Large-Scale Dextral Strike-Slip Movement and Associated Tectonic Deformation Along the Red-River Fault Zone     

Xiang Hongfa 《中国地震研究》2005,19(2):125-138

INTRODUCTION TheRedRiverfaultinsouthwestChina,aboundaryfaultbetweentheIndochinaplateandthe Yangtzeplate,haslongbeenatopicofgeneralinterest.Manystudieshavebeendoneonthegenesis,evolutionandtectonicchangesinthehistoryoftheAilaoshan RedRivertectoniczoneinterm…  相似文献   

Seismic evidence of divergent rifting and subsequent deformation in the southern Japan Sea, and a Cenozoic tectonic synthesis of the eastern Eurasian margin   总被引：1，自引：0，他引：1  

Yasuto Itoh  Koji Uno  Hiroyuki Arato 《Journal of Asian Earth Sciences》2006,27(6):933-942

Neogene rift system configuration for the back-arc of southwest Japan, southern rim of the Japan Sea, is argued on the basis of reflection seismic interpretation. Divergent rifting and subsequent contraction provoked by an arc–arc collisional event are manifested by the formation of faulted grabens and their inverted deformation, respectively. We identified the following four Cenozoic tectonic epochs as a decomposition process of the eastern Eurasian margin based on reliable paleomagnetic data: (1) Plate margin rearrangement on a regional left-lateral fault through southwest Japan and Sikhote Alin, which constituted a continuous geologic province before the early Tertiary differential motion; (2) Early Tertiary clockwise rotation (>20°) of the east Tan-Lu block relative to the North China block; (3) Oligocene to early Miocene divergent rifting and spreading of the Japan Sea, which divided southwest Japan from the east Tan-Lu block; (4) Middle Miocene bending and back-arc inversion of southwest Japan caused by collision with the Izu-Bonin arc. According to the estimation of relative motions during these events, a paleogeographic reconstruction is presented through Cenozoic time.  相似文献   

塔里木盆地西南坳陷柯东1号构造白垩系原油特征     

张亮  曾昌民  黄智斌  陈才  朱礼春  沈春光  吕惠贤 《新疆地质》2013,(2)

柯东1号构造是塔里木盆地西南坳陷昆仑山前发育的断鼻型圈闭,钻探kd1井白垩系获高产工业油气流.原油地球化学特征表明,其为高含蜡中质成熟原油,甾烷中C27、C28、C29甾烷呈反“L”型分布,以C29甾烷含量高为特征,萜烷类C29、C30重排霍烷、C30未知萜烷、C24四环萜烷、Ts含量相对较高.生物标志物特征表明,该原油来源于二叠系烃源岩.据原油成熟度分析认为,该原油高分子量芳烃和低分子量的轻烃是烃源岩分别在成熟阶段与高-过熟阶段产物.因此,kd1井白垩系原油是二叠系烃源岩成熟期、高熟期两期充注的混合原油.  相似文献   

中国西南夏季降水预测的统计降尺度建模分析     

舒建川  蒋兴文  黄小梅  伍清 《高原气象》2019,(2):349-358

利用BP-CCA方法并结合当前国际先进气候预测模式结果,探讨了如何建立对西南夏季降水具有较高预测技巧的统计降尺度模型及其可预报性来源。结果表明,将热带区域海表温度作为预测因子的降尺度模型的预测能力优于亚洲区域和热带区域500 h Pa位势高度作为预测因子的模型。对模型可预报性来源的分析表明,热带区域海表温度作为预测因子的降尺度模型的预测能力年与年之间的差异主要受热带海表温度EOF第二模态的影响。该模态表现为在热带东南印度洋及西太平洋区域有正载荷值,而在热带中东太平洋区域有负载荷中心,其与影响西南夏季降水的菲律宾和海洋大陆西部对流有较好的相关,并且ECMWF和NCEP业务气候预测模式对其有较好的预测能力。  相似文献   

青藏高原东部重力波过程与西南涡活动的统计关系     

陈炜  李跃清 《大气科学》2019,43(4):773-782

本文利用2012～2015年西南涡加密观测大气科学实验的剑阁、金川、九龙和名山四站探空资料,统计分析了6～7月西南涡活动期间对流层中、高层（6～12 km）的重力波过程,结果表明:青藏高原东部川西高原南部的九龙站与其余三站不同,重力波源主要来自对流层上层,波能传播方向向上,剑阁、金川和名山三站重力的波源主要来自对流层下层,波能传播方向向下。重力波过程在不同类型的西南涡活动中有明显差异,在移出型西南涡活动初期,重力波水平传播方向主要为东北向,其上传概率远大于下传概率,波动的动能和潜能较大且变化剧烈;而对应源地型西南涡,初期主要呈西北—东南向传播且重力波上传与下传概率相当,动能和潜能较小且变化相对平缓同时本次研究表明,重力波水平传播方向对西南涡的移动方向也有一定指示作用。按照发生时刻本文将重力波分为日发型重力波和夜发型重力波,在夜发型西南涡初期,重力波活动夜发（北京时20:00～08:00）的概率较大,这表明重力波的夜发性与西南涡的夜发性可能存在一定关联。  相似文献   

