Fluids (fluorine, chlorine, and OH) in accessory minerals (apatite, titanite and allanite) of Pan-African granitoids (Group-I granitoids, Group-II granitoids and Mefjell Plutonic Complex) from the S?r Rondane Mountains, East Antarctica were precisely measured by an electronic microprobe analyzer in this study. Apatites in the granites have commonly high fluorine contents. However, fluorine contents from the Group-I, Group-II granitoids and Mefjell Plutonic Complex (MPC) are of important variation, which F contents (3.21~7.20 wt%) in apatite from the Group-II granitoids are much higher than those from the Group-I granitoids (1.22~3.60 wt%) and the MPC (3.21~4.11 wt%). Titanite in the MPC has a low fluorine content (0.23~0.50 wt%), being less than those in the Group-I granitoids (2.28 wt%) and Group-II granitoids (1.85~2.78 wt%). Fluorine in allanite in the Group-II granitoids seems to have much lower contents than those from the Group-I granitoids and the MPC. Higher fluorine contents in the titanite from the Group-II granitoids may be mainly controlled by late-magmatic fluid-rock interaction processes associated with melt, but may not be indicative of original magma contents based on its petrographic feature. Due to very lower chlorine contents from all of accessory minerals, the authors suggest that titanite and apatite with higher fluorine contents in the Group-II granitoids have much lower H2O (OH) contents compared with those in the Group-I granitoids according to the partition among (F, Cl, OH). Fluorine contents in whole-rock samples show a variation from the higher in the Group-I granitoids to the lower in the Group-II granitoids and the MPC, which are consistent with the changes of those from the biotite and hornblende as well as fluorite occurred in the Group-I granitoids reported previously. Based on the above study of fluorine in accessory minerals and combined with the previous fluorine contents from biotites and hornblendes, the authors suggest that apatites and titanites with higher F contents in th
LI Zi-longCHEN Han-linYANG Shu-fengTAINOSHO YoshiakiSHIRAISHI KazuyukiOWADA Masaaki
酒泉盆地南缘冲断带具有多层次的逆冲结构,包括浅层的远距离冲断系统、中层的近距离冲断系统和深层的原地冲断系统。远距离冲断系统由奥陶系和志留系构成,局部地区表现为飞来峰;近距离冲断系统由古生界和中生界构成,大部分隐伏在远距离冲断系统之下,局部地带以构造窗的形式出露地表,其变形样式主要为叠瓦状的冲断变形;原地冲断系统隐伏在近距离冲断系统和第四系之下,其南部的变形主要表现为双冲构造或堆垛构造,往NE方向变形逐渐简单,主要表现为断层传播褶皱和断层弯曲褶皱,前锋地带表现为三角带的突起构造。酒泉盆地南缘冲断带的变形是一个具有大缩短量的薄皮冲断系统,旱峡剖面的构造缩短量为52.7 km,缩短率为55.1%。酒泉盆地南缘冲断带的变形时期大致开始于9.0 M a,并以“前展式”向北扩张,变形时间向北变新,前锋断层开始活动时间约为8.3 M a。
