A high-resolution clay mineralogical record in the northern South China Sea since the Last Glacial Maximum,and its time series provenance analysis

High-resolution clay mineralogical analysis of Core MD05-2904 in the northern South China Sea (SCS) covering the period since the Last Glacial Maximum shows that illite (29%–48%), smectite (14%–45%), chlorite (17%–28%), and minor kaolinite (6%–14%) comprise the clay mineral assemblage, and that time series variation does not present glacial-interglacial cyclicity. Provenance analysis indicates three end-member sources: almost all smectite derives from Luzon, all kaolinite is sourced from the Pearl River, and illite and chlorite originate from both the Pearl River and Taiwan. By comparing clay mineral compositions in surface sediments from the three major source areas and of the SCS, we reconstructed a time series of clay mineral contribution from the major provenances to the northern slope of the SCS using the linear separation method for illite crystallinity. There were three stages of provenance change. (1) During 24.1–17.5 ka BP, contributions from Taiwan and Luzon were similar (30%–40%), while that from the Pearl River was only 25%. (2) During 17.5–14.0 ka BP, the contribution from Luzon decreased rapidly to 20%–25%, while that from Taiwan increased to 35% from an average of 25% at 18 ka BP, and that from the Pearl River increased largely to 40%. (3) During the Holocene, differences in contributions from the three major provenances increased: the contribution from Luzon increased slightly and then remained at 27%–35%, that from Taiwan increased rapidly and then remained at 55%–60%, and that from the Pearl River decreased to 15%. The change in clay mineral contributions from different provenances is influenced mainly by clay mineral production, monsoon rainfall denudation, oceanic current transport, and sea-level change.     

Clay mineral composition and their sources for the fluvial sediments of Taiwanese rivers

Located at the collision boundary between the Philippine Sea Plate and the Eurasian Continental Plate,the island of Taiwan is generally recognized as an important example in the MARGINS Program Science Plan and "source-to-sink" research because of its high tectonic activity,heavy rainfall and unique geography.Large suspended sediment loads are transported to the adjacent ocean by Taiwanese rivers every year,making Taiwan an important source of sediments into the adjacent seas and a natural laboratory for studying the systemic movement of fluvial sediments from source to sink.A detailed study on the clay mineral composition of surface sediments collected from the drainage basins of 12 Taiwanese rivers using X-ray diffraction methods was conducted.Our results indicated that the clay mineral assemblages consisted dominantly of illite(approximately 73%) and chlorite(approximately 24%),with lesser abundances of kaolinite(approximately 3%) and even lower levels of smectite from the Danshuei River sediments in northwestern Taiwan.The Jhuoshuei River sediments from western Taiwan contained clay mineral assemblages that consisted of illite(approximately 75%) and chlorite(approximately 25%),but they lacked kaolinite and smectite.In southwestern Taiwan,the clay mineral assemblages were dominated by illite(approximately 75%) and chlorite(approximately 23%),but had a low abundance of kaolinite(generally < 2%) and no smectite.The clay mineral assemblages in eastern Taiwan are obviously different from those in western parts of the island.The most noticeable difference is that the average abundance of chlorite in the Hualien River from eastern Taiwan was the highest(approximately 48%) of all the Taiwanese rivers.We concluded that,in general,the clay mineral assemblages in Taiwanese rivers were mainly composed of illite and chlorite with kaolinite and smectite being scarce,and these trends are different from those in China’s mainland rivers.The clay mineral composition shown in this study was primarily determined by the properties of the bedrock,and the differential weathering intensities of the drainage area.The surface sediments in Taiwan’s rivers showed a greater abundance of illite and chlorite because the outcropped rocks were mainly composed of Tertiary sedimentary rocks,especially sandstone,shale and slate,and show strong physical weathering.The relatively high relief and more abundant rainfall also caused the clay minerals in the fluvial sediments to be transported to the estuaries down rivers from the mountains and then delivered to the adjacent seas by currents and waves over a shorter time scale.     

