Comparative paleofloristics of the Albian-early Paleocene in the Anadyr-Koryak and North Alaska Subregions,Part 1: The Anadyr-Koryak Subregion

A high-resolution phytostratigraphic scheme based on plant macrofossils is suggested for the first time for the Albian and Upper Cretaceous of the Anadyr-Koryak Subregion of the North Pacific. Seven phytostratigraphic horizons of the subregion are distinguished based on successive stages in flora evolution substantiated by comprehensive data on described floral assemblages.     

Albian-Paleocene flora of the north pacific: Systematic composition, palaeofloristics and phytostratigraphy

Principal attention is focused on phytostratigraphy and comparative palaeofloristics of the Anadyr-Koryak (AKSR) and Northern Alaska (NASR) subregions of the North Pacific Region. The high-resolution Upper Albian-Paleocene phytostratigraphic schemes of these subregions are based on perceived stages of their floral evolution. In the AKSR the scheme includes seven subdivisions of subregional extent: the Early Ginter (upper Albian), Grebenka (upper Albian-Cenomanian-lower Turonian), Penzhina (upper Turonian), Kaivayam (Coniacian), Barykov (Santonian-lower to ?middle Campanian), Gornorechenian (?upper Campanian-lower Maastrichtian), and Koryak (lower to upper Maastrichtian-?Danian) phytostratigraphic horizons. The phytostratigraphic scheme of the NASR includes three subregional phytostratigraphic horizons and five plant-bearing beds. These are the Kukpowruk (?lower to middle-?upper Albian), Niakogon (upper Albian-Cenomanian), Kaolak (Turonian) horizons and beds with the Tuluvak (Coniacian), Early Kogosukruk (upper Santonian-Campanian), Late Kogosukruk (Campanian-Maastrichtian), Early Sagwon (Danian-Selandian), and Late Sagwon (Selandian-Thanetian) floras. The comparative analysis of coeval (or close in age) floras distinguished in the AKSR and NASR shows that they are either similar to each other (floras Early Ginter and Kukpowruk, Grebenka and Niakogon, Penzhina and Kaolak, Koryak and Early Sagwon) or different in systematic composition (floras Kaivayam and Tuluvak, Gornorechenian and Kogosukruk). Similarities between the floras imply that plant assemblages of two subregions evolved under comparable climatic conditions and freely intercommunicated via the Bering Land Bridge during the Albian-Turonian and terminal Maastrichtian-Paleocene. Floras of the AKSR and NASR, which are of different composition, existed in particular intervals of geological history when trans-Beringian plant migrations were limited or even ceased because of palaeoclimatic difference between the subregions. Floras of the AKSR and NASR survived crisis at the Cretaceous-Paleogene boundary without essential evolutionary consequence which does not support a hypothesis of a global ecological crisis at this boundary. From the analysis of the Arctic end-Cretaceous flora and palaeoclimate we conclude that the large Northern Alaskan dinosaurs were driven by lack of resources (food and shelter) to migrate 1200–1300 kilometres to the South to find forage, warmer temperatures and better light conditions before winter set in. A scenario of the Albian-Late Cretaceous florogenesis in the North Pacific Region is proposed. A primary driver of Albian-Late Cretaceous florogenesis was the gradual invasion by novel angiosperm-rich plant communities into the Asiatic continental interiors and a replacement of pre-existing vegetation dominated by ancient ferns and gymnosperms. Plant fossils representing Mesophytic and Cenophytic communities usually do not mix in the individual assemblages.     

Late Weichselian glaciation history of the northern North Sea

Based on new data from the Fladen, Sleipner and Troll areas, combined with earlier published results, a glaciation curve for the Late Weichselian in the northern North Sea is constructed. The youngest date on marine sedimentation prior to the late Weichselian maximum ice extent is 29.4 ka BP. At this time the North Sea and probably large parts of southern Norway were deglaciated (corresponding to the Alesund interstadial in western Norway). In a period between 29.4 and c. 22 ka BP, the northern North Sea experienced its maximum Weichselian glaciation with a coalescing British and Scandinavian ice sheet. The first recorded marine inundation is found in the Fladen area where marine sedimentation started close to 22 ka BP. After this the ice fronts receded both to the east and west. The North Sea Plateau, and possibly parts of the Norwegian Trench, were ice-free close to 19.0 ka, and after this a short readvance occurred in this area. This event is correlated with the advance recorded at Dimlington, Yorkshire, and the corresponding climatostratigraphic unit is denoted the Dimlington Stadial (18.5 ka to 15.1 ka). The Norwegian Trench was deglaciated at 15.1 ka in the Troll area. The data from the North Sea, together with the results from Andwa, northern Norway (Vorren et al . 1988; Møller et al . 1992), suggest that the maximum extent of the last glaciation along the NW-European seaboard from the British Isles to northern Norway was prior to c . 22 ka BP.     

