潍北平原地区全新世以来的海侵与海岸线变迁

末次冰期后,在全新世大暖期及区域沉降的影响下,渤海湾沿岸普遍发育海侵现象,位于莱州湾南岸的潍北平原区在经历全新世最大海泛面后,海水退却过程中留下了数条古海岸线,形成了多处贝壳堤、牡蛎礁等海岸带遗迹.研究区内新发现常家村、后柳家2处牡蛎礁,其14C年龄分别为(5130±30)a B.P.和(6030±30)a B.P.;...     

云南中甸五村-移山晚三叠世沉积及盆地特征

五村-移山地区晚三叠世地层发育齐全，并在中咱地块边缘至甘孜-理塘结合带之间构成一个较为完整的沉积盆地。中甸、格咱和弥里淌三条平行控制性断裂将盆地由西向东依次横向分割成中咱微大陆五村台地边缘三角洲、哈工弧后断陷盆地、属都火山复理石盆地和尼汝弧前斜坡(盆地)。在上述4种构造-相区中沉积了各具特色的沉积物，具有不同基本层序结构、不同生物组合及沉积相特征。显示盆地经历下降-抬升-下降-抬升两个周期性演化过程。     

Implications of the Precambrian Non-stromatolitic Carbonate Succession Making up the Third Member of Mesoproterozoic Gaoyuzhuang Formation in Yanshan Area of North China

A particular non-stromatolitic carbonate succession making up the third member of the Mesoproterozoic Gaoyuzhuang (高于庄) Formation might demonstrate that a stromatolite decline of the Mesoproterozoic occurring at ca. 1 450 Ma besides other three events of the Proterozoic,respectively,occurred at ca. 2 000 Ma,ca. 1 000 Ma,and ca. 675 Ma. The forming duration of this non-stromatolitic carbonate succession can be generally correlative to that of a similar depositional succession in North America,i.e. a non-stromatolitic carbonate succession made up by the Helena Formation of the Belt Supergroup,which suggests that the stromatolite decline occurring at ca. 1 450 Ma may be a global event. This information endows the non-stromatolitic carbonate succession making up the third member of the Gaoyuzhuang Formation in the Yanshan (燕山) area with important significance for the further understanding of Precambrian sedimentology. The Mesoproterozoic Gaoyuzhuang Formation in Yanshan area is a set of more than 1 000 m thick carbonate strata that can be divided into four members (or subformations). The first member (or the Guandi (官地) subformation) is marked by a set of stromatolitic dolomites overlying a set of transgressive sandstones; the second member (or the Sangshu'an (桑树鞍) subformation) is a set of manganese dolomites with a few stromatolites; the third member (or the Zhangjiayu (张家峪) subformation) is chiefly made up of leiolite and laminite limestones and is characterized by the development of molar-tooth structures in leiolite limestone; the fourth member (or the Huanxiusi (环秀寺) subformation) is composed of a set of dolomites of stromatolitic reefs or lithoherms. Sequence-stratigraphic divisions at two sections,i.e. the Jixian (蓟县) Section in Tianjin (天津) and the Qiangou (千沟) Section of Yanqing (延庆) County in Beijing (北京),demonstrate that a particularly non-stromatolitic succession making up the third member of the Mesoproterozoic Gaoyuzhuang Formation is developed in the Yanshan area of North China,in which lots of grotesque matground structures (wrinkle structures and palimpsest ripples) are developed in beds of leiolite limestone at the Qiangou Section and lots of molar-tooth structures are developed in beds of leiolite limestone at the Jixian Section. The time scale of the Gaoyuzhuang Formation is deduced as 200 Ma (from 1 600 Ma to 1 400 Ma). The duration of an obvious hiatus between the Gaoyuzhuang Formation and the underlying Dahongyu (大红峪) Formation is deduced as 50 Ma to 100 Ma,thus the forming duration of the GaoyuzhuangFormation is thought as 100 Ma (1 500 Ma to 1 400 Ma). Furthermore,the age of the subface of the third member of the Gaoyuzhuang Formation that is just in the mid position of the Gaoyuzhuang Formation can be deduced as about 1 450 Ma,which is the basis to infer a stromatolite decline of the Mesoproterozoic occurring at ca. 1 450 Ma. Importantly,several features of both the molar-tooth structure and the stromatolite,such as the particular forming environment,the important facies-indicative meaning,and the episodic distribution in the earth history,might express the evolutionary periodicity of the surface environment of the earth and can provide meaningful clues for the understanding of the Precambrian world,although their origin and forming mechanism is highly contentious. Therefore,like other three stromatolitic declines,respectively,occurring at ca. 675 Ma,ca. 1 000 Ma,and ca. 2 000 Ma,the identification of the stromatolite decline occurring at ca. 1 450 Ma during the Golden Age of stromatolites (2 800 Ma to 1 000 Ma) has important meaning for the further understanding of the evolving carbonate world of the Precambrian.     

