發(fā)布時間：2018-05-03 23:26

  本文選題：華南地塊 + 構(gòu)造體制轉(zhuǎn)換　； 參考：《地學(xué)前緣》2017年04期

【摘要】：長期的華南地塊研究取得了一系列重要成果,但是古太平洋俯沖作用于華南的地質(zhì)記錄不是很清晰,尚存爭論。一派認(rèn)為始于二疊紀(jì),另一派認(rèn)為中生代。本文試圖通過華南中生代EW向特提斯構(gòu)造域和NE向古太平洋構(gòu)造域的構(gòu)造轉(zhuǎn)換過程及轉(zhuǎn)換時間入手,探討古太平洋俯沖啟動。雪峰山地區(qū)早侏羅世地層以及侏羅紀(jì)類磨拉石建造呈NE或NNE向展布,燕山期主要發(fā)育2期褶皺變形,早期褶皺軸向為NE—NNE向,晚期為NNE或近南北向的隔槽式褶皺;而印支期也發(fā)育2期褶皺變形,D1期為EW—NEE向,D2期為NNE向的緊閉褶皺。這些都說明晚三疊世雪峰山地區(qū)已經(jīng)從EW向特提斯構(gòu)造域向NE—NNE向太平洋構(gòu)造域的構(gòu)造方向轉(zhuǎn)換。而南嶺地區(qū),以及更南部的南海北部海域,構(gòu)造轉(zhuǎn)換時間相對較晚,為早—中侏羅世。綜合前人的測年數(shù)據(jù),德興斑巖型銅礦三個含礦斑巖體形成于大約172 Ma,形成于古太平洋板塊俯沖所形成的活動大陸邊緣環(huán)境,成礦物質(zhì)來源于俯沖洋殼的部分熔融,與地幔楔發(fā)生混染,推測與該時期古太平洋板塊的平板俯沖、板片撕裂、拆沉和俯沖后撤一系列過程密切相關(guān)。同期,華南東南部發(fā)育了NE—NNE向、NW向和近EW向三組斷裂,其中白堊紀(jì)(135~100 Ma)華南NE—NNE向的走滑斷裂強(qiáng)烈活動,從東向西依次為:濱海斷裂、長樂—南澳斷裂、政和—大埔、邵武—河源—陽江斷裂、吳川—四會斷裂和合浦—北流斷裂,主要表現(xiàn)為右旋走滑作用,在東南沿海地區(qū)形成一系列的拉分盆地,并非典型的"盆嶺構(gòu)造"。根據(jù)群速度和S波速度層析成像,華南地塊總體上從西向東地殼的厚度整體上逐漸減薄;華南地塊東部發(fā)生兩次殼幔相互作用,對應(yīng)兩次巖石圈拆沉,這兩次拆沉都與古太平洋板塊的俯沖有關(guān),第一次拆沉為古太平洋板塊平板俯沖時板片撕裂所致,第二次拆沉為俯沖板片俯沖后撤和高角度俯沖造成。
[Abstract]:A series of important achievements have been made in the study of the South China landmass for a long time, but the geological records of the subduction of the ancient Pacific Ocean in South China are not very clear. One school of thought began in the Permian and the other believed that the Mesozoic era. This paper attempts to discuss the initiation of paleo-Pacific subduction through the tectonic transformation process and transition time of Mesozoic EW to Tethys tectonic domain and NE to paleo-Pacific tectonic domain in South China. The early Jurassic strata and Jurassic Molarasite formations in Xuefengshan area were distributed in NE or NNE direction. In Yanshanian period, the fold deformation was mainly in 2 stages, the axial direction of the early fold was NE-NNE, and the late stage was NNE or the near south-north trench fold. In the Indosinian period, there are also two stages of fold deformation, namely, the closed fold in the D _ 1 stage of EW-NEE and NNE direction in D _ 2 phase. All these indicate that the late Triassic Xuefeng Mountain area has been transformed from EW to Tethys tectonic domain to NE-NNE to Pacific tectonic domain. The tectonic transition time of Nanling region and the northern waters of the South China Sea is relatively late, which is early and Middle Jurassic. Based on the previous dating data, the three ore-bearing porphyry deposits of Dexing porphyry copper deposit were formed at about 172 Ma, formed in the active continental margin environment formed by the subduction of the paleo-Pacific plate, and the ore-forming materials originated from the partial melting of the subducted oceanic crust. Mixing with the mantle wedge is inferred to be closely related to a series of processes of plate subduction, plate tearing, delamination and subduction backward of the paleo-Pacific plate during this period. In the same period, there are three groups of faults in the southeast of South China: the NE-NNE trending NW and the near EW. Among them, the Cretaceous NE-NNE trending strike-slip faults are strongly active. The sequence from east to west is Binhai fault, Changle Nanao fault, Zheng he Tai Po, etc. Shaowu-Heyuan-Yangjiang fault, Wuchuan-Sihui fault and Hepu-north current fault, mainly manifested as dextral strike-slip, formed a series of pull-apart basins in the southeast coastal area, not typical "basin-ridge structure". According to the group velocity and S-wave velocity tomography, the thickness of the crust of South China block decreases gradually from west to east, and two crust-mantle interactions occur in the eastern part of South China block, corresponding to two lithospheric delamination. These two desinks are related to the subduction of the paleo-Pacific plate. The first was caused by the tearing of the plate during the subduction of the paleo-Pacific plate, and the second was caused by the subduction of the subduction plate and the high-angle subduction.
【作者單位】： 海底科學(xué)與探測技術(shù)教育部重點(diǎn)實(shí)驗室中國海洋大學(xué)海洋地球科學(xué)學(xué)院;青島海洋科學(xué)與技術(shù)國家實(shí)驗室海洋地質(zhì)功能實(shí)驗室;
【基金】：國家自然科學(xué)基金杰出青年基金項目(41325009) 山東省泰山學(xué)者特聘教授項目 鰲山卓越科學(xué)家計劃(2015ASTP-0S10) 國家海洋局重大專項(GASI-GEOGE-01)
【分類號】：P542

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本文編號：1840570