Interaction between trench retreat and Anatolian escape as recorded by neogene basins in the northern Aegean Sea

The evolution of the North Aegean Sea is studied through the development of three deep basins: the North Aegean Trough, the North Skyros Basin and the Ikaria Basin. Bathymetric data, a 2D seismic dataset and the well-investigated stratigraphic records of the onshore deep basins of northern Greece and Western Turkey were used to make structural and seismic stratigraphic interpretations. The study area shows two sharp unconformities that correspond to the Eocene-Oligocene transition and the Miocene-Pliocene shift. These discontinuities were used as marker horizons for a more detailed structural and seismic stratigraphic interpretation resulting in the identification of several seismic units. A general seismic signature chart was established using onshore basin stratigraphy and well data, which was then used to constrain the ages of the different seismic units. The main features observed in the basins are interpreted as: 1) trans-tensional growth patterns in Pliocene and Quaternary sediments that combine NE–SW trending and steeply dipping fault zones that likely correspond to strike-slip corridors and E-W/WNW-ESE trending normal faults, 2) regional erosional truncations of Miocene sediments, likely related to the Messinian Salinity Crisis (MSC), 3) thick delta-turbidite deposits of Neogene age. Only the North Aegean Trough shows evidence of earlier development and polyphase deformation through inversion structures, and additional seismic units. Extension processes in the Aegean region have been driven by the Hellenic slab rollback since the middle Eocene. The widespread development of Neogene basins at the whole Aegean scale attests to a major tectonic change due to an acceleration of the trench retreat in the middle Miocene. The present study shows that the Neogene basins of the North Aegean Sea developed in dextral transtension with the northward migration of the associated NE-SW trending strike-slip faults. At regional scale, this tectonic pattern indicates that the westward escape of Anatolia started to interact with the trench retreat in the middle Miocene, around 10 Myr before the arrival of the North Anatolian Fault in the North Aegean Sea.     

含油气盆地地球动力学模式

文章讨论了含油气盆地地球动力学模式,其中着重讨论了以下几个问题:(1)沉积盆地地球动力学研究的进展,使得能够提出一种根据盆地所处的板块位置和地球动力学模型进行划分的含油气盆地分类;(2)尽管我们有一些古生代克拉通盆地的地球动力学模式,但其成因机制仍缺乏令人信服的解释;(3)通过大陆内裂谷火山岩化学成分、地温场、构造变形、岩石圈结构以及区域板块构造背景综合分析,我们建立了六种大陆裂谷形成的地球动力学模式;(4)前陆盆地的形成与其周缘造山带密切相关,其地球动力学模式是大陆岩石圈对褶皱冲断带构造负载的挠曲响应;     

入海泥沙减少对黄河三角洲潮滩粒度特征的影响

为探究不同悬沙浓度下潮滩粒度特征的变化,对黄河三角洲潮滩进行了物理模拟实验。使用采自研究区的潮滩表层沉积物,设定与实际潮滩尺寸按比例缩小的室内水槽以及波浪潮汐动力模拟,对不同悬沙浓度条件（0～14.9 kg/m3）下的模拟“潮滩”进行粒度分析。结果表明,随着悬沙浓度的减少,潮滩粒度特征发生了明显变化。随着含沙量的减少,整个潮滩的细颗粒沉积物分布范围减小,总体上沉积物呈现粗化特征,但颗粒较大的极粗粉砂的分布同样减少;在不同含沙量条件下,分选系数、偏度和峰度均值总体呈现出潮下带上部高、潮间带和潮下带下部低的特征,反映了模拟的潮间带上部和潮下带前缘的分选较潮滩中部更好的特征。含沙量的变化同样影响了模拟潮滩的微地貌形态,随着含沙量的降低,潮滩微地貌逐渐侵蚀破碎。潮滩物理模型实验有助于快速再现潮滩冲淤形态和变化特征,使特定条件下潮滩的变化具备可预见性,从而为人类有针对性地进行生产活动提供参考。     

黄河口及其邻近海域大型底栖动物的初步研究——(二)生物与沉积环境的关系

1985年5—6月对黄河口及其邻近海域的27个站进行了大型底栖动物的首航次定量调查。分别对18种环境因子和68个优势种和习见种所做的聚类分析显示了黄河口水下三角洲与邻近海域的某些差异,并联系沉积环境将所研究海域划分为四个区:黄河口水下三角洲、莱州湾、渤海中部和渤海湾东部。对大型底栖动物与沉积速率的关系也做了初步探讨。     

红树林海岸的沉积物输运和碳沉降特征

Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often "environmentally sensitive" to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.     

