本文選題：北礁凹陷 + 梅山組��； 參考：《海洋學(xué)報(bào)》2017年05期

【摘要】：南海瓊東南盆地北礁凹陷中中新統(tǒng)梅山組頂部丘形反射目前引起廣泛關(guān)注,前人推測為生物礁、重力蠕動(dòng)與底流疊加成因、等深積丘等。本文通過鉆井資料、二維、三維地震資料精細(xì)刻畫丘形反射(殘丘)和丘間水道特征及其成因。殘丘及水道在北礁凸起不發(fā)育,在邊緣斜坡中部和高地較發(fā)育,且有向高地兩邊規(guī)模減小趨勢,不具對稱性,殘丘和水道呈平行-亞平行近E-W向展布,局部有合并分叉現(xiàn)象,與北礁凸起走向呈一小角度;丘寬562~1 223m,丘高29~87m,丘長10km左右,存在丘翼削蝕,水道底蝕現(xiàn)象。地震屬性分析表明三維工區(qū)西南部殘丘間水道由砂泥巖互層充填,形成長條形強(qiáng)振幅,而殘丘為中-低振幅;地震、鉆井資料分析表明丘形反射(殘丘)由鈣質(zhì)泥巖和泥巖組成,屬于半深海沉積,且殘丘內(nèi)部波阻抗為5.0×10~6~6.5×10~6 kg/m~3·m/s,低于火山巖、灰?guī)r波阻抗,屬于砂泥巖地層范疇;根據(jù)梅山組下段水道由西向東強(qiáng)振幅變?nèi)�、分叉、前積反射和海山附近底流(等深流)沉積剝蝕特征綜合判定底流古流向自西向東,根據(jù)海山兩翼地震反射特征推測底流可追溯至晚中新世早期(11.6Ma BP),綜合分析認(rèn)為,研究區(qū)中中新統(tǒng)梅山組丘形反射是晚中新世早期底流切割梅山組地層形成的殘丘。
[Abstract]:The mound reflection at the top of Miocene Meishan formation in Beijiao depression, Qiongdongnan Basin, South China Sea, has attracted wide attention. Through drilling data, 2D and 3D seismic data, the characteristics and origin of mound reflection (residual mound) and interdune waterway are described in detail in this paper. The residual hills and waterways are not developed in the uplift of the northern reef, and are relatively developed in the middle of the marginal slope and in the highlands. The scale of the residual hills and waterways decreases towards both sides of the highlands without symmetry. The residual hills and waterways are distributed in a parallel sub-parallel near E-W direction, and there is a phenomenon of amalgamation and bifurcation in some areas. At a small angle to the strike of the North Reef uplift, the width of the mound is 562 ~ 1223m, the height of the mound is 29 ~ 87m, the length of the mound is about 10km, and there exists the phenomenon of clipping of the hill and erosion of the bottom of the waterway. The seismic attribute analysis shows that the channel between the residual hills in the southwest of the three dimensional working area is filled with sand and mudstone interbedded, forming long stripe strong amplitude, while the residual hill is medium to low amplitude. The analysis of drilling data shows that the mound reflection (residual mound) is composed of calcareous mudstone and mudstone, and belongs to semi-deep sea sediment, and the internal wave impedance of residual mound is 5.0 脳 10 ~ (6) ~ (6) 脳 10 ~ (-6) kg/m~3 路m ~ (-1), which is lower than that of volcanic rock and limestone wave impedance, which belongs to the category of sand and mudstone strata. According to the characteristics of weak amplitude from west to east, bifurcation, forward product reflection and denudation of the bottom flow (isodeep current) near the seamounts in the lower reach of Meishan formation, the paleo-flow direction from west to east is determined. Based on the seismic reflection characteristics of the two wings of the seamounts, it is inferred that the bottom flow can be traced back to the late Miocene early Miocene (11.6 Ma) BPU. The comprehensive analysis shows that the mound reflection of the Miocene Meishan formation is the residual mound formed by the late Miocene undercurrent cutting the Meishan formation.
【作者單位】： 西北大學(xué)大陸動(dòng)力學(xué)國家重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家科技重大專項(xiàng)(2011ZX05025-006-02) 國家自然科學(xué)基金(41390451)
【分類號】：P736.1;P618.13
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本文編號：1847187