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首页> 外文期刊>Paleoceanography >Holocene Changes in Deep Water Circulation Inferred From Authigenic Nd and Hf Isotopes in Sediment Records From the Chukchi-Alaskan and Canadian Beaufort Margins
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Holocene Changes in Deep Water Circulation Inferred From Authigenic Nd and Hf Isotopes in Sediment Records From the Chukchi-Alaskan and Canadian Beaufort Margins

机译：从Chukchi-Alaskan和Canadian Beaufort边缘的沉积物记录中的Authigenic Nd和HF同位素中的深水循环中的全新世变化

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The rare earth element concentrations and radiogenic isotope (Sr-Nd-Hf) compositions measured in bulk sediment leachates, together with bulk and clay mineralogical data, from two piston cores recovered in the Canadian Beaufort (AMD0214-02PC) and Chukchi-Alaskan (HLY0501-01JPC) margins were studied to investigate changes in the weathering regimes and deep water circulation during the Holocene. The coupled evolutions of the Nd and Hf isotopic compositions (expressed in epsilon units: ?Nd and ?Hf, respectively) are in good agreement with modern seawater and bulk sediment leachate data from Pacific water, Atlantic water, and the Mackenzie River. This agreement supports the idea that boundary exchange and brine formation likely play a significant role in the ?Nd and ?Hf values of the bottom waters in the western Arctic Ocean. The ?Nd and ?Hf records from the Canadian Beaufort and Chukchi- Alaskan margins reveal changes toward more radiogenic values from the early to late Holocene. Based on the ?Nd and ?Hf records, we suggest that the unradiogenic values are not controlled by water mass provenance and mixing but rather by provenance and a change in the weathering regime in the Mackenzie and Yukon drainage basins during the early to mid-Holocene. In contrast, the more radiogenic ?Nd and ?Hf values in the Chukchi-Alaskan margin and the mineralogical records in the late Holocene have primarily been controlled by an increase in the contributions of seawater and detrital particles from the Bering Sea via the Bering Strait inflow, which is likely related to major changes in the Pacific Ocean-atmospheric dynamics.
机译：研究了在加拿大博福特（AMD0214-02PC）和楚科奇-阿拉斯加（HLY0501-01JPC）边缘回收的两个活塞岩芯的散装沉积物浸出液中测得的稀土元素浓度和放射性同位素（Sr-Nd-Hf）组成，以及散装和粘土矿物学数据，以调查全新世期间风化状态和深水循环的变化。Nd和Hf同位素组成的耦合演化（分别以ε单位表示：？Nd和？Hf）与来自太平洋水、大西洋水和麦肯锡河的现代海水和大量沉积物渗滤液数据非常一致。该协议支持边界交换和盐水形成可能在该地区发挥重要作用的观点？然后呢？北冰洋西部底水的Hf值。这个然后呢？来自加拿大博福特和楚科奇-阿拉斯加边缘的高频记录揭示了从全新世早期到晚期更多放射成因值的变化。基于？然后呢？根据Hf记录，我们认为，非放射性值不受水团来源和混合的控制，而是受来源和麦肯齐和育空流域早中全新世期间风化状态的变化的控制。相比之下，更多的放射成因？然后呢？楚科奇-阿拉斯加边缘的Hf值和全新世晚期的矿物学记录主要由白令海通过白令海峡流入的海水和碎屑颗粒的增加所控制，这可能与太平洋大气动力学的重大变化有关。

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