Geochemistry of Cretaceous volcanic-intrusive magmatism in western Guangdong and its geological significance

Hongyan Geng, Xisheng Xu

Research output: Contribution to journalMeeting abstractpeer-review

Abstract

Late Mesozoic intermediate-acidic volcanic rocks are widespread
in the coastal area of southeast China, while they have little
distribution inland. Systematic zircon LA-ICPMS U–Pb
dating reveals that Cretaceous volcanic-intrusive activities developed
in western Guangdong (inland). Representative volcanic
rocks, i.e. Maanshan and Zhougongding rhyodacites, have zircon
U–Pb isotopic ages of 100 ± 1 Ma, and the intrusive ones including
the Deqing monzonitic granite body and the Xinghua granodiorite
body in the Shidong complex, as well as the Tiaocun
granodiorite body in the Guangping complex yield ages of
99 ± 2 Ma, ca. 100 Ma, and 104 ± 3 Ma, respectively. The biotite-
granites of the Shidong complex main body (461 ± 35 Ma)
and that of the Guangping complex (444 ± 6 Ma) are Caledonian.
Both Cretaceous volcanic-intrusive rocks and Caledonian
intrusive rocks are characterized by high-K calc-alkali features,
enrichment in Rb, Th, Ce, Zr, Hf, Sm, depletion in Ba, Nb, Ta,
P, Ti, and weak REE tetrad effects. But there are some differences
in the negative Eu anomalies with Caledonian intrusive rocks
showing the most distinct one, and Cretaceous volcanic rocks
having the least distinct. Studies of Sr–Nd isotopes show that
the Cretaceous rhyodacite, granitoids, and the Caledonian biotite
granite all have high (87Sr/86Sr)i values (0.7105 to 0.7518), low
eNd(t) values (7.23 to 11.39), and two-stage Nd modal ages
(T2DM) ranging from 1.6 to 2.0 Ga, which indicate that they
may all derive from the Proterozoic crust basement by partial
melting processes.
The petrochemical features of Cretaceous volcanic-intrusive
magmatism in western Guangdong are similar to those of the Late
Mesozoic volcanic-intrusive magmatisms in the coastal area of SE
China. Their occurrences are related with the important lithospheric
extension event in southeast China at ca. 100 Ma. This
study also enable us to extend the ‘‘volcanic line’’ southwestward
to western Guangdong.
Original languageEnglish
Pages (from-to)A197-A197
Number of pages1
JournalGeochimica et Cosmochimica Acta
Volume70
Issue number18 supplement
DOIs
Publication statusPublished - 2006
EventGoldschmidt Conference (16th : 2006) - Melbourne, Australia
Duration: 27 Aug 20061 Sep 2006

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