Dinocyst biostratigraphy of the Lower Cretaceous in North Siberia

The described scheme of the Lower Cretaceous (Berriasian-Barremian) stratigraphic subdivisions is elaborated based on palynological study of sections in the Khatanga depression, Ust-Yenisei region, Pur-Taz interfluve, and around the Ob River latitudinal segment, the North Siberia. Stratigraphic distribution of microphytoplankton studied in detail is used to distinguish 10 biostratigraphic units in the rank of dinocysts zones. Stratigraphic position of the zones is determined with confidence using data on the Lower Cretaceous reference sections in the Khatanga depression, which were principal ones by constructing the Boreal standard zonation. In majority, boundaries of the dinocysts beds are of a high correlation potential and can be regarded as reliable stratigraphic markers, as they are recognizable not only in Siberia, but also in northern Europe and America.     

华北克拉通破坏动力学过程研究中的几个构造问题

华北克拉通破坏问题,是通过对古生代时期和新生代以来华北东部岩石圈厚度、热状态、岩石圈地幔组成与时代等特征的比较研究中,逐渐认识到的一个重大的大陆构造动力学问题。岩石圈厚度的巨大变薄是克拉通破坏的重要标志之一,已有的构造动力学模型从不同角度着重讨论了克拉通岩石圈是如何减薄的问题,但由于岩石圈减薄远不是克拉通破坏的全部,因此,即使已有动力学模型可以对减薄过程给出比较合理的解释,也还难以成为克拉通破坏的综合动力学模型。文中针对目前流行的华北克拉通岩石圈减薄动力学模型存在的问题,提出了在构建克拉通破坏综合动力学模型时需要关注的一些主要构造问题:(1)从构造变形、沉积作用、火山活动及其事件序列特征角度,甄别和评价主动裂谷作用和被动裂谷作用在克拉通破坏过程中所发挥的作用;热 化学侵蚀岩石圈减薄模型可能需要与上述裂谷作用模型相结合,才可能成为克拉通岩石圈破坏的候选模型。(2)从拆沉相关岩浆侵入和火山活动时空演变规律、地壳表层快速隆起及相关沉积作用和构造变形、地壳热状态异常、拆沉引起的热弱化地壳对区域应力场的响应、拆沉导致的局部应力场模拟等方面展开研究,检验、充实或修正岩石圈拆沉模型。(3)从区域构造变形和相关沉积作用、火山活动相结合的综合研究角度,探索华北克拉通的破坏是在古老克拉通基础上的直接破坏,还是在古老克拉通基础上经历了造山作用过程之后的造山带伸展垮塌,这是涉及华北克拉通破坏动力学模型建立的根本问题之一。     

Stratigraphy and sedimentology of Jurassic bedded chert overlying ophiolites in the North Apennines, Italy

