震害损毁建筑物高分辨率遥感信息提取方法

利用高分辨率遥感数据,针对“512”地震中都江堰紫坪铺镇震害损毁建筑物的特征,研究了基于像元和面向对象两种快速提取方法.基于像元提出了基于“多层次区域分割”的震害损毁建筑物提取方法,与传统的分类提取方法相比,它体现着面向对象分析方法中的多层、分割思想.面向对象,利用多尺度分割思想,按照分割尺度的大小建立了三层体系结构,根据每一层的特征提取不同地物类别,分析其光谱、纹理、形状、上下文关系、空间位置等特征,建立各自的模糊判定规则,进行损毁建筑物的提取.分别从提取精度、目视效果和方法原理三方面对两种提取结果进行综合比较,结果显示:两种方法均能快速、准确地提取震害损毁建筑物信息,而面向对象提取方法成功地抑制了由于单个像元光谱异质性大而导致的高光谱遥感分类“胡椒盐”噪声,有效地解决了基于像元方法中存在的“同物异谱,同谱异物”现象,其总体精度(90.38％)比基于像元方法的总体精度(76.84％)更高.     

阿尔金山西段巴什库尔干群斜长角闪岩地球化学特征及构造意义

长城系巴什库尔干群斜长角闪岩主要分布于阿尔金构造带西段北缘,一般呈似层状、透镜体状夹于云母石英片岩、变粒岩、石英岩、黑云二长片麻岩、大理岩等中。通过岩石学、岩石化学、微量元素和稀土元素地球化学研究表明,该斜长角闪岩的原岩为中-基性火山岩类,并形成于两种构造环境:一种斜长角闪岩的球粒陨石标准化配分曲线显示出LREE明显富集,具有类似大陆(板内)裂谷火山岩特有的稀土元素组成特征;另一种斜长角闪岩的球粒陨石标准化配分曲线呈略富集(近平坦)型,与洋中脊玄武岩类非常相似。表明在长城纪时期,阿尔金构造带西段北缘主要处于板内大陆裂谷环境,随着大陆裂谷的进一步扩张,局部地区已形成初始洋盆环境。     

大兴安岭南段锡多金属矿床成矿规律与矿床模型

大兴安岭南段是我国北方最重要的锡矿带,本文对其时空分布和成矿规律进行了系统总结,并提出了大兴安岭南段锡多金属矿深部动力学模型和矿床模型,旨在推动区域进一步锡银找矿工作。研究表明,锡多金属矿形成于伸展构造环境,具有明显的成群分布特点,空间上夹持在二连—贺根山、黄岗—甘珠尔庙和西拉木伦深大断裂带之间,矿化时代集中在150~130 Ma之间,但在个别大中型矿床中表现出多期成矿的特征。尽管锡矿化规模巨大,但目前揭露的高分异含矿花岗岩体并不多见,成矿作用可能与该区高的成矿元素背景值有关,但同时矿体下部可能存在隐伏高分异岩体。锡多金属成矿系统以锡铅锌银为主,鲜有共生或伴生钨矿化,不同阶段或类型矿化是深部岩浆房多期次出溶的不同或相同性质流体共同作用的结果,同时成矿流体与围岩的反应也会影响流体的组成和演化。岩浆流体出溶、地层活化萃取、地幔物质、大气降水、热卤水和变质热液共同参与了成矿作用,尤其是深部镁铁质岩浆底侵及脱气不仅为成矿提供了热源,同时也可能提供了大量的成矿元素和挥发组分。在成矿过程中,流体温压的下降、不同来源流体混合、超临界流体不混溶作用、流体多次沸腾和水岩反应等是金属元素超常富集的主要机制。     

引入结点度的线/面拓扑关系细分方法与应用

针对线/面细分拓扑关系研究存在的不足,提出了一种基于结点度的线/面细分拓扑关系描述与计算方法。该方法在定义线/面单元交线并分析其特点的基础上,引入结点度来区分线/面单元交线细分类型。根据单元交线端点在线/面目标组成图形结构中结点度的不同,及线目标在度为3和4的交线端点处是否有相连线段、相连线段位于多边形的边界上、内部或外部4个谓词推导出了21种有意义的线/面交线细分拓扑关系类型。在此基础上分析比较了本文方法与现有方法的异同与优势,举例说明本文方法在复杂线/面细分拓扑关系描述中的应用。最后用Visual C#语言编程实现了该方法,并将其应用到线状道路/面状河流目标间的数据质量检查与修正中,验证可行性。     

