文安MS5.1地震前区域形变异常研究

对2006-07-04文安MS5.1地震前2001~2004年区域GPS站速度场和应变率场使用刚性-线弹性运动模型拟合处理的结果进行研究,获得文安MS5.1地震的1~3 a期的前兆异常。结果表明,地震发生在异常区高异常体发育的边缘梯度带的转折处。     

Zircon U-Pb geochronology and geochemistry of syenogranites in western Niubiziliang,northwestern Qaidam,Qinghai

The study presents the results of U-Pb dating of zircons and whole-rock geochemical analyses of a syenogranite located in the western Niubiziliang area,China with the aim of determining its formation time,petrogenesis and the regional tectonic setting. Zircons within the syenogranite are euhedral-subhedral and display rhythmic growth zoning,indicating a magmatic origin. Zircon U-Pb data obtained by LA-ICP-MS indicate the syenogranite formed in the Late Permian (260.7±1.5 Ma). The w(SiO_2) of syenogranites is 70.82%--73.59%,w(Al_2O_3) is 13.49%--14.82%,and w(Na_2O + K_2O) is 7.85%--8.52%,and yield K_2O/Na_2O ratios of 1.06--1.26. Therefore,the syenogranites belong to the high-K calc-alkaline and metaluminous (A/CNK 1,A/NK 1) series which display I-type granites similarly. The syenogranites also show the geochemical characteristics of volcanic arc rocks,being enriched in large-ion lithophile elements (LILEs; K,Rb) and light rare-earth elements (LREEs; La,Ce,Sm,Nd),but depleted in high field strength elements( HFSEs; Ta,Nb,P,Ti). On the whole,trace element ratios are close to the mean of the Earth's crust,indicating a lowercrust magma source. The low Sr (161--214) ×10~(-6) and Yb (1.08--1.80)×10~(-6) concentrations indicate that plagioclase and hornblende are residual mineral phases in the source. The regional geology and whole-rock geochemistry suggest that the formation of the syenogranites was related to subduction of the Zongwulong Ocean crust,and the north margin of Qaidam Block during the Late Permian was in an active continental margin tectonic setting.     

构造应力场三维数值模拟的有限单元法

目前构造应力场的研究主要是基于平面的二维分析,随着油气成藏过程三维模拟的发展,应力场的三维数值模拟显得越来越重要.从三维空间角度出发,分析了应力场的有限元模拟与求解的整个过程.基于不规则六面体单元的角点网格数据模型,对有限元求解法进行了分析与研究并提出计算方法.基于不规则角点网格数据模型的三维构造应力场有限元计算方法是本文的创新点.最后用上述方法对东营凹陷的牛庄-王家岗区域三维应力场进行了实际模拟计算,计算结果相比于其他数据模型更符合实际情况.      

2010年玉树Ms7.1地震前的重力变化

利用中国地壳运动观测网络1998—2008年绝对重力和相对重力观测资料,获得了玉树地震区域重力场及其动态变化,从动态的观点研究了2010年4月14日玉树Ms7.1地震前区域重力场演化特征及其与地震活动的关系。结果表明：1)重力变化与甘孜 玉树断裂构造活动存在密切的空间联系,重力测量较好地反映了伴随活动断层的物质迁移和构造变形引起的地表重力变化效应;2)区域重力场动态图像较完整地反映了2010年4月14日玉树7.1级地震孕育、发生过程中出现的流动重力观测得到的异常前兆信息;3)玉树震中附近重力点值时序变化累积量超过80× 10^-8 ms-2,较好地反映了玉树地震前重力测点随时间的剧烈波动性上升变化。     

龙门山断裂带三维滑动速率反演及其分段性研究

基于负位错模型,结合粒子群算法反演龙门山中央断裂段的三维滑动速率。反演结果表明,龙门山断裂带的现今构造运动整体而言为右旋逆冲断层,滑动速率较小,其运动特征具有显著的分段性。断裂带南段以逆冲为主,兼有左旋特征;在向北延展过程中逐渐转化为右旋走滑,且走滑分量逐渐加大;龙门山断裂带南北两端具有挤压特征,其中段显示一定的拉张。由此推断,龙门山断裂带现今构造活动,在青藏块体整体移动的影响下,还与其区域应力场和内部地壳结构有关。基于负位错模型,结合粒子群算法反演龙门山中央断裂段的三维滑动速率。反演结果表明,龙门山断裂带的现今构造运动整体而言为右旋逆冲断层,滑动速率较小,其运动特征具有显著的分段性。断裂带南段以逆冲为主,兼有左旋特征;在向北延展过程中逐渐转化为右旋走滑,且走滑分量逐渐加大;龙门山断裂带南北两端具有挤压特征,其中段显示一定的拉张。由此推断,龙门山断裂带现今构造活动,在青藏块体整体移动的影响下,还与其区域应力场和内部地壳结构有关。     

