Influenced by the sedimentary models of turbidity currents and the turbidite mind set, the concepts of turbidity currents and turbidites have been expanded gradually since 1970s. Specially, Some deposition of debris flows and bottom flows are considered as turbidites by the introduction of the term “highdensity turbidity currents” and the incorrect comparison of subaerial rive currents and subaqueous turbidity currents. Turbidity currents and debris flows, especially sandy debris flows, have been rerecognized with application of modern observation facilities and detailed description of conventional cores. Turbidity currents are sedimentgravity flows with Newtonian rheology and turbulent state in which sediment is supported by fluid turbulence. Debris flows are sedimentgravity flows with plastic rheology and laminar state in which sediment is mainly  supported by matrix strength and frictional strength (caused by interlocking of grains and clasts). The normal grading is the main sedimentary rhythm of turbidites. The basal contacts of turbidites are invariably sharp or erosive, and the top contacts are gradational. Generally, the sedimentary rhythm of debris flows consist of the rigid raft with massive bedding in the upper part and the laminar flow zone with planar clast fabrics in the lower part.  When debris flows undergo only partial transformation by assimilation of ambient fluids (i.e., the diluteion effect), strongly coherent debris flows can transform into moderately coherent and weakly coherent debris flows, and its depositions from the bottom to the top are characterized by inverse to normal grading with complications (such as floating quartzose granules, mudstone clasts and so on), which distinguish from the turbidites with simple normal grading. Both basal and top contacts of debris flows are sharp. Depositional models of turbidity currents are simple baseofslope models with smooth basin floors, whereas the debris flows are complex slope models.

受浊流沉积模式（即鲍马序列和浊积扇模式）的驱动和浊积岩思维定势的影响，自1970s浊流与浊积岩的概念逐渐扩大，特别是通过“高密度浊流”术语的引入，以及将水下浊流与陆上河流的错误类比，使得一部分碎屑流与底流的沉积被认为是浊积岩。随着现代观测设备的应用以及详细的岩芯观察，碎屑流（特别是砂质碎屑流）和浊流被重新认识。浊流是一种具牛顿流变性质和紊乱状态的沉积物重力流，其沉积物支撑机制是湍流。碎屑流是一种具塑性流变性质和层流状态的沉积物重力流，其沉积物支撑机制主要是基质强度和颗粒间的摩擦强度。浊流沉积具特征的正粒序韵律结构，底部为突变接触而顶部为渐变接触；碎屑流沉积一般具上、下两层韵律结构，即下部发育具平行碎屑结构的层流段，上部发育具块状层理的“刚性”筏流段。但当碎屑流被周围流体整体稀释改造且改造不彻底时，强碎屑流可变为中—弱碎屑流，相应自下而上可形成逆—正粒序的沉积韵律结构，其中发育有呈漂浮状的石英颗粒和泥质撕裂屑等碎屑颗粒，明显区别于浊流沉积单一的正粒序韵律结构特征。碎屑流沉积顶、底部均为突变接触。浊流的沉积模式为简单的具平坦盆底的坡底模式，而碎屑流则为复杂的斜坡模式。

建立中国晚前寒武纪地层标准剖面一直是华北中、新元古代地层研究的主要目标, 获得高质量同位素年龄数据是实现这一目标的关键之一. 然而, 多年来关键层位仍缺乏高质量同位素年龄的约束. 对原“青白口系”下马岭组的层凝灰岩进行研究, 并在河北省宣化地区下马岭组发现10层凝灰岩层(斑脱岩), 获得大量岩浆型锆石, 利用SHRIMPⅡ技术, 进行了高精度定年, 测得凝灰岩层锆石 207 Pb/ 206 Pb加权平均年龄为(1366 ± 9) Ma. 结合区域资料和北京西山下马岭组的锆石年龄讨论了锆石年龄的地质意义. 这一新的同位素年龄数据为华北“青白口系”下马岭组在地层柱中的定位增添新的依据, 它不仅再次准确地确定了地层的形成时代, 而且对整个华北地台中、新元古代地层的地质演化史的认识和下马岭组宏观藻类演化在中元古代年代地层柱准确定位都有着重要的地质意义.

