CAJ | 학술논문

古生代时期,北山地区的地壳活动非常强烈,主要表现为:早古生代初期大陆的裂解,一直到中奥陶世广阔大洋盆的发育.志留纪末,洋盆在自南向北的俯冲中封闭,使北侧的哈萨克斯坦板块和南侧的塔里木板块拼贴,并在碰撞造山过程中又构成了一个相对统一的陆块.在晚古生代,北山地区地壳又在另外一种形式中异常强烈活动,特别是自石炭纪到二叠纪,大规模的中酸性岩浆侵入活动构成本区重要的地质事件,其出露的花岗岩类占到了全区总面积的近1/3,但泥盆纪时期的地壳活动,特别是花岗岩浆的侵入活动常被人们忽视,笔者据泥盆纪时期的沉积-火山作用及挤压构造活动也较发育认为,海西早期也应有较强的花岗岩浆侵入活动.本文有针对性地对北山地区,原定为海西中期的东七一山花岗岩岩基,在岩石学和地球化学等方面研究基础上,对3处岩石中锆石首次进行了 SHRIMP U-Pb 年龄测定,其结果分别是(355±4) Ma、(359±4) Ma、(355±5) Ma,这表明东七一山花岗岩形成于泥盆纪晚期,从而确定了北山晚古生代早期也有花岗岩浆的强烈活动,这对深化北山古生代地壳演化过程有积极意义.
고생대시기,북산지구적지각활동비상강렬,주요표현위:조고생대초기대륙적렬해,일직도중오도세엄활대양분적발육.지류기말,양분재자남향북적부충중봉폐,사북측적합살극사탄판괴화남측적탑리목판괴병첩,병재팽당조산과정중우구성료일개상대통일적륙괴.재만고생대,북산지구지각우재령외일충형식중이상강렬활동,특별시자석탄기도이첩기,대규모적중산성암장침입활동구성본구중요적지질사건,기출로적화강암류점도료전구총면적적근1/3,단니분기시기적지각활동,특별시화강암장적침입활동상피인문홀시,필자거니분기시기적침적-화산작용급제압구조활동야교발육인위,해서조기야응유교강적화강암장침입활동.본문유침대성지대북산지구,원정위해서중기적동칠일산화강암암기,재암석학화지구화학등방면연구기출상,대3처암석중고석수차진행료 SHRIMP U-Pb 년령측정,기결과분별시(355±4) Ma、(359±4) Ma、(355±5) Ma,저표명동칠일산화강암형성우니분기만기,종이학정료북산만고생대조기야유화강암장적강렬활동,저대심화북산고생대지각연화과정유적겁의의.
@@@@During Paleozoic, the crustal movement was intense in Beishan area, which mainly found expression in the splitting of Early Palaeozoic unified continent and the formation of ocean basin in Middle Ordovician. At the end of Silurian, the oceanic basin was underthrusting in SN direction and was finally closed, that caused the collage between the northern side of the Kazakhstan plate and the southern Tarim plate as well as the formation of a relatively uniform plate. In Late Paleozoic, another movement occurred. From Carboniferous to Permian, the acid-intermediate magmatic intrusions in these areas made up important geological events. The outcropped area of granite occupies 1/3 of the total area. Nevertheless, researchers tend to ignore the crustal movement, especially the intrusion of granitic magma in Devonian period. The authors hold that the volcano-sedimentary and tectonic activities did occur in Devonian, so there existed strong magmatic intrusive activities in these areas in Hercynian period. Petrological and geochemical researches were conducted, and zircon SHRIMP U-Pb dating was performed for three granites, which yielded ages of (355±4) Ma, (359±4) Ma, (355±5) Ma respectively, suggesting that Dongqiyishan granitic batholith was formed in Late Devonian instead of in Middle Hercynian. It is thus thought that the collisional orogenesis in the Beishan Mountain during Early Late Paleozoic was accompanied by strong granitic magma activity, which played an important role in deepening the crustal evolution process of Palaeozoic in Beishan area.