【摘要】：蚌埠隆起位于華北板塊南緣,其受到華北、揚子板塊碰撞及之后燕山運動的影響,記錄了重要的構(gòu)造信息,值得開展構(gòu)造解析研究。近期我們在蚌埠鳳陽地區(qū)發(fā)現(xiàn)了一條近東西走向的逆沖推覆構(gòu)造,本文運用多種方法,對該逆沖推覆構(gòu)造的幾何學、運動學、形成年代與環(huán)境進行了精細的研究和探討,經(jīng)過對馬山、小紅山以及西蘆山三條橫過推覆構(gòu)造的剖面進行系統(tǒng)的測量、采樣、分析和研究得出以下幾點共識：(1)蚌埠鳳陽地區(qū)的逆沖推覆構(gòu)造具有由南向北推覆的運動學特征；(2)利用應(yīng)力場軟件對研究區(qū)進行應(yīng)力狀態(tài)分析,得出鳳陽地區(qū)受到近南北向和北西-南東向兩種方向的擠壓力,與石英顆粒渦度分析所顯示的擠壓背景一致；(3)從推覆構(gòu)造帶內(nèi)兩期不同的變形特征、兩組代表性面理182°∠10°和142°-∠33。,再結(jié)合推覆構(gòu)造內(nèi)石英ESR測年得到268.6±25.0～208.3±20.0Ma和163.4±16.0～151.5±15.0Ma的年齡,推測此逆沖推覆經(jīng)過兩期構(gòu)造,一期受到印支期階段華北板塊與揚子板塊完全碰撞近南北向的擠壓；另一期受到早-中燕山階段,太平洋板塊與亞洲陸塊碰撞近北西向的擠壓。(4)利用角閃-斜長溫壓計、二長溫度計及多硅白云母壓力計測得鳳陽逆沖推覆形成的溫度在300～490℃之間,對應(yīng)的壓力在0.28-0.63GPa,屬于中低溫中壓環(huán)境。由于鳳陽地區(qū)風化較嚴重,巖石出露極少,所以研究程度有限,有很多問題還沒能徹底研究清楚,包括推覆距離及具體規(guī)模等,有待于進一步的研究確定。
[Abstract]:Bengbu uplift is located in the southern margin of the North China plate, which is influenced by the collision of North China and Yangtze plates and the Yanshanian movement, which records important tectonic information and deserves to be studied by tectonic analysis. Recently, we found a near east-west thrust nappe structure in Fengyang area of Bengbu. In this paper, the geometry, kinematics, age and environment of the thrust nappe structure are studied and discussed in detail by using various methods. After systematic measurement and sampling of three sections across the nappe structure in Ma Shan, Xiao Hong Shan and Xilushan, The conclusions are as follows: (1) the thrust nappe structure in Bengbu Fengyang area has the kinematic characteristics of thrusting from south to north; (2) using the software of stress field to analyze the stress state in the study area, it is concluded that the Fengyang area is subjected to extrusion pressure in the direction of NNE and NW-SE, which is consistent with the extrusion background of quartz particle vorticity analysis. (3) according to the different deformation characteristics of two stages in the nappe tectonic belt, the two groups of representative planes 182 擄~ 10 擄and 142 擄~ 33. Combined with the ESR dating of quartz in the nappe structure, the ages of 268.6 鹵25.0U 208.3 鹵20.0Ma and 163.4 鹵16.0U 151.5 鹵15.0Ma are obtained. It is inferred that the thrust-nappe passed through two stages of tectonics. The first stage was squeezed by the collision between North China plate and Yangtze plate in the Indosinian period. The other stage is squeezed by the collision of the Pacific plate with the Asian continent block in the early and middle Yanshanian stage. (4) using the hornblender-oblique long temperature and pressure meter, Two long thermometers and polysilicon Muscovite pressure gauges show that the temperature of the thrust nappe of Fengyang is between 300 ~ 490 鈩，

本文編號：2418420