Meso-Neoproterozoic terrigenous clastic and carbonate rocks cover the metamorphic crystalline basement with angular unconformity in the southern margin of the North China Craton (NCC), which can be divided into Songshan-Jishan, Mianchi-Queshan and Xiong'ershan stratigraphic provinces. The Songshan-Jishan stratigraphic province, in the northeast of the Xiong'er basin, is composed of siliceous clastic rocks. The Mianchi-Queshan province, in the northern margin of the Xiong'er basin, consists of the transitional facies of siliceous clastic-carbonate rocks. The Xiong'ershan province, in the southern margin of the basin, is mainly composed of carbonate rocks. Based on their stratigraphic and petrologic characteristics, these sedimentary sequences formed in typical fluvial-marine environment with water depth shallowing from south to north. They can be divided into low sea depth, transgression and high sea depth depositional system accordingly. The petrologic and geochemical signatures show that these sedimentary rocks sourced from post-Archean felsic components with minor basic rocks and formed in a passive continental margin during Mesoproterozoic. However, the Neoproterozoic sequences formed in sedimentary basin related to a continental arc. It implies that more crustal activities and distinct changes in tectonic settings from passive to active continental margin from Mesoproterozoic to Neoproterozoic, a possible effect of the early tectonic events of the Qinling Orogenic Belt. Laser ablation ICP-MS U-Pb dating of detrital zircons from these sedimentary sequences yields ages ranging from ca. 1.50Ga to 2.70Ga with most Paleoproterozoic ages (1.70~2.40Ga) and minor Archean ages, indicating the detritus mainly sourced from Paleoproterozoic geologic bodies. The youngest ages at the bottom of the sequences of ~1600Ma can constrain the maximum age of deposition. The pronounced age peak at ~1.93Ga corresponds to the significant Early Precambrian metamorphic event of the NCC. All detrital zircons have obvious negative to moderately positive ε Hf ( t ) values from -20 to +6, indicating the contribution of juvenile materials with positive ε Hf ( t ) values and reworking of Archean crustal materials with negative ε Hf ( t ) values. The Hf model ages ( t DM C ) range from 3.8Ga to 2.3Ga and cluster between 3.0Ga and 2.6Ga with a peak at ~2.75Ga, implying the major crustal growth occurred at Late Archean.

华北克拉通南缘新太古代-古元古代变质结晶基底之上不整合覆盖着巨厚的中-新元古代陆源碎屑岩-碳酸盐岩沉积盖层,根据沉积建造特征,将其划分为三个不同的地层分布小区,分别为嵩箕地层小区、渑池-确山地层小区和熊耳山地层小区。嵩箕小区位于熊耳裂谷盆地东北缘,以硅质碎屑岩(砂岩)为主,渑池-确山地层小区位于熊耳裂谷盆地北缘,以硅质碎屑岩-碳酸盐岩(白云岩)过渡相为主,熊耳山地层小区位于熊耳裂谷盆地南缘,以碳酸盐岩为主。本文通过对三个地层小区的沉积地层剖面和岩石学特征进行研究,认为华北南缘从中元古代开始处于河流相-浅海相的沉积环境,从南向北,海水由深变浅。根据地层的岩性、沉积构造及其组合特征,将其划分为低水位、海侵和高水位沉积体系,最大海侵时期为青白口系早期。通过对熊耳山地区的官道口群的岩相学和地球化学分析,并结合其已有的碎屑锆石年龄和另外两个地层小区的五佛山群和汝阳群的碎屑锆石年龄以及它们的地球化学特征,表明三个地层区的沉积地层在中元古代均处于被动大陆边缘环境,而新元古代则可能处于与大陆岛弧相关的沉积盆地,这一结果表明从中元古代到新元古代华北南缘可能受到秦岭造山带早期微陆块俯冲碰撞的影响,由被动大陆边缘向活动大陆边缘过渡的过程。三套地层最年轻的碎屑锆石 207 Pb/ 206 Pb年龄基本上在1600Ma左右,从而限定了其最大沉积时代不早于1600Ma。其锆石年龄大多数都分布于古元古代(1700~2400Ma),太古代的年龄极少,说明其物源区以古元古代的地质体为主,且碎屑锆石年龄峰值为~1.93Ga,反映了华北南缘在~1.93Ga发生过重要的构造-热事件,与华北克拉通古元古代中期发生的变质作用时间(~1.91Ga)一致。三套沉积地层的碎屑锆石 ε Hf ( t )值变化较大(-20~+6),表明既有新生地壳物质的加入,也有古老地壳物质的再循环。Hf两阶段模式年龄分布于2.3~3.8Ga之间,明显大于其 207 Pb/ 206 Pb年龄,大部分锆石的Hf同位素组成集中于2.6Ga和3.0Ga地壳演化线区域内,峰值为2.75Ga,表明2.75Ga左右是华北克拉通南缘重要的陆壳生长期。

