【摘要】：航空磁測(cè)△T圖上清楚顯示出沿雅魯藏布江縫合帶具有南北兩條航磁異常,地質(zhì)研究確認(rèn)沿雅魯藏布江縫合帶的蛇綠巖體呈帶狀東西向延續(xù)近2000 km,但已知主要含鉻蛇綠巖體分布于雅魯藏布江南岸。在羅布莎和澤當(dāng)?shù)乇碛^測(cè)到斷續(xù)分布著含鉻蛇綠巖體,地質(zhì)研究程度較高,巖體規(guī)模不大。向西地表有出露日喀則巖體,再西段有當(dāng)窮、普蘭、東坡等規(guī)模巨大的巖體。航空磁測(cè)圖上顯示出日喀則、東坡、普蘭、當(dāng)窮等巖體與清晰的航磁異常對(duì)應(yīng)。對(duì)上述巖體進(jìn)行的地面磁測(cè)準(zhǔn)確地確定了已知巖體與航磁異常的關(guān)系,位于雅魯藏布江東段的羅布莎與澤當(dāng)巖體屬于其南部強(qiáng)航磁異常北緣的負(fù)異常范圍內(nèi)的小巖體。西部沿江含鉻蛇綠巖體是斷續(xù)分布的,呈短條帶狀或較大的三度體;地面磁測(cè)異常突出反映出地表巖體磁鐵礦分布的不均勻性,在巖體邊緣(包括近巖體圍巖)的蛇紋石化較強(qiáng),磁異常亦較強(qiáng),并由此較準(zhǔn)確地圈定出巖體范圍。航磁異常反映出巖體內(nèi)部有相對(duì)富積的磁性礦物和磁性體,它們可能來(lái)自深部含F(xiàn)e O、Fe2O3等礦物在巖漿上涌到上地殼由于蛇紋石化而生成了Fe3O4,當(dāng)溫度低于480℃時(shí)形成較強(qiáng)的磁性。反演計(jì)算了磁性體位于3~5 km深度上,雖然蛇綠巖體及其圍巖中存在的磁鐵礦非直接來(lái)源于地幔物質(zhì),但含鉻蛇綠巖體的巖漿物質(zhì)是生成磁鐵礦的主要物質(zhì)貢獻(xiàn)者。由此將航磁和地面磁測(cè)異常與大地電磁法、反射地震等方法結(jié)合可以給出巖體深部結(jié)構(gòu)的地球物理特征,這有利于圈定找礦的遠(yuǎn)景地段。
[Abstract]:The aeromagnetic T map clearly shows two aeromagnetic anomalies along the Yarlung Zangbo suture zone. Geological studies confirm that the ophiolite along the Yarlung Zangbo suture zone extends in a zonal east-west direction for nearly 2000 km,. But the main chromium-bearing ophiolite is known to be distributed on the south bank of the Yarlung Zangbo River. Chromium-bearing ophiolitic bodies are observed intermittently on the surface of Robusa and Zedang. The geological studies are relatively high and the scale of the rocks is not large. To the west there are exposed Xigaze rock bodies, and then the west section of Dang poor, Plain, East Slope and other large rock mass. The aeromagnetic maps show that the Xigaze, Dongpo, Plain and Dangfang rock masses correspond to clear aeromagnetic anomalies. The relationship between the known rock mass and aeromagnetic anomaly is accurately determined by the surface magnetic survey of the above rock mass. The Rocksa and Zedang rock bodies located in the eastern section of the Yarlung Zangbo River belong to the small rock mass within the negative anomaly range of the northern margin of the strong aeromagnetic anomaly in the south of the rock mass. The chromium-bearing ophiolitic rock bodies in the western part of the Yangtze River are distributed intermittently, with short banded or larger cubic bodies. The surface magnetic anomaly highlights the heterogeneity of the distribution of magnetite in the surface rock mass. The serpentine and magnetic anomalies are stronger at the edge of the rock mass (including the surrounding rock mass), and the range of the rock mass is delineated more accurately. Aeromagnetic anomalies reflect relatively rich magnetic minerals and magnetic bodies inside the rock body, which may be derived from minerals such as Fe O _ 2O _ 3 in the deep layer, which upwelled to the upper crust of magma and formed Fe3O4, due to serpentinization. When the temperature is below 480 鈩，

本文編號(hào)：2392993