江西宜丰-德兴叠覆造山带的基本特征及其意义

Basic features and significance of Yifeng-Dexing superimposition orogenic belt, Jiangxi Province

宜丰—德兴一带存在新的一种造山带类型,称之为晋宁期—加里东期宜丰-德兴叠覆型造山带,总体呈半月形舌状展布,是经北南双向多期碰撞叠覆的隐伏-半隐伏型造山带。经对多个出露于造山带内的构造岩片进行时态、位态、相态的研究与恢复,建立了该造山带的结构样式和构造演化序列,具有3层结构模式。分别由代表中新元古代华南洋的残迹蛇绿混杂岩、扬子陆缘弧前盆地火山-沉积变质岩系、下南华统次深海相沉积的浅变质岩片与怀玉—广丰地区青白口纪晚期—早古生代沉积的下南华统浅变质岩片组成。造山带两侧的宜丰-景德镇与德兴-弋阳推覆带是中国重要的铜、金多金属矿集区,伏于变质岩之下的晚古生代煤系地层有巨大的找煤潜力。

During the study and compilation of new generation of Jiangxi Regional Geology, the authors found a new kind of oro- genic belt type in the Yifeng-Dexing area, which is called Jinningian-Caledonian Yifeng-Dexing superimposition type orogenic belt that is spread in the semilunar tongue form. It is a concealed-semiconcealed type orogenic belt formed through N-S bidirection- al multi-periodic collision and superimposition. Based on studying and recovering the tense state, site state and phase state of the tec- tonic slices exposed along orogenic belts, the authors established a tectonic evolution sequence model with a three-layer structure. The model of structure includes the remnants of ophiolite of South China Sea, metamorphosed volcanic sedimentary series of fore- arc basin on the Yangtze continental margin in Middle-Late Proterozoic, abyssal facies sedimentary epimetamorphic rock slice of Lower Nanhua System, and Lower Nanhua System epimetamorphic rock slice of Late Qingbaikou Period-Early Paleozoic Period in Huaiyu-Guangfeng area. Yifeng-Dexing and Jingdezhen-Yiyang nappe zone on both sides of the orogenic belt is an important ore concentration area of copper, gold polymetallic resources, and the Late Paleozoic coal seam under metamorphic strata has a huge po- tential in search for coal.