本文選題：藏南　切入點：床得剖面　出處：《科學通報》2017年04期 　論文類型：期刊論文

【摘要】：特提斯喜馬拉雅位于大印度最北端,其構造演化是理解印度-亞洲大陸碰撞過程的關鍵之一.為了更好地限定特提斯喜馬拉雅中生代以來的古地理位置及其漂移歷史,本文對藏南江孜床得剖面侏羅系下熱組、維美組和白堊系床得組開展了古地磁研究.古地磁樣品取自39個采樣點,其中下熱組5個,巖性為青灰色安山巖;維美組25個,巖性為粉砂巖和砂巖;床得組9個,巖性為灰?guī)r.對118個古地磁柱狀樣品進行的逐步熱退磁和交變退磁結果顯示,下熱組和維美組樣品未能分離出穩(wěn)定的特征剩磁;床得組樣品分離出了穩(wěn)定的特征剩磁(Ch RM),且具有正反極性,并通過了倒轉(zhuǎn)檢驗.結合沉積學和巖石磁學結果,床得組樣品的特征剩磁很可能為原生剩磁,其年齡為86.3~74.0 Ma.床得組樣品特征剩磁的平均方向為Ds=152.0°,Is=?52.9°,?=18.0,?95=5.9°.該數(shù)據(jù)表明,特提斯喜馬拉雅江孜地區(qū)在晚白堊世(80.1±6.2 Ma)所處的古緯度為南緯33.1°±5.6°,與印度板塊北緣同時代所處的古緯度一致(參考點28.0°N,88.5°E),說明二者至少在晚白堊世之前從運動學意義上仍然是一個塊體,缺乏大洋分隔的證據(jù).這為理解印度-亞洲大陸碰撞方式提供了新的古地磁約束.
[Abstract]:The Tethys Himalayas are located at the northernmost tip of Greater India, and their tectonic evolution is one of the keys to understanding the process of the Indo-Asian continent collision. In order to better define the paleogeographic location and drift history of the Tethys Himalayas since the Mesozoic, In this paper, paleomagnetic studies have been carried out on the lower Jurassic heat formation, the Weimei formation and the Cretaceous bed formation in Jiangzi bed section of southern Tibet. The paleomagnetic samples were collected from 39 sampling sites, of which 5 were from the lower heat formation, and 25 from the Weimei formation, with the lithology of bluish-gray andesite and the Weimei formation. The lithology is siltstone and sandstone, the bed formation is 9 and the lithology is limestone. The results of gradual thermal demagnetization and alternating demagnetization of 118 paleomagnetic columnar samples show that the samples of lower heat formation and Weimei formation can not separate stable characteristic remanence. The stable characteristic remanent magnetic remanence (CHRMN) was separated from the bed group, and it had positive and negative polarity, and passed the inversion test. Combined with the results of sedimentology and rock magnetism, the remanent magnetism of the bed group was likely to be primary remanent magnetism. The average direction of remanent magnetism of the bed samples is Ds=152.0 擄Isa? 52.9 擄? 18. 0? 955.9 擄. The data show that, The paleolatitude of the Tethys Himalayan Jiangzi area in the late Cretaceous (80.1 鹵6.2 MaA) is 33.1 擄鹵5.6 擄south latitude, which is the same as that of the northern margin of the Indian plate (reference point 28.0 擄Nwe 88.5 擄E ~ (-1)), which indicates that the paleolatitudes of the two regions were kinematic at least before the late Cretaceous. It's still a block, The lack of evidence of ocean separation provides a new paleomagnetic constraint for understanding the Indian-Asian continental collision pattern.
【作者單位】： 南京大學地球科學與工程學院內(nèi)生金屬礦床成礦機制研究國家重點實驗室;
【基金】：國家自然科學基金(41274071,41525007) 國家重點基礎研究發(fā)展計劃(2012CB822001)資助
【分類號】：P318.44;P542

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本文編號：1565907