Insights from heavy minerals and zircon U-Pb ages into the middle Miocene-Pliocene provenance evolution of the Yinggehai Basin, northwestern South China Sea
Insights from heavy minerals and zircon U-Pb ages into the middle Miocene-Pliocene provenance evolution of the Yinggehai Basin, northwestern South China Sea
复制标题
重矿物和锆石U-Pb年龄对南海西北莺歌海盆地中中新世-上新世物源演化的认识
DOI：
10.1016/j.sedgeo.2015.07.011
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发表时间：
2015-08-15
影响因子：
2.8
通讯作者：
Sun, Hui
中科院分区：
文献类型：
--
作者：
Jiang, Tao;Cao, Licheng;Sun, Hui
南海莺歌海盆地保存完好的新生代沉积记录，为探讨东南亚构造和气候演化提供了有利条件。红河是该地区的一个大型河流系统，以前被认为是该盆地的主要泥沙来源。本文将重矿物分析与碎屑锆石U-Pb定年相结合，在盆地尺度上对中中新世—上新世物源演化有了新的认识。结果清楚地揭示了红河以外的潜在源区。英东斜坡南段具有较高的锆石含量和燕山期U-Pb年龄，表明沉积物由海南岛向近端输送。在中坳陷中新世上部明显发现了来自越南中部的物源，其沉积物以少量变质重矿物为特征，U-Pb年龄模式在250 Ma和440 Ma左右达到峰值。同时期大规模的相对海平面下降和沿越南边缘的快速挖掘可能共同促进了这种长距离的沉积物运输。红河沉积物的来源似乎随时间而改变。主流北侧的松洛河可能来自东北向，在中新世中期将新元古代—早古生代的锆石带入莺歌海盆地。晚中新世以来，沿红河断裂带的岩石成为主要的烃源岩。因此，莺歌海盆地中央凹陷广泛分布的变质矿物，结合强烈的河流切割和高的近海沉积速率，表明上新世红河的沉积物供应增加。(C) 2015 Elsevier B.V.版权所有
The well-preserved Cenozoic sedimentary record in the Yinggehai Basin, South China Sea, is suitable to explore the tectonic and climatic evolution of SE Asia. Red River, a large-scale fluvial system in this region, was previously regarded as the major sediment source for the basin. Here we combine heavy mineral analysis and detrital zircon U-Pb dating to shed new light on the middle Miocene-Pliocene provenance evolution at a basin scale. The results clearly reveal potential source areas additional to the Red River. Sediments have been delivered to the proximal areas from Hainan Island, as indicated by the high zircon content and the Yanshanian U-Pb ages in the southern segment of the Yingdong Slope. A provenance from Central Vietnam is explicitly discemed in the upper Miocene of the Central Depression, where sediments are characterized by few metamorphic heavy minerals and the U-Pb age pattern peaking at around 250 Ma and 440 Ma. Coeval large-scale relative sea-level fall and rapid exhumation along the Vietnamese margin together may have facilitated this long-distance sediment transport. Provenance of sediments from the Red River seems to change over time. Song Lo River, on the north side of the main stream, probably flowed from the NE and carried Neoproterozoic-early Paleozoic zircons to the Yinggehai Basin during the middle Miocene. Since the late Miocene, rocks along the Red River Fault Zone have become the dominant source. Subsequently, widespread metamorphic minerals in the Central Depression of the Yinggehai Basin, combined with the strong river incision and high offshore sedimentation rates, indicate an increased sediment supply from the Red River in the Pliocene. (C) 2015 Elsevier B.V. All rights reserved.