Age vs Depth profile of core GC12, collected from the Capricorn Channel off the Eastern Australian Coast

A gravity core (GC12) was collected from a depth of 990.5 mbsl within the Capricorn Channel, southern Great Barrier Reef (GBR). Isotopic values for 18-O and 13-C were obtained from Globigerinoides ruber and correlated with the SPECMAP age-model. Radiocarbon dating of Globigerinoides sacculifer was also undertaken at nine sample depths, and then corrected and correlated with the curve. This yielded an age vs. depth profile from which it was possible to determine approximate sedimentation rates. From the age-model we see the evidence of MIS 1 through to 5a with sedimentation rates ranging from 2 cm/kyr to 20 cm/kyr, with an average of 10cm/kyr. This is a high sedimentation rate for a sedimentary basin, however the core is situated on the increased slope of the Capricorn Channel, therefore sediments scoured off the shallow gradient slope above may feasibly be focused at this depth on the slope. The sedimentation rate exhibits a unorthodox pattern, with a very high rate (25 cm/kyr) during the middle of MIS 3.

研究人员从大堡礁（Great Barrier Reef，GBR）南部的摩羯水道内，水深990.5米（meters below sea level，缩写mbsl）处采集获得重力岩心（gravity core）GC12。从红拟抱球虫（Globigerinoides ruber）壳体中测定得到氧18（¹⁸O）与碳13（¹³C）的同位素比值，并将该结果与SPECMAP年代模型进行关联比对。同时，针对9个采样层位的箭状抱球虫（Globigerinoides sacculifer）开展了放射性碳定年，经校正后与对应同位素曲线进行关联，由此构建了年龄-深度剖面，据此可推算近似沉积速率。基于该年代模型，可识别出海洋同位素阶段（Marine Isotope Stage，MIS）1至5a的沉积记录，对应沉积速率介于2厘米/千年至20厘米/千年之间，平均沉积速率为10厘米/千年。该沉积速率对于沉积盆地而言属于较高水平，但该岩心赋存于摩羯水道的坡度增大地段，因此上方缓坡被冲刷侵蚀的沉积物可合理地在此斜坡处富集。该沉积速率呈现出非常规的变化模式，其中在海洋同位素阶段3（MIS 3）中期出现了高达25厘米/千年的沉积速率。