In the North Apennines of Italy, Upper Jurassic bedded chert stratigraphically overlies ophiolitic rocks and is overlain by Lower to Middle Cretaceous pelagic limestone and shale, and Upper Cretaceous flysch. The bedded chert, best exposed in East Liguria and on Elba, is typically 30–80 m thick, but occasionally reaches 150–200 m thickness. It consists of two main alternating lithologïes: siliceous mudstone (SM) and radiolarite (R). Chert sections commonly show characteristic stratigraphic changes. Lower cherts display a striking rhythmic alternation of R and ferruginous SM beds. In middle cherts, SM beds are much less ferruginous and shalier intercalations are locally present. In upper cherts, R beds are less frequent and SM beds are essentially non-ferruginous. R beds are generally 1–4 cm thick, and consist of 80–90% quartz, 5–15% clays and usually < 1% hematite. They are commonly parallel-laminated, and rarely size-graded. In size-graded beds, large radiolaria are more abundant near the bed base (commonly together with ophiolitic or SM clasts) and small radiolaria more abundant near the bed top. Sorting is poor throughout most R beds. R beds are interpreted as turbidites (cf. Nisbet & Price, 1974). Model calculations suggest that typical settling velocities of radiolaria during redeposition are < 1 cm sec^?1, which is low and of restricted range relative to the 1–10 cm sec^?1 settling velocities of clastic grains of comparable size range. Radiolaria therefore should have only a limited tendency to grade and sort during deposition from a turbulent current. SM beds are commonly 1–7 cm thick, although much thicker ones occur near the base of sections, and consist mainly of 50–70% quartz, 15–35% clays and 0–15% hematite. Microscopic clay-silica aggregates and highly corroded remnants of radiolaria are common. SM beds are interpreted as mainly ambient pelagic sediment which accumulated slowly in topographic lows, and which was modified by near-surface dissolution of biogenic silica. In SM beds which contain two texturally different layers, the lower one is interpreted as the top of the underlying radiolarian turbidite. North Apennine cherts represent the first sediment deposited on oceanic crust formed during the opening of the North Apennine part of the Tethys. The ophiolitic basement had a rugged topography which favoured the redeposition of siliceous sediment. Hematite and local Mn enrichments in SM beds in the lower chert sections represent hydrothermal precipitates inferred to have originated at a spreading axis. During seafloor spreading, accumulation of siliceous sediments progressively reduced the topography. Deposition of ophiolitic detritus within the sediments phased out during early chert sedimentation, and the hydrothermal contribution during early-middle chert sedimentation. As local basins filled, during late chert sedimentation, radiolarian turbidites became less frequent. The first limestones at the top of chert sections are calcareous ooze turbidites derived from above the CCD and deposited slightly below it. Gradual descent of the CCD to ocean floor depths at the end of the Jurassic (Bosellini & Winterer, 1975) led to the replacement of siliceous by carbonate sedimentation.     

Laminated–bioturbated cycles in Maastrichtian chalk of the North Sea: oxygenation fluctuations within the Milankovitch frequency band

The Maastrichtian chalk of the southern Central Graben, Danish North Sea, is a homogeneous pure white coccolithic chalk mudstone deposited in a deep epeiric shelf sea, which covered large parts of northern Europe. The sediment displays a pronounced cyclicity marked by decimetre‐thick bioturbated beds alternating with slightly thinner non‐bioturbated, mainly laminated beds. The laminated half‐cycles consist of alternating millimetre‐thick, graded, high‐porosity laminae and non‐graded, low‐porosity laminae. The cyclicity has been interpreted previously as caused by periods of slow background sedimentation and bioturbation interrupted by periods of rapid deposition of laminated beds, with the latter reflecting random and local resedimentation processes. Based on textural and structural analysis, the millimetre‐scale, non‐graded laminae are interpreted as having been deposited directly from pelagic rain of pelleted coccoliths representing the primary production. The graded laminae were deposited from small‐volume, low‐density turbidity currents and suspension clouds. The sedimentation rates of the cyclical chalk are similar to those known elsewhere, and the lamination is interpreted as having been preserved from destruction through bioturbation by anoxic conditions at the seafloor. Bioturbated–laminated cycles are thus formed by slow sedimentation during alternating seafloor redox conditions probably on a Milankovitch scale. A direct implication of this interpretation is that the cycles are areally widespread, probably extending throughout the southern Central Graben area and may be useful for correlation and high‐resolution cyclostratigraphy in the chalk fields of the Danish North sea. If the laminated half‐cycles represent a few rapid resedimentation events, with a high sedimentation rate as suggested by most workers, then the sediment would not be truly cyclic, but would represent event sedimentation within a pelagic background represented by the bioturbated beds. In this case, the cycles would have very limited potential for correlation.     

Quaternary stratigraphy of the fladen area,central North Sea: A multidisciplinary study

Based on detailed stratigraphic investigations on a 200.6m long core (BGS borehole No. 81/26) from the Fladen Ground area (British sector), core material from the Sleipner field (Norwegian sector) and shallow seismic profiles between the core-sites, the following conclusions are drawn: (1) The North Sea was glaciated sometime during th elaterpart of Matuyama reversed period. A complete glacial-interglacial-glacial cycle is recorded in these sediments. (2) In a period of marine sedimentation in the Middle Pleistocene, a transgression-regression cycle under boreal-arctic regime is recorded. (3) The Fladen area has subsided between 0.9 and 0.6 m/ka through the later parts of the Quaternary (4) A major glacial event dated at between 130 and 200 ka is recorded as a thick till unit in 81/26. This till, which was deposited by ice moving from the southwest (Scotland), probably represents a period when the Scandinavian and British ice sheets coalesced in the North Sea. (5) Based on the seismic data and the stratigraphy of the Sleipner core, an ice-free, open embayment/dry land is favoured for the central North Sea during the Late Weichselian. (6) From the amino-acid data, it is shown that there has been an episodic style of sedimentation through the Quaternary. (7) of the investigated sediments (which span the last 1 mill. year) ca 98% have been deposited under arctic to boreal-arctic conditions.     