青藏高原东缘大渡河中游深切河谷沉积物及其地震地质意义

青藏高原东缘的大渡河中游泸定—石棉段呈深切河谷地貌,发育岩崩、滑坡、古地震堰塞湖、冲洪积扇等不同类型的堆积物、沉积物。基于野外调查、遥感解译、剖面测量和光释光测年(OSL)发现,这些沉积物记录了龙门山断裂带西南段——冷碛镇断裂2万年来的两期活动,可能是2次古地震事件。第一期发生在18ka左右,冷碛镇断裂切割了晚更新世的角砾状砂层和岩崩堆积物,显示右行走滑特征。这期变形促使大渡河堵塞,形成得威乡古堰塞湖,其堵江位置位于加郡乡—得妥乡的V型深切河谷段。第二期活动冷碛镇断裂切割了湖相地层,并破坏了堰塞湖,可能发生在11ka左右。新发现对于全面认识龙门山断裂带的活动历史、序列及方式具有重要意义。     

SLIP RATES OF THE RIYUE MT. FAULT AT DEZHOU SEGMENT SINCE LATE PLEISTOCENE

The Riyue Mt. Fault is a secondary fault controlled by the major regional boundary faults (East Kunlun Fault and Qilian-Haiyuan Fault). It lies in the interior of Qaidam-Qilianshan block and between the major regional boundary faults. The Riyue Mt. fault zone locates in the special tectonic setting which can provide some evidences for recent activity of outward extension of NE Tibetan plateau, so it is of significance to determine the activity of Riyue Mt. Fault since late Pleistocene to Holocene. In this paper, we have obtained some findings along the Dezhou segment of Riyue Mt. Fault by interpreting the piedmont alluvial fans, measuring fault scarps, and excavating trenches across the fault scarp. The findings are as follows:(1) Since the late Pleistocene, there are an alluvial fan f_p and three river terraces T₁-T₃ formed on the Dezhou segment. The abandonment age of f_p is approximately (21.2±0.6) ka, and that of the river terrace T₂ is (12.4±0.11) ka. (2) Since the late Pleistocene, the dextral strike-slip rate of the Riyue Mt. Fault is (2.41±0.25) mm/a. In the Holocene, the dextral strike-slip rate of the fault is (2.18±0.40) mm/a, and its vertical displacement rate is (0.24±0.16) mm/a. This result indicates that the dextral strike-slip rate of the Riyue Mt. Fault has not changed since the late Pleistocene. It is believed that, as one of the dextral strikeslip faults, sandwiched between the the regional big left-lateral strike-slip faults, the Riyue Mt. Fault didn't cut the boundary zone of the large block. What's more, the dextral strike-slip faults play an important role in the coordination of deformation between the sub-blocks during the long term growth and expansion of the northeast Tibetan plateau.     

