Late Neogene sediment properties in the Wilkes Land continental rise (IODP Exp. 318 Hole U1359A), East Antarctica

详细信息    查看全文

• 作者：Boo-Keun Khim ; Buhan Song ; Hyen Goo Cho ; Trevor Williams…
• 关键词：Key wordsbiogenic opal ; NGR ; clay mineralogy ; sea ice ; East Antarctic Ice Sheet ; Wilkes Land ; IODP
• 刊名：Geosciences Journal
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：21
• 期：1
• 页码：21-32
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth Sciences, general;
• 出版者：The Geological Society of Korea
• ISSN：1598-7477
• 卷排序：21

文摘

On the basis of the variations of sediment properties such as biogenic opal, grain size, natural gamma radiation (NGR), and clay mineralogy, we differentiate two types of late Neogene marine sediments that record paleoclimate changes associated with the growth and retreat of the East Antarctic Ice Sheet (EAIS) and associated changes in sea ice cover. The first type of sediments are massive muds characterized by high biogenic opal (30~55%), low NGR (15~30 counts per second (cps)), large mean grain size (>8.3 μm), and low smectite/(illite + chlorite) [S/(I + C)] ratios (<~0.2). We interpret these sediments as the result from deposition by hemipelagic sedimentation during interglacial conditions. In contrast, the second type of sediments are laminated muds characterized by low biogenic opal (5~7%), high NGR (45~67 cps), small mean grain size (<6.3 μm), and high S/(I + C) ratios (>~0.2). We interpret these sediments as the result from deposition by either turbiditic or contouritic processes during glacial conditions. All these sediment properties indicate that the Wilkes Land continental rise recorded late Neogene paleoclimatic changes in terms of surface water productivity, sediment provenance and transport pathway, and depositional processes that are related to the growth and retreat of EAIS. In addition, the decreased maxima of biogenic opal content at Hole U1359A highlights the temporal climatic change between the late Pliocene (~2.0 Ma to ~3.7 Ma) and the early Pliocene to late Miocene (~3.7 Ma to ~6.3 Ma), confirming the important role of sea ice to the surface water productivity associated with the global cooling trend in the East Antarctica.