南海北部陆缘黏土矿物组合特征与地质意义

采用沉积矿物分析方法对南海北部九口探井渐新世—中新世沉积物进行系统的黏土矿物分析.结果表明:南海北部沉积物黏土矿物组成随时间及空间呈现规律性变化,黏土矿物伊/蒙转化深度具有自北向南逐步变浅的规律,与地温梯度升高变化趋势基本一致,这种黏土矿物伊/蒙转化的变化规律反映了南海北部洋陆过渡地壳减薄,莫霍面抬升,热流值升高的趋势.通过黏土矿物组合演变特征与热流变化趋势的相关关系,可以预测区域性温度场变化规律,加深对南海北部洋陆过渡地壳厚度变化的认识.     

鹤岗煤田泥质岩粘土矿物类型及其地质意义

为了确定鹤岗煤田泥质岩粘土矿物类型及其地质意义,本文采用X射线衍射仪和扫描电镜研究了鹤岗煤田12个泥质岩样品中的粘土矿物。结果表明:本区泥质岩共有4种类型的粘土矿物,并揭示出高岭石主要为来自剥蚀区的碎屑粘土矿物,少部分为自生矿物,伊利石一部分由剥蚀区搬运来,另外则由长石、云母等铝硅酸盐矿物风化形成,伊蒙混层矿物是在成岩过程中,由蒙脱石向伊利石转化的过渡产物,绿泥石则是在深埋阶段由高岭石转变而成。这项研究说明该区在整个晚侏罗世演化过程中处于近中性环境,并在弱酸弱碱环境中频繁振荡。     

淮北煤田上石盒子组泥质岩的矿物学研究

淮北煤田上石盒子组泥质岩中粘土矿物以高岭石、伊利石为主,绿泥石、蒙脱石次之,3煤段上部泥质岩中伊利石增多,地球化学指标也表明为半成水环境,说明上石盒子组上部为一套受海水影响的岩性组合。     

城市红树林湿地沉积物的矿物组成特征及影响因素

以深圳城市红树林湿地沉积物为研究对象, 分析其矿物组分和理化性质, 探究其矿物组成特征及影响因素。结果表明: 1) 深圳市红树林湿地表层沉积物的矿物组成以黏土矿物(16.5%~73.5%)和石英(22.0%~81.2%)为主, 随着深度增加, 不同样地的沉积物中钾长石、黄铁矿和石盐等矿物含量存在差异; 2) 表层沉积物中, 黏土矿物主要为伊蒙混层矿物(44%~76%)、高岭石(0%~40%)、绿泥石(0%~24%)和伊利石(2%~21%), 以伊蒙混层矿物为主; 3) 不同深度的沉积物中黏土矿物组成与表层沉积物基本上一致, 与沿海区域没有植被的珠江口和大亚湾等地的沉积物存在显著差异。相关性分析结果表明, 深圳市红树林湿地沉积物的矿物组成主要受盐度、总硫(TS)和总有机碳(TOC)影响, 其黏土矿物组成则主要受pH值、盐度、TOC和沉积物粒径影响。     

致密砂岩储层黏土矿物特征及敏感性分析—以鄂尔多斯盆地吴起油田寨子河地区长6油层为例

致密砂岩储层孔喉结构复杂、比表面积大,岩石颗粒表面附着大量的黏土矿物,容易受到外来流体的影响,发生颗粒膨胀、迁移、离子沉淀等反应伤害储层,从而影响生产效率。本文以鄂尔多斯盆地吴起油田寨子河地区延长组6段油层为例,通过岩石薄片观察、扫描电镜、X射线衍射仪(X-RD)实验、压汞实验和储层敏感性实验等方法,对研究区储层物性、孔喉结构、黏土矿物特征和储层敏感性类型、伤害程度及敏感性影响因素进行分析。岩心分析实验表明,储层黏土矿物由绿泥石、高岭石、伊利石和伊蒙混层4种矿物组成,影响储层渗透性的敏感性伤害强弱依次为酸敏、水敏、碱敏、盐敏和速敏。并结合实际生产中存在的问题,提出绿泥石富集区域尽量避免储层酸化等改造措施;对伊利石及伊蒙混层含量高、易水敏的地区,压裂改造过程需要提高压裂液砂比,减小压裂液量,从而降低储层损害。     

