胶南造山带及邻近地区的重磁场特征及地质解释  

FEATURES OF GRAVITY AND MAGNETIC FIELDS AND GEOLOGICAL EXPLANATION OF THE JIAONAN OROGENIC BELT AND ITS NEIGHBOUR AREAS

作　　者：马兆同 刘慧勤 马兆祥 

机构地区：[1]山东省物化探勘查院

出　　处：《山东地质》1997年第1期92-102,共11页Geology of Shandong

摘　　要：胶南造山带的重磁场特征为一条醒目的重力低、磁力高值带，走向北东－南西，陆上部分长约450km，宽40～70km。其重磁场值一般为0×10－5m／S2～20×10－5m／S2、0～300nT，反映胶南造山带的轮廓及带内低密度的早元古代晋宁期花岗岩基和中强磁性的中生代燕山晚期岩浆岩的分布。根据重力场降低、磁异常升高程度和规模大小（宽窄），该重磁场带又可分为日照－青岛、乳山－威海、即墨－海阳三段，前者重力低、磁力高的程度较强，范围较大。造山带内重磁异常值具负相关关系，域值呈正相关性，即重力值越低的地区磁异常值越高，二者的范围大体相当。这一特征反映了造山带内部早元古代晋宁期花岗片麻岩的发育程度和中生代岩浆岩侵入的规模。胶南造山带的重力低、磁力高值带与连云港－苏山岛重力高、磁力低值带恰成对照。后者重磁场值一般为10×10－5m／S2～30×10-5m／S2、一50～-100nT，反映连云港－苏山岛块体的结晶基底由高密度、低磁性的原东海群、荆山群包体和无古宙侵入岩组成。该造山带南东侧西低东高的重力梯度带（Vzz＝1．2×10－5m·S－2／km～1．75×10－5m·S－2／km）反映了赣榆一荣成断裂（倾向NW）的存在；北西侧正磁异常带表明该断裂为控岩断裂，其南段的正负重力梯度带（Vzz＝1．0×10-5m·S-The gravity and magnetic fields of the Jiaonan orogenic belt is feaured by a distinct zone of gravity low and magnetic high striking in NE-SW direction. On the land, it is 450km long and 40～70km wide. Its gravity and magnetic values are 0 × 10-5m/S2～20 × 10-5m/S2 and 0～300nT, respectively,in general. This reflects the outline of the Jiaonan orogenic belt, and the distribution of the low-density Neo-proterozoic granite batholiths of the Jinning phase, and of the Mesozoic magmatic rocks with medium-grade magnetism in the late Yanshan epoch. The gravity and magnetic field zone can be divided into three sections:Rizhao-Qingdao, Rushan-Weihai and Jimo-Wendeng ones, and for the gravity low and magnetic high is in the first section,with a wide range as well. Within the orogenic belt,the gravity and magnetic anormaly values are correlated with each other,while the values have a positive correlation. This reflects the development of granites of the Neo-proterozoic Jinning epoch and the intrusion scale of the Mesozoic magmatic rocks in the orogenic belt. The zone with gravity low and magnetic high in the Jiaonan orogenic belt is contrast to that of the gravity high and magnetic values low in the Lianyungang-Sushandao. The gravity and magnetic values of the latter reflects that the crystallized basement of the Lianyungang -sushandao block is composed of the Doughal group, Jinshan group inclusions and Proterozoic intrusive rocks with high density and low magnetism. The gravity gradient zone low in the west and high in the east (Vu＝ 1. 2～1.75 × 10-5m·S-2/km in the SE flank of the belt reflects the existence of Ganyu-Rongcheng fault (which dips to NW) while the positive magnetic anormaly zone in the NW side of the belt reflects that the fault in a rock controlling fault,and the positive and negative gravity gradient zones in the south section (Vu＝1. 0 ×10-5m· S2/km～1. 3 ×10-5m· S2/km) of the belt are the reflection of the Wulian-Qingdao fault (dipping to SE). The gentle and undulate gradient zone in the

关 键 词：造山带 邻近地区 重磁场 胶南造山带 地质解释 

分 类 号：P542.2[天文地球—构造地质学] P631.2[天文地球—地质学]