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高校地质学报 ›› 2024, Vol. 30 ›› Issue (01): 72-88.DOI: 10.16108/j.issn1006-7493.2022077

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华南雪峰山地区新元古代岩石弹性性质研究

普腾飞   

  1. 内生金属矿床成矿机制研究国家重点实验室,南京大学 地球科学与工程学院,南京 210023
  • 出版日期:2024-02-18 发布日期:2024-02-18

Elastic Properties of Neoproterozoic Rocks from Xuefengshan Belt, South China

PU Tengfei   

  1. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
  • Online:2024-02-18 Published:2024-02-18

摘要: 雪峰山构造带位于华南大陆中部,中国深地专项对雪峰山构造带进行地震探测,并且获取了地震剖面,通过地震资料解释认为雪峰山下面存在隐伏造山带,时代为古元古代(2.05~1.75 Ga),并且经历了新元古代裂谷作用改造,该裂谷作用可能与罗迪尼亚超大陆裂解有关,对于重新认识华南大地构造演化历史以及重建全球罗迪尼亚超大陆和哥伦比亚超大陆演化模式具有重要意义。论文通过采用超声波脉冲透射方法研究雪峰山地区新元古代板溪群、冷家溪群轻变质—沉积岩波速特征,结果表明波速随压力呈非线性迅速增加,超过临界压力后,波速随压力呈逐渐缓慢线性增加。线理、面理发育的岩石,最快波方向平行面理、线理,最慢波方向垂直面理、线理,岩石地震波速各向异性介于2%~12%之间。对比理论计算波速与实验测量波速可知,理论计算结果与实际测量结果一致性较好,说明实验测量波速大小基本准确,为雪峰山地区地震资料解释提供了波速数据。

关键词: 轻变质—沉积岩, 岩石波速—压力, 大陆碰撞, 块体拼贴, 造山作用, 裂谷作用

Abstract: Xuefengshan belt is located in the central part of South China. China’s Sinoprobe Project obtained a 400-kmlong high-resolution seismic-reflection profile across the central South China including Xuefeng-Jiangnan thrust belt. Interpretation of seismic data suggests that there is a hidden orogenic belt under Xuefengshan belt, which is Paleoproterozoic (2.05-1.75ga) and modified by Neoproterozoic rifting. This rifting may be related to the breakup of Rodinia supercontinent, and thus is of great significance for understanding the tectonic evolution history of South China and reconstructing the evolution of supercontinents Rodinia and Columbia. In this paper, the wave velocity characteristics of the low-grade metamorphic sedimentary rocks of the Neoproterozoic Banxi Group and Lengjiaxi Group in the Xuefengshan area are studied using the ultrasonic pulse transmission method. The results show that the wave velocity increases rapidly and nonlinearly with pressure, after the critical pressure, velocity increases slowly and linearly with the pressure. For rocks with lineation and foliation, the fastest wave propagation direction is parallel to the foliation and lineation, and the slowest wave propagation direction is vertical to the foliation and lineation. The anisotropy of rock seismic wave is 2%~12%. The theoretical calculation results are in good agreement with the actual measurement data. Therefore, the experimental measurements of velocity provide velocity data for the seismic data interpretation in Xuefengshan belt. 

Key words: low-grade metamorphic-sedimentary rocks, rock velocity-pressure, continental collision, assembly of blocks;
orogenesis,
rifting

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