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青海省扎日根结扎群火山岩形成时代及构造背景分析

青海扎日根结扎群火山岩中基性岩以贫硅、钾,高钛、钙,中性岩类以低硅、中钾、钛、钙,酸性岩类以高硅、钾,中钛,低钙为特征。根据Fe＊/MgO-TiO2图解上显示出本区火山岩绝大多数火山岩落在岛弧区。微量元素中Th/Nb=0.9〉0.11,Nb/Zr〉0.04显示出其构造背景为陆-陆碰撞形成的岛弧区。扎日根结扎群火山岩时代Rb-Sr同位素等时线给出的年龄为231±28Ma和225±8 Ma,属晚三叠世。另外Sr同位素的初始比值ISr=0.70522±0.00023,小于0.719,表明岩浆（原始）来源于上地幔,并且在上升的过程中受到地壳的混染。     

大连开发区大小窑湾港址区域及场地稳定性研究

本文在分析区域地质新构造运动、地震及工程地质资料的基础上,对大连经济技术开发区大小窑湾港址的区域及场地稳定性作了研究,认为该区属次不稳定区,对场地而言,缓丘,红粘土砾石段和粘性土等地段为稳定性较好的地段。     

Origin of CO_2 in natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin

The natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin contains high H2S whereas relatively low CO2 concentrations and the CO2 display high δ13C values (ranging from -5.81‰ to 3.3‰ (PDB)). This seems to contradict the conventional wisdom that TSR should be a primary source of CO2 in natural gas from the Feixianguan Formation. In contrast, many authigenic calcite samples from these sites display very low δ13C values (ranging from -18.4‰ to -10.3‰ (PDB)). This suggests that the carbon from TSR source dominated the formation of calcite whereas the carbon from inorganic source came into CO2 in natural gas. In order to assess the origin of CO2 from these H2S-rich sites, we have calculated the relative contributions of organic and inorganic carbon sources to the CO2 and authigenic calcite. The organic carbon source possibly originated from TSR, whereas the inorganic one might be generated from marine carbonates dissolution. This calculation is based on the carbon isotopic compositions of CO2 and authigenic calcite as well as an isotopic mass balance. The results show that the contribution of organic carbon source to the CO2 is only 2%, whereas that to authigenic calcite is as high as 43% on average. Such results combined with thermodynamic evidence indicate that the isotopically light CO2 produced by TSR process may contribute to authigenic calcite precipitation during burial diagenesis. Distinguishable from Ordovician reservoir of Tarim Basin, Feixianguan reservoir of Northeast Sichuan Basin experienced rapid tectonic uplift due to Yanshanian movement after TSR occurred. Such tectonic event could induce temperature decrease and further promote carbonates dissolution. During these processes, secondary porosity has developed in Feixianguan carbonate reservoirs. Therefore, much attention should be paid to the structural highs in search of high quality carbonate reservoirs.     

下扬子区海相中、古生界地质结构分区及其油气勘探选区意义

基于对下扬子区海相中、古生界构造及沉积沉降特征的研究, 以影响和反映构造稳定及晚期生烃的基底性质、构造变形特征、印支面埋深、沉积沉降中心迁移特征等为依据, 将下扬子区划分为5个一级、17个二级地质结构区。以构造稳定、有效保存及晚期生烃、晚期成藏等为评价标准, 综合评价南黄海中部晚期隆起稳定区(Ⅰ₂)、江都-东台-南黄海南部晚期沉降深冲断区(Ⅰ₃)、泰兴-海安晚期沉降深冲断区(Ⅱ₁)、南通-南黄海南部晚期沉降浅推覆区(Ⅱ₂)及太湖晚期沉降浅推覆区(Ⅱ₄)为下古生界油气勘探有利区; 南黄海北部晚期沉降深冲断区(Ⅰ₁)、江都-东台-南黄海南部晚期沉降深冲断区(Ⅰ₃)、滨海-大丰晚期沉降深下古卷入区(Ⅰ₄)和泰兴-海安晚期沉降深冲断区(Ⅱ₁)为上古生界油气勘探有利区; 南黄海北部晚期沉降深冲断区(Ⅰ₁)、滨海-大丰晚期沉降深下古卷入区(Ⅰ₄)、金湖-高邮晚期沉降深下古卷入区(Ⅰ₅)及泰兴-海安晚期沉降深冲断区(Ⅱ₁)为古潜山油气勘探有利区。研究对于该区海相中古生界勘探选区具有重要意义。