二连盆地巴彦乌拉铀矿床目的层粘土矿物特征及其意义

二连盆地巴彦乌拉铀矿床是我国典型的古河谷砂岩型铀矿床,铀主要经潜水-层间氧化作用富集成矿。为了研究其粘土矿物组成、含量、形态特征及其产状,对区内目的层粘土矿物进行了X射线衍射、扫描电镜及能谱分析。分析结果表明,二连盆地巴彦乌拉铀矿床目的层粘土矿物成分基本一致,主要为蒙脱石、高岭石、伊利石,个别样品中见少量绿泥石。蒙脱石集合体呈花朵状、片状,高岭石集合体呈书页状、扇状,伊利石集合体呈片状,绿泥石集合体呈玫瑰花朵状。粘土矿物以分散质点式不完全充填于孔隙中和薄膜式贴附于颗粒表面。根据分析结果,文章总结了该矿床氧化带分带粘土矿物特征,并探讨了粘土矿物对砂岩的孔隙度和渗透率的影响及其与铀成矿的关系。     

木钵延10油层水敏伤害研究

目的 为保护储层以及提高油层采收率提供依据。方法 利用真实砂岩微观模型对木钵延10油层进行了水敏伤害研究。结果 该油层黏土含量4．4％～11％，黏土组成以伊利石为主，伊／蒙混层和高岭石黏土矿物次之，不含或极少含有绿泥石；黏土矿物具有膨胀、分散、运移的特性，易造成储层的水敏和速敏伤害；目前的注入水将对储层造成中等程度的水敏伤害，采取高矿化度盐水及逐渐降低矿化度的注入方式，对减弱储层水敏伤害有利，最佳注入水盐度为15.6～5．2g／L。结论 水敏伤害是造成木钵延10区块注水压力高、注水量低的不可忽视的原因，应尽量使注入水矿化度高于注入流体的矿化度阈值(5．2～2．18g/L)，以减轻水敏伤害。     

粘土矿物分析及其指示的气候意义 ——以毛乌素沙漠滴哨沟湾为例

以毛乌素沙漠东南缘萨拉乌苏河流域滴哨沟湾剖面DGS1层段为代表,对其粘土矿物组成进行分析.结果显示,DGS1层段粘土矿物以石英、钾长石、钠长石、伊利石、蒙脱石、方解石和绿泥石为主,各层位均不含高岭石.各种沉积相矿物组成基本一致,说明该地区的矿物来源基本一致.不同沉积相粘土矿物含量不尽相同,沙丘砂、次生黄土中的石英、长石、伊利石、绿泥石等代表干、寒气候的粘土矿物含量高,湖沼相中的蒙脱石、方解石等代表暖湿气候的粘土矿物含量高,个别湖沼相层位出现了白云石.粘土矿物组分表现出萨拉乌苏河流域全新世气候特征:本地区全新世总体偏冷干,各沉积相缺失高岭石而均存在绿泥石可为证明;本地区全新世气候分为两个主要气候阶段,早期到中期堆积湖沼相为主的时期气候相对温暖湿润;中期以后到现在堆积次生黄土和沙丘砂的阶段气候相对寒冷干燥.     

