| 摘要: |
| 地层方面,将原上二叠统蒙拉组重新厘定为前奥陶系松多岩群;将旁多群解体;将原桑巴群细分为马里组和桑卡拉佣组;在嘉黎断裂带内发现了多尼组。岩石方面,确定了发育于嘉黎断裂带中的超镁铁质—镁铁质岩为嘉黎缝合带内的蛇绿岩,形成于晚三叠世;发现冈底斯岩浆弧带上存在晚三叠世花岗岩;沿色日绒—巴嘎一带发现了晚侏罗世二云母花岗岩;在扎雪地区发现了钾玄质的浅成侵入岩;证实了区内始新世火山岩的存在;将区内的变质期划分为加里东期和燕山期两期,并查明了其温压条件。构造方面,发现了扎雪-门巴韧性变形带和色日绒-巴嘎脆韧性变形带;确定测区构造至少经历4次不同层次的构造变形。 |
| 关键词: 1:25万 地质调查 门巴区幅 成果与进展 西藏 |
| DOI： |
| 附件 |
| 投稿时间：2004-12-10 |
| 基金项目: |
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| 1:250 000 Mainba Sheet in Xizang |
| Institute of Geological Survey, Jilin University |
| (Institute of Geological Survey, Jilin University, Changchun 130061, Jilin, China) |
| Abstract: |
| Stratigraphically, the previously Late Permian Mengla Formation is redefined as the pre-Ordovician Songduo Group Complex. The Pangduo Group is redivided into Nuoco, Laigu and Luobadui Formations, and the previously Sangba Group into the Mali and Sangkalayong Formations. The Duoni Formation is recognized within the Lhari fault. Petrologically, the ultramafic-mafic rocks within the Lhari fault are redefined as the ophiolites dated back to the Late Triassic in age. There occur the Late Triassic granites along the Gangdise magmatic arc, Late Jurassic two-mica granites in the Sebrong-Bagar zone, shonshonitic hypabyssal intrusive rocks in the Zaxoi region, and Eocene volcanic rocks in the Zaxoi region, Lhunzhub. The metamorphism may be discriminated into two phases:the Caledonian and Yanshanian, with the temperatures of metamorphism ranging between 450℃ and 605℃ and pressures between 0.93 GPa and 1.15 Gpa. Tectonically, the investigation of the structural features permits the identification of the Zaxoi-Mainba ductile deformational zone and Sebrong-Bagar brittle-ductile deformational zone. There exist at least four phases of structural deformations throughout the surveyed area. |
| Key words: 1:250 000 geological survey Mainba Sheet development Xizang |