Three-dimensional numerical modeling of Late Quaternary paleoceanography and sedimentation in the northern North Atlantic

Modelling of Late Quaternary paleoceanography and sedimentation in the northern North Atlantic (NNA) is achieved by coupling the ocean general circulation model SCINNA (Sensitivity and Circulation In the NNA) to the sedimentation models SENNA (Sedimentation In the NNA) and PATRINNA (PArticle Tracing In the NNA).SCINNA is based on the primitive equations with conservation of mass, momentum, energy, heat and salt. SENNA and PATRINNA are driven by temperature, salinity and velocity fields derived from SCINNA. The modelling includes three-dimensional circulation of the ocean, sediment transport in the water column and two-dimensional sedimentary processes in a thin bottom layer. SENNA calculates the erosion, transport and deposition of sediments, resulting in sedimentation patterns for specific time intervals. PATRINNA models the transport paths of single sediment grains corresponding to the ocean circulation.The NNA reacts in a highly sensitive manner to small forcing changes, as shown by our sensitivity experiments. From these experiments it is possible to model specific circulation regimes for glacial and interglacial periods, for melt water events and for the onset of glaciation. The different climatic stages in the circulation model produce different sediment patterns in the sedimentation models, which correspond closely to the sedimentary record.     

长江口北支沉积物粒度特征与沉积环境

长江口北支为喇叭口型中潮河口,在径流－潮流共同作用下,塑造了典型的心滩、边滩、沙嘴、潮流脊和潮汐汊道等地貌形态。本文根据所采集的长江口北支底质的粒度分析结果,利用数字地质方法对粒度参数进行对应分析;并在此基础上分析北支的沉积特征及沉积环境,揭示其沉积作用的动力机制。     

南海北部陆坡混合沉积地层模式及地震响应特征

混合沉积是指碳酸盐岩与陆源硅质碎屑在沉积上的混合,它是一种沉积机理特殊而又具有重要意义的沉积现象。混合沉积分为4种沉积模式:间断混合,相混合,原地混合和源地混合。通过对南海北部陆坡的研究,识别了其中中新世碳酸盐岩台地、碳酸盐岩斜坡和混合沉积,并对其平面分布进行了研究。结合前人研究,参考区域构造背景,通过地震资料的解释认为研究区的混合沉积属于源地混合沉积,并建立了适合研究区的混合沉积模式。研究区陆源硅质碎屑分别来自北部华南隆起以及西南部中南半岛,而碳酸盐岩碎屑则来自神狐隆起、西沙隆起以及南部的广乐隆起。研究区对混合沉积的影响因素包括构造作用、物源、再改造和沉积作用、海平面升降变化以及气候,对研究区混合沉积起主要作用的是构造作用及海平面升降变化。     

Micromorphological evidence supporting Late Weichselian glaciation of the Northern North Sea

Thirteen samples from three cores and boreholes are examined using micromorphology to test existing interpretations of Late Quaternary sedimentary sequences from the Norwegian Channel, North Sea Fan and the North Sea Plateau. Previous studies have interpreted these sediments using arbitrary parameters as reflecting Late Weichselian subglacial and glacimarine conditions associated with the Scandinavian Ice Sheet and Norwegian Channel ice stream. This study develops existing micromorphological criteria to interpret the samples as reflecting specific processes of subglacial deformation and proximal and distal glacimarine sedimentation during and subsequent to the Last Glacial Maximum. The study concludes by outlining diagnostic criteria for the identification of these sediment types from core and borehole samples of other Quaternary sediments.     