废黄河口海岸近期侵蚀特征与机理

苏北废黄河三角洲经历了150多a的侵蚀演变过程,目前仍处在侵蚀演变中.据2007-08和2008-07废黄河口附近断面调查结果显示,沉积类型出现粗化趋势,10 m以浅的浅水区,砂粒含量达60%以上,平均粒径达0.06 mm,物质粗化显著,岸滩呈现了强烈的波蚀作用;10 m以深至15 m的深水区,泥粒含量增多,平均粒径为...     

庙岛群岛海域沉积动力环境分区及沉积物输运趋势

基于庙岛群岛海域的107个表层沉积物样品粒度分析结果,利用Pejrup三角图、Gao-Collins粒径趋势分析等方法,对庙岛群岛海域沉积动力环境进行分区,并探讨了沉积物的输运趋势。结果表明,研究区沉积动力环境可划分为5个分区(A、CⅢ、CⅣ、DⅢ、DⅣ),以庙岛海峡为中心,各分区基本呈左右对称分布,与潮流流速中部辐聚、两侧辐散的分布特征相对应,研究区沉积物分布及沉积动力格局主要受潮流控制。研究区内存在两个沉积物输运趋势的汇聚中心,沉积物的长期输运趋势在海峡区主要受控于往复潮流,波流共同作用在外海区影响较为显著,使其具有与海峡区截然不同的特点。     

蓬莱19—3地区新近系物源分析及应用

鉴于蓬莱19—3地区物源存在一定的分歧,通过对蓬莱19—3地区新近系砂岩碎屑轻矿物、重矿物、粒度分析、砂岩展布特征、地震资料及动态资料的分析认为该地区物源主要来自于东边。结合物源及藻类分析认为蓬莱19—3以西存在一定的水体,明下段表现出浅水三角洲窄河道绫罗分布的特征,而馆陶组以辫状三角洲平原为主。建议在油田地质油藏研究过程中考虑物源及沉积相,完善产液结构,从而改善油田开发效果。     

Tectonostratigraphy and sedimentary architecture of rift basins, with reference to the northern North Sea

A tectonostratigraphic model for the evolution of rift basins has been built, involving three distinct stages of basin development separated by key unconformities or unconformity complexes. The architecture and signature of the sediment infill for each stage are discussed, with reference to the northern North Sea palaeorift system. The proto-rift stage describes the rift onset with either doming or flexural subsidence. In the case of early doming, a proto-rift unconformity separates this stage from the subsequent main rift stage. Active stretching and rotation of fault blocks during the rift stage is terminated by the development of the syn-rift unconformity. Where crustal separation is accomplished, a break-up unconformity commonly marks the boundary to the overlying thermal relaxation or post-rift stage. Tabular architectures, thickening across relatively steep faults, characterize the proto-rift stage. Syn-rift architectures are much more variable. Depending on the ability of the sediment supply to fill the waxing and waning accommodation created during rotation and subsidence, one-, two- or three-fold lithosome architectures are likely to develop. During the post-rift stage, an early phase with coarse clastic infilling of remnant rift topography often precedes late stage widening of the basin and filling with fine-grained sediments.     

福清湾北部及其以东近岸海域沉积环境和沉积特征

本文对福清湾北部及其以东近岸海域的地质地貌，潮流和波浪等沉积环境因素，以及对沉积物和悬浮泥沙的粒度，矿物特征进行研究，认为福清湾为溺谷型的半封闭潮汐汊道海湾存在着较大的潮差和潮流流速，沉积物沿潮流方向呈东粗西细和岸边细、向海变粗的潮流分异特征，潮流控制着沉积物的布局，而属于潮控的浅海沉积环境。