本文選題：砂質(zhì)紋層 + 分粒級頻率曲線　； 參考：《海洋地質(zhì)與第四紀(jì)地質(zhì)》2016年04期

【摘要】：根據(jù)165個柱狀樣頂部1m的沉積構(gòu)造和粒度分析結(jié)果,對長江口各地貌單元的沉積物特征進(jìn)行了規(guī)律性總結(jié),以應(yīng)用于鉆孔沉積相的判斷。結(jié)果顯示,河口心灘、上河口段落潮槽和攔門沙為主要砂質(zhì)沉積區(qū),屬于牽引流沉積,分粒級頻率曲線的峰值主要出現(xiàn)在63~125μm及125~250μm粒級,且峰值在125~250μm粒級的樣品向海逐漸增多。而殘留砂沉積物粒徑大、分選好,特征明顯。其余地貌單元均以泥質(zhì)沉積為主,典型特征有:(1)潮坪層偶發(fā)育,砂質(zhì)紋層密集;(2)在分粒級頻率曲線中,口內(nèi)漲潮槽主峰以4μm為主,口外漲潮槽變粗為31~63μm占主導(dǎo),且砂質(zhì)薄層增多;(3)下河口段落潮槽紋層很多,極薄紋層占主導(dǎo);(4)南匯邊灘分粒級曲線常見雙峰現(xiàn)象,平均中值粒徑在泥質(zhì)沉積區(qū)最大,部分沉積物位于C-M圖的遞變懸浮段;(5)三角洲前緣復(fù)式河槽沉積物明顯細(xì)于其他前緣沉積,反映了滯流點(diǎn)附近的弱水動力特征;(6)前三角洲為均質(zhì)泥,紋層少見,為長江口區(qū)最細(xì)的沉積。
[Abstract]:Based on the results of sedimentary structure and grain size analysis of 165 columnar samples at the top of 1m, the sediment characteristics of various geomorphological units in the Changjiang Estuary are summarized regularly, which can be used to judge the sedimentary facies in boreholes. The results show that the main sandy sedimentary area is the estuarine core beach, the tidal channel in the upper estuary section and the bar sand, which belongs to the tractive flow deposition. The peak value of the frequency curve of grain size mainly appears at the grain levels of 63 ~ 125 渭 m and 125 ~ (250) 渭 m, and the peak value increases gradually at the level of 125 ~ 250 渭 m. However, the residual sand sediment has large particle size, good separation and obvious characteristics. The other geomorphologic units are mainly muddy, typical features are: (1) the tidal flat is occasionally developed, and the sand grain is dense, (2) in the grain-level frequency curve, the main peak of the intraoral flood trough is mainly 4 渭 m, and the main peak of the in-mouth tidal trough is mainly 4 渭 m, and the outer tidal trough is thickened to 31 ~ (63) 渭 m. And the sand thin layer increased; (3) there are many tidal channel layers in the lower estuary section, and the very thin grain layer dominates; (4) there are two peaks in the grain-grade curve of Nanhui beach, and the mean median particle size is the largest in the muddy sedimentary area. Some of the sediments are located in the progressive suspension section of C-M diagram, (5) the sediment of the delta front composite channel is much smaller than other front sediments, which reflects the weak hydrodynamic characteristics near the stagnation point, (6) the pre-delta is homogeneous mud, and the laminar layer is rare. It is the thinnest deposit in the Changjiang Estuary.
【作者單位】： 華東師范大學(xué)河口海岸國家重點(diǎn)實(shí)驗(yàn)室;上海市地質(zhì)調(diào)查研究院;
【基金】：國土資源部公益項(xiàng)目(201211009)
【分類號】：P737.1

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