Nd isotopic variations and its implications in the recent sediments from the northern South China Sea

The chondrite-normalized REE distribution patterns in recent sediments from the northern South China Sea and surrounding areas are similar, with the HREE values being almost equal to or slightly higher, and the La_N/Lu_N ratio being lower, than PAAS standards. However, samples from the Xijiang River, a major branch of the Pearl River system, show opposite trends, i.e., with slightly lower HREE values and higher La_N/Lu_N ratio than PAAS. The distribution of Nd isotopes in sediments from the northern South China Sea was controlled by the Pearl River and the inshore area of South China, respectively. The volume of ε_Nd(0) from inshore areas of southern China is apparently higher than that from the Pearl River, and ε_Nd(0) values in offshore sediments and Taiwan Island are between these values. The results clearly show that ε_Nd(0) volume in the northeastern South China Sea is higher than in the southwest part of the northern South China Sea, indicating different source rock types. The main source rock of the Pearl River sediment is carbonate types and affects sediment deposition in the southwest of the northern South China Sea, while the source rock in the inshore area of southern China, mainly Mesozoic and Cenozoic granites, contributes to sediments in the northeastern area of the northern South China Sea. Due to different source rock types, the HREE values and the volume of ε_Nd(0) in recent sediments supplied by the inshore area of southern China are higher than those from the Pearl River. Over 80% of the rapidly accumulated sediments on the northern slope of the South China Sea in the southeast of Dongsha Islands area were derived from Taiwan Island and from inshore areas of South China, with only less than 20% from the Pearl River. Supported by National Natural Science Foundation of China (Grant Nos. 40276019, 40238060 and 40621063), and National Basic Research Program of China (Grant No. 2007CB819501)     

新生代早期南海北部水系演变

 珠江在早渐新世仅是涉及华南沿海地区的小河；到晚渐新世，向西延伸到云贵高原前缘地带；到中新世，现代珠江流域格局初步形成。证据显示，南海北部还发育过一条源自南海西部隆起区的大型水系-昆莺琼古河，后淹没在南海之中，但在南海的沉积充填过程中扮演了重要角色。南海北部水系及沉积环境的重建，对于深刻认识南海新生代早期古地理特征以及该地区的油气勘探均具有重要意义。     

黑龙江七台河地区城子河组绿泥石垂向分布异常分析

运用X射线衍射和X射线荧光分析技术,对黑龙江七台河地区侏罗系上统城子河组的87、90、95和98号煤层顶底板及夹矸中的绿泥石进行了研究.结果表明,研究区粘土矿物以伊蒙间层矿物、伊利石和绿泥石为主,绿泥石含量在2％～17％.随着埋藏深度增加,成岩作用增强,绿泥石含量逐渐降低,且由富Mg绿泥石转变为富Fe绿泥石.研究区绿泥...     

Late quaternary glacial cycle and precessional period of clay mineral assemblages in the western pacific warm pool

Variability of clay mineral assemblages in the Western Pacific Warm Pool (WPWP) over the past 370 ka shows the prominent glacial-interglacial cyclicity. Smectite (62%?C91%) is the dominant clay mineral, with decreased contents during interglacials while increased in glacials. In contrast, variations in chlorite (4%?C21%), illite (4%?C12%), and kaolinite (2%?C10%) share a similar pattern with higher contents during interglacials than glacials, mirroring to that of smectite. The results indicate that the smectite-dominated clay minerals derive mainly from the river detrital inputs of New Guinea. The glacial-interglacial cycle of clay mineral assemblages well correspond to the fluctuation of sea level. When the sea level was low, the river materials can travel more easily across the narrow shelf off the island of New Guinea, inject directly into the subsurface currents flowing westwards, then merge into the Equatorial Undercurrent (EUC), and eventually deposit on the central part of WPWP. Precessional periods of the smectite content indicate the intensity of mechanical erosion in its provenance of New Guinea, responding to the river runoff and precipitation, and this could also be linked to the meridional migration of the Intertropical Convergence Zone (ITCZ).     