As an important sedimentary phenomenon, gravity flow sedimentation is widespread in deepmarine and deeplacustrine environments. Obviously, differentiation of different types of gravityflow sediments is crucial for reconstructing paleodepositional environment. Four distinct types of gravity flows and their diagnostic sedimentary structures are introduced, which can be used as guide for field identification. Debris flow depositions are characterized of their disorganized internal texture, flat bed base, and parallelism of planar clasts to bedding. Thickbedded and massive sandstones are usually formed by hyperconcentrated density flow; typified by occurrence of outsized clasts, ripup mudstones, water escape structures and other liquefactionrelated structures. Grain flow is a subtype of hyperconcentrated density flows, and inverse grading is characteristic of its deposits. Concentrated density flow possesses the depositional characteristics of both hyperconcentrated density flow and turbidity current. Tad divisions in Bouma sequence are the products of one turbidity current event, but only Ta is formed from turbidity current. Tbc divisions are actually generated from traction flow, whereas Td division is fallout deposits. Flow transformation can occur in the processes of gravity flows, and the gravityflow sediments are often reworked by bottom currents and bypass flows to varying degrees.

重力流沉积是（半）深海和深湖环境中一种重要的沉积现象，因此准确识别重力流沉积对恢复古代沉积环境具有重要意义。从沉积物重力流的基本理论出发，介绍四类重力流沉积的特点和野外鉴别特征。碎屑流沉积表现为颗粒大小混杂，底面平坦，板条状砾石平行层面排列；超高密度流沉积的砂岩呈厚层状或块状，砂岩内部经常出现较大砾石或泥岩碎片，泄水构造和液化构造常见，具逆粒序的颗粒流也属于超高密度流；高密度流沉积兼具超高密度流和浊流沉积的特点；鲍玛层序Tad段是一次浊流事件的产物，但只有Ta段为浊流沉积，Tbc段为牵引流沉积，Td段为悬浮沉积。在重力流发展过程中可出现各种流动转换。底流和过路流对重力流沉积的改造也是一种普遍现象。

The Qingbaikou group of the Yenshan Mountains may be divided into three formations, Xiamaling, Longshan and Jingeryu, in ascending order.The Xiamaling formation rests on the underlying Tieling formation with a remarkable, though low-angle, unconformity. The basal part of the Xiamaling formation displays a clear section of typical residual deposits of a lateritic type. For this widespread epeirogenic uplifting at the end of the deposition of the Jixian group and the consequent continental erosional gap thereon, the name "Qinyu movement" is here proposed.The Qingbaikou group, which lies between the unconformity marking the Qinyu movement below and that reflecting the Jixian movement above, is an entity representing a complete sequence of marine transgression. The foundation of the Qingbaikou sedimentary basin is composed of geological formations of different ages. In its central part is distributed the Tieling formation, while near both the eastern and the western ends of the basin occurs the still lower Wumishan formation. Further outwards, along the margin of the basin, are old crystalline rocks. Resulting from -such a framework of the foundation, the Longshan formation, which occupies a higher position in the Qingbaikou group, usually overlaps either the old karst topography of the Wumishan formation or the erosional surface formed on more ancient crystalline rocks. It is therefore evident that the Qinyu movement tectonically demarcated two marine transgression cycles ’iof deposition belonging to different ages.The microflora recovered from the Qingbaikou group bears distinctive characteristics of its own, and is rather different from that of the underlying Jixian and Changcheng groups. A broad correlation based upon the microflora as well as the isotopie ages of these rocks indicates that the unconformity below the Qingbaikou group as resulted from the Qinyu movement is roughly contemporaneous with that below the Sinian of South China, which, resulted from the Jinning movement,Evidences in various lines-stratigraphical, sedimentational, epeirogenic andpaleontological-all indicate that the Qingbaikou group is chronologically equivalentto the Lower Sinian of South China, which comprises the strata above the unconformity connected with the Jinning movement and below the unconformity caused by the Chengjiang movement. These two sequences form the genuine platform blanket of East China.The "Sinian" of Jixian, the type section of the "Sinian" of North China, consists of three groups, in ascending order: the Changcheng, the Jixian and the Qingbaikou. They represent several independent stratigraphical sequences, among which the Qingbaikou group is an outstanding one, distinct from the others.Further investigation of this remarkably well-developed section would make it possible to establish more than one chronostratigraphic units of the system rank in the Late Proterozoic time scale.

