地质学报
地質學報
지질학보
ACTA GEOLOGICA SINICA
2009年
11期
1584-1600
,共17页
谢春林%杨建国%王立社%王育习%王静平
謝春林%楊建國%王立社%王育習%王靜平
사춘림%양건국%왕립사%왕육습%왕정평
甘肃北山%雀儿山-英安山地区%北山岛弧带%陆缘增生地体
甘肅北山%雀兒山-英安山地區%北山島弧帶%陸緣增生地體
감숙북산%작인산-영안산지구%북산도호대%륙연증생지체
Gansu Beishan%Queershan-Yinganshan area%island arc zone%continental margin accretionary terrain
综合研究得出结论:"甘肃北山红石山断裂带以北的雀儿山-英安山地区为一种与俯冲洋壳板块相关的岛弧带,它记录了古亚洲大洋向南缘东天山古陆系统下俯冲消减的整个地史过程".主要依据:①该地区缺少古老基底陆壳;②发育于区内的中奥陶世-泥盆纪不同时代地层中的火山岩和石炭-三叠纪的中酸性侵入岩,主要以钙碱性或TTG或埃达克成分系列为主要标志,揭示深部有消减洋壳板片或岩源的存在;③从中奥陶世和志留纪火山岩的玄武岩、安山岩和英安岩组合,到泥盆纪以安山岩、英安岩为主的流纹岩、玄武岩组合,至三叠纪马鞍山、小草湖中酸性侵入岩序列的部分高钾钙碱性岩石类型组合,反映古亚洲大洋在南侧消减带之上从一种不成熟岛弧到成熟岛弧和大陆边缘弧发育演化的过程;文章提出代表古亚洲大洋南缘消减带的实际位置应在雀儿山-英安山一线以北的蒙古境内,而北山岛弧带实属南侧东天山古陆陆缘增生地体的一部分.
綜閤研究得齣結論:"甘肅北山紅石山斷裂帶以北的雀兒山-英安山地區為一種與俯遲洋殼闆塊相關的島弧帶,它記錄瞭古亞洲大洋嚮南緣東天山古陸繫統下俯遲消減的整箇地史過程".主要依據:①該地區缺少古老基底陸殼;②髮育于區內的中奧陶世-泥盆紀不同時代地層中的火山巖和石炭-三疊紀的中痠性侵入巖,主要以鈣堿性或TTG或埃達剋成分繫列為主要標誌,揭示深部有消減洋殼闆片或巖源的存在;③從中奧陶世和誌留紀火山巖的玄武巖、安山巖和英安巖組閤,到泥盆紀以安山巖、英安巖為主的流紋巖、玄武巖組閤,至三疊紀馬鞍山、小草湖中痠性侵入巖序列的部分高鉀鈣堿性巖石類型組閤,反映古亞洲大洋在南側消減帶之上從一種不成熟島弧到成熟島弧和大陸邊緣弧髮育縯化的過程;文章提齣代錶古亞洲大洋南緣消減帶的實際位置應在雀兒山-英安山一線以北的矇古境內,而北山島弧帶實屬南側東天山古陸陸緣增生地體的一部分.
종합연구득출결론:"감숙북산홍석산단렬대이북적작인산-영안산지구위일충여부충양각판괴상관적도호대,타기록료고아주대양향남연동천산고륙계통하부충소감적정개지사과정".주요의거:①해지구결소고로기저륙각;②발육우구내적중오도세-니분기불동시대지층중적화산암화석탄-삼첩기적중산성침입암,주요이개감성혹TTG혹애체극성분계렬위주요표지,게시심부유소감양각판편혹암원적존재;③종중오도세화지류기화산암적현무암、안산암화영안암조합,도니분기이안산암、영안암위주적류문암、현무암조합,지삼첩기마안산、소초호중산성침입암서렬적부분고갑개감성암석류형조합,반영고아주대양재남측소감대지상종일충불성숙도호도성숙도호화대륙변연호발육연화적과정;문장제출대표고아주대양남연소감대적실제위치응재작인산-영안산일선이북적몽고경내,이북산도호대실속남측동천산고륙륙연증생지체적일부분.
Based on the comprehesvie analysis of previsou research results, the study concludes that the Que'ershan-Yinganshan area, which is to the north of Hongshishan fault belt in Beishan Mt., Gansu province is an island arc associated with subduction ocean crust and records the geological process of the subduction of the ancient Asian Ocean crust subducted into the southern margin of East Tianshan old land. The conclusion is based on the facts as follows:① this area is lack of ancient continental crust basement; ② subducted ocean crust relicts are indicated by volcanic rocks contained various age strata ranging from mid-Ordovician to Devonian and Carboniferous-Triassic intermediate-acidic intrusions. These rocks are represented by some calc-alkaline rock association or TTG or adakite series; ③the evolution process of ancient Asian Ocean, which began with immature arc island, followed by mature island arc and ended by continental marginal arc, was successively testified by volcanic rock associations such as basalt, andesite and dacite in mid-Ordovician and Silurian, dominated by andesite and dacite interclating rhyolite in Devonian, and parts of high K calc-alkaline rock association of intermediate-acidic intrusions in Maanshan and Xiaocaohu in Triassic. Furthermore, it is suggested that the south subduction zone of ancient Asian Ocean should be really located in Mongolia, and the island arc zone should belong to part of continental margin accretionary terrain of East Tianshan old land.