中、上扬子白垩纪以来的剥蚀过程及构造意义——低温年代学数据约束

通过对磷灰石裂变径迹（AFT）数据系统的对比,本文从整体上分析了中、上扬子区块各地质单元在晚中生代、新生带抬升冷却特征,并初步构建了区域上中-新生代构造活动与内陆变形的时空关系.它们的构造活动在空间上具有分区性和连续性特征,在时间上具有幕式性特征.空间上的分区性与连续性主要表现在各地质单元隆升特征的差异性,即中扬子北缘江汉盆地、黄陵隆起最早开始冷却到大巴山逆冲带、米仓山-汉南隆起晚侏罗世自北（东）向南（西）的隆升与江南-雪峰山隆起、湘鄂西褶皱带、川东褶皱带及川东北地区自南东向北西依次递进逆冲褶皱变形的差异;构造活动时间上的幕式特征主要表现在阶段性的快速冷却及其相间的缓慢冷却过程.中、上扬子北缘大巴山逆冲带、米仓山-汉南隆起磷灰石裂变径迹年龄从北（东）向南（西）逐渐变小,它们在晚中生代、新生代处于秦岭-大别造山带向扬子地块逆冲挤压变形的动力学背景;而湘鄂西褶皱带、川东褶皱带及川东北地区磷灰石裂变径迹年龄自南东向北西方向减小的趋势主要受控于太平洋板块的俯冲挤压效应.中、上扬子喜山晚期的快速冷却主要是青藏高原隆升及其向东与南东方向构造逃逸挤压作用及亚洲季风等气候变化的响应.磷灰石裂变径迹的系统分析为中、上扬子递进扩展构造变形提供了年代学约束.     

对怀远运动的再认识

怀远运动是华北地台早古生代一次重要的区域性构造运动.以往的地质研究仅局限于其构造剥蚀面.依据鲁西及邻区的区域地质调查成果,认为怀远运动经历了一个较长时期(中寒武世张夏期→早奥陶世大湾期)的发展过程,可分为三山子组白云岩形成→隆起剥蚀→马家沟组底部同生构造角砾岩的形成→滑褶带的产生等四个阶段,文中对该运动的形成机制作了探讨.     

长江三峡库区现代坡地剥蚀速率研究

三峡库区以山地为主 ,人口密度较大 ,三峡工程引起的移民搬迁以及经济建设的需要 ,造成坡地上人类活动强度越来越大 ,从而造成现代坡地剥蚀作用的加剧。采用简便、实用且操作方便的地貌测量方法 ,对三峡库区草堂河流域三个坡段进行了现代坡地剥蚀速率研究。结果表明 ,<15°的缓坡、15°～ 4 5°的斜坡和 >4 5°的陡坡的现代剥蚀速率分别为 4 .0、4 .9和 7.1mm/a。当地平均现代坡地剥蚀速率已达 4 .9mm/a (790 2t/km2 ·a) ,即达到强度剥蚀标准 ,未来三峡库区坡地退耕还林 (草 )以及水土保持等生态建设任务十分艰巨。     

新疆阿尔泰铁热克提岩体热历史的磷灰石裂变径迹法研究

通过对新疆阿尔泰铁热克提岩体4个磷灰石裂变径迹样品分析研究表明,具有3个阶段的热演化模式:①大约 120 Ma之前,温度为105~130 ℃或90~120 ℃,属于较高温稳定期;②60~120 Ma,温度为90~120 ℃或20~65 ℃,系快速冷却与隆升期;③60 Ma以来为20~65 ℃或12~18 ℃,属低温稳定期.第2阶段(60~90 Ma期间),冷却速率为2.5~3.23 ℃/Ma,相当于抬升速率为83.3~107.7 m/Ma.60~120 Ma的快速隆升作用以及80.4~91.9 Ma的裂变径迹年龄,证实燕山晚期发生过新的陆内挤压造山活动.     

Late Quaternary denudation of the Alps,valley and lake fillings and modern river loads

The coastal areas of the island of Delos, located at the centre of the Cyclades archipelago (Greece), are rich in submerged Hellenistic archaeological vestiges. This submersion can be explained by changes in relative sea-level: the recent 14C datings of submerged beachrock occurrences of Delos and the nearby islands of Mykonos and Rhenia suggest that the sea level was at about -2.5 m (± 0.5 m) around 400 BC [1, 2]. Such result has enabled to confirm and refine Negris'early-twentieth-century hypothesis that the submersion can be accounted for by the relative sea-level rise.

From this result, together with bathymetric maps, archaeological studies and stratigraphic data, the Hellenistic coastal landscapes on the western side of Delos have been reconstructed.

