Deep‐Water Formation in the North Pacific During the Late Miocene Global Cooling

Zhai, Lina; Wan, Shiming; Colin, Christophe; Zhao, Debo; Ye, Yuntao; Song, Zhaojun; Yin, Xue‐Bo; Shi, Xuefa; Li, Anchun

doi:10.1029/2020pa003946

Cited by 11 publications

(23 citation statements)

References 95 publications

(164 reference statements)

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“…This picture generally matches interpretations of drift sedimentation in the northeastern Atlantic (Uenzelmann-Neben & Gruetzner, 2019), but not in Newfoundland where sediment drifts suggest a later final intensification of NADW in the Pleistocene (Boyle et al, 2017). A focused study on North Pacific εNd suggests NPDW was being produced until 14 Ma, after which a southern source takes over (Kender et al, 2018), although see Zhai et al (2021) and Burls et al (2017). Holbourn et al (2013a)…”

Section: Deep Water Provenance From εNdsupporting

confidence: 58%

“…It has also been suggested that the LMCIS was primarily the result of background biological overprinting due to changes in photosynthetic pathways in marine and terrestrial primary producers that influenced δ 13 C org and therefore δ 13 C DIC (Falkowski et al, 2005;Katz et al, 2005). Zhai et al (2021) add to this picture with the first geochemical evidence of the Biogenic Bloom in the Japan Sea.…”

Section: Evidence Of Changes In the Miocene Carbon Cyclementioning

confidence: 91%

“…Zhai et al. (2021) add to this picture with the first geochemical evidence of the Biogenic Bloom in the Japan Sea.…”

Section: Atmospheric Co2 and Carbon Cycle Dynamicsmentioning

confidence: 98%

“…A focused study on North Pacific εNd suggests NPDW was being produced until 14 Ma, after which a southern source takes over (Kender et al., 2018), although see Zhai et al. (2021) and Burls et al. (2017).…”

Section: Overturning Circulationmentioning

confidence: 99%

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The Miocene: The Future of the Past

Steinthorsdottir

Coxall

Boer

et al. 2021

Paleoceanog and Paleoclimatol

271

179

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The Miocene epoch (23.03-5.33 Ma) was a time interval of global warmth, relative to today.Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval-the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO 2 , and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO 2 (∼400-600 ppm), the MCO has been suggested as a particularly appropriate analog for future climate scenarios, and for assessing the predictive accuracy of numerical climate models-the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re-interpretation of proxies, which might mitigate the model-data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here, we review the state-of-the-art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modeling studies. Plain Language Summary During the Miocene time period (∼23-5 million years ago),Planet Earth looked similar to today, with some important differences: the climate was generally warmer and highly variable, while atmospheric CO 2 was not much higher. Continental-sized ice sheets were only present on Antarctica, but not in the northern hemisphere. The continents drifted to near their modernday positions, and plants and animals evolved into the many (near) modern species. Scientists study the Miocene because present-day and projected future CO 2 levels are in the same range as those reconstructed for the Miocene. Therefore, if we can understand climate changes and their biotic responses from the Miocene past, we are able to better predict current and future global changes. By comparing Miocene climate reconstructions from fossil and chemical data to climate simulations produced by computer models, scientists are able to test their understanding of the Earth system under higher CO 2 and warmer conditions than those of today. This helps in constraining future warming scenarios for the coming STEINTHORSDOTTIR ET AL.

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Section: Deep Water Provenance From εNdsupporting

confidence: 58%

Section: Evidence Of Changes In the Miocene Carbon Cyclementioning

confidence: 91%

“…Zhai et al. (2021) add to this picture with the first geochemical evidence of the Biogenic Bloom in the Japan Sea.…”

Section: Atmospheric Co2 and Carbon Cycle Dynamicsmentioning

confidence: 98%

Section: Overturning Circulationmentioning

confidence: 99%

See 2 more Smart Citations

The Miocene: The Future of the Past

Steinthorsdottir

Coxall

Boer

et al. 2021

Paleoceanog and Paleoclimatol

271

179

View full text Add to dashboard Cite

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“…Then, these pretreated sediments were digested by a concentrated HF + HNO 3 +HClO 4 mixture in Teflon vessels for the elemental analysis. The major and trace element concentrations were determined at the Institute of Oceanology, Chinese Academy of Sciences (IOCAS), Qingdao, using a Thermo Icap6300 ICP‐AES and a Perkin‐Elmer ELAN DRC II ICP‐MS, respectively (Zhai et al., 2021). Several USGS and Chinese rock and sediment standards (BCR‐2, BHVO‐2, GBW07315, and GBW07316) and blanks were repeatedly digested and analyzed in parallel with the samples to monitor the quality of measurements.…”

Section: Methodsmentioning

confidence: 99%

Tectonic and Orbital Imprints in the Redox History of Japan Sea Since the Pliocene

Zhao

Wan

Zhai

et al. 2022

Paleoceanog and Paleoclimatol

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Oxygen content in the deep ocean plays a vital role in biogeochemical processes and has significant impacts on the global carbon cycle. The Japan Sea is a semiclosed basin with only shallow water connection to the Western North Pacific, and its redox history has been sensitively affected by tectonic and climatic changes in the past. Studies of paleo‐redox changes in the Japan Sea focused on the tectonic and orbital scales since the Pliocene remain scarce to date. Here, we present two high‐resolution paleo‐redox records during the last 4 Ma at IODP Sites U1425 and U1430 drilled in the Japan Sea. Our authigenic U (uranium) and U/Al records suggest remarkable changes of Japan Sea redox history from relatively oxic to periodic oxic‐anoxic conditions at ∼1.7 Ma. This was mainly caused by the restricted input of North Pacific oxygen‐rich water due to the uplift of northeastern Japan during late Pliocene and early Pleistocene, and opening of the Tsushima Strait and the periodic intrusion of Tsushima Warm Current following sea level change during glacial‐interglacial cycles since ∼1.7 Ma. Orbital changes of Japan Sea redox history suggest the existence of a long eccentricity cycle of 400 ka associated with East Asian summer monsoon rainfall evolution throughout the last 4 Ma. Changes of the amplitude of sea level and inflow of Tsushima Warm Current combined with the East Asian monsoon evolution produced eccentricity and obliquity cycles in Japan Sea redox environment after ∼1.7 Ma, as well as a transition from relatively oxic to anoxic conditions during glacials before and after Middle Pleistocene Transition.

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