A NEW DISCOVERY OF ACTIVITY OF FUSHAN SECTION OF THE TAN-LU FAULT ZONE IN THE LATE QUATERNARY

The east branch fault of Tan-Lu fault zone extends from Fengshan Town of Sihong County on the north shore of the Huaihe River in Jiangsu Province, into Fushan Town of Mingguang City on the south shore of Huaihe River in Anhui Province. The landform changes from Subei plain on the north of Huaihe River to Zhangbaling uplift area on the south of Huaihe River. The terrain rises gradually with larger relief amplitude. The Fushan section of the Tan-Lu fault zone is located in Ziyang to Fushan area of Mingguang City. The fault is shown in the satellite image as a clear linear image, and the fault extends along the east side of a NNE-trending hillock. In this section the Quaternary strata are unevenly distributed, which causes some difficulties in the study of recent fault activity.In recent years, the author has found that the fault of the Fushan section of the Tan-Lu fault zone on the south of the Huaihe River still has a certain control effect on the landform and the Quaternary strata. Based on satellite imagery and geological data, we select the appropriate location in the Fushan section to excavate the Santang trench Tc1 and Fushannan trench Tc2, and clean up the Fushannan profile Pm, which reveals rich phenomena of recent fault activity. Santang trench reveals three faults, and the faulting phenomenon is obvious. One of the faults shows the characteristic of right-lateral strike-slip normal faulting; Fushannan profile reveals one fault, with the same faulting behavior of right-lateral strike-slip normal fault. Comprehensive stratigraphic sample dating results indicate that the fault dislocated the middle Pleistocene strata, late Quaternary strata and early Holocene strata. All our work shows that the fault of Fushan section has intensive activity since late Pleistocene, and the latest active age can reach early Holocene. The latest earthquake occurred at(10.6±0.8)~(7.6±0.5)ka BP. The faults exposed by trenches and profiles show the characteristics of right-lateral strike-slip normal faulting, which reflects the complexity of the tectonic stress field in the area where the fault locates.     

VELOCITY STRUCTURE TOMOGRAPHY OF REGIONS DOWNSTREAM THE JINSHA RIVER BASED ON DENSE OBSERVATION

In this paper, the double difference seismic tomography method is applied to the phase arrival times of 7 465 seismic events to determine the hypocenter parameters of events as well as detailed 3D velocity structure at the northern segment of Xiaojiang Fault and its surrounding area. The data was recorded by 42 stations of the Jinshajiang River network from August 2013 to November 2016. At 2~6km, V_P and V_S present low velocity anomalies along the northern segment of Xiaojiang Fault, and the V_S anomaly is especially remarkable. On both sides of the Xiaojiang Fault, there also exist obvious P and S wave low velocity areas. These low velocity areas correspond to the terrain, lithology distribution and the watershed of Jinsha River at shallower layer in the study area. Starting from 6km, a NE-directed high V_P band along Zhaotong-Ludian and Huize-Yiliang Fault is formed on the eastern side of the northern segment of Xiaojiang Fault. V_S also shows the high value in the area bounded by Lianfeng Fault, Baogunao-Xiaohe Fault and Huize-Yiliang Fault. Above 10km depth, to the west side of the Xiaojiang Fault including the Ninghui Fault, V_P shows a significant low-velocity anomaly, while to the east side it presents high velocity feature. The Xiaojiang fault zone shows a significant low V_P from north to south in the study region, and the low velocity anomaly in the northern segment is relatively significant, especially the low velocity anomaly area reaches 15km deep around Qiaojia area. Beneath the Baihetan Dam, a significant low V_P area reaching to 5km deep is found. The earthquakes around the dam formed a strip from shallow to deep on the low-velocity area side. Whereas, a stable high-velocity area is found under the Wudongde Dam. The events relocation result shows that:all the focal depths in the study area are shallower than 20km, and the predominant focal depth is within 15km. Different from the NE-trending of the major faults in the study area, the relocated seismic events are obviously distributed nearly east-west along Matang Fault and Daduo Fault and the region around Huize. The focal depths of M_S6.5 Ludian earthquake sequences are shallower than 15km, and mostly less than 10km. The aftershocks within 2a after the Ludian M6.5 earthquake form two predominant bands of about 40km and 20km along near EW and SN direction, respectively.     

龙门山断裂带南段岩石圈磁场变化分析

根据巴颜喀拉块体东部2011—2014年3期岩石圈磁场年变化情况,结合地壳应力资料,重点分析龙门山断裂带南段的岩石圈磁场变化与应力积累的关系。该区域2011—2012年和2012—2013年岩石圈磁场变化明显弱于周边区域,实测地壳应力结果反映汶川M_S8.0地震震后应力积累水平很高。压磁效应分析认为汶川M_S8.0地震后该区域高应力积累、低应变率的动力学背景是控制该区域岩石圈磁场弱变化的主要因素。此外,芦山M_S7.0地震及康定M_S6.3地震前震中区存在局部岩石圈磁场水平矢量的弱变化现象,尤其是2012—2013年水平矢量大小和方向均与周边区域相比存在明显差异,这可能是两次地震的前兆异常。