U-Pb age and Hf-O isotopes of detrital zircons from Hainan Island: Implications for Mesozoic subduction models
U-Pb age and Hf-O isotopes of detrital zircons from Hainan Island: Implications for Mesozoic subduction models
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海南岛碎屑锆石U-Pb年龄和Hf-O同位素：对中生代俯冲模型的启示
DOI：
10.1016/j.lithos.2015.10.006
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发表时间：
2015-12
期刊：
影响因子：
3.5
通讯作者：
Huang Hui-Qi
中科院分区：
文献类型：
--
作者：
Jiang Xiao-Yan;Li Xian-Hua;Collins W.J.;Huang Hui-Qi
华南中生代岩浆年龄的汇编表明，在约1000年有多个“岩浆平静”期。公元前205-195年。150-140 Ma和ca。125-115 Ma，质疑构造模式，建议正在进行的安第斯型俯冲沿着华南大陆边缘。对采自海南岛白垩纪鹿木湾组的两个碎屑锆石样品进行的西姆斯U-Pb分析表明，该地区的锆石主要有三个年龄峰，其年龄峰位于约1000年。120 Ma，ca. 155、我和你235 Ma.这些年龄的锆石大多为自形物，并显示出典型的岩浆振荡分带，表明来自附近岩浆源的短距离迁移。极罕见的CA。120 Ma的岩浆记录表明，该年龄的碎屑锆石可能来自海南岛附近的一个源区，但目前还没有发现。中生代碎屑锆石的原位Hf和O同位素分析表明，εHf（t）（− 21.2 ~ 10.5）和δ 18 O（4.4‰ ~ 13.6‰）值变化较大。它们之间的一般负相关性表明旧的表壳物质的改造（平均地壳居住年龄约为1000年）。2.0 Ga），由年轻的幔源岩浆形成。从三叠纪到白垩纪，锆石εHf（t）值逐渐增大，δ 18 O值逐渐减小，这表明中生代地壳经历了一个渐进的生长过程。这一结果与活动大陆边缘的杂交相一致。我们简要地回顾了印支造山带的构造模式，并提出岩石学证据表明，中生代岩浆活动是不晚于约2000年沿着东亚大陆边缘形成的环太平洋增生造山带的一部分。250 Ma，并至少持续到晚白垩世。
A compilation of magmatic ages from the Mesozoic South China Block suggests a number of “magmatic quiescence” periods at ca. 205–195 Ma, ca. 150–140 Ma and ca. 125–115 Ma, casting doubt on tectonic models that suggest ongoing Andean-type subduction along the South China continental margin. However, SIMS U-Pb analyses on two detrital zircon samples from the Cretaceous Lumuwan Formation on Hainan Island, southeast China, reveal three major age peaks at ca. 120 Ma, ca. 155 Ma and ca. 235 Ma. Zircons of these ages are mostly euhedral and show typical magmatic oscillatory zoning, suggesting short-distance transport from nearby magmatic sources. The extremely rare occurrence of ca. 120 Ma magmatic records onshore suggests that detrital zircons of this age population may be derived from a source proximal to Hainan Island but presently missing. Therefore, our data provide new evidence for ongoing magmatic activity in late Mesozoic South China.In situHf and O isotope analyses of the Mesozoic detrital zircons reveal large variations in bothεHf(t) (− 21.2 to 10.5) and δ18O (4.4‰ to 13.6‰) values. A general negative correlation between them suggests the reworking of old supracrustal materials (average crustal residence age of ca. 2.0 Ga) by juvenile mantle-derived magmas. The progression of increasingεHf(t) and decreasing δ18O values of zircons from the Triassic to the Cretaceous suggests progressive crustal growth during the Mesozoic. The results are consistent with hybridization at an active continental margin. We briefly review tectonic models for the Indosinian orogeny and suggest that the petrologic evidence indicates that Mesozoic magmatism was part of the circum-Pacific accretionary orogens that formed along the continental margin of East Asia no later than ca. 250 Ma and continued at least to the late Cretaceous.
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影响因子：
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作者：
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