苏宏图白垩系粘土岩元素地球化学和粘土矿物特征及其古气候意义

为了探究苏宏图地区白垩系苏红图组的古气候环境,应用X射线荧光光谱(XRF) 和电感耦合等离子体质谱(ICP-MS) 方法研究了粘土岩样品的元素地球化学特征,结果表明：P、Mn、Sr/Cu、Mg/Ca、SiO2/Al2O3等元素特征指示白垩系苏红图组总体呈现极度干燥的沉积环境,不同亚相之间沉积环境稍有干湿变化,且扇三角洲相对湿暖;通过XRD和SEM方法研究了全岩矿物组成和粘土矿物类型和组合特征,结果表明：伊利石为主要的粘土矿物,其次为绿泥石、高岭石,粘土矿物的组合类型为伊利石、绿泥石的组合,且绿泥石和高岭石呈现此消彼长的现象,反映了干燥寒冷的沉积环境,并伴随着干湿的气候变化。     

柴达木盆地北缘下侏罗统储集岩成岩作用及其对孔隙演化的影响

柴达木盆地北缘下侏罗统储集岩主要是由长石岩屑砂岩和岩屑砂岩组成,主要的成岩作用有压实作用、胶结作用、溶蚀作用、交代作用和重结晶作用,它们对孔隙的发育影响很大.压实作用和碳酸盐的胶结作用使原生孔隙大大减少.长石的溶蚀作用改善了孔隙的发育.蒙皂石、伊利石、高岭石、绿泥石和伊蒙混层含量均在较大范围内变化,与深度的关系不明显.成岩作用进入晚成岩作用末期.一些储集岩经历了表生成岩作用.     

强震区典型窄陡沟道型泥石流发育特征

针对汶川强震区5条典型窄陡沟道型泥石流进行实地勘察。通过室内颗分试验、激光衍射粒度分析试验、X射线衍射试验,分析了强震区窄陡沟道型泥石流的基本发育特征、堆积物颗粒级配和黏土矿物定量组成。结果表明：(1)强震区窄陡沟道型泥石流典型发育特征除了地形地貌上的“窄”和“陡”外,震后松散物源量中崩滑物源和沟道堆积物源显著增多,动储量比例增大,造成强震区窄陡沟道型泥石流危险性显著提高;(2)强震区窄陡沟道型泥石流堆积物固体颗粒级配分布范围较广,连续性较好。级配曲线不均匀系数均大于5,曲率系数在0.95～3,无缺失粒组;粒径小于0.075 mm的粉粒含量均在0.5%以下,粒径小于0.005 mm黏粒含量均在0.11%以下,不同沟道间差别较小;(3)强震区窄陡沟道型泥石流堆积物黏土矿物主要由伊利石、绿泥石和伊蒙混层3种黏土矿物组成,各自含量平均值分别为45.6%、38.8%、15.6%。伊利石和绿泥石总含量均超过75%,伊蒙混层含量均在25%以下。开展汶川强震区的典型窄沟型泥石流发育特征分析,对于地质灾害泥石流风险评估、监测预警和防控具有重要意义。     

南海碳的生物地球化学研究进展

简述南海碳的生物地球化学的研究进展,重点介绍国家杰出青年基金课题“南海碳的生物地球化学循环研究-胶体的显著作用”的研究内容,报道了近年来我们在该领域的最新阶段性研究成果。     

贵州早、中三叠世间绿豆岩粘土矿物学研究

运用Ｘ射线衍射、红外光谱、差热分析、扫描电镜等分析方法，对贵州绿豆岩进行了系统的粘土矿物学研究。确定了贵州绿豆岩中粘土矿物主要有伊利石、蒙脱石、高岭石和伊利石／蒙脱石混层矿物，为贵州绿豆岩的成因研究和开发利用提供了依据。     

粘土矿物定量分析偏差的修正

应用Ｘ射线衍射定量分析方法中的基体清洗法及其演化而来的自清洗法对粘土中常见矿物蒙脱石、绿泥石、高岭石、伊利石、长石、方解石、白云石、赤铁矿、蛋白石的Ｋ值进行了实验测定。在此基础上提出了采用稀释法,即外加一定量石英对由于粘土矿物结晶度和定向度差异所引起定量分析偏差进行修正的方法。