青白口群地层学的研究,涉及我国震旦系的范围和界线。无产阶级文化大革命以来,由于全国区域地质调查工作的丰硕成果和对震旦系的深入研究,目前有更好的条件重新讨论青白口群的层序、界面、内部分组、区域分布、对比及其在地层柱中的位置。 一、青白口群岩石地层单位的讨论 表1概括地表示青白口群及其地层单位划分和时代界线的研究史略。

The Neoproterozoic Xiamaling Formation in the Yanliao depression consists mainly of black-gray shale, yellowish green shale, silty mudstone and cherts. In the black-gray shale, laminar and thin-bedded cherts are widely distributed. Samples systemically collected from the Xiamaling section in Beijing and Xiahuayuan section in Hebei Province are analyzed with the X-ray fluorescence spectrum and analysis of pyrolysis (Rock-Eval) instrument. The results shows that the content of SiO2 in the organic -rich layers ranges from 69. 63% to 91. 09%, higher than in the normal mudstone, and is in direct proportion to the total organic carbon (TOC), but in inverse proportion to the contents of TiO2, which is typical of terrigenous component. The elements of Pb, Zn, P, Co, Ni and V, which are related to hydrothermal venting on the seafloor, and are rich in the organic-rich sediments,and in direct proportion to TOC. The ratio of Ba/Sr in the organic-rich sediments ranges from 5. 6 to 31. 8, which suggests that hydrothermal venting on the seafloor was strong. In the Xiamaling section, laminar and thin-bedded cherts in shale increase in volume gradually from Qb1x3 to upper strata, along with a rapid increase in the content of TOC. The geology and geochemistry indicate that the basin was in strong extension and depression during the formation of the organic-rich sediments of the Xiamaling formation and hydrothermal venting followed with tectonism. Hydrothermal venting on the seafloor can supply nutrition for thermophile microorganism blooming in the area of hot water, and result in the formation of anoxia in bottom water beneficial for the preservation of organic matter.

对华北新元古界青白口系下马岭组富有机质层段的常量元素、微量元素和有机质含量进行了系统分析，其基本特征是富有机质沉积层段的SiO2含量明显高于泥质岩中的含量，SiO2含量与TOC成正相关系，与TiO2含量成反比，Si／(Si Al Fe)比值与TOC成正相关关系；与海底热水流体活动有关的P、Cu、Zn、Co、Ni、V等元素含量明显富集，Ba／Sr比值远远大于1，且与TOC之间成正相关关系。在下马岭组剖面上，从Qb1x^3向上纹层～薄层状硅质岩夹层蹭多，有机质含量也开始急剧增高。地质地球化学特征表明，在下马岭组富有机质沉积层段形成时，盆地拉张沉降作用强烈，海底热水活动与之紧密相伴，而且海底热水流体活动是导致该富有机质沉积层段形成的主要原因。

华北地区沉积了巨厚的中上元古界海相碳酸盐岩夹碎屑岩地层,自下而上分别为长城系、蓟县系和青白口系。通过系统的古地磁、岩性、岩相及古地理学分析推断了中上元古界烃源岩的沉积环境,同时总结了该区烃源岩的有机质丰度、热演化程度及生烃潜力的评价,得出了华北中上元古界五个具有较好生烃潜力的烃源岩层位,即长城系的高于庄组,蓟县系的铁岭组、洪水庄组、雾迷山组以及青白口系的下马岭组。