东太平洋柱状沉积物的古气候和古环境记录

太平洋深海盆地的远洋沉积物在物质组成和来源上远较大陆边缘简单.由于远离大陆,又有海沟与周边大陆分隔,太平洋深海沉积物中通常不包含由河流水系搬运而来的悬浮物,因此从深海沉积物中提取古气候、古环境信息可以避免诸多地质因素相互叠加和干扰[1].深海远洋沉积物中的主要组分是风成陆源碎屑(包括火山碎屑)和来自上层海水的生源组分(降落到洋底的生物壳体)以及由海解作用形成的自生矿物[2],其中陆源碎屑的相对含量、粒度及矿物成分可以反映大气环流的强度及物源区的气候环境[1],生源组分的组成、相对含量和丰度以及种属含量变化则与表层海水的生产力和溶解作用有关.     

L'accident du Toulourenc : une limite tectonique entre la plate-forme provençale et le Bassin vocontien à l'Aptien–Albien (SE France)

The WNW–ESE trending Toulourenc Fault Zone (TFZ) is the western segment of the major Ventoux–Lure Fault Zone, which separates the Provençal platform from the Baronnies Vocontian Basin. The TFZ was subject to polyphased Mid-Cretaceous movements, during the Early Aptian and Middle–Late Albian times. The latter faulting episode generated conglomerates and olistoliths resulting from dismantled faultscarps cutting Barremian–Bedoulian limestones. The deformation is related to compressional wrench faulting (NE–SW sinistral faults; dextral component for the TFZ). It induced the uplift of the northwestern corner of the platform, as indicated by a mid-Cretaceous hiatus (Early Aptian pro parte to Early Albian) narrowly delimited in space. The opening of submeridian grabens within the platform favoured the northward transit of channelised coarse-grained Albian sands originating from a southern area. To cite this article: C. Montenat et al., C. R. Geoscience 336 (2004).     

1960—2019年西北地区气候变化中的Hiatus现象及特征

1998—2012年全球地表平均温度发生变暖停滞（Hiatus）,然而Hiatus现象是否在全球各地均存在尚有争议,其在西北地区的表现及特征缺乏深入研究。本文基于1960—2019年气温地面观测数据,利用累积距平曲线、Mann-Kendall突变检验、滑动t检验及Yamamoto检验进行气候突变分析,结合线性倾向估计进行气候变化趋势分析,对西北地区气候变化中的Hiatus现象及其特征进行了探讨。结果表明：① 西北地区年均气温在1986年、1996年和2012年分别突变,1996年突变升温后在1998—2012年间保持高位震荡;② 1998—2012年间西北地区年均温变化率为-0.20 ℃/10a,呈现明显Hiatus现象,分季节看,冬季降温幅度最大,夏季仍保持升温,春季均温比秋、冬季提前1年开始和结束停滞期,从空间上看,西北地区东南部降温最显著,青藏高原不存在Hiatus;③ 2012年Hiatus结束后西北地区气温普遍快速升高,季节上以冬季升温最快,空间上以南疆升温最快。综合来看,1998—2012年的Hiatus现象在除青藏高原外的西北地区表现明显,停滞后的快速升温值得高度关注。     

Joint inversion of temperature,vitrinite reflectance and fission tracks in apatite with examples from the eastern North Sea area

As sediment accumulation indicates basin subsidence, erosion often is understood as tectonic uplift, but the amplitude and timing may be difficult to determine because the sedimentary record is missing. Quantification of erosion therefore requires indirect evidence, for example thermal indicators such as temperature, vitrinite reflectance and fission tracks in apatite. However, as always, the types and quality of data and the choice of models are important to the results. For example, considering only the thermal evolution of the sedimentary section discards the thermal time constant of the lithosphere and essentially ignores the temporal continuity of the thermal structure. Furthermore, the types and density of thermal indicators determine the solution space of deposition and erosion, the quantification of which calls for the use of inverse methods, which can only be successful when all models are mutually consistent. Here, we use integrated basin modelling and Markov Chain Monte Carlo inversion of four deep boreholes to show that the erosional pattern along the Sorgenfrei–Tornquist Zone (STZ) in the eastern North Sea is consistent with a tectonic model of tectonic inversion based on compression and relaxation of an elastic plate. Three wells in close proximity SW of the STZ have different data and exhibit characteristic differences in erosion estimates but are consistent with the formation of a thick chalk sequence, followed by minor Cenozoic erosion during relaxation inversion. The well on the inversion ridge requires ca. 1.7 km Jurassic-Early Cretaceous sedimentation followed by Late Cretaceous–Palaeocene erosion during inversion. No well demands thick Cenozoic sedimentation followed by equivalent significant Neogene exhumation. When data are of high quality and models are consistent, the thermal indicator method yields significant results with important tectonic and geodynamic implications.     

