中文摘要：

丰富的 TiO2-II，钛二氧化物的高压的多形体，从 Xiuyan 坑在生产影响的角砾岩的片麻岩碎片被发现。在片麻岩的金红石严重地被碎裂并且有细密纹理的 clasts 在尺寸的不到 2 m 被转变了到 TiO2-II。不规则的薄分层的 TiO2-II 也在纹理粗糙的金红石碎片被观察，在的地方 TiO2-II 层在金红石散布破裂和裂缝。在片麻岩的大约 30% 金红石被转变了到 TiO2-II。TiO2-II 显示的好谷物点亮带蓝色的灰色在极化飞机的反映的光点亮黄褐。结晶的调查证明 TiO2-II 与空间组 Pbcn 有斜方晶的结构。房间参数是 a=4.543 (1 )? ， b=5.491 (9 ) 吗？并且 c=4.895 (2 )? 。它根据二个氧原子计算的实验公式能是被写(Ti0.985Fe0.008Nb0.006-Si0.003Zr0.001 ) 1.003O2，或简单地公式 TiO2。根据石英和长石的吃惊效果，在 TiO2-II-bearing 片麻岩的山峰吃惊压力和吃惊以后的温度被估计在 35 和 43 GPa 和 300900 戠敥 ? 湩牣慥楳杮祬攠瑳 'L 楬桳摥椠 ? 桃湩 ? 畤楲杮琠敨瀠獡 ? 敤慣敤 ? 灡汰捩瑡潩獮漠 ? 桴 ? 之间獩瑯灯捩洠捩潲湡污獹獩愠敲猠楴汬氠浩瑩摥搠敵琠? 桳牯慴敧漠 ? 癡楡慬汢?瑳湡慤摲 s

英文摘要：

Abundant TiO2-II, a high-pressure polymorph of titanium dioxide, was found in the gneiss fragments of impact-produced breccias from the Xiuyan crater. Rutile in the gneiss was severely fragmented and fine-grained clasts less than 2 ~tm in size had been transformed to TiO2-II. Irregular thin layered TiO2-II is also observed in coarse-grained ruffle fragments, where the TiO2-II layers distributes along fractures and cracks in rutile, About 30 percent of rutile in the gneiss had been transformed to TiO2-II. Fine grains of TiO2-II display light bluish grey to light yellow brown in plane-polarized reflected light. Crystallographic investigation shows that TiO2-II has an orthorhombic structure with space group Pbcn. The cell parameters are a=4.543（1）/~, b=5.491（9）/~ and c=4.895（2） ,~. Its empirical formula calculated on the basis of two oxygen atoms can be written as （Tio.985Feo.oosNbo.oor- Si0.003Zr0.0Ol）l.0O302, or simply formula TiO2. According to the shock effects of quartz and feldspars, the peak shock pressure and post-shock temperature in the TiO2-II-bearing gneiss are estimated to be between 35 and 43 GPa and 300-900~C, respectively. The finding of TiO2-II in the shock-metamorphosed gneiss provides another mineral physics evidence for shock origin of the Xiuyan crater.