On the basis of the basic principles of optimization algorithms and classification algorithms, the Self-Organizing feature Map neural network (SOM) is applied to establish the predictive model of lithology for the K-Means optimized data set including core data, logging data and well tests data. Additionally, the decision tree and support vector machine are used to build the predictive model of fluid on the basis of the lithology identification. The optimization algorithms, including genetic, grid and quadratic, are adopted to optimize the important parameters of C-SVC and ν-SVC, such as C, ν and γ, so as to accurately identify the complex lithologies and multiphase fluids of complicated reservoirs. The SOM model and the decision tree and support vector machine are utilized to process four new wells in the complicated Carboniferous reservoirs of the Wucaiwan Sag, eastern Junggar Basin. The accuracy of lithology identification is 91.30%, and the accuracy of fluid identification is 95.65%. The lithologic complexity is not the main factor leading to the differences of fluids in the reservoirs. Because the complexity and nonlinearity of data set are not strong enough, the accuracy of the decision tree model is better than that of the support vector machine. Their accuracy rates are 94.31% and 86.97%, respectively. The performance of linear polynomial function is better than that of the radial basis function RBF and the neural function Sigmoid. The classification performance and generalization ability of C-SVC are stronger than that of the ν-SVC.
We propose a quality factor tomography which handles the strong velocity anomalies during ray tracing, makes better use of straight raypath to balance ray density, reduces singularity of the inversion matrix, and then greatly increases the stability of tomography. Meanwhile, the tomography in this paper also employs the accurate picking of the frequency peak. When computing frequency spectrum, we also compute the auto-correlation of the signal in short time windows, which makes the amplitude spectra more Ricker-like, enhances the stability and accuracy of the frequency peaks and makes the inversion more stable with greater resolution. Presentation Date: Tuesday, October 16, 2018 Start Time: 1:50:00 PM Location: Poster Station 20 Presentation Type: Poster
Early Precambrian geological events in the Zhongtiao Mountain of China provide important clues for understanding Neoarchean to Paleoproterozoic crustal evolution in the southern segment of North China Craton (NCC). Based on analysis and compare of the component features, spatial and temporal distribution and geochemical features of the crystalline basements in the Zhongtiao Mountain with its surroundings, we identify five distinct episodes of the early Precambrian geological events in the Zhongtiao Mountain as: ca. 2.72–2.61 Ga, ca. 2.56–2.44 Ga, ca. 2.35–2.20 Ga, ca. 2.20–2.0 Ga and ca. 1.97–1.85 Ga. The ca. 2.72–2.61 Ga magmatism mainly involved a significant period of crustal growth with some crustal reworking. These ca. 2.72–2.70 Ga TTG gneisses were produced by partial melting of a subducted oceanic slab, and the ca. 2.62–2.61 Ga granitic rocks were originated from the partial melting of a protolith of juvenile origin (such as the pre-existing ca. 2.72–2.70 Ga TTG suite) together with its intermixing with mantle material. Together with other ca. 2.90–2.61 Ga old rocks in the southern segment of NCC, they made up the 'Southern Ancient Terrane'. The ca. 2.56–2.44 Ga magmatism represented a major crustal reworking (melting) event with some juvenile addition in the Zhongtiao Mountain, and the formation of TTGs and K-rich granitic rocks during ca. 2.56–2.44 Ga marked a tectono-magmatic event resulting in stabilization of the NCC. The ca. 2.35–2.20 Ga magmatic activities reflected another stage of crustal extension and reworking of the basement rocks. The ca. 2.20–2.0 Ga volcanic-sedimentary rocks, A-type granites, and metamorphic basic volcanic rocks indicated that the stabilized blocks in the NCC still experienced the stage of extension. The ca. 1.97–1.85 Ga magmatic and metamorphic events formed in a phase of compressional deformation and led to the reworking of pre-existed old rocks.
