柴达木盆地水资源环境及生态效应地球卫星遥感监测研究定位站

柴达木盆地水资源环境及生态效应地球卫星遥感监测研究定位站胡东生（中国科学院青海盐湖研究所，西宁，８１０００８）关键词水资源环境生态效应，地球卫星遥感监测，定位研究站，柴达木盆地，青藏高原１．立现依据和研究意义柴达木盆地处于青藏高原的东北部，四周群山环...     

欠压实地层古地层压力恢复的统计模拟法及其在松辽盆地中的应用

恢复烃源岩古地层压力和对于研究其生留排烃过程具有重要意义。Ｎａｋａｙａｍａ［１］等在开展盆地模拟研究时应用Ｒｕｂｅｙ（１９５９）和Ｃｈａｐｍａｎ（１９７）等人提出的数学地质模型对欠压实地层的古地层压力进行恢复。本文通过对松辽盆地欠压实地层的研究发现欠压实因子随地层厚度、埋深、围岩渗透性等地质条件的不同而改变，在此基础上提出了欠压实地层压力恢复的统计模拟法，克服了目前Ｎａｋａｙａｍａ［１］等将地层埋藏过程中的欠压实因子视为常数的不足，从而使计算结果更接近实际。统计模拟法在松辽盆地的应用结果表明了这一方法在实用中的可行性和有效性。     

辽东湾北部浅海区泥沙输送及其沉积特征

根据实测资料，本文定量分析了辽东湾北部泥沙输送及其分布，并对辽河三角洲沉积区划作了初步讨论。研究表明本区泥沙以纵向搬运为特征。双台子河以西来沙和辽河西水道入海泥沙是区域东部拦门沙体和浅滩发育的主导因素。汛季大潮期，泥沙自西向东运移落淤在河口及毗邻浅水域；小潮期，泥沙除向东扩散外，大部泥沙向海方搬运。调查区可划分六个现代沉积作用区，即潮坪沉积区、辽河水下三角洲细粒沉积区、河口沙洲沉积区、波浪潮流冲蚀沉积区、河口冲积沉积区以及潮汐水道沉积区。     

柴达木盆地西部新生代气候与地形演变

从孢粉植物分异及演变，干旱碎屑及膏盐沉积分布等方面，对柴达木盆地西部新生代气候与地形的演变进行了探讨。结果表明，盆地西部新生代两个极端干燥气候期（膏盐发育期）分别出现在始新世至渐新世及上新世至第四纪。前者与老第三纪行星环流控制下的副热带干燥带有关，而后者与青藏高原的隆升有关。早第三纪盆地西部及周围地区的地势不象以前所认为的那么低平。在第三纪，昆仑山比祁连山低。晚新生代盆地向北推移了７－１１个纬距。     

青藏高原北缘新构造运动特征

ＮＥＥ向阿尔金主断裂带的新构造运动以左旋压扭性活动为特征，仅西端发育张性构造，并可划分出两期变形，新构造运动强度在时间上自上新世晚期开始至第四纪断裂活动强度增大，在空间上自ＳＷＷ向ＮＥＥ方向断裂活动强度逐渐减弱；柴达木北缘的新构造运动可划分为两期，其主要构造特征表现为向柴达木盆地逆冲的前进式叠瓦道冲带，柴达木盆地第四纪时的北界相对于第三纪时的北界向南迁移了数十公里；河西走廊盆地的新构造运动主要表现为盆地边缘断裂的逆冲兼走滑，盆地接受新生代沉积、盆地内第三系的轴面南倾的褶皱；ＮＥＥ向阿尔金主断裂带与其南侧的ＮＷＷ向断裂带是在统一构造应力场作用下相互协调、同时活动的两组关系紧密的构造带，两者的共同活动构成了断块运动。     

露头剖面层序中的海平面变化研究

在以往的沉积研究中，常常用露头剖面中的相对水深变化来讨论海平面的变化规律，本文通过对塔里木盆地北部寒武纪反映相对海平面变化的上超点变化曲线与肖尔布拉克地区寒武系露头剖面中相对水深变化曲线的对比研究发现，上超点变化曲线与相对水深变化曲线具有明显的差异，前者在寒武纪呈持续上升趋势，而后者除早期有一快速上升外，总体呈持续下降趋势，这说明相对水深变化虽与海平面变化存在着本质的联系，但单凭露头剖面中相对水深     