First high-resolution luminescence dating of loess in Western Siberia

The south of Western Siberia is an important part of the Eurasian loess belt, containing an extensive record of Quaternary landscape and climate evolution in up to 100 m thick loess deposits with as many as 10 pedocomplexes. However, this important Quaternary archive lacks a reliable absolute chronology, and this has prevented the linking of the widely accepted regional chronostratigraphic correlations with those of other parts of the Eurasian loess belt. Here we present the first results of detailed luminescence dating of the Late Pleistocene loess-palaeosol sequence at the Western Siberian stratotype section of Lozhok. According to the classical regional chronostratigraphic scheme, this sequence records the main stages of the environmental evolution of the region, including three palaeosols correlated with the warming stages of MIS 5e, MIS 5c and MIS 3. Our absolute chronology is based on 38 new luminescence ages (OSL, IR₅₀, pIRIR₂₉₀). Good agreement between the OSL and pIRIR₂₉₀ ages suggests sufficient bleaching before deposition. The resulting chronology reveals that, rather than being only Upper Pleistocene in age, the loess-palaeosol sequence at Lozhok actually formed in the Middle and Upper Pleistocene. The ages of individual horizons do not correspond to the previously accepted stratigraphic units and morphological features of pedocomplexes. Our Bayesian chronological model reveals remarkable variation in dust accumulation and preservation at the site. The new results unambiguously identify the presence of an erosional boundary with a hiatus lasting ∼90 ka. The upper pedocomplex, immediately below this discontinuity, formed in sediment deposited between 131 ± 9 ka and 122 ± 11 ka and clearly corresponds to MIS 5. The lower pedocomplex is found in sediment deposited between 240 ± 12 and 199 ± 9 ka, and correlates closely with MIS 7. These new findings demonstrate the urgent need for a wider programme to date the main stratotypes of loess-palaeosol sections in Western Siberia. Only then can the global implications of the regional climate record in this important continental-scale archive be correctly interpreted.     

中国气温变化对全球变暖停滞的响应

1998-2012年出现的全球变暖停滞（global warming hiatus）现象,近年来受到各界的广泛关注。基于中国622个气象站的气温数据,研究了全国及三大自然区气温变化对全球变暖停滞的响应。结果表明：① 1998-2012年间,中国气温变化率为-0.221 ℃/10 a,较1960-1998年增温率下降0.427 ℃/10 a,存在同全球变暖停滞类似的增温减缓现象,且减缓程度更明显,其中冬季对中国增温减缓的贡献最大,贡献率为74.13%,夏季最小;② 中国气温变化对全球变暖停滞的响应存在显著的区域差异,从不同自然区看,1998-2012年东部季风区和西北干旱区降温显著,其中东部季风区为中国最强降温区,为全国增温减缓贡献了53.79%,并且具有显著的季节依赖性,减缓期冬季气温下降了0.896 ℃/10 a,而夏季上升了0.134 ℃/10 a。青藏高寒区1998-2012年增温率达0.204 ℃/10 a,对全球变暖停滞的响应并不显著;③ 中国增温减缓可能受太平洋年代际振荡（PDO）负相位、太阳黑子数与太阳总辐照减小等因素的影响;④ 1998-2012年中国虽出现增温减缓现象,但2012年之后气温快速升高,且从周期变化看,未来几年可能持续升温。     

藏北北羌塘盆地晚三叠世古风化壳地质地球化学特征及其意义

对最近在藏北羌塘盆地菊花山、肖茶卡、石水河等地区新发现的肖茶卡组顶部的粘土质角砾岩的地质、地球化学特征研究表明:其岩石矿物成分、结构构造、角砾层产状及剖面演化序列等与古风化壳的形成及其特征较为一致;相对于基岩,古风化壳的主量元素表现为CaO、CO2的淋失和SiO2、Al2O3、Fe2O3、K2O、Na2O、MnO、P2O5等不同程度的相对富集;古风化壳中的粘土质风化残积层的稀土元素具有明显的富集,表现为LREE含量远大于HREE的特征,存在明显的Ce的正异常以及Eu的负异常;微量元素除Mo、Sn和U外,粘土质风化残积层的其余元素含量均有明显的增加。这些特征从另一角度证实了北羌塘盆地晚三叠世存在明显的沉积间断。晚三叠世肖茶卡组顶部古风化壳的发现,为了解区域地壳发展史、古气候、古地理演化、层序地层的划分与对比、羌塘含油气盆地分析等提供了重要的依据。     

