南海的形成演化与新特提斯在南海的重新活化

南海位于印度板块、欧亚板块和太平洋板块之间,是世界上最大的边缘海,其构造位置处于太平洋构造域和特提斯构造域,地质构造复杂。关于南海形成演化的动力学机制存在有多种不同观点,其中最重要的一个观点是印度板块与欧亚板块的碰撞致使华南地块和印支地块地幔物质沿东南方向蠕动,从而导致南海的海底扩张。从特提斯的演化规律,以及新特提斯的闭合过程来看,南海并不是特提斯洋的残留海,而是新特提斯在闭合过程中配合印度板块与欧亚板块碰撞导致华南地块和印支地块地幔物质东南方向蠕动的动力学机制下,在南海重新活化的结果。     

西北干旱地区凝结水试验研究

采用称重法,分别在非冻结期和冻结期,对不同土质的土样进行凝结水观测试验,分析讨论凝结水发生的条件、凝结水发生的时间、凝结水形成的主要影响因素、积雪条件下的凝结水、凝结水的数量及其变化以及凝结水的生态环境意义,研究成果对于认识干旱地区凝结水的形成机制及其生态环境意义具有重要价值.     

Geochemical constraints on the modes of carbonate precipitation in peridotites from the Logatchev Hydrothermal Vent Field and Gakkel Ridge

The ultramafic-hosted Logatchev Hydrothermal Field (LHF) at 15°N on the Mid-Atlantic Ridge and the Arctic Gakkel Ridge (GR) feature carbonate precipitates (aragonite, calcite, and dolomite) in voids and fractures within different types of host rocks. We present chemical and Sr isotopic compositions of these different carbonates to examine the conditions that led to their formation. Our data reveal that different processes have led to the precipitation of carbonates in the various settings. Seawater-like ⁸⁷Sr/⁸⁶Sr ratios for aragonite in serpentinites (0.70909 to 0.70917) from the LHF are similar to those of aragonite from the GR (0.70912 to 0.70917) and indicate aragonite precipitation from seawater at ambient conditions at both sites. Aragonite veins in sulfide breccias from LHF also have seawater-like Sr isotope compositions (0.70909 to 0.70915), however, their rare earth element (REE) patterns show a clear positive europium (Eu) anomaly indicative of a small (< 1%) hydrothermal contribution. In contrast to aragonite, dolomite from the LHF has precipitated at much higher temperatures (~ 100 °C), and yet its ⁸⁷Sr/⁸⁶Sr ratios (0.70896 to 0.70907) are only slightly lower than those of aragonite. Even higher temperatures are calculated for the precipitation of deformed calcite veins in serpentine–talc fault schists form north of the LHF. These calcites show unradiogenic ⁸⁷Sr/⁸⁶Sr ratios (0.70460 to 0.70499) indicative of precipitation from evolved hydrothermal fluids. A simple mixing model based on Sr mass balance and enthalpy conservation indicates strongly variable conditions of fluid mixing and heat transfers involved in carbonate formation. Dolomite precipitated from a mixture of 97% seawater and 3% hydrothermal fluid that should have had a temperature of approximately 14 °C assuming that no heat was transferred. The much higher apparent precipitation temperatures based on oxygen isotopes (~ 100 °C) may be indicative of conductive heating, probably of seawater prior to mixing. The hydrothermal calcite in the fault schist has precipitated from a mixture of 67% hydrothermal fluid and 33% seawater, which should have had an isenthalpic mixing temperature of ~ 250 °C. The significantly lower temperatures calculated from oxygen isotopes are likely due to conductive cooling of hydrothermal fluid discharging along faults. Rare earth element patterns corroborate the results of the mixing model, since the hydrothermal calcite, which formed from waters with the greatest hydrothermal contribution, has REE patterns that closely resemble those of vent fluids from the LHF. Our results demonstrate, for the first time, that (1) precipitation from pure seawater, (2) conductive heating of seawater, and (3) conductive cooling of hydrothermal fluids in the sub-seafloor all can lead to carbonate precipitation within a single ultramafic-hosted hydrothermal system.     

地下水化学动力学基本理论在矿井水文地质中的应用

根据西峪煤矿水化学及相关水文地质资料,运用地下水化学动力学的基本理论和方法,对西峪煤矿奥陶系峰峰组岩溶含水层水文地质条件进行了定量评价,从而划分出了含水层的强、弱径流带,为煤矿的安全生产提供了依据。     

鄂尔多斯盆地奥陶系海相碳酸盐岩生烃性能与中部长庆气田气源成因研究

用激光 -荧光显微镜等有机岩石学方法 ,挑选样品中有明显生、排烃现象的碳酸盐岩 ,再以测定的这类碳酸盐岩的有机碳含量为依据 ,确定本区高成熟碳酸盐气源岩残余有机碳的下限指标用 0 .13%～ 0 .14 %比较合理。根据碳酸盐岩储层孔隙中充填沥青和皮膜状残余沥青的分布和含量 ,论证了陕参 1井等奥陶系碳酸盐岩地层在地质历史中 ,存在若干油气有效储层。采用连续升温 ,步进取样的热模拟实验方法 ,揭示了本区煤与碳酸盐岩干酪根随热演化作用增强 ,烃类气体产物的干燥系数增大 ,δ1 3C1 、δ1 3C2 明显变重的规律 ,并根据样品实验结果推算 ,本区石炭系—二叠系煤最大生气阶段的δ1 3C1 应为 - 2 7‰～ - 2 8‰ ,碳酸盐岩最大生气阶段的δ1 3C1 应为- 31.7‰～ - 33‰。在气源成因判识中 ,根据主生气期阶段对天然气成藏储聚的贡献最大、甲烷碳同位素较重以及长庆气田风化壳气藏天然气δ1 3C1 重值区并不与石炭系—二叠系煤的镜质组反射率高值区匹配的现象等进行气源判识 ,认为长庆奥陶系风化壳气藏 ,具有下古生界海相碳酸盐岩气与上古生界石炭系—二叠系煤成气的混源成因     

