Detrital zircon geochronology of river sands from Taiwan: implications for sedimentary provenance of Taiwan and its source link with the east China mainland
一念起，万水千山；一念灭，沧海桑田。人的心境变幻莫测，大自然亦如是。
在几千万年以前，那时的台湾岛还是大片的松散沉积物，静静地躺在东亚陆架之上。也就最近几个百万年的时间，得益于菲律宾板块与欧亚大陆的“对抗”，这些沉积物才终于结束了暗无天日的海底生活，快速抬升几千米而成岛。那么，这些作为宝岛“骨架”的沉积物，最早都是从哪儿来的呢？又是如何搬运至现今的位置？要想解决这两个充满哲学意味的问题，得从新生代东亚地区的河流系统演化、古地理格局变迁以及陆架沉积环境转变等角度综合考虑。
杨守业教授团队采用碎屑锆石U-Pb年代学作为物源示踪手段，通过对比中国大陆与台湾的碎屑锆石年龄谱图差异，揭示了两者之间的源—汇联系，并提出将多阶段沉积物搬运和沉积后迁移相结合的模式来阐述台湾新生代的沉积演化过程。结果显示，在中新世以前，古台湾地区的沉积物主要来自邻近华夏板块的小河流。自早中新世起，东亚地形逐渐倒转（由“东高西低”变为“西高东低”），大型东流水系建立，它们能够携带着扬子板块和华北板块的物质，一路穿过当时暴露的东亚陆架并进入海区。随后，这些河流沉积物将通过沿岸流向南搬运至古台湾地区。晚中新世以来，在菲律宾板块与欧亚大陆的碰撞作用下，这些不同时期的沉积物被挤压至一处，并隆升形成现今的台湾岛。因为组成台湾岛的岩石主要源自中国大陆，所以这也证明台湾自古以来（新生代）就是中国领土不可分割的一部分。
图1. 晚始新世以来台湾构造—沉积演化简图
该研究成果正式发表于《Earth-Science Reviews》第164卷（2017年1月）。ESR为地球科学领域一区顶级杂志，影响因子为7.337。本文第一作者为我院博士研究生邓凯，通讯作者为我院杨守业教授。
作者主页：
杨守业：http://mlab.tongji.edu.cn/16/56/c8723a71254/page.htm
Citation：
Deng K, Yang S, Li C, et al. Detrital zircon geochronology of river sands from Taiwan: Implications for sedimentary provenance of Taiwan and its source link with the east China mainland[J]. Earth-Science Reviews, 2017, 164:31-47.
全文链接：http://www.sciencedirect.com/science/article/pii/S0012825216303956
Abstract：
Cenozoic sedimentary strata of the continental margin are well-preserved on Taiwan Island thus providing an excellent geological window into the tectonic and environmental changes that occurred in East Asia during this interval. In this study, we report U-Pb ages of detrital zircons from sandy sediments of the Lanyang River in east Taiwan and the Zhuoshui River in west Taiwan. Detrital zircons from the two rivers display seven major age groups: 200–100 Ma, 300–200 Ma, 550–360 Ma, 850–700 Ma, 1.1–0.9 Ga, 2.0–1.8 Ga and 2.6–2.4 Ga. However, significant differences in zircon age distributions exist between the two rivers, showing a high proportion of Phanerozoic zircons in the Lanyang River sediments and a more complex age population and more Precambrian zircons in the Zhuoshui River sediments. This suggests that both rivers must be sampling sedimentary rocks with different zircon age populations and provenances. By comparing the detrital zircon geochronology between Taiwan and three major tectonic blocks in the east China mainland, the Cenozoic sedimentary provenance of Taiwan and its source link with mainland China are revealed. The Eocene–upper Oligocene strata of the Hsuehshan Range and the Miocene turbidites of the west Central Range are mainly sourced from the Cathaysia Block, while the Miocene–Pleistocene strata in the Western Foothills are primarily derived from the Yangtze Block and the North China Block. We infer that the sedimentary evolution of Taiwan is closely related to the interacting processes between the drainage reorganization in East China and the paleogeographic evolution and sedimentary environmental changes in the continental margin. Furthermore, a detailed scenario combining multistep sediment transport with post-depositional migration is proposed to decipher this evolution.