Flow pattern within a Permian submarine slump recorded by oblique folds and deformed fossils, Ulladulla, south-eastern Australia

The flow pattern within a slump in Permian marine rocks of the southern Sydney Basin, Australia, is recorded by folds and deformed fossils. Abundant brachiopod and bryzoan fossils in the slumped rocks are relatively undeformed, but fossil crinoid stems have been deformed by relative rotation of individual ossicles. Measurement of the strain indicates that the deformation of the crinoids is consistent with flexural flow folding within the slump. Previous models assume that curved slump fold axes remain parallel to the enveloping bedding surface of a slump sheet. Detailed measurements of the orientation of slump folds in this study found fold axes to be oblique to bedding, which is interpreted as a result of folds plunging downward towards the flanks of the slump or slump lobes. In the present model, fold axes are not generally parallel to the strike of the fold axial surface, and this can explain differences between the orientations of slump fold axes and axial surfaces when these are used as directional indicators of slump movement.     

山东省灵山岛早白垩世软沉积物变形构造特征*

利用野外露头和镜下薄片等资料、地质统计等方法, 对山东省灵山岛老虎嘴剖面和船厂滑塌剖面软沉积物变形构造分布特征和形成期次进行了研究。船厂剖面发育滑塌褶皱、负载构造、阶梯断层、布丁构造、球—枕构造等典型的软沉积物变形构造;老虎嘴剖面发育层内褶皱、微阶梯断层、层内角砾岩等。根据形成时间、发育部位和形态特征, 将船厂剖面变形划分为滑塌前变形和滑塌中变形, 滑塌前变形又可以细分滑塌体下部变形和滑塌体内部变形。滑塌褶皱具有多级别、多尺度的特点;以厚岩层组成的滑塌褶皱为主, 尺寸为米级;岩层内部纹层形成的次级褶皱为辅, 尺寸为毫米级。滑塌过程中岩层不同部位应力不同, 伴生其他变形构造, 如拉张形成的布丁构造和挤压形成剪切褶皱等。滑塌前已经形成的负载构造等在滑塌过程中保持原来形态, 不因地层变形而变形。这些古地震触发形成的软沉积变形构造证明灵山岛在早白垩世古地震活动频繁。     

河南南部的燕山运动

燕山运动是我国东部的一次强烈而重要的构造变动,在河南南部形成了一系列坳陷、断陷,堆积了一套特殊的类磨拉石沉积建造,发育强烈的褶皱和断裂,并有大规模的岩浆喷发和侵入活动,蕴含了丰富的矿产。燕山运动可分早、晚两期5幕,各幕强弱表现不同。早期Ⅰ、Ⅱ幕主要发生在大别山一带,以隆升与小规模岩浆侵入活动为主;晚期Ⅲ幕以火山活动局部发育岩浆侵入活动为特征;Ⅳ幕为断裂、岩浆活动发育,是重要的成矿期;Ⅴ幕使盆地由断陷转入坳陷发育阶段,造成白垩系与三叠系之间普遍不整合或假整合接触。分析认为,燕山期发生的太平洋板块与欧亚板块相互作用及印度板块对中国的推挤,使中国东部始终处于一种以挤压为主局部拉伸的构造应力场中。     

上扬子北部褶皱带的构造应力场演化规律

在对大量逆冲与平移断层运动学详细分析与观测的基础上,本文利用实测断层擦痕矢量数据组进行了区域应力场反演,根据对断层叠加关系的分析及叠加褶皱的验证,划分出上扬子北部经历过3期挤压构造应力场演化,从早到晚分别为:第1期北西—南东向挤压应力场,第2期近东西向挤压应力场和第3期北东—南西向挤压应力场。结合相关的地质现象,认为在这3期挤压应力场作用下分别形成了晚侏罗世末—早白垩世初的湘鄂西隔槽式褶皱带、早白垩世末—晚白垩世初的川东隔档式褶皱带和南大巴山弧形褶皱带。由此表明,上扬子北部褶皱带的形成顺序为湘鄂西隔槽式褶皱带→川东隔档式褶皱带→南大巴山弧形褶皱带。     

华南某大型铀矿床成因新识

华南某大型铀矿床具典型的岩溶特征。研究发现矿石中铀主要以微脉浸染状沥青铀矿形式存在，沥青铀矿的晶胞参数ａ０＝５．４１６～５．４２８，含氧系数为２．３１～２．３４，属低、中温热液成因。矿床中出现一套低、中温热液矿物组合。测得成矿温度为１５０～１８１℃（均一法）。矿床中热水叠加改造特征明显，故建议称之为岩溶热造铀矿床，是一种特殊的新成矿类型。     