江苏西南部晚侏罗世西横山组沉积特征及成因

江苏西南部晚侏罗世西横山组为一套粗碎屑岩—细碎屑岩及泥灰岩组成的陆相沉积岩，普遍含有火山物质。从地层分布、岩性特征、碎屑岩粒度统计分析表明，天生桥盆地和西横山盆地基本上是连续、贯通的，自东向西，由冲积扇相—河流相—湖泊相逐渐过渡，属于同一水中盆地中不同沉积相的产物。沉积物主要来自盆地东部，可能与“古茅山”隆起带有关。     

花江喀斯特峡谷地区石漠化成因初探

花江喀斯特峡谷区地下水埋藏深,地表干旱,存在显著的人为加速土壤侵蚀过程,植被次生性明显,生境干热特征显著,是已石漠化和半石漠化的生态系统。其中地质构造、地貌演化、岩溶形态、可开发利用的水资源、植被群落可能是石漠化过程的主要自然成因,以土地利用为表现形式的强烈人类活动是石漠化的驱动力。基于此,提出了石漠化地区的土地利用方式和生态恢复过程的建议,旨在为石漠化的演化研究及生态重建提供参考。     

蒙古国查干苏布尔加大型铜-钼矿床地质特征及成因

查干苏布尔加斑岩铜钼矿床位于西伯利亚板块南缘近东西向和北东向深大断裂所夹持的南蒙古构造岩浆带内,容矿围岩二长花岗斑岩与花岗闪长斑岩主量元素高SiO2(64.69×10-2~73.42×10-2),高Al2O3(15.33×10-2~18.35×10-2),贫MgO(0.13×10-2~0.56×10-2),微量元素Sr二长花岗斑岩略低(144×10-6~175×10-6).花岗闪长斑岩表现为高Sr(样品>300×10-6,476×10-6~720×10-6),二者均低Y(Y<18×10-6,2.21×10-6~10.20×10-6),低Yb(Yb<1.9×10-6,0.30×10-6~1.48×10-6),高Sr/Y(Sr/Y>20,21.8~63.52),稀土元素特征为亏损重稀土,无明显负铕异常,(87Sr/86Sr)i=0.70154~0.70397,(143Nd/144Nd)i=0.512290~0.512600,εNd(t)为+2.4~+8.5,二长花岗斑岩和花岗闪长斑岩均具有埃达克质岩特征,但二长花岗斑岩与花岗闪长斑岩主、微量和稀土元素又存在一定差别,它们可能是岩浆不同演化阶段的产物.通过年龄测定,获得辉钼矿Re-Os等时线年龄为(370.0±5.9)Ma,二长花岗斑岩锆石SHRIMP U-Pb加权平均年龄为(365.7±3.6)Ma,铜钼矿形成时代与二长花岗斑岩形成时代相近,均形成于晚泥盆世.铜钼矿床与二长花岗斑岩、花岗闪长斑岩紧密共生,矿区范围内二长花岗斑岩与花岗闪长斑岩多被蚀变并矿化,表明二长花岗斑岩、花岗闪长斑岩与铜钼矿化存在密切的时空关系,为铜钼成矿提供了主要成矿物质和流体来源.     

无循环钻进工艺在易坍塌、缩孔和卵砾石地层的应用

无循环钻进工艺是我国现在和将来桩孔施工领域的主要施工工艺之一,通过对无循环钻进工艺及器具的研究,解决了我国桩孔施工在无水地区和岩石层、卵砾石、淤泥、流沙层进行桩孔钻进的难题,大大减少了孔内事故,提高了无循环钻进工艺在复杂地层中钻进的效率。根据我国目前全套管施工设备少,而旋挖钻机保用量已超过3000多台的现状,通过新的钻具和工艺的结合,用旋挖钻进工艺与全套管跟管钻进、全套管护壁钻进等特殊工法和特殊钻具的配套施工,解决了全套管钻进的成本问题,推动了无循环钻进工艺、机具及全套管配套技术的研究。     

东北地区珍珠岩矿床成因分析

东北地区珍珠岩矿床分布于中生代陆相盆地中,含矿层位主要为中生代早期的中酸性火山岩,沿北北东向展布.矿体形态多为似层状.矿床类型属于大陆边缘岛弧型.矿床系酸性岩浆大量释放挥发组分,经温度、压力突降后岩浆固结形成.找矿方向主要为中生代酸性火山岩,北北东向分布的一系列断陷火山盆地为找矿主要靶区.珍珠岩与球泡流纹岩、气孔流纹岩、凝灰岩、球珠岩紧密共生,系良好的找矿标志.