大地的位移——断层 地球表面的震动叫作地震,通常由断层活动、岩浆活动、火山喷发、陨石撞击或者重力塌陷所引起,尤以断层活动为首要原因.人工核爆炸或采矿、采集油气等也可引起地震,但震级通常较小,破坏范围有限. 而断层是指地壳受力发生断裂,沿断裂面两侧岩块发生的显著相对位移的构造,相应的破裂面就称为断层面.断层也是地壳中最常见和最重要的构造现象之一.

5月13日,在广东深圳海域,重达1.5万吨的恩平20-4海上钻采平台进行了动力定位浮托安装.它是恩平油田群的重要组成部分,油田群全面投产后,将进一步加快新油田开发建设步伐,助力中国海洋石油、天然气(统称油气)产能建设再提速! 除了海底油气资源之外,海洋里还有哪些矿产资源?它们又是如何形成的?这些资源对人类有哪些用途呢?

泥河湾自20世纪20年代起从一个小山村的名字升华为一个科学名词.本文对泥河湾的概念、"泥河湾层"的界定与研究历史,以及泥河湾盆地许家窑组的建立进行了讨论.泥河湾的概念是华北早更新世的河湖相堆积泥河湾组及其所蕴藏的各种地质事件.泥河湾盆地发育晚新生代地层,其中蕴藏大量古人类旧石器遗存与丰富的哺乳动物化石.泥河湾盆地充填着巨厚的河湖相沉积层,包括新近系的上新统和第四系的更新统和全新统.泥河湾盆地曾经被"大同湖"占据,大约3万年前,"大同湖"开始消亡,桑干河在盆地出现.泥河湾盆地堪称东亚的奥杜威峡谷,它们具有极其相似的地质演变过程.泥河湾盆地的科学研究,地层学是基础.泥河湾在探究华北第四纪地层和地貌发育、古人类演化与技术发展序列的构建方面具有得天独厚的有利条件.

The Mesoproterozoic Wumishan Formation in Beijing area is mainly composed of chert banded dolostone, chert nodule dolostone, stromatolite dolostone and a small amount of terrigenous silty clastic dolostone. It is widely exposed in the Beijing mountain area with a thickness of 2000～3500 meters. The provenance and cause of the formation of a large number of Mesoproterozoic siliceous sediments represented by the Wumishan Formation have been a controversial issue in the geoscience field for a long time. Most researchers believe that layered chert is biogenic and nodular chert is the diagenetic replacement. After detailed field investigations in the Western Hills of Beijing and other places, the authors have found that most of the siliceous bands or siliceous nodules（generally referred to as chert mat or siliceous gel mat in the following） occur on the sedimentary discontinuity surface, especially on the ancient erosion surface. The underlying dolostone gravels are often cemented with the siliceous material. The interior of chert mats is often mixed with impurities, especially organic matter, showing various dark and mottled colors. Chert mats were formed at the same time with surrounding dolomitic debris before the accumulation of the overlying dolomitic sediments. There is a relationship of mutual interpenetration and wrapping between chert mats and dolomitic sediments, but the boundaries between them are clear. Neither dolostone debris nor chert mat has obvious replacement trace. Therefore, the author believes that the “concretion” of chert is the result of silica gel aggregation and solidification. Silica gel solidification is the only genetic mechanism of primary chert in Wumishan Formation. Usually, the cementation rate of dolomitic mud and intraclast is obviously faster than that of silica gel mat. When an earthquake occurs or the overlying sediment is too thick, the soft silica gel will intrude upward or squeeze downward along the weakly consolidated dolostone fissure to form siliceous dykes. In the event of later magma intrusion or transformation by thermal metamorphism, the composition and color of chert strips and chert concretions will change accordingly. The texture becomes pure, and the color changes from dark to light, but the original bedding or texture is still retained, which is easily mistaken for diagenetic or post-diagenetic siliceous replacement of carbonate minerals.

