A Preliminary Interpretation of Near-field Observation Data of the Zhangbei Earthquake

In this paper, a preliminary data processing was made for tbe aftershock records or theZhangbei M6.2 earthquake on Jan. 10, 1998. The hypocenters of 205 earthquakes with M_L≥0.5 were located. The result shows that most aftershockS were concentrated in a more than10 km long and 5～8 km wide NE-trending beIt. The source mechanism solutions of largeraftersbocks were also calculated, from which it can be inferred that the faulted zone of themain shock is an NE-trending fault. Furthermore, the spectral analysis of P waves was made.The corner frequency is about 10 Hz.     

滇西北高原一次冰雹灾害天气过程成因诊断及预报

对2010年7月27日发生在滇西北宁蒗县境内一次局地降雹灾害过程进行诊断分析,结果表明:本次降雹过程的主要客观物理量条件是具备充沛的水汽条件、不稳定条件及较强的垂直上升运动条件,但过程前除具备降雹的不稳定条件外,水汽及动力条件均不满足;降雹过程前的数值预报产品分析表明,数值预报产品对本次过程的主要影响系统、水汽条件、垂直运动条件、不稳定条件均有一定的预测能力。因此,在分析主要影响系统及物理量诊断产品(包括数值预报产品)条件下,结合卫星云图及雷达回波可对局地冰雹灾害天气提前预报预警。     

DISCUSSION ABOUT THE PETROGENESIS OF THE CENOZOIC VOLCANIC ROCKS FROM YUMEN AND HOH XIL AREA, QINGHAI-TIBET PLATEAU

DISCUSSION ABOUT THE PETROGENESIS OF THE CENOZOIC VOLCANIC ROCKS FROM YUMEN AND HOH XIL AREA, QINGHAI-TIBET PLATEAU     

颅颌面外科与三维重建技术

目的 探讨电子束ＣＴ三维重建技术在颅颌面外科的适应症和应用价值。方法 采用美国Ｉｍａｔｒｏｎ公司的电子束ＣＴ（ｅｌｅｃｔｒｏｎ ｂｅａｍ ＣＴ,以下简称ＥＢＣＴ）Ｃ－１５０,对７６例严重颅颌面病人实行薄层ＣＴ容积扫描。将所获ＣＴ 象经数字接口传至加拿大ＩＳＧ公司生产的Ａｌｌｅｇｒｏ工作站进行三维重建。结果 ＥＢＣＴ成像技术能立体的、详尽和精确的显示机体组织三维解剖结构极其相互关系。其再现畸形或病体     

四川筠连地质遗迹景观资源特征及保护开发建议

筠连地质遗迹景观区具有丰富的泉类、岩溶峰丛地貌等景观。其中尤以间歇潮涌泉、洞内泉类钙化沉积边石坝、石莲花地质遗迹景观最具特色。这些地质景观资源具有重要的科学考察意义和旅游观赏价值,其他配套旅游资源及开发条件良好。细述了各个景观资源的特征,提出了建设筠连地质公园的构想和开发保护的建议。     

湛江观海长廊红树林土壤-植物体系重金属富集与迁移规律

选取湛江市霞山区观海长廊红树林湿地为研究区域,运用电感耦合等离子体质谱仪(ICP-MS)测定红树林表层土壤及红树植物根、枝、叶中重金属(铜Cu、锌Zn、铅Pb、镉Cd、铬Cr、镍Ni、砷As)的质量分数;运用Hakanson潜在生态风险指数评估红树林土壤的重金属污染风险水平,结合相关性分析和聚类分析探讨重金属的影响因素...     

成都平原区水稻土成土剖面Cd形态分布特征及影响因素研究

成土过程中不同形态镉(Cd)迁移转化的影响因素研究对于了解Cd的地球化学行为具有非常重要的意义。以四川省成都平原区农田生态系统水稻土剖面中不同形态Cd分布特征为例,探讨成土过程中不同形态Cd的迁移转化影响因素及其生态危害性。结果表明:总量Cd、离子交换态Cd和碳酸盐Cd均表现出表层富集,深层含量稳定的特征;岷江流域和沱江流域水稻土Cd含量的背景值分别为0.147,0.215mg·kg-1。外源输入耕层土壤中Cd主要为活动态,其增加量占Cd总量增加量的60.71%~90.52%,向下垂向迁移能力非常弱。成土过程随着土壤中Cd总量增加,稳定态Cd含量显著增加,而活动态Cd含量明显降低。土壤的pH值主要对碳酸盐态Cd含量有影响,pH值越大,其含量越高;随着土壤成熟度增高,粉粒和粘粒含量增加的同时,残渣态Cd含量显著降低,而有机结合态Cd含量显著增高。耕层土壤中Cd的生物有效性系数高达0.59~0.65,已经严重地影响到农作物安全。     

