Changes in area of shallow siliciclastic marine habitat in response to sediment deposition: implications for onshore-offshore paleobiologic patterns

Models presented here of shallow-marine siliciclastic deposition show that the widths of depth-defined regions differ markedly in response to sea-level change. These models add to recent studies that have emphasized the highly specific response of habitat area to sea-level change. Collectively, these studies indicate that a particular bathymetric zone on a particular margin may vary substantially in area during a sea-level change, while other such zones and margins may experience little or even opposite responses. In the models presented here, intermediate- depth and deep-water regions tend to show sinusoidal variations in width, with widening during relative falls in sea level and narrowing during relative rises. The shallow-water region displays markedly non-sinusoidal change and is consistently characterized by abrupt widening at the beginning of the highstand systems tract and an equally abrupt narrowing at the onset of sea-level fall at the beginning of the falling-stage systems tr...

本文所呈现的浅海碎屑岩沉积（shallow-marine siliciclastic deposition）模型表明，受海平面变化影响，不同深度界定区域的宽度差异显著。此类模型补充了近期相关研究成果——这些研究着重强调了生境面积（habitat area）对海平面变化的高度特异性响应。综合来看，这些研究指出，某一大陆边缘（margin）上的特定水深带（bathymetric zone），其面积在海平面变化过程中可能发生大幅变动；而其他同类水深带与大陆边缘，其面积变化则微乎其微，甚至会呈现相反的响应趋势。在本文所呈现的模型中，中深层与深水区域的宽度多呈现正弦式变化：相对海平面下降时宽度拓宽，相对海平面上升时则收窄。浅水区的变化则显著偏离正弦规律，其特征始终为：高位体系域（highstand systems tract）初始阶段宽度骤然拓宽，而在海平面下降伊始、即下降体系域（falling-stage systems tract）起始阶段时宽度同样会骤然收窄