渤海湾西岸西汉先民用海的新发现及对“西汉海侵”的启示

New Discovery of a Fishing Site during Western Han Dynasty and an Enlightenment for the “Western Han Dynasty's Transgression”on the West Coast of Bohai Bay

地质学(古环境重建与AMS14C测年)和考古学研究,发现了位于渤海湾西岸距现代岸线仅5km的大港穿港路采土场贝壳质河口沙坝海滩层上的、具海水捕捞特征的西汉先民短暂居停遗址,及其上覆的、持续约700~800年的1.6m厚海相层。这是渤海湾西岸迄今所发现的距现代海岸线最近的、被海相层覆盖的西汉先民用海遗址。全新世中期海退以来,渤海湾西岸至少有5道主要的贝壳堤——岭地古海岸线,它们的初始年龄分别是6.6~6.2ka cal BP、5.5 ka cal BP、3.3 ka cal BP、2.4~2 ka cal BP和0.9ka cal BP(即4650~4250 BC、3550 BC、1350 BC、450~50 BC和1050 AD)。每一道堤——岭岸线在其形成发育期,均构成当时的海、陆界线:界线向海一侧是古海区、向陆一侧是高水头海水影响的低地。上古林——齐家阜堤——岭岸线形成于战国——西汉时期,岸线后的大面积洼地直至东晋——北魏时期曾频繁地被高水头海水淹浸,穿港路西汉遗址则直接被海相层覆盖,二者共同为"西汉海侵说"提供了地质学证据。

Based on geological and archaeological studies,including palaeoreconstruction of the sedimentary environment and AMS14 C dating,a new fishing camp in Chuanganglu Pit,located ~ 5 km west to the present shoreline on the west coast of Bohai Bay,left by the West Han people was found recently from a buried shelly beach and it was overlayed by 1. 6-m- thick marine layer which lasted for 700 ~ 800 years. Until now,this West Han people ruin which was overlayed by marine layer is the nearest one to the modern shoreline on the west coast of Bohai Bay. Following the mid-Holocene marine regression, at least five chenier——linear earthy mound palaeoshorelines existed on the west coast of Bohai Bay. Their forming ages were 6. 6 ~ 6. 2 ka cal BP,5. 5 ka cal BP,3. 3 ka cal BP,2. 4 ~ 2 ka cal BP and 0. 9 ka cal BP( 4650 ~ 4250 BC,3350BC,1350 BC,450 ~ 50 BC and1050AD),respectively. Each chenier——linear earthy mound shoreline was a boundary between land and sea in a certain time period,during which its seaward area was ancient sea while its landward depression area was frequently inundated by high waters( both storm surges and spring tides). Of them,the Shanggulin——Qijiafu chenier——linear earthy mound shoreline emerged during the Warring States to West Han Dynasty and dead a thousand years later in the East Jin——North Wei Dynasties. During this period,seaward area was occupied by sea water and landward depressions were frequently influenced by high waters. On the other hand,the West Han ruin at the Chuanganglu site was directly buried by the marine layer. Both of them provided plausible geological evidence for the West Han Transgression existence on the west coast of Bohai Bay.