吉南太古宙岩群中的大型构造置换及其对BIF矿体的控制

以吉林省白山市板石沟铁矿区为典型实例,系统地论述了太古宙岩群中广泛发育的大型和区域性构造置换的几何特征和对BIF矿体的控制规律。本区构造置换主要表现为:在紧闭同斜褶皱发育的持续变形过程中形成S1≈S0,并伴有钩状褶皱、石香肠构造和各类型线理的生成。按照主构造面均匀性法则,划分了构造均匀区段,并对其中8个区段(Ⅰ～Ⅷ)进行了详细的SFLπ组构分析。基于构造置换规律研究,提出本区褶皱轴与包络线双向找矿的理论与方法,经工程验证,取得显著的经济效益。     

渤海P油田河流相多层砂岩油藏储层连通性分析

为解决渤海P油田注水开发过程中逐渐暴露出的注水井吸水不均衡、注入水单层突进、储量动用不均衡等问题,以搞清剩余油分布及指导油田井网优化。通过对压力变化、水淹状况、生产干扰情况及储层沉积、储层展布等方面的分析,对河流相多层砂岩油藏储层连通性及控制因素进行了研究。认为不同沉积类型条件下,馆陶组辨状河沉积储层连通性优于明化镇组曲流河沉积,相同沉积类型中,沉积规模广、砂体呈垂向叠加,且夹层不发育的储层连通性好。可见,研究区储层连通性主要受沉积类型、沉积规模、砂体叠加模式及夹层展布的影响。     

热储特征对砂岩热储采灌井距的影响

水热型地热资源的回灌式开采是公认的地热可持续开采方式,而采灌井距是地热项目中需要着重关注的问题,以避免开采井中的热突破现象。回灌水在热储中的运移取决于热储特征,也就是储层的透水能力,主要指热储的孔隙度、渗透率及砂泥岩组合关系等参数。基于济阳坳陷典型地热田的储层数据,采用Tough2为核心的Petrasim软件建立数值模型,系统研究了储层孔隙度、渗透率及单砂体厚度对热储中回灌水的运移以及温度场的影响。模拟结果显示：（1）储层孔隙度对回灌压力与采灌井距几乎没有影响;（2）储层渗透率对采灌率和采灌压力影响较大,控制着热储的回灌能力,但对采灌井距没有影响;（3）多次叠置的薄砂层热储中的泥岩隔层影响回灌水运移,在多层薄砂叠置的热储中回灌水水平运移距离远,温度影响范围更大,应扩大采灌井距。该研究对地热开发项目的可持续运行具有指导意义。     

辽宁丹东四道沟金矿床叠生成因的流体包裹体证据

四道沟金矿床为辽东南地区一重要蚀变岩型矿床,其空间产出受构造、盖县组变质地层及区内岩浆活动的联合制约。矿化分3种类型、4个成矿阶段。流体包裹体研究表明,成矿早期流体为一中温、低盐度且富含CO2及CH4等挥发份的热液;矿区主成矿阶段成矿流体为一中温高盐度类型热液。综合分析认为,四道沟金矿床是燕山晚期不同来源及性质的热液先后叠加成矿作用的产物,矿床属叠生成因类型。     

Superposed folding in the Rockley district,Lachlan Fold Belt,New South Wales

Low grade metasediments and metavolcanics of the Hill End Synclinorial Zone within the Rockley district, NSW have experienced two phases of macroscopic folding (D1 and D2), both of which are post‐latest Silurian in age. No hiatus is evident between D1 and D2. D1 produced large Fi folds (λ/2 usually > 2 km) lacking mesoscopic elements and having variable axial trends. D2 was associated with the development of regional slaty cleavage (S2) and mesoscopic folds which are parasitic on plunging macroscopic F2 folds (λ/2=0.4–2 km). D2 strain is variable, being most intense in the north of the district where slaty cleavage and tight mesoscopic F2 folds are well developed, and weakest in the south where mesoscopic folds are absent or usually gentle and cleavage is often feebly developed even in mica‐rich rocks, which are stratigraphic equivalents to slates and schists in the north. The F1 fold mechanism may involve multiple folding, simultaneous folding in more than one direction, or complex buckling of layers of variable thickness. D1 and D2 are tentatively correlated with folding events elsewhere in the Hill End Synclinorial Zone.