Quantifying the magnitude of an earthquake is very important for long-term and medium-term earthquake prediction, post-earthquake emergency rescue and seismic hazard assessment. Paleo-seismology is the investigation of past earthquakes in the geological record, in particular their location, timing and size. Uncertainties remain in the paleo-earthquake magnitudes determined by traditional surface rupture parameters, especially because most seismic events do not result in surface ruptures or are of less than 0.3 m (M =  ~ 6–6.8). To address the problem of magnitude evaluation of earthquakes that did not reveal major dislocations, this paper deals with the methods used to determine the seismic shaking intensity based on the types and forms of soft-sediment deformation structures, including maximum liquefaction distance, thickness of disturbed layer, empirical formulae, and thickness of rapidly deposited sand layer. Then we discuss and analyze these methods in terms of their theoretical basis, advantages and disadvantages, accuracy, applicability and problems. We chose two case studies: first, a typical seismics-related deposit (liquefied layer and disrupted layer) represented by a seismite in the late-Pleistocene Lake Lisan section near Masada in the Dead Sea Basin; and second, the liquefied diapir triggered by an earthquake in the late-Quaternary lacustrine sediments at Luobozhai in the upper reaches of the Minjiang River, East Tibet. The five methods listed above are employed to determine earthquake magnitudes associated with the seismics-related deposit and liquefied diapir, yielding magnitudes of 5.5–6.5 and 6.0–7.0, respectively. The combination of the five methods, provided a new and relatively convenient method for determining seismic shaking, especially in lacustrine sediments. This study can serve as a valid reference for comparing methods of calculating the magnitude of a paleo-earthquake based on surface rupture parameters, and provides a better understanding of the long-term seismic activity and risk in tectonically active regions.

The Nihewan Basin is a rift basin at the junction of northern Shanxi Province and northwestern Hebei Province in north China. The basin is known for its rich paleontological fossils and ancient human remains. There are also abundant soft-sediment deformation structures (SSDS) in the thick lacustrine sediments. Previously, most SSDS have been interpreted as ice-edge features or ignored entirely. Recently, the authors have carried out several field surveys in the Nihewan Basin and found that many SSDS are sandwiched between normal lacustrine strata at multiple sections. In the excavation pit at the 10th Locality of Maliang Site (ML10), 10 horizontal SSDS layers and two vertically developed geological features have been identified. Based on genesis analysis and related criteria, these features are divided into two categories: cryoturbation-triggered SSDS and earthquake-triggered SSDS. Among them, a special type of ancient ice-wedge pseudomorph (SSDS-8) of ML10 is recognized in the basin for the first time. The other 9 horizontal SSDS are mainly caused by earthquake-triggered liquefaction and slumping. They can be further divided into 14 seismic event layers. These findings indicate that the tectonic activity in the Nihewan Basin is very strong and frequent, and there were cold periods in the geological history of the basin. At the same time, the SSDS with distinct morphological characteristics and stable horizontal distribution in the basin can be used as an important indicator of stratigraphic correlation.

造型奇怪的锥形山包 在山西省北部与河北省西北部的桑干河流域,有一个面积近1万平方千米的大盆地,称为大同一泥河湾盆地,它坐落在冀北山地、蒙古高原与山西高原之间的过渡地带,大同市就坐落在盆地的西北侧. 从大同市区向东30～60千米的范围内,有一系列高差几十米到几百米的锥形山包,这些矗立在盆地内的山包形态比较特别,大部分内低外高,外围又往往有个缺口,特别像马蹄或簸箕.古人利用这些山势,在山顶建有寺庙或烽燧,在山下耕种安居.1929年,法国古生物学家兼神学家德日进与中国古生物学家杨钟健在此地进行古生物调查时,确认这些山包是一个火山群.

你看那戈壁荒漠,沙砾飞扬;你听那风沙呼啸,肆虐持强. 而胡杨却在沙漠上站成了一道永恒的风景,一座永恒的雕像…… 《生如胡杨》由中国当代著名诗人阿紫创作,其作品以讴歌生命、吟咏抒情和励志感恩为主要题材,传颂人间的真善美.

相信大家都对石林有所耳闻,最著名的莫过于云南石林景区.云南石林由坚硬的石灰岩在风化作用,特别是地表流水的溶蚀作用下形成的,数十米高锥状、尖塔状岩柱,密密匝匝组合在一起,构成了蔚为壮观的石林.土林则是由松散的沉积物在流水侵蚀作用下形成的景观.如果说石林是凝固的雕塑,那土林就是流动的油画.