PETROCHEMISTRY AND MINERALOGY EVIDENCES FOR THE WEATHERING PROCESS OF THE WEATHERING PITS ON ROCK SURFACES OF MOUNTAIN LAOSHAN,CHINA

2011年5月对崂山山顶风化坑进行考察和采样,通过对风化坑内碎屑和坑外岩石的粉晶X射线衍射矿物分析、X射线荧光光谱化学全量分析,研究了风化坑内外的矿物风化及各元素迁移特征,对风化坑的成因过程进行探讨.研究结果表明:1)崂山山顶风化坑碎屑的英长比总是大于其周边岩石的英长比,说明风化坑的形成是花岗岩造岩矿物差异风化的结果;2)风化坑风化过程中被风化的岩石矿物主要是条纹长石和钾长石;3)风化坑中大量的Mg和Ca主要是外部加入的;4)崂山山顶风化坑内碎屑,坑外岩石面均受到化学风化的作用;5)崂山山顶风化坑内外的风化指数CIA值并不反映崂山当地的气候,山上山下CIA值的差异是风化时间长短不同造成的;6)LOI能很好地反映崂山风化坑内外风化强度的差异,说明长石主要在水解作用下发生分解,也说明了风化坑的积水成因.     

相山及邻区七个火山盆地火山岩岩性特征及成因探讨

本文研究赣杭构造带西南端相山及其邻区7个火山盆地主体岩石的特征和成因,从地质产状、岩性、岩石化学等方面做了论述。采用了红外光谱、矿物包裹体、高温实验等研究方法,探讨了岩石的形成机理。相山主体岩石是一种成因特殊的火山碎屑（斑）熔岩,即岩颈碎屑熔岩和岩流碎屑熔岩。相山等火山盆地主体岩石边部的塑性岩屑不是熔离成因,而是由火山喷发作用形成的。火山碎屑熔岩中的斜长石牌号变化大,钾长石主要是低透长石,表明岩石的形成具有高温特征。不同岩石相的矿物中的熔融包裹体有明显的形态标型。碎眉熔岩中的石英碎斑结构,主要是高温热炸裂成因的。7个火山盆地中的主体岩石可划分两大类:相山、玉华山和礼陂火山盆地的主体岩石是火山碎屑熔岩;高家、林家、谙源和谭港火山盆地的主体岩石是弱熔结凝灰岩。     

CH4 inclusions in orogenic harzburgite: Evidence for reduced slab fluids and implication for redox melting in mantle wedge

Fluids released from the subducting oceanic lithosphere are generally accepted to cause mantle wedge peridotite melting that produces arc magmas. These fluids have long been considered to be dominated by highly oxidized H₂O and CO₂ as inferred from erupted arc lavas. This inference is also consistent with the geochemistry of peridotite xenoliths in some arc basalts. However, the exact nature of these fluids in the mantle wedge melting region is unknown. Here, we report observations of abundant CH₄ + C + H₂ fluid inclusions in olivine of a fresh orogenic harzburgite in the Early Paleozoic Qilian suture zone in Northwest China. The petrotectonic association suggests that this harzburgite body represents a remnant of a Paleozoic mantle wedge exhumed subsequently in response to the tectonic collision. The mineralogy, mineral compositions and bulk-rock trace element systematics of the harzburgite corroborate further that the harzburgite represents a high-degree melting residue in a mantle wedge environment. Furthermore, existing and new C, He, Ne and Ar isotopes of these fluid inclusions are consistent with their being of shallow (i.e., crustal vs. deep mantle) origin, likely released from serpentinized peridotites and sediments of the subducting oceanic lithosphere. These observations, if common to subduction systems, provide additional perspectives on mantle wedge melting and subduction-zone magmatism. That is, mantle wedge melting may in some cases be triggered by redox reactions; the highly reduced (∼ΔFMQ-5, i.e., 5 log units below the fayalite-magnetite-quartz oxygen fugacity buffer) CH₄-rich fluids released from the subducting slab interact with the relatively oxidized (∼ΔFMQ-1) mantle wedge peridotite, producing H₂O and CO₂ that then lowers the solidus and incites partial melting for arc magmatism. The significance of slab-component contribution to the geochemistry of arc magmatism would depend on elemental selection and solubility in highly reduced fluids, for which experimental data are needed. We do not advocate the above to be the primary mechanism of arc magmatism, but we do suggest that the observed highly reduced fluids are present in mantle wedge peridotites and their potential roles in arc magmatism need attention.