Overprinting porphyry‐type veinlets on the intrusive rocks and phreatomagmatic breccias in the Southwest prospect,southwestern Sto. Tomas II (Philex), Baguio District,Philippines     

Avriel Venis L. Cirineo  Akira Imai  Ryohei Takahashi  Redempta P. Baluda  Noel C. Oliveros  Victor B. Maglambayan  Roy Ronald C. Luis  Maria Lourdes M. Faustino  Jacky Almadin 《Resource Geology》2021,71(1):1-40

The Southwest prospect is located at the southwestern periphery of the Sto. Tomas II porphyry copper–gold deposit in the Baguio District, northwestern Luzon, Philippines. The Southwest prospect hosts a copper‐gold mineralization related to a complex of porphyry intrusions, breccia facies, and overlapping porphyry‐type veinlets emplaced within the basement Pugo metavolcanics rocks and conglomerates of the Zigzag Formation. The occurrences of porphyry‐type veinlets and potassic alteration hosted in the complex are thought to be indications of the presence of blind porphyry deposits within the Sto. Tomas II vicinity. The complex is composed of at least four broadly mineralogically similar dioritic intrusive rocks that vary in texture and alteration type and intensity. These intrusions were accompanied with at least five breccia facies that were formed by the explosive brecciation, induced by the magmatic–hydrothermal processes and phreatomagmatic activities during the emplacement of the various intrusions. Hydrothermal alteration assemblages consisting of potassic, chlorite–magnetite, propylitic and sericite–chlorite alteration, and contemporaneous veinlet types were developed on the host rocks. Elevated copper and gold grades correspond to (a) chalcopyrite–bornite assemblage in the potassic alteration in the syn‐mineralization early‐mineralization diorite (EMD) and contemporaneous veinlets and (b) chalcopyrite‐rich mineralization associated with the chalcopyrite–magnetite–chlorite–actinolite±sericite veinlets contemporaneous with the chlorite–magnetite alteration. Erratic remarkable concentrations of gold were also present in the late‐mineralization Late Diorite (LD). High X_Mg of calcic amphiboles (>0.60) in the intrusive rocks indicate that the magmas have been oxidizing since the early stages of crystallization, while a gap in the composition of Al between the rim and the cores of the calcic amphiboles in the EMD and LD indicate decompression at some point during the crystallization of these intrusive rocks. Fluid inclusion microthermometry suggests the trapping of immiscible fluids that formed the potassic alteration, associated ore mineralization, and sheeted quartz veinlets. The corresponding formation conditions of the shallower and deeper quartz veinlets were estimated at pressures of 50 and 30 MPa and temperatures of 554 and 436°C at depths of 1.9 and 1.1 km. Temperature data from the chlorite indicate that the chalcopyrite‐rich mineralization associated with the chlorite–magnetite alteration was formed at a much lower temperature (ca. 290°C) than the potassic alteration. Evidence from the vein offsetting matrix suggests multiple intrusions within the EMD, despite the K‐Ar ages of the potassic alteration in EMD and hornblende in the LD of about the same age at 3.5 ± 0.3 Ma. The K‐Ar age of the potassic alteration was likely to be thermally reset as a result of the overprinting hydrothermal alteration. The constrained K‐Ar ages also indicate earlier formed intrusive rocks in the Southwest prospect, possibly coeval to the earliest “dark diorite” intrusion in the Sto. Tomas II deposit. In addition, the range of δ³⁴S of sulfide minerals from +1.8‰ to +5.1‰ in the Southwest prospect closely overlaps with the rest of the porphyry copper and epithermal deposits in the Sto. Tomas II deposit and its vicinity. This indicates that the sulfides may have formed from a homogeneous source of the porphyry copper deposits and epithermal deposits in the Sto. Tomas II orebody and its vicinity. The evidence presented in this work proves that the porphyry copper‐type veinlets and the adjacent potassic alteration in the Southwest prospect are formed earlier and at a shallower level in contrast with the other porphyry deposits in the Baguio District.  相似文献   

基于综合区划的中国西南地区自然资源动态变化特征分析     

赖明  吴淑玉  张海燕  刘玖芬  王新华  陈熹卓 《中国地质调查》2021,8(2):83-91

为研究中国西南地区自然资源的动态变化特征,基于中国自然资源综合区划一级分区成果,以西南林耕自然资源大区为研究对象,通过选取符合区域特征的要素指标,确定指标权重,按照区划方案对西南林耕自然资源大区进行二级、三级区划,将其划分为6个自然资源亚区(二级区划)和11个自然资源地区(三级区划),并对区划单元内的自然资源动态变化进行了特征分析。研究区内自然资源以森林、耕地和草原为主,1990—2018年,自然资源变化主要表现为森林、耕地和草原三者间的相互转变,森林和耕地之间的相互转变主要分布于贵州和重庆的地区,森林和草原、耕地和草原之间的相互转变主要分布于云南和陕西的地区。建设用地明显增加,集中分布于各省会城市和直辖市。各类资源相互之间有明显转变,但面积在总体上基本保持动态平衡,表明自然资源的转变在合理范围内,其中四川盆地内的耕地和广西西部的森林受保护较好。各区划内优势资源明显,区划间变化特征彼此相异,可为全国或西南地区的自然资源配置、国土空间规划等自然资源统一管理提供决策支撑。  相似文献   

