Institute of Earth Sciences, The Hebrew University, Jerusalem 91904, Israel.
J Hum Evol. 2011 Apr;60(4):407-16. doi: 10.1016/j.jhevol.2010.07.026. Epub 2010 Oct 30.
Aquifers dominated by Pleistocene basalts and Jurassic to Cretaceous calcareous rocks feed the Hula basin which is drained by the Jordan River into Lake Kinneret. The sedimentary sequence of Lower-Middle Pleistocene Benot Ya'akov Formation (BYF) exposed by excavations of the 0.78 Ma lake-side site of Gesher Benot Ya'aqov (GBY) consists of six cycles representing ca. 100 ka history of the Hula basin. This study characterizes the types of water sources in the catchment, tests the use of the Strontium (Sr) isotopes in the common extant snail Melanopsis sp. as a tracer for water in its habitat, and uses this tracer in the fossil specimens from GBY to investigate the palaeohydrology of the Hula paleolake during the corresponding period. The Sr isotope composition ((87)Sr/(86)Sr) of extant Melanopsis shells in the Hula catchment range widely (0.7046-0.7079). These analyses define distinct groups of water sources and aquifers, while the Jordan River at the GBY site has values around 0.70685. The values for fossil Melanopsis from GBY vary along stratigraphy; they are highest around 0.70710 in Cycles 1 and 2, decrease to around 0.70685 in Cycle 3, and exhibit upward trending fluctuations in the subsequent cycles to 0.70703 in Cycle 6. This trend reveals the dominance of the Hermon Jurassic aquifer during the earlier, colder periods before the Matuyama-Brunhes Boundary (MBB) and enhanced influence of the Golan basaltic aquifers, in subsequent warmer periods, indicating that the MBB coincides with climate warming as supported by other indicators. Hence, this global geochronological indicator of 0.78 Ma is also potentially a global palaeoclimatic marker. The similarity between the Sr isotope composition of the Jordan River waters and Melanopsis and those from Cycle 3 suggests that the current climate corresponds to that of the warmest period within the record of GBY, clarifying the comparative interpretation of this 100 k.yr. climate record.
下更新统本诺雅科夫组（Benot Ya'akov Formation，简称 BYF）和中更新统地层构成了胡拉流域的主要含水层，其地下水通过约旦河补给加利利海。在 Gesher Benot Ya'aqov（GBY）0.78Ma 湖岸点的挖掘中，揭示了下-中更新统贝诺雅科夫组（Benot Ya'akov Formation，简称 BYF）的沉积序列，由六个旋回组成，代表了胡拉流域约 100ka 的历史。本研究分析了流域内的水源类型，测试了常见现存蜗牛 Melanopsis sp. 的锶（Sr）同位素作为其栖息地水的示踪剂的用途，并将其应用于 GBY 的化石样本中，以研究相应时期胡拉古湖的古水文学。胡拉流域现存 Melanopsis 壳的锶同位素组成（((87)Sr/(86)Sr)范围很广（0.7046-0.7079）。这些分析确定了不同的水源和含水层群，而 GBY 点的约旦河值约为 0.70685。GBY 的化石 Melanopsis 的值沿地层变化；它们在第 1 周期和第 2 周期周围最高，约为 0.70710，在第 3 周期下降至约 0.70685，随后的周期呈向上波动趋势，在第 6 周期达到 0.70703。这种趋势表明，在 Matuyama-Brunhes 边界（MBB）之前的较冷时期，赫尔蒙山侏罗纪含水层占主导地位，而在随后的较暖时期，戈兰玄武岩含水层的影响增强，表明 MBB 与其他指标所支持的气候变暖相对应。因此，这个 0.78Ma 的全球地质年代学指标也可能是一个全球古气候标志。约旦河的水以及 Melanopsis 和第 3 周期的 Sr 同位素组成之间的相似性表明，当前的气候与 GBY 记录中最温暖时期的气候相对应，澄清了对这 100ka 气候记录的比较解释。