Abstract Quantifying the magnitude of an earthquake is very important for long-term and medium-term earthquake prediction, post-earthquake emergency rescue and seismic hazard assessment. Paleoseismology is the investigation of past earthquakes in the geological record, in particular their location, timing and size. Uncertainties remain in the paleoearthquake magnitudes determined by traditional surface rupture parameters, especially because most seismic events do not result in surface ruptures. In order to address the problem of magnitude evaluation of earthquakes that did not reveal major dislocations, this paper deals with the methods used to determine the seismic shaking intensity based on the types and forms of soft-sediment deformation structures, including maximum liquefaction distance, thickness of disturbed layer, empirical formulae, and thickness of rapidly deposited sand layer. Then we discuss and analyze these methods in terms of their theoretical basis, advantages and disadvantages, accuracy, applicability and problems. We chose two case studies: first, a typical seismics-related deposit (liquefied layer and dsirupted layer) represented by a seismite in the late-Pleistocene Lake Lisan section near Masada in the Dead Sea Basin; and second, the liquefied diapir triggered by an earthquake in the late-Quaternary lacustrine sediments at Luobozhai in the upper reaches of the Minjiang River, east Tibet. The six methods listed above are employed to determine earthquake magnitudes associated with the seismics-related deposit and liquefied diapir, yielding magnitudes of 5.5-6.5 and 6-7, respectively. The combination of the six methods, provided a new and relatively convenient method for determining seismic shaking, especially in lacustrine sediments. This study can serves as a valid reference for comparing methods of calculating the magnitude of a paleoearthquake based on surface rupture parameters, and provides a better understanding of the long-term seismic activity and risk in tectonically active regions.

揭开大漠天池神秘的面纱 考察第一天,科考队很早就从额济纳旗出发,沿着巴丹吉林沙漠的简易公路向大漠天池景区赶路.趁着太阳还未落山,全体成员顾不上旅途劳顿,直接奔赴天池. 大漠天池景区是由一个很小的水库与一片天然湿地和天然湖泊共同构成的综合景观,呈长条状分布在巨大的花岗岩体与巴丹吉林沙漠的接合部位,水库北口与湿地和沙漠相接.山口处有个简易的水坝,把上游方向的水拦截成一个浅而狭长的小水库.整个水库向北偏西方向延伸150米、位于宽约十几米的峡谷底部,两侧则是因流水侵蚀和重力崩塌而形成的数十米高的花岗岩崖壁.花岗岩体内发育了大量裂隙,这些裂隙大小不等,部分裂隙被更新鲜的浅红色花岗质岩石充填.

北京西山拥有异常丰富的地质现象,是中国地质学的发源地.1920年,由中国人绘制、撰写的第一份中文地质报告就诞生于北京西山.100多年来,成千上万的地质工作者在北京西山进行地质考察或实习,因此被称为中国地质的摇篮.而丁家滩-下苇甸之间的地层是北京西山沉积学现象最集中、又较容易到达的路线,在中国地学界久负盛名,许多地质迷走过十几遍甚至上百遍(图1).

"金张掖"的母亲河——黑水河 黑水河亦称为黑河,是中国第二大内陆河,其源头位于青海境内的祁连山腹地,上游自西向东,在祁连山脉绵延200余千米的山谷中"左突右冲",吸纳了祁连山脉大量的冰雪融水,切穿近百千米宽的祁连山脉,从位于张掖市西南侧的莺落峡涌出.平均每年流经莺落峡的水量有15.8亿立方米之多.当祁连山中的暴雨与大量冰川融水合二为一时,咆哮的黑河水夹杂着大量的泥沙、碎石源源不断堆积在峡谷外围.

前传——地球的诞生 在主角登场之前,我们先了解一下地球的演化史.46亿年前,刚刚诞生的地球是由无数围绕太阳旋转的星际碎片在重力作用下吸积而成的,密度大的物质逐渐向中心聚集,相对较轻的物质则向外溢出,形成了原始的分层结构.这个重力调整过程本身会产生大量的热,加上当时还有持续不断的星际物质的加入,大小不等的陨石、陨冰不断撞击地球.强烈的撞击使得地球表面的温度达到千摄氏度以上,足够把一切物质熔化.

为什么要研究古地震 对某一地区进行有效的地震预测或进行地震区划的前提是必须清楚这一地区地震的空间分布范围和时间上的活动趋势,如地震的强度变化规律、地震的复发时间间隔等. 与自然界数十亿年的演化史相比,人类有文字记录的历史只有几千年,借助现代地震仪记录地震的历史不到两百年.而一个地震活动区相邻两次大地震的间隔时间通常为数百至数千年,仅靠人类的历史记录或现代的仪器记录来研究某一地区的地震发生规律几乎是不可能的,这正是地震难以预测的主要原因之一.

1 研究目的(Objective) 微生物礁是沉积盆地内的微生物钙化格架堆积或微生物生长过程中吸附、黏结水体中的灰泥和其他生物碎屑形成的以碳酸盐为主的、在地貌上凸出的沉积体,小型生物礁有时也称为生物丘.近年来,北美早中寒武世和华北地台东、中部已有诸多报道,例如穆西南等(2003)对山东、辽宁中寒武世微生物礁的研究,梅冥相等(2006)对北京西山下苇甸剖面寒武系崮山组中叠层石生物丘的研究以及陈吉涛等(2014)对华北地台晚寒武世微生物礁的研究,但未见对华北地台中西部寒武系中微生物礁的研究成果.