第四纪以来天津北部燕山隆升与山前盆地的形成*

文中报道了天津市北部燕山山前地带共4个高岩心采取率钻孔的沉积学、地层学、年代学和微体古生物综合研究。420个热退磁样品的磁倾角曲线显示,具147 m厚松散地层的标准孔Z3孔下部地层属于2.58 Ma的松山(Matuyama)极性带。随着地壳沉降,只是从早更新世,冲积扇侧缘泥质沉积物才开始充填了底砾岩层之上的沉积空间,形成广义的山前盆地中的泛滥平原;与传统上视为上新统特征沉积的红棕色黏土类似的亮黄橙-黄橙色-亮红棕色黏土,延续出现到早更新世中期,当时区域沉降中心位于距离山前断裂不足4 km处。0.78 Ma以来的布容(Brunhes)极性带厚57.8 m。谨慎地依据120 ka的布莱克(Blake)亚时确定上更新统后,可见中更新统大部缺失,与天津市区沧县隆起和北京永定河冲积平原南部所见此时的地层间断十分相近。3个钻孔的7个¹⁴C测年数据证实,距离山前断裂不足2 km的钻孔45 ka以来的地层最厚达41 m;显示自MIS3初始期,沉降中心向北迁移更靠近山前断裂,且在构造断裂作用下形成了新的狭义的山前盆地。研究区可见15 ka富有机质黏土及上覆泥炭,表明末次冰消期开始的气候转暖首先影响到华北平原山前地区。此项工作为研究晚新生代以来“源到汇”过程中渤海湾西岸的沉降提供了一个基准点。     

The relationship between the growth process of the ferromanganese crusts in the pacific seamount and Cenozoic ocean evolvement

Base on the Os isotope stratigraphy together with the empirical growth rate models using Co concentrations, the growth ages of the ferromanganese crusts MHD79 and MP3D10 distributed in the seamount of Pacific are confirmed. Through the contrast and research on the previous achievements including ODP Leg 144 and the crusts CD29-2, N5E-06 and N1–15 of the seamount of the Central Pacific, the uniform five growth and growth hiatus periods of them are found, and closely related to the Cenozoic ocean evolvement process. In the Paleocene Carbon Isotope Maximum (PCIM), the rise of the global ocean productivity promoted the growth of the seamount crust; the first growth hiatus (I) of the ferromanganese crust finished. In the Paleocene-Eocene Thermal Maximum (PETM), though the vertical exchange of seawater was weakened, the strong terrestrial chemical weathering led to the input of a great amount of the terrigenous nutrients, which made the bioproductivity rise, so there were no crust hiatuses. During 52–50 Ma, the Early Eocene Optimum Climate (EECO), the two poles were warm, the latitudinal temperature gradient was small, the wind-driven sea circulation and upwelling activity were weak, the terrestrial weathering was also weakened, the open ocean bioproductivity decreased, and the ferromanganese crust had growth hiatus again (II). From early Middle Eocene-Late Eocene, Oligocene, it was a long-term gradually cooling process, the strengthening of the sea circulation and upwelling led to a rise of bioproductivity, and increase of the content of the hydrogenous element Fe, Mn and Co and the biogenous element Cu, Zn, so that was the most favorable stage for the growth of ferromanganese crust (growth periods III and IV) in the studied area. The hiatus III corresponded with the Eocene- Oligocene boundary, is inferred to relate with the global climate transformation, celestial body impact event in the Eocene-Oligocene transition. From the early to the middle Miocene, a large-scale growth hiatus (hiatus period IV) of the ferromanganese crust in the studied area is inferred to relate with temporary warm up climate and ephemeral withdrawal of Antarctic bottom water in the early Miocene. After that, the Antarctic ice sheets extended, the bottom water circumfluence strengthened, the ocean fertility increased, and the once interrupted crust continued to grow in the late Miocene (growth period V). Supported by China Ocean Mineral Resources Research and Development Association “10th Five Year” Topic (Grant No. DY105-01-04-14)