The Sacred Harbour (including the Agora of the Competaliasts) and the “Pointe des Pilastres” landscapes (located to the South) resembled those of the current Greek harbours: the paved walkways or esplanades bordering buildings or shops were separated from the sea by a beach onto which boats were drawn. The landscape of the “Maisons au flanc de la Colline” sector (located to the North) seems to have been different. These houses were located on a rocky platform, in a sector exposed to the north swell.     

Denudation history of the Kiso Range,central Japan,and its tectonic implications: Constraints from low‐temperature thermochronology

Fission‐track (FT) and (U–Th–Sm)/He (He) analyses are used to constrain the denudation pattern and history of the Kiso Range, a Japanese fault‐block mountain range which has been uplifted since ca 0.8 Ma. We obtained nine zircon FT ages ranging 59.3–42.1 Ma, 18 apatite FT ages ranging 81.9–2.3 Ma, and 13 apatite He ages ranging 36.7–2.2 Ma. The apatite FT and He ages are divided into an older group comparable to the zircon FT age range and a younger group of <18 Ma. The younger ages are interpreted as a reflection of uplift of the Kiso Range because they were obtained only to the east of the Seinaiji‐touge Fault, and the event age estimated from apatite FT data is consistent with the timing of the onset of the Kiso Range uplift. On the basis of the distribution of the younger ages, we propose westward tilting uplift of the Kiso Range between the boundary fault of the Inadani Fault Zone and Seinaiji‐touge Fault, which implies a model of bedrock uplift that is intermediate between two existing models: a pop‐up model in which the Kiso Range is squeezed upward between the two faults and a tilted uplift model which assumes that the Kiso Range is uplifted and tilted to the west by the Inadani Fault Zone. The original land surface before the onset of uplift/denudation of the Kiso Range is estimated to have been uplifted to an elevation of 2700–4900 m. We estimated denudation rates at 1.3–4.0 mm/y and maximum bedrock uplift rates at 3.4–6.1 mm/y since ca 0.8 Ma. The Seinaiji‐touge fault is interpreted as a back thrust of the west‐dipping Inadani Fault Zone. The older group of apatite FT and He ages is interpreted to reflect long‐term peneplanation with a probable denudation rate of <0.1 mm/y.     

Rate of Glacial Valley Deepening During the Late Quaternary in Assynt,Scotland

A dated landscape history of the Allt nan Uamh valley in the Assynt area is constructed, spanning the last 300 ka, using geomorphological analysis, U-series speleothem dating, and existing cave surveys. The mean rate of valley deepening is estimated to lie between 47 and 68 m per glacial/interglacial cycle of 100 ka. This, combined with an estimated duration of glaciation, implies glacial erosion rates of about 2 mm a⁻¹, in agreement with modern process measurements. © 1997 by John Wiley & Sons, Ltd.     

A Compilation of New and Existing Thermochronology Data Concerning the Lhasa Terrane Combined with a Geological Synthesis of the Area

The history and geodynamic mechanisms of Cenozoic exhumation and denudation of the Lhasa terrane (LT), southern Tibetan Plateau, remain poorly constrained. Most previous studies investigating the exhumation of the LT have relied on extrapolating interpretations based on a few well-studied but small areas, which inevitably introduce bias. Here, our compilation of new and published thermochronologic ages are plotted against latitude, longitude, and elevation, to illustrate the distribution of cooling ages across broad regions of the LT. Primary results reveal that (1) the north LT experienced significant exhumation during 80–40 Ma; (2) compared with north LT, exhumation and erosion in the south LT continued after ~40 Ma; and (3) N–S striking rifting, E–W striking river incision, and thrusts led to continued local denudation of the south LT between 20–5 Ma.     

吉林省新生代火山分布特征

吉林省新生代火山分布，自西向东呈现出数量及面积逐渐增加、形太民及排列方式逐渐多样，喷发规模逐渐增大，喷发强度逐渐加强、喷发类型逐渐复杂、形成时代逐渐变等等特征，且有同源岩浆演化的连续性和继承性，并表现出由碱性橄榄玄武岩－拉斑玄武岩－粗面岩－碱流岩的演化系列。     

洛伊地区侏罗纪原型盆地形成与演化

以洛伊地区石油地震、钻井及地化资料为基础,利用镜质体反射率（Ro）进行单井剥蚀厚度恢复,应用平衡剖面恢复的早-中侏罗世古地貌呈"三凹三凸"特征,其中,中条山、熊耳山、嵩山由于隆升无早-中侏罗世沉积,在洛阳-济源、义马-宜阳、伊川形成3个沉降中心。依据盆地充填序列及沉积相带进行分析,认为研究区早-中侏罗世为山间坳陷盆地,其形成与演化受控于印支末期-燕山早期的秦岭-大别造山带陆内造山作用。