A new interpretation for the interference zone between the southern Brasília belt and the central Ribeira belt,SE Brazil     

《Journal of South American Earth Sciences》2013

In southeastern Brazil, the Neoproterozoic NNW–SSE trending southern Brasília belt is apparently truncated by the ENE–WSW central Ribeira belt. Different interpretations in the literature of the transition between these two belts motivated detailed mapping and additional age dating along the contact zone. The result is a new interpretation presented in this paper. The southern Brasília belt resulted from E-W collision between the active margin of the Paranapanema paleocontinent, on the western side, now forming the Socorro-Guaxupé Nappe, with the passive margin of the São Francisco paleocontinent on the eastern side. The collision produced an east vergent nappe stack, the Andrelândia Nappe System, along the suture. At its southern extreme the Brasília belt was thought to be cut off by a shear zone, the “Rio Jaguari mylonites”, at the contact with the Embu terrane, pertaining to the Central Ribeira belt. Our detailed mapping revealed that the transition between the Socorro-Guaxupé Nappe (Brasília belt) and the Embu terrane (Ribeira belt) is not a fault but rather a gradational transition that does not strictly coincide with the Rio Jaguari mylonites. A typical Cordilleran type magmatic arc batholith of the Socorro-Guaxupé Nappe with an age of ca. 640 Ma intrudes biotite schists of the Embu terrane and the age of zircon grains from three samples of metasedimentary rocks, one to the south, one to the north and one along the mylonite zone, show a similar pattern of derivation from a Rhyacian source area with rims of 670–600 Ma interpreted as metamorphic overgrowth. We dated by LA-MC-ICPMS laser ablation (U–Pb) zircon grains from a calc-alkaline granite, the Serra do Quebra-Cangalha Batholith, located within the Embu terrane at a distance of about 40 km south of the contact with the Socorro Nappe, yielding an age of 680 ± 13 Ma. This age indicates that the Embu terrane was part of the upper plate (Socorro-Guaxupé Nappe) by this time. Detailed mapping indicates that the mylonite zone is not a plate boundary because motion along it is maximum a few tens of kilometres and the same litho-stratigraphic units are present on either side. Based on these arguments, the new interpretation is that the Embu terrane is the continuation of the Socorro-Guaxupé Nappe and therefore also part of the active margin of the Paranapanema paleocontinent. The Brasília belt is preserved even further within the central Ribeira belt than previously envisaged.  相似文献   

地震仪表系统中电磁干扰识别与排除方法研究     

姜丹  邹彤  陈志高  郭唐永 《大地测量与地球动力学》2009,29(Z1):128-130

针对地震仪表系统受电磁干扰易发生误报警的情况，提出运用有限状态机来实现电磁干扰识别及排除。运用该方法 可有效地降低系统的误报警率，提高系统的可靠性。  相似文献   

日像仪的电磁干扰分析     

王威  陈志军  刘玉英  颜毅华  姬国枢 《天文研究与技术》2006,3(2):176-182

讨论了日像仪的干扰容限，列出了干扰源分布，估算出干扰测试仪灵敏度。计算了同步卫星干扰及干扰时间预测，也分析了中低轨道卫星干扰问题。对移动通信基站产生的干扰作了传播分析、计算，对脉冲雷达干扰作了谱分析及保守计算。  相似文献   

利用信号非线性变换进行抗干扰的原理分析与电路设计     

闫守华 《成都信息工程学院学报》1997,(1)

介绍了对信号与强噪声干扰所进行的非线性变换，以实现对噪声干扰的抑制，可获得高质量的有用信号  相似文献   

成都标准基线场的设计及光干涉测量     

赵景瞻裴维礼  胡正元张胜书 J．雅克拉 M．波坦尼 《四川测绘》2004,27(2):88-91

本文较详尽地阐述了成都标准基线场的设计特点及其理论依据，并介绍了光干涉测量及其配合的EDM测量、光干涉测量计算结果和精度分析。  相似文献   

山西奇村水汞异常干扰因素分析     

范雪芳  张淑亮  张正霞 《山西地震》2003,(3):59-61

2002年5月，山西忻州奇村水汞观测出现短期高值异常变化，变化幅度是正常值的10倍左右。从变化时间上分析，比较好地对应了2002年9月3日太原ML50地震，但通过调查和对比观测等分析。认为此异常系仪器不稳定、试剂污染及所配试剂用的蒸馏水不符合规范要求造成的。  相似文献   

银川台形变数字化观测干扰识别   总被引：2，自引：0，他引：2  

李国斌 《高原地震》2006,18(1):46-51

收集整理了宁夏回族自治区银川台形变数字化观测固体潮分钟值资料,论述了抽水、降雨、大风、进人、仪器调零、断电或者电压不稳定以及其它仪器故障等因素对形变数字化高频记录的影响及其机理,为利用数字化资料及时识别干扰、准确捕捉地震短临异常提供了可借鉴的实例。  相似文献   

强震台址规避干扰源的定量实验研究   总被引：1，自引：0，他引：1  

李佐唐  党红  田秀丰 《内陆地震》2011,25(1):43-51

为了在强震台址勘选中对火车站和采石场这两类常见干扰源的规避有个定量参考依据,以便减少盲目性,提高台址勘选效率,本工作在野外作了定量试验,取得了实地测试数据,初步探讨了两类干扰源的振动衰减关系.研究认为,强震固定观测台站,离开火车站(或铁路线)的距离应不小于210 m,离开采石场的距离应不小于700m.  相似文献   

固原体应变观测资料综合分析   总被引：1，自引：0，他引：1  

李国斌  赵卫明 《内陆地震》2011,25(1):78-84

对固原海子峡体应变2008年1月以来的观测数据进行了连续率、日漂移、内在精度以及噪声水平等方面的统计分析,结果显示观测资料连续率高,内在精度高,漂移快,噪声水平相对偏高.并从中选取了4个时段与气压进行相关分析,结果显示两者存在高度相关性,且体应变随气压变化在时间上存在40min的滞后效应,应用相关分析方法去除气压对体应...  相似文献   

高速铁路建设对宝鸡地电场观测干扰分析     

马世虎  王秋宁  李垚奇  乔波 《高原地震》2011,23(4):37-40

高速铁路（简称高铁）建设是新时期中国经济实现又好又快发展的重大战略举措。不久的将来,我国将建成遍布大江南北总进程达到16 000 km的高铁网络。地电场观测是地震前兆观测的重要手段,截止2010年,全国共建成并投入运行的地电场观测台站已经达到110个。由于高铁的设计线路与地电场观测场地难免发生＂冲突＂,因此,研究和分析...  相似文献