洛川黄土纳米尺度观察：纳米棒状方解石

本文对洛川黄土剖面典型样品进行了透射电镜分析，发现黄土中存在纳米棒状方解石。此类方解石直径30～50nm，长度几百纳米至几微米。纳米棒状晶体有圆滑地粗细变化和弯曲现象，偶见晶体连接成树枝状或晶体直角连接形成框架状形态。X-射线能谱分析显示方解石有少量的镁、磷和硫，这种纳米棒状方解石在国内外文献中鲜有报道。根据纳米尺度研究结果推测，这种纳米棒状方解石形成与生物衍生物诱导的定向结晶有关。纳米棒状方解石是一种重要的黄土堆积时期干旱环境指示矿物，其碳、氧稳定同位素组成代表黄土堆积时气候参数。纳米棒状方解石的发现，对环境中纳米矿物研究、黄土中碳酸盐碳成因及古气候研究具有重要价值。     

时间域瞬变电磁法在地质勘查中的应用

在介绍对瞬变电磁法原理、方法技术以及资料解释等的基础上，论述了该方法在金属矿产勘查中的深埋矿体的探测、划分构造格局以及利用井中TEM确定井旁盲矿等方面的应用实例。应用结果表明，瞬变电磁法在固体矿产找矿中，具有工作效率高、分辨率高且勘探深度较大和空间定位效果好等优点，它是固体矿产勘查的有效方法之一。     

Recrystallization mechanisms of fergusonite from metamict mineral precursors

The metamict state and recrystallization of fergusonite in metamict natural samples were studied by thermal methods (TGA-DTA), X-ray powder diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and electron microprobe (EPMA). Two metamict mineral samples of fergusonite were investigated in order to identify the original premetamict crystal structure and to identify recrystallization mechanisms. The TEM data and RS provided evidence on the partial preservation of the original structure in the investigated minerals, which are X-ray amorphous. It was shown that fergusonite could recrystallize from a metamict mineral with original fergusonite structure or from metamictized pyrochlore, which was altered before or after metamictization. Two recrystallization mechanisms were recognized: (a) epitaxial growth occurring at the boundary between preserved premetamict structure fragments and completely metamictized areas, and (b) nucleation-crystal growth mechanism occurring in completely amorphous areas of the minerals, and resulting in recrystallization of the original mineral as well as in the crystallization of a new mineral with a modified chemical composition as compared to the initial matrix.     

大别高压和超高压榴辉岩中绿辉石的透射电镜研究

近年来有关大别山超高压变质岩的研究取得了重要进展。但对榴辉岩的显微和超微构造的研究仍然不足。榴辉岩主要由石榴石和绿辉石组成,其中石榴石基本上相当于刚性体,除非在很高温条件下石榴石才发生韧性变形［１～４］。因此,笔者对高压和超高压榴辉岩中的绿辉石进行了...     

钙稀土氟碳酸盐中四种B10S8新规则混层矿物的透射电镜研究

根据HRTEM研究，在四川西昌地区的钙稀土氟碳酸盐矿物衍生多晶体中发现了四种不同的B10S8型[即氟碳怖矿（B）／直氟碳钙铈矿（S）为10：8]新规则混层矿物（B10S8－I，B10S8－Ⅱ，B10S8-Ⅱ和B10S8－Ⅳ）。用SAED和HREM方法确定了四种新规则混层矿物的晶体结构对称性、晶胞参数、结构堆垛模式及晶体化学式等。四种B10S8新规则混层矿物结构中，Ce－F离子层的堆垛层序以及两个Ce－F离子层之间的碳酸根离子层的排列方式均不同。同时还观察到该类矿物中的畸结构及堆垛层错等。     

清镇陨石中顽火辉石的高分辨电镜研究

清镇陨石中顽火辉石的(010)取向结构象清楚地显示出单斜顽火辉石(CLEN)和顽火辉石(OREN)连生现象其特点说明它经历了急冷且受到很弱的后期热变质作用,同时,电子衍射和光学衍射及结构象均显示其中有27的长周期结构。     

Botryococcus—A planktonic green alga, the source of petroleum through the ages: Transmission electron microscopical studies of oil shales and petroleum source rocks

The hydrocarbon secreting alga Botryococcus has been identified in organic remains of sediments ranging from Precambrian to Recent, and is believed to have been a major source material for petroleum generation throughout the geological time. In some petroleum source rocks of Lower Palaeozoic and Precambrian age, identification of the alga is only possible by electron microscopy. Transmission electron microscopy (TEM) has been used in the present study to identify microstructures of the algal remains in a range of oil shales and petroleum source rocks. It has been established that Botryococcus is the predominant alga in the Kukersite oil shale of Estonia. Similarly, the alga has been shown to be a major contributor to petroleum source rocks in Cambrian and Precambrian sedimentary basins in Australia. TEM has been applied to observations of Botryococcus in torbanites and to products from simulated maturation experiments on torbanite. A comparison with algal remains from Cambrian and Precambrian sediments ranging from undermature to overmature, enabled the distinction of organic matter in various stages of oil generation. Maturation/thermal effects on alginite have been established by reflectance and fluorescence, and compared with experimental results.     

天然钒钛磁铁矿中出溶现象的高分辨电镜观察

利用高分辨电子显微镜及微区X射线能谱成分测定的方法,对含钒的天然磁铁矿的精细结构进行了研究。结果表明,[110]方向的高分辨像清楚地显示钒钛磁铁矿在磁铁矿基体中以共(110)面紧密连生的方式与基体共生,形成波状连生体。这种成份调制波结构表明它们是出溶产物。     

Further studies on torbanites and coorongite using transmission electron microscopy and C-isotope analysis

Transmission electron microscopy of torbanites from various localities in eastern Australia has revealed micro-organisms of possible methanogenic affinity. Botryococcus remains in the torbanites displayed close resemblance to the rubbery B. braunii accumulations deposited in recent bodies of freshwater origin. Compaction and collapse of structure seem to be the major visible alteration to the algal colonies. C-isotope compositions of the torbanites favour methanogenic activity. Comparison with recent botroyococcal accumulations support diagenetic alteration at a very early stage of deposition.     

Cation ordering in omphacite and effect on deformation mechanism and lattice preferred orientation (LPO)

We present microstructural data and lattice preferred orientations (LPOs) of omphacites from a suite of eclogites, from the Adula/Cima Lunga nappe (Central Alps). Our work shows a surprisingly strong correlation between the measured LPO and the ordering state of cations in omphacite. Estimates of deformation temperature from metamorphic petrology, together with measured omphacite compositions and LPOs, determine the field (ordering state), on the omphacite phase diagram, into which each sample falls. LPOs dominated by L-type and S-type signatures are developed in samples that fall in the P2/n field (ordered structure) and C2/c field (disordered structure), respectively.Dislocations with b=1/2−110 or b=[001] are observed in the transmission electron microscope (TEM) in all samples. The former change from a perfect dislocation in the C2/c structure to a partial in P2/n. Any movement of a partial dislocation requires the formation or growth of a stacking fault. Furthermore, in order to pass an obstacle a partial dislocation has to constrict to a unit dislocation. The energy to form a constriction is high in omphacite due to the large separation width. Thus, the activity of the b=1/2−110 dislocation is hindered in the P2/n structure relative to the C2/c structure, which change the balance between the two and might give rise to the different LPOs.