末次冰消期以来东海内陆架沉积速率及其气候环境响应

对位于东海内陆架浙-闽沿岸泥质带的EC2005孔岩性、粒度以及AMS14C年代进行了分析,着重探讨了研究区自末次冰消期以来的沉积速率变化,划分出4个大的沉积阶段和4次快速沉积事件.千年时间尺度上大的沉积阶段主要受控于物源供应、海平面变化以及可容空间的大小.百年时间尺度上揭示的4次快速沉积事件主要受控于东亚冬季风的增强或...     

贵州织金新华磷矿床首次发现独立的稀土矿物

产于晚震旦世和早寒武世的不少海相沉积磷矿床富含碘、稀土、钒、镍、钼等可综合利用的元素。贵州早寒武世梅树村组早期的沉积磷块岩以富含稀土元素为特征,查明其中稀土元素的赋存状态有重要的理论和实际意义。不少研究认为稀土元素主要是赋存于胶磷矿中,但由于缺少有力的实验证据,对于稀土元素在胶磷矿中的具体存在形式,仅从理论上推测稀土元素是以类质同象的形式存在。最近,我们利用电子探针对贵州织金新华磷矿稀土元素赋存状态进行研究,在胶磷矿中发现了独立的稀土矿物———方铈矿。织金新华磷矿产于早寒武世梅树村及筇竹寺阶底部含磷岩…     

滇东曲靖地区志留纪四射珊瑚的动物群特征及地层时代讨论

本文着重从四射珊瑚动物群的角度讨论了滇东曲靖地区志留系的地层划分及对比问题。并提出曲靖地区的中、晚志留世具有4个珊瑚化石组合。对部分四射珊瑚属种（其中包括9个新种,4个相似种和一个未定属种）进行了描述。     

河南窑场铁矿床成因矿物学研究及其地质意义

窑场铁矿床位于河南鲁山地区,大地构造位置属于华北陆块南缘,控矿地层为太华群铁山岭组,主要矿体共有两个,主要有辉石铁英岩和角闪石铁英岩组成,夹有少量的黑云角闪片岩、大理岩和花岗质混合岩,主要的矿石矿物为磁铁矿(30%～35%),少量赤铁矿(5%)和镜铁矿(3%)。脉石矿物有石英、角闪石、辉石、石榴子石等。围岩的组成包括黑云辉石岩、黑云角闪岩、黑云角闪片岩、黑云片岩、角闪黑云变粒岩、大理岩及少量的花岗质混合岩。矿石中的角闪石均属于镁角闪石,辉石有富铁透辉石、斜铁辉石,磁铁矿以纯磁铁矿为特征;围岩中的角闪石属于镁角闪石和纯镁闪石,辉石主要为透辉石,黑云母为镁质黑云母,伴有少量金云母,石榴子石以铁铝榴石为主,含有镁铝榴石、钙铝榴石分子。化学成分分析显示本区的变质相达角闪岩相,估算其变质的压力范围为0.36GPa～0.74GPa。与典型华北陆块前寒武纪铁矿床对比,窑场铁矿床的矿物组合、变质等级以及沉积相类型均与新太古代的条带状铁建造相似。磁铁矿高Ni、低Co的特点表明其成矿来源与深部物质有关。     