The Neopleistocene of North European Russia: Stratigraphy,paleogeography, and paleoclimate

The Pleistocene sediments of North European Russia have been studied using different methods to establish their composition and identify the enclosed organic remains. The results obtained elucidate natural climatic environments of the Pleistocene and corresponding sedimentation cycles and development stages. Glaciation centers are identified for different Pleistocene epochs based on lithological criteria. The established secular trends characterizing spatial distribution and composition of different-age glacial horizons facilitate their regional correlation. Climatic conditions and paleogeographic settings of sedimentation during interglacial epochs of the middle-late Pleistocene and Holocene are reconstructed. Variations in development of vegetation, temperature, and humidity are detected for the first time in the Timan-Pechora-Vychegda, Arkhangel’sk and Vologda regions with parallel coordination of obtained data. As is concluded, there was a tendency of climate cooling in North European Russia during the Neopleistocene.     

天津蓟县中元古界铁岭组叠层石灰岩中原地海绿石的沉积学意义

天津蓟县剖面中元古界铁岭组二段叠层石灰岩中普遍发育海绿石。野外观察表明,海绿石主要分布在叠层石柱体间的泥晶灰岩中,呈薄膜状富集在叠层石鞘外缘;微观特征分析表明,海绿石呈不规则状的胶体形式,显示了原地海绿石的基本特点。电子探针的组分分析表明,铁岭组中的海绿石为中成熟度的海绿石。由于产在潮下高能柱状叠层石灰岩中,铁岭组中的海绿石并不反映低沉积速率或沉积间断的沉积条件,与现代海绿石的形成环境具有明显的差异。因此,中元古界铁岭组叠层石灰岩中的中成熟度原地海绿石是特殊沉积背景下的独特产物,为研究海绿石在地质历史时期产出的多样性提供了一个重要实例。     

Erosion of the Laurentide region of North America by glacial and glaciofluvial processes

Collection of seismic reflection data from continental margins and ocean basins surrounding North America makes it possible to estimate the amount of material eroded from the area formerly covered by Laurentide ice sheets since major glaciation began in North America. A minimum estimate is made of 1.62 × 10⁶ km³, or an average 120 m of rock physically eroded from the Laurentide region. This figure is an order of magnitude higher than earlier estimates based on the volume of glacial drift, Cenozoic marine sediments, and modern sediment loads of rivers. Most of the sediment produced during Laurentide glaciation has already been transported to the oceans. The importance of continental glaciation as a geomorphic agency in North America may have to be reevaluated. Evidence from sedimentation rates in ocean basins surrounding Greenland and Antarctica suggests that sediment production, sediment transport, and possibly denudation by permanent ice caps may be substantially lower than by periodic ice caps, such as the Laurentide. Low rates of sediment survival from the time of the Permo-Carboniferous and Precambrian glaciations suggest that predominance of marine deposition during some glacial epochs results in shorter lived sediment because of preferential tectonism and cycling of oceanic crust versus continental crust.     

北黄海盆地构造演化特征分析

依据最新油气资源调查资料,在简述北黄海盆地区域构造特征的基础上,重点分析了盆地的沉降史与构造演化特征。研究表明:(1)北黄海盆地的基本沉降曲线型式为7段折线状,其中晚侏罗世、早白垩世、始新世、渐新世、新近纪为曲线下降段,代表盆地5幕较明显的沉降;晚白垩世—古新世以及中新世早期为曲线上升段,反映盆地的抬升剥蚀。(2)盆地沉降作用自中生代至新生代总体由东向西迁移,东部坳陷以中生代沉降作用最为显著,中部坳陷主沉降期为始新世,而西部坳陷的快速沉降主要发生在始新世,并一直持续到渐新世。(3)盆地构造演化大致可划分为中生代断陷盆地、古近纪叠加断陷盆地以及新近纪坳陷盆地等3大发展阶段,其中,中生代断陷盆地发育阶段是北黄海盆地油气勘探研究的重点。     

Paleoecological evidence of human impacts on the Neuse and Pamlico estuaries of North Carolina,USA

Sediment cores were collected from the Neuse and Pamlico River estuaries, North Carolina, at seven different sites, and the data show strong anthropogenic influence on water quality. The sediments from these cores were dated using²¹⁰Pb,¹³⁷Cs,¹⁴C, and pollen horizon techniques. Specific parameters investigated include bulk density, sedimentation rates, diatom assemblage changes, nutrient and trace metal flux, and vegetation changes as recorded in the pollen record. The greatest increases in sedimentation, nutrient and metal flux and changes in diatom assemblages have occurred in the past 50–60 yr in the Pamlico and Neuse. Diatom diversity has decreased and small planktonic forms have become dominant over time, most likely due to eutrophication and increased turbidity and sedimentation. Major changes occur before phytoplankton surveys and monitoring were initiated. Overall trends are similar to those found in Chesapeake Bay, although the time frame of major changes is more recent. Dominant small planktonic diatom species differ between Chesapeake Bay and the Neuse and Pamlico. Variance in paleoecological indicators between these mid-Atlantic estuaries may be due to geomorphology and land use history.     

