水载荷及其对盆地沉降的影响

盆地沉降是构造作用与充填盆地的沉积物和水体载荷产生的重力作用共同作用的结果。文章提出了水载荷沉降的概念,推导出了水载荷沉降的计算公式,定量地分析了水载荷对盆地沉降的贡献,并在充分考虑沉积物载荷、水载荷、海平面变化、古水深等的情况下,对Steckler和Watts构造沉降量计算公式作了修正。对美国纽约大西洋大陆边缘COSTB-2井的定量分析表明,每发生1km的构造沉降将产生约0.435km的水载荷沉降,去除水载荷影响后的实际构造沉降比Steckler和Watts估算的结果约小30.3%,水载荷是导致美国大西洋大陆边缘强烈沉降的重要因素之一。

Water Loads and Its Effect on Basin Subsidence

Basin subsidence can be induced by many factors, such as tectonic activity, sedimentary loading, and water loading, and so on. This paper puts forward a concept of water loads subsidence, deduces a calculation formula of water loads subsidence, quantitatively analyzes the contribution of water loads to basin subsidence. Furthermore, fully considering the effects of sediment loads,water loads,sea-level changes, and paleao-water depth on basin subsidence, this paper gives a revision to the formula used to calculate the tectonic subsidence by Steckler and Watts. The quantitative analysis of the COST B-2 well located in Atlantic-type continental margin of New York, U.S.A indicated that each 1km tectonic subsidence can simultaneously results in 0.435 km water loads subsidence, the "true" tectonic subsidence that removed water loads effect on basin subsidence is about 30.3% lower than the result calculated using Steckler and Watts formula. So, we can conclude that water loads are one of the important factors, which result in the intensive subsidence of Atlantic-type continental margin.