Zircon constraints on granite derivation in the northern North China Craton
Zircon constraints on granite derivation in the northern North China Craton
复制标题
华北克拉通北部花岗岩演化的锆石约束
DOI：
10.1016/j.lithos.2020.105370
复制
发表时间：
2020-03
期刊：
影响因子：
3.5
通讯作者：
Hu J.
中科院分区：
文献类型：
--
作者：
Fan W.B.;Jiang N.;Zhai M.G.;Hu J.
具有核-环结构的锆石在世界范围内的花岗岩类中很常见。大多数情况下，核心有显着的年龄比轮辋。锆石核是继承自花岗岩类的源岩，还是只是在岩浆上升过程中偶尔从围岩中捕获的，这是非常有争议的。本文报道了华北丰宁地区三个具有不同时代和地球化学成分的中生代花岗岩，它们的~ 1.8Ga锆石核一致。冰山梁I型花岗岩中锆石的δ 18 O值（8.3‰ ~ 10.1‰）远高于岩浆锆石，这与冰山梁I型花岗岩的锆石来源不符。相反，它们可能来自岩浆上升过程中的围岩。这一结论与该区存在的~ 1.8Ga S型花岗岩和变质沉积岩具有高δ 18 O值的特征相一致。同样，五道营和牛泉子坝花岗岩中的锆石核在微量元素上与广泛出露的1.8Ga花岗岩类有许多相似之处，表明它们可能来自古元古代花岗岩类。1.8Ga锆石核中缺乏明显的变质内部结构和微量元素印记，进一步支持了捕虏晶的推测，如果它们来自花岗岩源区的话，可能是由于中生代深熔作用的影响。结合岩石Nd同位素和岩浆锆石Hf同位素组成，认为这三个中生代花岗岩来自晚太古代下地壳。推测华北东部其它地区中生代花岗岩类中的~2.5锆石核也可能是岩浆侵入~ 2.5Ga基底岩石过程中从围岩捕获的颗粒，而不是来自源区。五道营和牛泉子坝花岗岩中的岩浆锆石微量元素分别具有埃达克质和A型特征，可作为花岗岩起源的示踪剂。
Zircons with core-rim structure are common in granitoids worldwide. Mostly, the cores have strikingly older ages than the rims. Whether the zircon cores are inherited from the source of the granitoids or just occasionally captured from the wallrocks during magma ascent is highly controversial. In this paper, three Mesozoic granites with diverse ages and geochemical compositions but uniformly ~1.8 Ga zircon cores are reported from the Fengning area of North China Craton. The zircon cores in the Bingshanliang I-type granites have much higher δ18O values (8.3‰ to 10.1‰) than the magmatic zircons, strongly arguing against that these zircon cores are from the source of the granites. Instead, they could come from the wallrock during magma ascent. This conclusion is consistent with the occurrence of ~1.8 Ga S-type granites and meta-sedimentary rocks in the region which are characterized by high δ18O values. Similarly, zircon cores in the Wudaoying and Niuquanziba granites share many similarities in trace elements with the widely outcropped ~1.8 Ga granitoids, suggesting their probably xenocrystic origin from the Paleoproterozoic granitoids. The xenocrystic speculation is further supported by the lack of obviously modified internal textures and trace element imprints in the ~1.8 Ga zircon cores due to the effect of the Mesozoic anatexis if they had been derived from the source region of the granites. Combined with the bulk rock Nd isotopic and magmatic zircon Hf isotopic compositions, the three Mesozoic granites are suggested to be derived from the late Archean lower crust. It is inferred that ~2.5 zircon cores in some Mesozoic granitoids from other parts of the North China Craton are also likely captured grains from the wallrock during magma intrusion into the ~2.5 Ga basement rocks, rather than from the source. The magmatic zircon trace elements from the Wudaoying and Niuquanziba granites fingerprint the adakitic and A-type characters of their respective magma, implying their utility in tracing granites' derivation.
登录
查看更多内容
影响因子：
3.5
作者：
Neng Jiang;R. Carlson;Jinhui Guo
通讯作者：
Neng Jiang;R. Carlson;Jinhui Guo
DOI：
--
发表时间：
1986
期刊：
--
影响因子：
--
作者：
J. D. Cr-nlrnNs
通讯作者：
J. D. Cr-nlrnNs
影响因子：
3.5
作者：
Belousova, EA;Griffin, WL;Fisher, NI
通讯作者：
Fisher, NI
影响因子：
3.5
作者：
Li, Xian-Hua;Liu, Yu;Chamberlain, Kevin R.
通讯作者：
Chamberlain, Kevin R.
影响因子：
3
作者：
Fu-Yuan Wu;Guochun Zhao;S. Wilde;Deyou Sun
通讯作者：
Fu-Yuan Wu;Guochun Zhao;S. Wilde;Deyou Sun