The Permian sedimentary rocks in the Turpan–Hami Basin are key records of the tectonic evolution in the Eastern Tianshan area, although their depositional ages and provenances remain relatively less studied. Here, we conducted detrital zircon U–Pb geochronology on subsurface samples collected from Well LN1 in the Turpan–Hami Basin to understand the depositional ages and provenances of the Permian rocks. In this study, detrital zircon U–Pb ages from the Late Carboniferous Sumuke Formation yielded a notable Permian age population with the youngest single‐grain age at 282.6 Ma. Compiling this result with a published dataset from the surrounding regions of the Turpan–Hami Basin, it shows that the Sumuke Formation was actually deposited in the Early Permian and the Late Carboniferous palynological assemblages within it are of recycled origin. The detrital zircon age spectra of the three Early–Middle Permian samples from Well LN1 define similar unimodal distribution, with prominent late Carboniferous age peaks and scarce Precambrian ages, further indicating that the zircon grains in these three samples should be ultimately sourced from the Jueluotag, the southern branch of the North Tianshan. Regionally, the Bogda, the northern branch of the North Tianshan, as catchment areas recorded interaction between southern and northern sources, and thus, there was a single greater Junggar–Turpan Basin during the Early–Middle Permian. During the latest Middle Permian to Late Permian, provenance shifts occurred at the Jueluotag and the southern piedmont of the Bogda, reflecting the uplift of the Central Tianshan and the Bogda and the isolation of the Junggar Basin and Turpan–Hami Basin. Integrating regional geological studies and provenance evolution trends, we suggest that the Turpan–Hami Basin and its surrounding regions were in a rift setting controlled by post‐collision extension during Early–Middle Permian. By contrast, tectonic contraction and inversion occurred during the latest Middle Permian to Late Permian as a part of the intraplate orogenic process in the Tianshan, which responded to the convergence between the Songpan–Ganzi terrane and palaeo‐Eurasian Plate.
Abstract The detrimental infill‐frame interaction and vulnerable nature of the traditional solid infill walls might change the seismic behavior of the infilled reinforced concrete frames. To mitigate the adverse infill‐frame interaction and protect the fragile infill walls, in this paper, an innovative solution by partitioning the infill wall panels with low‐strength mortar sliding joints and uncoupling the infill from the boundary frame by flexible materials is presented for the reinforced concrete frames. Three 1/2 scale specimens designed in this context were examined experimentally and numerically, and a simplified model is developed for the proposed infill system. Test results show that the presented low‐damage infill system could effectively mitigate the adverse infill‐frame interaction and considerably prevent corner crushing or damage to the infill wall panels so that the reinforced concrete frame with the proposed infill system behaves similarly to the bare frame. Thanks to the working mechanism of the infill system, the proposed wall panels have a relatively high energy conversion efficiency from inter‐story displacement to the energy dissipation capacity of the infilled frame. Moreover, the developed simplified infill model could well capture the hysteretic behaviors of the proposed low‐damage infill system and improve the calculation efficiency. Parametric analysis results indicate that the friction factor of the sliding joints plays a significant role in enhancing the seismic behavior of the novel low‐damage infilled system.
Abstract The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track (AFT) thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan‐Shengrenqiao Fault (LSF) in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time‐temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ∼50°C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with ∼1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono‐sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north‐vergent fold‐and‐thrust belt. Moreover, the southern Ordos Basin experienced a multi‐stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust‐driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust‐driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of Qinling Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at ∼100 Ma.
This paper discusses how to use the ArcEngine components and Orcale database to quickly draw the Yunnan Province digital isoseisms. Besides the current general ellipse model, the paper was the first time to complete the line source model of isoseisms drawing. At the same time, it improved the Binary search algorithm in order to quickly find closest active fault. Then the existing isoseisms file provided three correction methods: parameter correction, aftershocks correction and manual correction, which were respectively applied for the different data and purpose of the correction. Finally, taking an example of the simulation for Ning'er 6.4 and Lijiang 7.0 earthquake to demonstrate the method of fast drawing Yunnan digital isoseisms, and the method turned out to be feasible and practicable.
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