本文選題：祝村組 + 地層單元解體�。� 參考：《巖石學(xué)報》2017年01期

【摘要】：浙東南沿海小雄盆地中"祝村組"火山巖的年代學(xué)研究表明,其形成時代(128Ma)不僅老于其上覆的上火山巖系(110~88Ma),還老于本應(yīng)在其下伏的九里坪組(122~120Ma)而與區(qū)域內(nèi)西山頭組時代相同(130~128Ma)。"祝村組"火山巖的鋯石Hf同位素組成表現(xiàn)出富集的特征并具有古元古代的地殼模式年齡(εHf(t)=-16.4~-13.6,tDM2=2.01~2.09Ga),同樣與磨石山群下部地層如西山頭組相似。結(jié)合火山碎屑巖-流紋巖的巖石組合以及區(qū)域地質(zhì)特征,本研究認為"祝村組"的建組理由不充分,建議將其解體。同時,"祝村組"火山巖富集的Hf同位素組成表明其源區(qū)為較為純粹的古元古代地殼基底物質(zhì),進一步暗示相對內(nèi)陸地區(qū)的下巖系早期火山巖形成過程中已有較明顯的虧損幔源物質(zhì)參與,這是以往研究中未明確識別出的。浙東南地區(qū)晚中生代火山巖巖石成因中底侵幔源物質(zhì)貢獻比例的升高和火山碎屑巖-流紋巖-雙峰式火山巖巖石組合均暗示了逐漸增強的巖石圈伸展應(yīng)力環(huán)境,這可能與古太平洋俯沖板片的后撤作用密切相關(guān)。
[Abstract]:A chronological study of the volcanic rocks of the Zhucun formation in the Xiaoxiong Basin, southeast Zhejiang Province, shows that the volcanic rocks formed at the age of 128MaA are not only older than that of the upper volcanic rocks overlying them, but also older than that of the Jiuliping formation, which should be located under it, and is the same as that of the Xishantou formation in the region. " The zircon HF isotopic composition of the volcanic rocks in the Zhucun formation shows the characteristics of enrichment and has the Gu Yuan age of the ancient crustal model (蔚 Hfltntnll-16.4- 13.6t DM2U 2.01U 2.09Ga), which is similar to that of the lower part of the Moshishan Group such as the Xishantou formation. Combined with the rock assemblage of pyroclastic rock and rhyolite and the regional geological characteristics, this study considers that the formation of Zhucun formation is not well-founded, and suggests to disintegrate it. At the same time, the HF isotopic composition of the volcanic rocks enriched in the "Zhucun formation" indicates that the source area is relatively pure Paleoproterozoic crustal basement material. It is further suggested that the depleted mantle source material has been involved in the formation of the early volcanic rocks in the lower rock series, which has not been clearly identified in previous studies. The increase of the contribution ratio of mantle source materials from the late Mesozoic volcanic rocks and the volcanic rock assemblages of pyroclastic rocks, rhyolite and bimodal volcanic rocks in southeastern Zhejiang suggest a gradually enhanced lithospheric extensional stress environment. This may be closely related to the retreat of the paleo-Pacific subduction plate.
【作者單位】： 桂林理工大學(xué)地球科學(xué)學(xué)院 廣西隱伏金屬礦產(chǎn)勘查重點實驗室;桂林理工大學(xué)廣西有色金屬隱伏礦床勘查及材料開發(fā)協(xié)同創(chuàng)新中心;南京大學(xué)地球科學(xué)與工程學(xué)院 內(nèi)生金屬礦床成礦機制研究國家重點實驗室;
【基金】：國家重點研發(fā)計劃項目(2016YFC0600203) 國家自然科學(xué)基金項目(41430208) 桂林理工大學(xué)科研啟動費資助項目聯(lián)合資助
【分類號】：P588.14

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