Variation in the eastern North Pacific subtropical gyre (California Current system) during the Middle to Late Miocene as inferred from radiolarian assemblages

Kamikuri, Shin-ichi; Motoyama, Isao

doi:10.1016/j.marmicro.2019.101817

Cited by 4 publications

(4 citation statements)

References 89 publications

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“…Radiolarian evidence 49 at the nearby ODP Site 1021 suggests enhanced coastal upwelling is unlikely in this region due to the timing of biosiliceous sedimentation in relation to known changes in the California Current. A potential increased production of North Atlantic Deep Water (NADW), the source of upwelling in this region, may have occurred between 11.5 to 10.0 Ma and from 7.6 to 6.5 Ma 49 (marked in Fig. 2 ).…”

Section: Resultsmentioning

confidence: 98%

“…Upwelling may mask the phytoplankton response to a changing pCO 2 , bringing the ocean out of equilibrium with the atmosphere as upwelling brings more 13 C-depleted CO 2[aq] from cold bottom waters to the surface 45 . Radiolarian evidence 49 at the nearby ODP Site 1021 suggests enhanced coastal upwelling is unlikely in this region due to the timing of biosiliceous sedimentation in relation to known changes in the California Current. A potential increased production of North Atlantic Deep Water (NADW), the source of upwelling in this region, may have occurred between 11.5 to 10.0 Ma and from 7.6 to 6.5 Ma 49 (marked in Fig.…”

Section: Resultsmentioning

confidence: 98%

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Continuous sterane and phytane δ13C record reveals a substantial pCO2 decline since the mid-Miocene

Witkowski,

von der Heydt,

Valdes

et al. 2024

Nat Commun

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Constraining the relationship between temperature and atmospheric concentrations of carbon dioxide (pCO2) is essential to model near-future climate. Here, we reconstruct pCO2 values over the past 15 million years (Myr), providing a series of analogues for possible near-future temperatures and pCO2, from a single continuous site (DSDP Site 467, California coast). We reconstruct pCO2 values using sterane and phytane, compounds that many phytoplankton produce and then become fossilised in sediment. From 15.0-0.3 Myr ago, our reconstructed pCO2 values steadily decline from 650 ± 150 to 280 ± 75 ppmv, mirroring global temperature decline. Using our new range of pCO2 values, we calculate average Earth system sensitivity and equilibrium climate sensitivity, resulting in 13.9 °C and 7.2 °C per doubling of pCO2, respectively. These values are significantly higher than IPCC global warming estimations, consistent or higher than some recent state-of-the-art climate models, and consistent with other proxy-based estimates.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 98%

Continuous sterane and phytane δ13C record reveals a substantial pCO2 decline since the mid-Miocene

Witkowski,

von der Heydt,

Valdes

et al. 2024

Nat Commun

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“…Recent studies in the Sea of Japan based on key ecological properties of radiolarians (Matsuzaki et al., 2018; Matsuzaki, Suzuki, & Tada, 2020; Matsuzaki et al., 2022) tried clarify the oceanographic changes that occurred during LMGC. Numerous studies published since 2000 have shown that radiolarian microfossils are suitable proxies for the reconstruction of paleoceanography of the North Pacific Ocean from Neogene to Holocene (Dong et al., 2021; Hernandez‐Almeida et al., 2017, 2020; Itaki & Ikehara, 2004; Itaki et al., 2007, 2012, 2022; Kamikuri & Motoyama, 2020; Kamikuri & Moore, 2017; Matsuzaki, Nishi, Suzuki, Cortese, et al., 2014; Matsuzaki, Nishi, Suzuki, Kawate, et al., 2014, Matsuzaki et al., 2015, 2018, 2019; Matsuzaki, Suzuki, & Tada, 2020; Matsuzaki et al., 2022). Based on the ecology of radiolarian species extant since ∼10 Ma, Matsuzaki, Suzuki, and Tada et al.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Oceanography of the Central Northwest Pacific Over the Past 10 Million Years With Focus on Late Miocene Global Cooling

Matsuzaki

2023

Paleoceanog and Paleoclimatol

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Since the middle Miocene climatic transition, the Earth's climate has steadily cooled. The late Miocene global cooling (LMGC) and the Northern Hemisphere Glaciation (NHG) were two key cooling events occurring during this time. To better understand the mechanisms underlying these cooling events, changes in radiolarian microfossil assemblages were examined in this study, aiming at the reconstructing of oceanographic changes that have occurred at Ocean Drilling Program site 1208 during the last 10 million years. Sea surface temperatures (SSTs) were reconstructed based on radiolarian species that were extant 0–10 million years ago. Reconstructed SSTs were then compared with previously published alkenone‐based SSTs at site 1208, and it was found that overall, using SSTs based only on extant radiolarian species yielded a correct record for the last 10 million years. However, large discrepancies were observed between radiolarian‐ and alkenone‐based SSTs during LMGC and the NHG. These discrepancies were attributed to the sustained influence of subsurface water (at depths from ∼50 to 100 m) on assemblages of radiolarians during extreme cooling events. Relative abundances of other radiolarian groups indicated that during LMGC, there was a reorganization of the regional oceanography that probably weakened the Pacific meridional overturning circulation, increased the meridional temperature gradient, and caused a southward migration of the subtropical front. Probably, the North Pacific intermediate water expanded southeastward during NHG.

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“…Numerous studies documented terrestrial faunal exchanges between North and South America after the closure of the Isthmus of Panama, also known as the Great American Biotic Interchange (Webb, 2006; Cody et al , 2010; Stehli & Webb, 2013; Leigh et al , 2014). In the Miocene, the progressive emergence of the Isthmus of Panama also impacted global ocean circulation (Schneider & Schmittner, 2006), resulting in the intensification of the Gulf Stream (Nie, 2018; Auderset et al , 2019), the California Current (Kamikuri & Motoyama, 2020), and the Humboldt Current (Amiot et al , 2008; Bosio et al , 2020). Moreover, this affected the composition of marine fauna and faunal connections between North and South America (Cuitiño et al , 2017; Trayler et al , 2020; del Río, 2021).…”

mentioning

confidence: 99%

New Species of the Genus Arbacia (Echinoidea, Arbaciidae) from the Neogene of Chile

Corville

Gonzalez²,

Mourgues³

et al. 2023

Ameghiniana

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Recent fieldwork on Neogene deposits of northern Chile led to the discovery of new material, including three new species of the echinoid genus Arbacia: Arbacia quyllur sp. nov. from the Miocene, Arbacia terraeignotae sp. nov., and Arbacia larraini sp. nov. from the Pliocene. In the Pleistocene, the new material includes the first fossil occurrence of the extant species Arbacia spatuligera and new specimens of the extant species Tetrapygyus niger. The specimens and new species described here reveal the significant past diversity of the genus Arbacia and increase our knowledge of the overall diversity of the genus in South America, showing an older origin (upper Miocene) and higher species richness of the genus Arbacia along the Chilean coasts than previously thought.

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Variation in the eastern North Pacific subtropical gyre (California Current system) during the Middle to Late Miocene as inferred from radiolarian assemblages

Cited by 4 publications

References 89 publications

Continuous sterane and phytane δ13C record reveals a substantial pCO2 decline since the mid-Miocene

Continuous sterane and phytane δ13C record reveals a substantial pCO2 decline since the mid-Miocene

Evolution of Oceanography of the Central Northwest Pacific Over the Past 10 Million Years With Focus on Late Miocene Global Cooling

New Species of the Genus Arbacia (Echinoidea, Arbaciidae) from the Neogene of Chile

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