排序方式: 共有27条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
城市大规模工程建设揭露了蕴含在土层中的丰富变形信息,调查发现合肥地区上更新统黏土中发育有数量众多的节理,节理成组产出,呈现不同交切、配套关系。通过对大量的调查数据进行统计分析,并绘制各调查点的节理玫瑰花图,将研究区内节理发育与断层分布逐一对比分析,结果显示合肥地区上更新统黏土中广泛发育的节理产状与场地附近的主要断层产状有关。走向玫瑰花图显示节理优势分布方位与场地附近主要断层走向近似一致;如果场地附近有多条断层交汇,土层中节理有以北西向较为优势的特征。 相似文献
5.
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. 相似文献
6.
7.
合肥下蜀土地球化学特征及其古气候意义 总被引:1,自引:0,他引:1
合肥地处长江中下游北岸,下蜀黄土广泛分布,通过对合肥地区BK2钻孔剖面岩性、氧化物含量及其地球化学风化参数的分析,研究合肥地区风成沉积物地球化学元素特征及其气候变化规律。结果表明:野外钻孔岩芯剖面显示地层较好连续性,结合年龄数据划分了该孔的第四纪沉积框架,Qh底界为1.20 m,Qp3底界为5 m,5~35.10 m属Qp2中晚期地层;合肥下蜀土主要化学成分(SiO2+Al2O3+Fe2O3)的平均含量之和达88.99%,这种显著的富硅铝铁现象表明了该区气候较为湿润;化学风化程度较强,下蜀土的CIA平均值及其脱Ca、Na、K的程度均大于洛川黄土,说明其堆积期古气候比同期堆积的洛川气候温湿,较宣城干凉,与南京、镇江气候较为接近;近0.5 Ma以来总体经历由湿热-干冷的变化,大致可分为35~14.50 m、14.50~4.50 m、4.50~1.20 m和1.20~0 m四个阶段,气候变化由温暖湿润-温暖偏干-冷凉偏干-温暖湿润,显示了区内更新世中晚期以来的气候变迁具有全球一致性特征。 相似文献
8.
9.
郯庐断裂带五河-明光段晚更新世活动的地质证据及活动特征 总被引:1,自引:0,他引:1
作为中国东部影响最大的走滑断裂,郯庐断裂因其强烈的地震活动性及沿断裂带一系列的大地震而备受学者关注。然而,大部分的调查研究都是针对郯庐断裂山东省境内及渤海湾内部分段落。并且,一般认为淮河以南的段落晚更新世以来不活动,也不具备孕育大震或强震的条件。然而,近期我们针对郯庐断裂的工作对这些认识提出了质疑,这些工作基于高分辨率卫星遥感影像解译和在安徽北部明光市、五河县附近的详细的野外调查。我们的研究认为郯庐断裂在淮河以南的五河-明光段包括四支断裂,并且至少一支在晚更新世以来活动。此段在晚第四纪以来主要以右旋走滑为主。不同于常常在基岩及第四纪沉积物中观察到的断层,在未固结的第四纪粘土中的断层形迹不清,但是能够被微观构造分析所确认。鉴于我们最近的工作和前人研究,我们认为年轻沉积物中的隐形断层更加值得注意,同时我们认为郯庐断裂淮河以南的“平静”段需要更深入的研究。 相似文献
10.
赤山地处安徽省泗县东北部,为郯庐断裂带西支断裂通过处。以往研究认为,郯庐断裂带赤山段第四纪以来有较为明显的活动。此次在垂直于赤山段开挖的多个探槽中均揭露出史前地震遗迹(多期逆断型崩积楔),具体表现为断层上盘砖红色上白垩统砂岩或黄白色中更新统砾石层向东叠置于褐黄色中、上更新统黏土之上。在楔状体根部均发现向NW陡倾的断裂,陡立的断面向上转变为缓倾的上翻垮落面。多条探槽揭示的断裂点的连线总体呈NNE走向,断裂通过处的上盘后缘大部分残留了凸起地貌,部分EW向冲沟被断裂右旋扭错。多条探槽两壁都一致显示出从西向东的推挤垮塌痕迹。其中Tc1~Tc4表现为砖红色砂岩(K2)逆冲垮落于黄褐色含铁锰结核黏土(Qp2-3)之上,Tc5则表现为红砂岩(K2)和黄白色砾石层(Qp2)逆冲垮塌于上述的黏土之上。在几个探槽的逆断型崩积楔上均揭示出此段曾有多次逆断型崩积事件发生,个别探槽揭露楔体较少,可能与其所处的位置、揭露深度和剥蚀残存的高度有关。对开挖探槽及光释光测年结果的详细分析初步得出,郯庐断裂带赤山段在中、晚更新世之交曾多次发生大规模逆断型黏滑事件,即曾多次发生史前大地震。 相似文献