本文關(guān)鍵詞： 古河道 環(huán)境演化 沿海低地 渤海灣　出處：《地學(xué)前緣》2016年04期 　論文類(lèi)型：期刊論文

【摘要】：在渤海灣沿海低地地區(qū)獲得1個(gè)30m的全取心機(jī)械鉆孔(QX01孔),對(duì)樣品進(jìn)行了沉積巖石學(xué)分析、底棲有孔蟲(chóng)鑒定、硅藻鑒定和粒度分析,結(jié)合AMS 14 C和OSL測(cè)年,重建了研究區(qū)晚更新世以來(lái)的古河道充填及環(huán)境演化過(guò)程。結(jié)果顯示QX01孔自下而上可以分為6段:(1)30~29.72 m,陸相洪泛沉積;(2)29.72~29.4m,海侵沉積,43.5ka BP;(3)29.4~17.7m,砂質(zhì)沉積物,河道填充沉積,37.9~29.7ka;(4)17.7~13.2m,沉積物由砂質(zhì)變?yōu)轲ね临|(zhì),29.7~8ka,由河道填充轉(zhuǎn)為淺湖沼環(huán)境;(5)13.2~5m,8~4ka,全新世海侵沉積,沉積環(huán)境由陸相轉(zhuǎn)為海陸過(guò)渡相,6 000~5 750cal BP海侵達(dá)到最強(qiáng),之后逐漸退出該區(qū);(6)5m以上,洪泛沉積,約1.7ka至今。沉積環(huán)境與海面具有很好的響應(yīng),MIS 4或6階段時(shí),海面較低,河流下切,形成古河道,下切最深處位于現(xiàn)代高程為-24.2m。MIS3階段早期時(shí),海面上升,37.9ka河道開(kāi)始填充,至29.7ka填充完成,對(duì)應(yīng)高程為-11.8m。末次盛冰期至早全新世時(shí)為淺湖沼環(huán)境,沉積作用停止或速率非常低。隨著末次盛冰期的結(jié)束,海洋作用增強(qiáng),進(jìn)入全新世海侵沉積階段,8~4ka cal BP。之后,沉積作用停止,至1.7ka以來(lái),隨著河流作用的不斷增強(qiáng),該區(qū)變?yōu)楹恿骺刂频暮榉撼练e為主。同時(shí),發(fā)現(xiàn)了兩次沉積間斷,分別發(fā)生在末次盛冰期的低海面時(shí)期和4~2ka時(shí)的海水退出、河流沉積尚不充分時(shí)期。
[Abstract]:A 30m full coring machine drill hole QX01 was obtained in the coastal lowland area of Bohai Bay. The samples were analyzed by sedimentary petrology, benthic foraminifera identification, diatom identification and particle size analysis, combined with AMS 14C and OSL dating. The course of paleochannel filling and environmental evolution since the late Pleistocene in the study area has been reconstructed. The results show that the QX01 hole can be divided into 6 sections from the bottom to the top of the study area. The results show that the QX01 hole can be divided into 6 sections: 1 / 1, 30 ~ (30) ~ 29.72 m, 2 ~ (29. 72) m of continental flood sediment, 43.5 ka B ~ ((1)) B ~ ((1)) of transgressive sediment, 329.417 ~ (7) m of sand sediment. The fluvial sediment was filled with 37.9 ~ 29.7 ka / L ~ (4) ~ (17. 7) m ~ (17. 7) m, the sediment changed from sandy to clay (29. 7 ~ 8 ka) and changed from river filling to shallow lake and marsh environment. The sediment was transgressive in Holocene, and the sedimentary environment reached its maximum from 6 000 to 6 000 ~ 5 750 cal BP transgression, and then gradually withdrew from the area to more than 65 m. Flood deposition, about 1.7 ka to the present. The sedimentary environment and sea surface have a good response to the MIS 4 or 6 stage, and the sea level is lower, and the river is cut down, forming paleochannel, the deepest of which is in the early stage of the modern elevation of -24.2m.MIS3. The upper sea level began to fill up at 37.9ka, and the filling was completed at 29.7ka, corresponding to -11.8m. from the last glacial to the early Holocene, there was a shallow lake-marsh environment, and the sedimentation stopped or the rate was very low. With the end of the last glacial period, the oceanic action increased. After entering the transgressive sedimentary stage of Holocene, 4ka cal BP. the sedimentation stopped, and since 1.7ka, with the increasing of fluvial action, the area has become fluvial controlled flood sedimentation. At the same time, two sedimentary discontinuities have been found. It occurred in the low sea stage of the last glacial age and the sea water exit at 4 ~ 2 ka, respectively, while the fluvial deposition was not sufficient.
【作者單位】： 中國(guó)地質(zhì)調(diào)查局天津地質(zhì)調(diào)查中心;中國(guó)地質(zhì)調(diào)查局泥質(zhì)海岸帶地質(zhì)環(huán)境重點(diǎn)實(shí)驗(yàn)室;天津地質(zhì)礦產(chǎn)研究所現(xiàn)代沉積物測(cè)年實(shí)驗(yàn)室;天津師范大學(xué)城市與環(huán)境科學(xué)學(xué)院;中國(guó)社會(huì)科學(xué)院考古研究所;
【基金】：國(guó)家自然科學(xué)基金面上項(xiàng)目(41476074) 中國(guó)地質(zhì)調(diào)查局項(xiàng)目(1212011120169)
【分類(lèi)號(hào)】：P736
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本文編號(hào)：1506495