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101.
The method of downward continuation is well known to those working in gravity, magnetic, SP and low-frequency electromagnetic exploration. It is demonstrated that the method of continuation can also be usefully employed in the interpretation of induced polarization gradient profiling using point electrodes to determine target depth. The apparent resistance Ra and chargeability Ma measurements obtained with point electrode excitation of the ground have been used to compute the values of (Ra)l and (Ma)l that would be obtained with a linear array. Continuation of the apparent polarizability profile thus obtained with the linear array gives a value for the depth of the target which agrees closely with that obtained by the continuation of the SP profile. On the other hand, continuation of the profile of the secondary transient signal (VS)L alone, yields a depth of the target which is in agreement with the borehole information. However, it is seen that the secondary transient voltage profiling response splits into two anomalies which fall on either side of the SP and/or (Ma)l anomaly centre, and does not coincide with that of the latter. 相似文献
102.
RAO D. RAMESHWAR; NARAYANA B. L.; CHARAN S. N.; NATARAJAN R. 《Journal of Petrology》1991,32(3):539-554
An investigation of a low- to high-grade transition area inDharmapuri district confirms a continuous section through aformer lower crust, with tonalitic gneisses predominating inthe upper part and enderbites in the lower part. Geothermometry and geobarometry show a prograde metamorphismof 5?5 ? 1?5 kb and 730 ?40 ?C in the transition zone near theorthopyroxene isograd in the north to {small tilde}8? 1?5 kband 775 ? 30 ?C in the south. The progressive increase in metamorphicgrade is demonstrated by the systematic change in mineral compositionsfrom tonalitic gneisses in the north to enderbites in the south.The pressure estimates record a depth of equilibration of mineralsat 1423 km and 2333 km in the intermediate andlower parts of the crust, respectively. The presence of suchrocks now at the surface of the continental crust ({small tilde}35 km) could be cited as evidence for this part of the EarlyProterozoic to Late Archean crust having been at least 5068km thick. The P-T data in this area do not support the division into thewestern high-pressure and eastern low-pressure blocks of thelowland region suggested by earlier workers. 相似文献
103.
D TWINKLE G SRINIVASA RAO M RADHAKRISHNA K S R MURTHY 《Journal of Earth System Science》2016,125(2):329-342
The Cauvery–Palar basin is a major peri-cratonic rift basin located along the Eastern Continental Margin of India (ECMI) that had formed during the rift-drift events associated with the breakup of eastern Gondwanaland (mainly India–Sri Lanka–East Antarctica). In the present study, we carry out an integrated analysis of the potential field data across the basin to understand the crustal structure and the associated rift tectonics. The composite-magnetic anomaly map of the basin clearly shows the onshore-to-offshore structural continuity, and presence of several high-low trends related to either intrusive rocks or the faults. The Curie depth estimated from the spectral analysis of offshore magnetic anomaly data gave rise to 23 km in the offshore Cauvery–Palar basin. The 2D gravity and magnetic crustal models indicate several crustal blocks separated by major structures or faults, and the rift-related volcanic intrusive rocks that characterize the basin. The crustal models further reveal that the crust below southeast Indian shield margin is ~36 km thick and thins down to as much as 13–16 km in the Ocean Continent Transition (OCT) region and increases to around 19–21 km towards deep oceanic areas of the basin. The faulted Moho geometry with maximum stretching in the Cauvery basin indicates shearing or low angle rifting at the time of breakup between India–Sri Lanka and the East Antarctica. However, the additional stretching observed in the Cauvery basin region could be ascribed to the subsequent rifting of Sri Lanka from India. The abnormal thinning of crust at the OCT is interpreted as the probable zone of emplaced Proto-Oceanic Crust (POC) rocks during the breakup. The derived crustal structure along with other geophysical data further reiterates sheared nature of the southern part of the ECMI. 相似文献
104.
古生界是中东地区重要的天然气和轻质原油勘探层系,阿拉伯板块构造--沉积演化为古生界油气聚集成藏提供了有利的石油地质条件。分析认为,前寒武纪—寒武纪早期Huqf群和志留纪Qusaiba段两套优质成熟的烃源岩、多套有利的储盖组合以及一系列大型基底隆起或盐拱成因背斜、断背斜圈闭控制着古生界油气的分布,构成了古生界Huqf和Qusaiba两套主要的含油气系统,每套含油气系统均包括多个油气成藏组合。受早期继承性古隆起和盐构造、有利储盖组合以及断裂通道3个主控因素的影响,古生界油气成藏以下生上储侧向+垂向断裂输导运聚成藏模式为主。 相似文献
105.