楚雄盆地铜、盐、有机质相互作用与砂岩铜矿生成

矿床的有机地球化学研究表明:楚雄盆地含煤、含铜和含膏盐建造中的有机质在来源、类型和成熟度上是不一致的。成岩期干酪根降解形成的短链羧酸是矿源层中铜活化的重要因素,石油烃是矿质搬运的重要载体。改造成矿期,天水淋滤膏盐展形成富SO_4~(2-)的下渗氧化性流体,为改造成矿提片供了硫源。另一方面,来自基底的含矿流体沿同生断裂上涌,混染煤系地层形成还原性流体,沿次级断裂进入到高渗透的砂岩储集层。当两种流体在砂岩中相遇时,发生氧化-还原作用而形成改造期矿体。     

Magmatic arc metamorphism: petrology and temperature history of metabasic rocks in the Coastal Cordillera of northern Chile

We investigated the metamorphic cooling history of underplated magmatic rocks at midcrustal depth. Granulites and amphibolites occur within the Jurassic magmatic belt of the Coast Range south of Antofagasta in northern Chile between 23°25' and 24°20' S. The protoliths of the metamorphic rocks are basic intrusions of Early Mesozoic age. They are part of the magmatically formed crust, and the essentially dry magmas were emplaced in an extensional regime. The granulites (clinopyroxene–orthopyroxene–plagioclase) show all stages of fabric development from magmatic to granoblastic fabrics. Pyroxene compositions were reset at temperatures around 800°  C independent of the stage of textural equilibration. The granulites were partially amphibolitized at upper amphibolite facies temperatures of 600–700°  C. Following cooling, a possible reheating to greenschist facies temperatures around 500°  C is indicated by prograde zoning in magnetite–ilmenite pairs. Mineral assemblages are not suitable for barometry, but a conservative estimation of the garnet-in reaction at given whole-rock compositions suggests maximum pressures in the granulite facies of around 5 kbar, and similar pressures are indicated by phengite barometry for the greenschist facies. The P–T  path of granulite–amphibolite metamorphism is one of slow cooling from magmatic temperatures with heterogeneous deformation. The thinning of the pre-Andean (Precambrian–Triassic) crust was apparently compensated by the magmatic underplating and this special tectonomagmatic setting caused the prolonged residence of the accreted rocks at midcrustal levels.     

The transition from passive to active margin tectonics: a case study from the zone of Samedan (eastern Switzerland)

The Zone of Samedan is part of a fossil, early Mesozoic rift system originally situated in the distal, Lower Austro-Alpine domain of the Adriatic passive continental margin. An early Mesozoic configuration of asymmetrical rift basins bounded by relative structural highs compartmentalized Late Cretaceous active margin tectonics; Jurassic half-grabens were folded into arcuate synclines, whereas relative structural highs engendered thin, imbricated thrust sheets. West-directed thrusting and folding initiated at the surface and continued to depths favoring mylonitization under lower greenschist-facies conditions. At this time Liguria-Piemontese ophiolites were accreted to Lower Austro-Alpine units directly underlying the Zone of Samedan. Late Cretaceous orogenic collapse of the Adriatic active margin involved the reactivation of west-directed thrusts as low-angle, top-to-the-east, normal faults. These faults accommodated extensional uplift of Liguria-Piemontese ophiolites and Lower Austro-Alpine units beneath and within the Zone of Samedan. During Paleogene collision, some Late Cretaceous faults in the Zone of Samedan were reactivated under lower anchizonal conditions as north-directed thrusts. The latter stages of this early Tertiary thickening were transitional to brittle, high-angle normal faulting associated with top-to-the-east extension and spreading above the warm, uplifting Lepontine dome.     

赣北修水观音阁砾岩特征及其构造意义

有关赣北地区双桥山群内角度不整合和地壳运动存在与否问题,一直争论不休。论文以较丰富的详细野外调查资料为基础,并结合前人研究成果和室内各类样品测试结果,围绕这个赣北地区重要的基础地质问题进行了讨论。作者认为“修水运动”不能成立,并提出了砾岩的沉积模式。