华北地区三叠纪地层发育特征及原始沉积格局分析

在对华北地区三叠系垂向发育特征及横向展布规律研究的基础上,从岩性特征、厚度变化、地层接触关系等方面进行分析,并结合有关地层剥蚀量方面的研究,对三叠纪期间华北地区的原始沉积格局进行了讨论：早、中三叠世、华北板块内部基本上继承了晚海西期以来的构造格局与沉积特点,为一大型内陆沉积盆地,以河湖相的稳定杂色砂泥岩沉积为主;晚三叠世开始的印支运动使华北东部全面抬升,盆地向西部退缩：西南部仍为统一的大型沉积盆地,发育温暖潮湿环境下的河流一湖泊相沉积;东部以隆升剥蚀为主,造成先期沉积的下、中三叠统的剥蚀缺失,一些地区剥蚀深及古生界,仅局部地区发育小型的山间盆地     

Recent and subrecent sedimentary conditions in the southern part of the North Sea–Baltic Sea transition

The recent rate of net sedimentation (0–5mm/yr) in the southern Kattegat is to a high degree governed by resuspension. In shallow areas (10–25 m) there is no or very little sedimentation. Sediments here are sandy lag sediments with a low content of organic matter (0.5–3.0%), nitrogen (0–0.1%) and phosphorus (0.01–0.05%). In deep water (30–60 m) the sediments are clays or fine silts and generally have high contents of organic matter (3.0–10.8%), nitrogen (0.1–0.34%) and phosphorus (0.05–0.10%). Shallow water sediments are relatively well sorted because of resuspension of fine material, which is transported to deeper water. Here the sorting becomes poor because relatively coarser material is supplied during exceptional storm events. Discrimination on erosion/transport bottoms and on depositional bottoms was based on resuspension calculations, grain-size parameters and Passegas (1964) CM diagrams. The IG/N ratio was an useful additional tool. From the sediment content of CaCO₃ it is suggested that recent sedimentation in the deeper parts of southern Kattegat is less influenced by contributions from the North Sea than it was during the early Holocene.     

Jurassic Tectonics of North China: A Synthetic View

This paper gives a synthetic view on the Jurassic tectonics of North China, with an attempt to propose a framework for the stepwise tectonic evolution history. Jurassic sedimentation, deformation and magmatism in North China have been divided into three stages. The earliest Jurassic is marked by a period of magmatism quiescence （in 205-190 Ma） and regional uplift, which are considered to be the continuation of the “Indosinian movement” characterized by continent-continent collision between the North and South China blocks. The Early to Middle Jurassic （in 190-170 Ma） was predominated by weak lithospheric extension expressed by mantle-derived plutonism and volcanism along the Yanshan belt and alongside the Tan-Lu fault zone, normal faulting and graben formation along the Yinshan- Yanshan tectonic belt, depression and resuming of coal-bearing sedimentation in vast regions of the North China block （NCB）. The Middle to Late Jurassic stage started at 165y.5 Ma and ended up before 136 Ma; it was dominated by intensive intraplate deformation resulting from multi-directional compressions. Two major deformation events have been identified. One is marked by stratigraphic unconformity beneath the thick Upper Jurassic molasic series in the foreland zones of the western Ordos thrust-fold belt and along the Yinshan-Yanshan belt; it was predated 160 Ma. The other one is indicated by stratigraphic unconformity at the base of the Lower Cretaceous and predated 135 Ma. During this last stage, two latitudinal tectonic belts, the Yinshan-Yanshan belt in the north and the Qinling-Dabie belt in the south, and the western margin of the Ordos basin were all activated by thrusting; the NCB itself was deformed by the NE to NNE-trending structural system involving thrusting, associated folding and sinistral strike-slip faulting, which were spatially partitioned. Foliated S-type granitic plutons aged 160-150 Ma were massively emplaced in the Jiao-Liao massif east of the Tan-Lu fault zone and indicate important crustal thicken