This study uses multiple sea surface temperature(SST) datasets to perform a parallel comparison of three super El Ni os and their effects on the stratosphere. The results show that, different from ordinary El Ni os, warm SST anomalies appear earliest in the western tropical Pacific and precede the super El Ni o peak by more than 18 months. In the previous winter,relative to the mature phase of El Ni o, as a precursor, North Pacific Oscillation-like circulation anomalies are observed. A Pacific–North America(PNA) teleconnection appears in the extratropical troposphere during the mature phase, in spite of the subtle differences between the intensities, as well as the zonal position, of the PNA lobes. Related to the negative rainfall response over the tropical Indian Ocean, the PNA teleconnection in the winter of 1997/98 is the strongest among the three super El Ni os. The northern winter stratosphere shows large anomalies in the polar cap temperature and the circumpolar westerly, if the interferences from other factors are linearly filtered from the circulation data. Associated with the positive PNA response in a super El Ni o winter, positive polar cap temperature anomalies and circumpolar easterly anomalies,though different in timing, are also observed in the mature winters of the three super El Ni os. The stratospheric polar vortex in the next winter relative to the 1982/83 and 1997/98 events is also anomalously weaker and warmer, and the stratospheric circulation conditions remain to be seen in the coming winter following the mature phase of the 2015/16 event. 相似文献
106.
107.
巴音戈壁盆地巴音戈壁组上段泥岩是中国高放废物深地质处置的目标研究层位之一,目前缺乏对该地层湖相泥岩粘土矿物组合特征及古盐度影响因素的相关认识。文章应用全岩的B含量、Sr/Ba比值、Rb/K比值及Na+K质量分数等方法和X衍射测试分析技术对巴音戈壁组上段古盐度进行综合判别。分析得出:(1)巴音戈壁组上段以半深湖—深湖沉积环境为主,发育有厚层深灰色泥岩,以半深湖至深湖相沉积为主;(2)研究区目的层岩性结构为泥粉质,该段泥岩伊利石、蒙脱石、伊蒙混层发育较好,绿泥石和高岭石极少;(3)选取样品的Sr/Ba、Rb/K、B/Ga、Na+K值同Couch公式恢复的古盐度变化趋向相似,其水体以半咸水、微咸为主;(4)随着深度增加,TZK-1井、TZK-2井的古盐度呈规律变化,具有升高—降低特点,与伊利石含量的变化一致,并且古盐度变化与古气候及氧化还原的相关研究在该岩性段位耦合。综上表明:目标区古盐度的研究不仅有利于湖盆古沉积环境的恢复,而且有助于揭示古盐度的变化特征对粘土矿物组合特征及演化的影响,为后期深入研究粘土矿物对核素吸附性能及核素在泥岩中的迁移情况提供一定依据。 相似文献
108.
介绍了AT88SC1608IC卡的特征和利用AT2051单片机设计的IC卡读写器的基本原理及编程。该卡片的存储和保密功能强,读写器的成本低,应用广泛。 相似文献
109.
110.
Zhong-Yang Lin Hong-Xiang Hu Wen-Bin Zhang Hui-Fen Zhang Zheng-Qin He Zhen-Ming Lin Tao-Xing Qiu 《地震学报(英文版)》1993,6(4):867-881
The preliminary interpretation of Project western Yunnan 86–87 is presented here. It shows that there obviously exists lateral
velocity heterogeneity from south to north in western Yunnan. The depth of Moho increases from 38 km in the southern end of
the profile to 58 km in its northern end. The mean crustal velocity is low in the south, and high in the north, about 6.17–6.45
km/s. The consolidated crust is a 3-layer structure respectively, the upper, middle and lower layer. P
1
0
is a weak interface the upper crust, P
2
0
and P
3
0
are the interfaces of middle-upper crust and middle-lower crust respectively. Another weak interface P
3
0′
can be locally traced in the interior of the lower crust. Interface Pg is 0–6 km deep, interface P
1
0
9.2–16.5 km deep, and interfaces P
2
0
and P
3
0
respectively 17.0–26.5 km, 25.0–38.0 km deep. The velocity of the upper crust gradually increases from the south to the north,
and reaches its maxmium between Nangaozhai and Zhiti, where the velocity of basement plane reaches 6.25–6.35 km/s, then it
becomes small northward. The velocity of the middle crust varies little, the middle crust is a low velocity layer with the
velocity of 6.30 km/s from Jinhe-Erhai fault to the north. The lower crust is a strong gradient layer. There exists respectively
a low velocity layer in the upper mantle between Jinggu and Jingyunqiao, and between Wuliangshan and Lancangjiang fault, the
velocity of Pn is only 7.70–7.80 km/s, it is also low to the north of Honghe fault, about 7.80 km/s. Interface P6/0 can be traced on the top of the upper mantle, its depth is 65 km in the southern end of the profile, and 85 km in the northern
end.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 427–440, 1993. 相似文献