Xiuyan crater, China: Impact origin confirmed

Abstract

The well-preserved 1.8-km-diameter Xiuyan crater is located in the low mountain-hill region of the northern part of Liaodong Peninsula of northern China. Recently, a 307-m-deep borehole at the centre of crater became available. After penetrating 107 m lacustrine sediments, a breccia lens about 188 m in thickness was encountered. The crater-fill breccia is deposits of rock clasts and fragments more or less shock-metamorphosed. The features of geological structure and stratigraphic configuration within the crater, shock-melted rocks, and PDFs in quartz found in the basement rocks close to the crater rim and in the crater-fill breccia provide clear evidence for an impact origin of the Xiuyan crater. Xiuyan crater, shock metamorphism, breccia, PDFs, glass Citation:Chen M, Xiao W S, Xie X D, et al.The Xiuyan crater is located at 40 21 55"N, 123 27 34"E in the northern part of Liaodong Peninsula of northern China (Figure 1(a)). It is a simple bowl-shaped crater located in a low mountain-hill region (Figure 1(b)). The crater is 16 km on northeast Xiuyan town. Since the 1990s, the origin of the crater has been drawing attention from Chinese scientists. After searching no evidence for a volcanic crater, Qin et al.[1] and Zhao [2] first suggested a possible impact origin for this structure. In 2007, Chen [3] conducted an investigation on shock metamorphism of the crater rocks and minerals, and found some quartz grains with planar deformation features (PDFs) in the basement rock of leucoleptite close to the crater rim. The first discovery of shock-produced PDFs in quartz has shed light on an impact origin of the crater. The features in shock metamorphism of target rocks and minerals are crucial for identification of impact structure [4][5][6][7][8][9]. Special mineral deformation and phase transformation features including PDFs in quartz, diaplectic glass, and shock-induced high-pressure polymorph transition are generally accepted to be diagnostic evidence for shock metamorphism and impact crater [4,5]. In addition, geological drilling is an important approach for the investigation of *Corresponding author (email: mchen@gig.ac.cn) impact crater. Drill cores provide not only crucial data in geological structure and stratigraphic configuration within the crater, but also the rock and mineral samples for investigation of shock metamorphism. In order to clarify the origin of the Xiuyan crater, a core drilling at the center of crater has been carried out in the year 2009 to reveal the inner structure and to collect the deposits within the crater.

High-pressure polymorph of TiO2-II from the Xiuyan crater of China

“…The target rocks of the crater were shock-metamorphosed, from which impact-produced breccia, coesite, planar deformation features in quartz have been identified [18][19][20]. In this paper, we report the occurrence and mineralogical features of TiO 2 -IIin the impact-produced breccias…”

Shock-metamorphic features in amphiboles from the Xiuyan crater of China

“…2). A borehole was drilled previously at the center of the Xiuyan crater (Chen et al 2010a). An impact breccia unit about 188 m in thickness is located under 107-m-thick lacustrine sediments (Fig.…”

“…1a) (Chen et al 2010a). The crystalline basement rocks of the crater is a Proterozoic metamorphic complex composed of amphibolite, gneiss, granulite, and marble (Fig.…”

Preparation of hollow ZSM-5 crystals in the presence of polyacrylamide

“…However, the relatively small micropores in zeolites prohibit the entrance of large molecules to internal catalytic sites and limit the diffusion of the reactants or products in the reaction, which restrict the application of zeolite catalysts [1][2][3]. The decrease of particle size of zeolite crystals may overcome the diffusion problem [4], but this method is limited owing to the difficult separation of zeolite nanocrystals from the reaction mixture.…”

“…Great efforts have been made to introduce mesopores in the zeolites through templating [5][6][7][8][9][10][11][12][13][14] or post-treatment methods [15][16][17][18][19][20][21]. This hierarchical porous zeolite structure can enhance diffusion and significantly improve the catalytic performance of zeolites [1,15].…”