls both the recent seismic process and the reactivation of ancient faults. It is demonstrated that the available seismological data can provide a basis for a detailed classification of faults by degree of their tectonic activity. Regularities in the distribution of strong earthquakes along the zone of the recent fracturing of the lithosphere are established, as well as regularities in the distribution of strong and weak seismic events relative to transform and other faults. The degree of the fault reactivation is determined by their spatial closeness to the axial zone of the recent rupturing of the lithosphere.