新疆乌恰县博索果山锰矿地质特征及找矿标志     

许明 《地质与勘探》2018,54(S1):1349-1355

近年,在新疆西南天山乌恰县吉根地区首次发现锰矿带,长大于28km,向北延伸至吉尔吉斯斯坦。锰矿层沿锰矿带断续出露长约14km。博索果山锰矿位于锰矿带南部,已发现具一定规模的富锰矿体,有望评价一处中型锰矿床。锰矿赋存于下泥盆统萨瓦亚尔顿组第二段,层控特征明显,属沉积成因。含矿岩石组合为硅质岩、硅质板岩、炭质页岩、硅质粉砂质板岩,夹泥晶灰岩透镜体等。锰矿受控于博索果山背、向斜构造。向斜核部更有利于储存厚度大、品位高的锰矿体,剥蚀程度小,有较大的找矿前景。乌恰地区锰矿找矿标志明显,地表基本能快速发现。  相似文献   

螺杆马达复合钻进在川西南幸福1井的应用          下载免费PDF全文

孙传佳  黎波 《探矿工程》2018,45(11):37-39

本文主要论述了川西南片区沐川县实施一口温泉井钻探,在钻进至软硬砂泥岩互层的须家河组时,出现时效缓慢、孔内事故频发等问题,采用了螺杆马达复合钻进工艺,提高了钻进效率,取得了良好的经济效益。对今后在该地区大口径深孔钻探施工具有一定的参考意义。  相似文献   

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge     

ZHANG Baisong  LI Zhenqing  HOU Zengqian  ZHANG Weiyan  XU Bo 《《地质学报》英文版》2018,92(5):1798-1822

Recent investigations found that hydrothermal activity and sulfide mineralization occurs along the Southwest Indian Ridge (SWIR). The Longqi and Duanqiao hydrothermal fields between 49° E and 53° E of the SWIR are two prospective mineralization areas discovered by Chinese scientists. With the aim to determine the mineralogical and chemical characteristics of sulfide minerals, we have conducted detailed studies for samples from the two areas using an optical microscope, X-ray diffractometer, scanning electron microscope, and electron microprobe. The mineralization processes in the Longqi area are divided into three main stages: (1) the low-medium-temperature stage: colloform pyrite (Py I) + marcasite → euhedral pyrite (Py II), (2) the high-temperature stage: isocubanite (±exsolved chalcopyrite) + pyrrhotite → coarse-grained chalcopyrite (Ccp I), and (3) the medium–low-temperature stage: sphalerite + fine-grained chalcopyrite inclusions (Ccp II) → aggregates of anhedral pyrite (Py III) ± marcasite → Fe-oxide (-hydroxide) + amorphous silica. The mineralization processes in the Duanqiao area are divided into two main stages: (1) the medium–high-temperature stage: subhedral and euhedral pyrite (Py I′) → coarse-grained chalcopyrite (Ccp I′) and (2) the medium–low-temperature stage: sphalerite → fine-grained chalcopyrite (Ccp II′) + chalcopyrite inclusions (Ccp II′) → silica-cemented pyrite (Py II′) + marcasite → Fe-oxide + amorphous silica. We suggest that the fine-grained chalcopyrite inclusions in sphalerite from Longqi and Duanqiao were formed by co-precipitation and replacement mechanisms, respectively. Primary sphalerites from both fields are enriched in Fe (avg. 5.84 wt% for the Longqi field vs. avg. 3.69 wt% for the Duanqiao field), Co (avg. 185.56 ppm for the Longqi field vs. 160.53 ppm for the Duanqiao field), and Cd (avg. 1950 ppm for the Longqi field vs. avg. 525.26 ppm for the Duanqiao field). Cu contents in pyrite from the Duanqiao field (Py I′: avg. 849.23 ppm and Py II′: avg. 1191.11 ppm) tend to be higher than those from the Longqi field (Py I: avg. 26.67 ppm, Py II: avg. 445 ppm, and Py III: avg. 179.29 ppm). Chalcopyrite from both fields is enriched in Zn (Ccp I: avg. 3226.67 ppm, Ccp II: avg. 9280 ppm, Ccp I′: avg. 848 ppm, Ccp II′ (inclusions): avg. 1098 ppm, and Ccp II′ (fine-grained): avg. 1795 ppm). The varying contents of Zn in the different pyrite and chalcopyrite generations may result from the zone refining process. An integrated study of the mineralogy and mineralogical chemistry suggests that the hydrothermal fluids of the Longqi area are likely conditioned with higher temperatures and relatively lower fO2 and fS2 than those of the Duanqiao area, but in contrast to the former, the latter is much affected by the compositions of the surrounding rocks.  相似文献