在华北有一条近南北走向,跨越河南、山西、河北和北京四省市,绵延400千米的重要山脉,它的西侧是海拔800～3000米的山西高原和黄土高原,东侧则是海拔几十米的华北大平原.这条山脉就是中国著名的太行山脉,它不仅是中国东部最重要的地理分界线,同时也是重要的地质构造单元和构造界线.

本文主要报道在华北克拉通北缘云岗石窟景区内侏罗系地层中发现的20余个由地震液化形成的砂岩柱.地震导致的砂土液化是非常普遍的自然现象,地震波的震动使埋藏在地下未固结的饱和砂质沉积物迅速变为流体并在巨大压力下喷涌至地表,形成砂火山或泥火山.2008年汶川8.0级大地震和2012年新西兰6.2级地震都产生了严重的液化现象,在对地表造成严重破坏的同时,分别在地表形成了一系列的溢出丘和形态完好的砂火山.古地震之后,液化砂质沉积物往往在上涌的通道内固结成岩,形成穿层的岩柱或岩管.近年来,美国科罗拉多大峡谷相继发现很多地震液化形成的中生代巨型碎屑岩柱.2018年,本文作者在云岗石窟景区内的侏罗系云岗组中发现了20多条直径15～20cm左右、高可达2m以上穿层“侵入”的砂岩柱,有的在纵向上呈串珠状排列,有的呈不规则的树枝状自下向上伸展,膨大狭缩、分支复合现象非常明显,砂岩柱内部结构均一,不见任何层理.砂岩柱顶端的泥质围岩石中有明显向上牵引、拖拽的痕迹.这些砂岩柱没有任何硅化木的特征,也不是普通成岩作用形成的结核,与暴雨、泥石流、重力滑塌等作用均无任何关系,是古地震液化作用在地层内保存的遗迹,故称为液化砂岩柱.地震液化砂岩柱发育的层位位于李振宏等人(2014)在宁武静乐盆地侏罗系云岗组顶部的凝灰质泥晶碳酸盐层位(160Ma)之下约40m处,初步判定形成这些液化砂岩柱的古地震发生于160.75 Ma～160 Ma之间的晚侏罗世.古地震的形成过程与燕山运动引起的地壳运动有直接的关联,是华北克拉通内与燕山运动伴生的古地震在地层中留下的最直接证据.

Typical cases of the soft-sediment deformation structures (SSDSs), triggered by the modern earthquakes to the oldest of paleo-earthquakes in the Mesoproterozoic, have been observed in China. These deformation structures have various geometry morphology, different interior structural architectures and sediment compositions, in centimetre to metre-scales. They are intercalated with the undeformed layers, which are composed of similar sediments of lithology and sedimentary environments. SSDSs are formed during sediments deposited but incompletely consolidated. And they exist in different periods and are closely related to the active or paleo-active faults. They occur nearby the faults and usually have the characteristics nearer to the faults and more. And they distribute parallel to the trending of the active faults and have the characters of the vertical duplication. They have responded to the high-frequency activity of different faults in tectonic movement and are the perfect records of the paleo-active faults.

英文seismite是德国地质学家赛拉赫在研究美国加州的一段特殊岩层之后,于1969年正式提出的,用以代表因受地震扰动而形成的一套岩石.此后,这一术语迅速被地质学界接受并加以发展,现在虽然还有部分地质学家对这一概念有不同的理解,但是绝大多数地质学家都同意seismite是受地震扰动而形成的岩层,是地层中的古地震记录.1987年和1988年,龚一鸣将seismite翻译成"震积岩".seismite自创立至今已经接近50年,其中文译名"震积岩"至今已存在30余年,其间一直没有大的争议.但是到了2016年,山穆玕(Shanmugam)开始质疑seismite一词,列举了十余条与这一术语有关的问题,并强烈建议地学界废弃这一术语.在将山穆玕的思想介绍到国内的过程中,冯增昭先生建议将seismite的中文译名更改为"地震岩".文章作者认为,山穆玕列举的问题几乎都不是真正的科学问题,沉积学界的地质学家早已经进行了更仔细和深入的讨论,"震积岩"这一中文译名既强调地震作用的影响,又很好地体现了seismite主要发生于沉积地层中,并且已经在国内被广泛接受.而地震岩不仅包括沉积岩,还包括与地震作用形成的岩浆岩和构造岩,与英文原文有很大出入.因此,文章作者认为,seismite不能被取消,建议其中文译名仍保留龚一鸣的原始译名,以防止在学术界引起不必要的混乱.