广西南宁盆地渐新世孢粉植物群及其古环境意义

文章系统研究南宁盆地琅东高坡邕宁组下含煤段的孢粉,建立1个孢粉组合和3个亚组合.孢粉组合以木本被子植物蕈树科、壳斗科、榆科、胡桃科、杨柳科和木犀科为主,同时见有槭树科、桦木科、芸香科、漆树科、椴树科、冬青科、大戟科、山龙眼科、楝科、珙桐科、忍冬科、山矾科和桑寄生科等成分;草本被子植物花粉少量见到,含莎草科、毛茛科、唇形科、禾本科、菊科、百合科、蓼科、黑三棱科和睡莲科;裸子植物花粉主要为杉科和松科,少量见到罗汉松科;蕨类植物孢子包括凤尾蕨科、水龙骨科、紫萁科、石松科、水藓科和海金沙科.此外,还见有部分藻类分布,含疑源类的皱面球藻属、瘤面球藻属和光面球藻属,亲缘关系不明的环纹藻属以及绿藻门水网藻科的盘星藻属.组合中,裸子植物花粉尤其松科的含量自下而上逐渐减少,藻类主要分布在剖面的中部,蕨类植物孢子更多地见于剖面的上部;因此进而分出3个亚组合.孢粉植物群反映沉积时期的气候温暖湿润,植被类型为亚热带湿生常绿、落叶阔叶混交林.结果表明当时的植物生境稳定、气候温暖,湖泊和湿地逐步发育,在后期形成沼泽环境;孢粉组合一定程度上反映了全球气候在始新世末期急剧变冷后,在渐新世早中期的逐渐回暖过程.     

柴北缘前寒武纪岩体（地层）变质年龄及其对早古生代造山作用的指示

柴北缘前寒武纪岩体（地层）分布广泛。为确定柴北缘地区前寒武纪岩体（地层）受早古生代碰撞造山作用的影响,采用LA—ICP—MS技术．对大柴旦地区前寒武纪黑云斜长片麻岩、斜长角闪岩及石榴子石斜长角闪岩中的锆石进行了u—Pb同位素定年。黑云斜长片麻岩获得479-472Ma的变质年龄,斜长角闪岩获得440Ma和470Ma2个变质年龄,石榴子石斜长角闪岩获得418．8Ma±3．0Ma的变质年龄。初步确定,柴北缘早古生代造山作用对前寒武纪岩体构成了3次强度不等的变质作用叠加,分别为大洋俯7中末期阶段（495-467Ma）岛弧花岗岩弱热烘烤变质作用、大陆碰撞造山阶段（467-423Ma）区域变质作用、S型花岗岩热动力变质作用和大陆后碰撞造山阶段（423-371Ma）I型花岗岩强烈接触热变质作用。     

贵州寒武纪地层的划分和对比

通过对贵州寒武纪地层的清理，现保留２２个岩石地层单位（组），４４个生物地层单位和继续沿用１３个年代地层单位。本文着重对２２个岩石地层单位的命名、涵义和顶、底界线及层型剖面地点进行了论述，进一步明确了各个组的涵义。此外，分区列述了生物地层单位，将扬子区划分为１９个生物地层单位，过渡区划分为１８个生物地层单位，江南区（中、上寒武统）划分为７个生物地层单位。在沿用我国所通用的年代地层单位中包括３个统和１０个阶。经过进一步的清理，基本上理顺了贵州寒武纪岩石地层、生物地层和年代地层的关系，并进行了对比（详见表１、表２）。