怀安麻粒岩锆石U-Pb年代学及Hf同位素：华北北缘下地壳增生再造过程研究

怀安杂岩体位于华北克拉通中北部,出露太古代-元古代的角闪岩相-麻粒岩相高级变质岩,记录了华北克拉通复杂的地壳形成和演化史.本文对其中的镁铁质麻粒岩和长英质麻粒岩进行了岩石学及锆石U-Pb年代学和Hf同位素组成研究,并在此基础上对其形成过程及所反映的华北北缘古老下地壳的增生再造过程进行讨论.镁铁质麻粒岩主要矿物组合为Cpx+ Pl+ Qz±Opx±Hb±Grt,粒状变晶结构,局部发育石榴子石的“白眼圈”现象,表明经历了高压麻粒岩相及后期近等温减压退变质作用过程.选择其中矿物组成为Cpx、Pl和少量Qz的单斜辉石麻粒岩进行锆石定年获得2461±20Ma的原岩形成年龄.这些岩浆锆石的εHf(t)为+2.1 ～ +9.7,最高值接近当时的亏损地幔值,其Hf亏损地幔模式年龄(tDM)集中在2.6～2.7Ga之间,最小为2412Ma和2461 Ma,接近原岩形成年龄.长英质麻粒岩主要组成矿物为Pl+ Kfs+ Cpx+ Qz+ Opx,粒状变晶结构.锆石测年获得2458±46Ma的原岩形成年龄.这些锆石εHf(t)范围为+2.9～ +5.3,锆石Hf两阶段模式年龄(t.ust)集中在2.8 ～2.7Ga之间.怀安麻粒岩的这些特征显示怀安地区在～2.5Ga发生亏损地幔的部分熔融,为单斜辉石麻粒岩提供了原岩物质,同时可能引起了先存(≥2.7Ga)地壳的重熔,即存在地壳再造,进一步为长英质麻粒岩提供了原岩物质.单斜辉石麻粒岩和长英质麻粒岩原岩都形成于～2.5Ga.     

郯庐断裂带赤山段中晚更新世之交的史前地震遗迹

Chishan is located in Sixian County of Anhui Province, and the west branch fault of Tancheng-Lujiang fault zone passes through here. According to previous research, the Chishan segment of Tancheng-Lujiang fault zone has been obviously active since the Quaternary. Trenches excavated perpendicular to the Chishan segment for this study have revealed many prehistoric earthquake ruins-the multi-phase reverse faulting colluvial wedge, which is represented as the western brick-red sandstone of the late Cretaceous or maize gravel stratum of the mid Pleistocene of the hanging wall of the fault overlapping eastward the mid-late Pleistocene brown clay. In the base of the wedges, steep NW-dipping faults were found, and the steep fault planes turned upward to gently dipping collapse planes. As revealed by the trenches, the connection line of the breaking points strikes NNE in general. Heaving landforms are preserved at most parts of the tailing edge of the hanging wall where the fault passes through, and some EW-trending gullies were offset by right-lateral faulting. The two walls of several trenches have consistently shown that the collapse of traces have been pushed by a west-to-east force. Among them, Tc1~Tc4 show that the brick red limestone(K2)overthrust and collapsed on the yellow-brown clay containing ferro-manganese nodules (Q2-3P); Tc5 reveals that the yellowish-white gravel (Q2P) and the sandstone (K2) and overthrust and collapsed on the aforementioned clay. Reverse faulting colluvial wedges are found on both walls of each of the 8 trenches, but the number of wedges revealed in different trenches is different: there is 1 wedge, and 2 wedges in Tc1 and Tc3. 3 wedges in Tc2, Tc4 and Tc5, and in individual trenches, few wedges are revealed. This may be related to the trench’s location, depth and height of the remaining denudation. From the analysis of the trenches and the thermoluminescence dating results, we can preliminarily conclude that multiple large-scale reverse faulting stick events have taken place on the Chishan segment of the Tancheng-Lujiang fault zone during the mid-late Pleistocene, that is to say, many pre-historic strong earthquakes have occurred.     

河北邯郸-邢台地区波速比和泊松比分布特征研究

根据多台和达法,利用邯郸—邢台地区9个数字地震台的观测数据研究了该区波速比和泊松比分布特征.结果显示:(1)9个小区域波速比值在1.696～1.737之间,相关系数在0.988 3～0.999 1之间,研究区平均波速比值为1.719,平均泊松比值为0.244,所得泊松比值与研究区内地壳介质以花岗岩为主一致.(2)研究区内波速比和泊松比变化比较复杂,反映了区内上地壳介质性质的不同乖地质构造的复杂性.     

抚松井水温动态特征分析

统计分析了抚松井2007年6月1日至2010年12月30日水温数字化观测资料,结果显示抚松井水温动态类型表现为：长期动态特征为上升漂移型;短期动态特征为短周期型,并结合环境和水文地质情况对水温动态的影响因素进行了初步的分析。     

X射线技术在安检领域的应用

X射线技术是一种成熟且应用非常广泛的安检技术,主要包括X射线透射法、双能X射线法、X射线背散射法和计算机断层扫描法等。其成像原理虽略有不同,但都是利用X射线与物质作用来提取物品的物理特征,从而达到安全检查的目的。在实际应用中,各类X射线技术都存在各自的缺点和不足,造成实际安检存在漏报、误报等问题,为解决这些问题,综合应用各类技术可能是一个有效的解决办法。     

田岗断层产状的确定方法

搞清断层赋存状态对矿井安全生产至关重要。针对目前以范围表示方法确定断层产状存在精度不足的问题,山东崔庄煤矿通过在井下施工断层探孔,探明了田岗断层地质层位关系等情况,并运用平面投影法和矿体几何要素较准确地确定了田岗断层的产状要素,包括断层倾角、断层落差和断层走向等,从而取代了通常对断层产状较模糊的范围表示法。本研究方法原理简单,易于掌握,其计算结果比原有地质资料更加准确可靠。      

利用海图数据与卫星影像计算海湾纳潮量——以胶州湾为例

以胶州湾为例,尝试获取胶州湾的三维地形,并利用海湾高、低潮所容纳的海水体积之差计算海湾纳潮量。计算结果表明:胶州湾1992年纳潮量为9.8×108 m3,2005年胶州湾纳潮量为8.9×108 m3,胶州湾纳潮能力下降0.9×108 m3。     

如何评定并提高城市土地利用效率

一、背景 当前我国城市化进程进入加速发展时期,城市化必须以土地作为载体,而我国的城市土地利用面临着世界上少有的严峻环境。一方面,国家目前正处于工业化和城市化的加速发展阶段,城市用地扩展是发展经济和提高人民生活质量的必然要求;