西太平洋暖池区气象学特征分析

本文根据ＴＯＧＡ－ＣＯＡＲＥ强化观测资料及卫星资料分析讨论了西太平洋暖池区１１－２月间海面气象要素的平均特征。分析发现海面气压平均日变化似乎同中纬度区明显不同。文中还分析讨论了在西太暖池区西风爆发、赤道浅涡、信风逆温及ＩＴＣＥ和南太平洋辐合带ＳＰＣＺ的变化特征。     

Validity of sea surface temperature observed with the TRITON buoy under diurnal heating conditions

In order to investigate the validity of buoy-observed sea surface temperature (SST), we installed special instruments to measure near-surface ocean temperature on the TRITON buoy moored at 2.07°N, 138.06°E from 2 to 13 March 2004, in addition to a standard buoy sensor for the regular SST measurement at 1.5-m depth. Large diurnal SST variations were observed during this period, and the variations of the temperatures at about 0.3-m depth could be approximately simulated by a one-dimensional numerical model. However, there was a notable discrepancy between the buoy-observed 1.5-m-depth SST (SST_1.5m) and the corresponding model-simulated temperature only during the daytime when the diurnal rise was large. The evaluation of the heat balance in the sea surface layer showed that the diurnal rise of the SST_1.5m in these cases could not be accounted for by solar heating alone. We examined the depth of the SST_1.5m sensor and the near-surface temperature observed from a ship near the buoy, and came to the conclusion that the solar heating of the buoy hull and/or a disturbance in the temperature field around the buoy hull would contribute to the excessive diurnal rise of the SST_1.5m observed with the TRITON buoy. However, the temperature around the hull was not sufficiently homogenized, as suggested in a previous paper. For the diurnal rise of the SST_1.5m exceeding 0.5 K, the daytime buoy data became doubtful, through dynamics that remain to be clarified. A simple formula is proposed to correct the unexpected diurnal amplitude of the buoy SST_1.5m.     

Responses of CO2 in surface water in subtropical West Pacific to El Niño event

In order to investigate the relationships between the change of TCO2, △PCO2 and SST, current, upwelling and biological activities during El Nin(～)o event in the subtropical Pacific, the responses of TCO2 and △PCO2 in surface water in the subtropical Pacific during El Nin(～)o and La Nina have been simulated using a three-dimension carbon cycle model with biota pump. The results of numerical simulations show that TCO2 in sea water increases with reducing of SST during mature phase of El Nin(～)o in the subtropical West Pacific . At the same period , the Kuroshio in this region was weakened , the zonal currents were divergence , the upwelling carried the water with high concentrations of CO2 to the sea surface , so both of TCO2 and △PCO2 in surface water were increased . But TCO2 and △pCO2 were decreased during La Nina period. These simulated results confirmed the observations in 1982/1983 , 1986/1987 ,1991/1995 and 1997/1998 El Nin(～)o events .     

Primary productivity in the western tropical Pacific and equatorial warm waters

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Sedimentary characteristics and the implications of cobalt-rich crusts resources at Caiwei Guyot in the Western Pacific Ocean

Abstract

Cobalt-rich crust has attracted increased attention due to their economic value. Studies have indicated that seamounts in the Western Pacific Ocean are rich in cobalt-rich crust resources. The Caiwei Guyot in Western Pacific Ocean is one of the cobalt-rich crust exploration areas contracted between China and the International Seabed Authority. A large volume of research has been conducted to elucidate the tectonic evolution, basement type, sediment type, gravity and magnetic anomaly characteristics, and geochemical characteristics of shallow surface sediments at Caiwei Guyot. However, a research gap exists on the sedimentary strata below the pelagic deposits and above the volcanic basement of the Caiwei Guyot. This paper summarizes that two main types of sediments existing on the top of Caiwei Guyot. The deposition thickness on the top of Caiwei Guyot is characterized by three sedimentary centers and exposed periphery. Pelagic sediments are difficult to form at the northeastern portion and edge area of Caiwei Guyot due to the strong bottom current environment, which makes these areas suitable for crust growth. This paper delineated three cobalt-rich crust prospective areas at the Caiwei Guyot with of significant implications for exploration and mining-lease-block selections at Caiwei Guyot.     

Preserved paleo-oceanic plateaus in accretionary complexes: Implications for the contributions of the Pacific superplume to global environmental change

We have reinvestigated the mid-Cretaceous plume pulse in relation to paleo-oceanic plateaus from accretionary prisms in the circum-Pacific region, and we have correlated the Pacific superplume activity with catastrophic environmental changes since the Neoproterozoic. The Paleo-oceanic plateaus are dated at 75–150 Ma; they were generated in the Pacific superplume region and are preserved in accretionary prisms. The volcanic edifice composed of both modern and paleo-oceanic plateaus is up to 10.7 × 10⁶ km² in area and 19.1 × 10⁷ km³ in volume. The degassing rate of CO₂ (0.82 − 1.1 × 10¹⁸ mol/m.y.) suggests a significant impact on Cretaceous global warming. The synchronous occurrence of paleo-oceanic plateaus in accretionary complexes indicates that Pacific superplume pulse activities roughly coincided at the Permo-Triassic boundary and the Vendian–Cambrian boundary interval. The CO₂ expelled by the Pacific superplume probably contributed to environmental catastrophes. The initiation of the Pacific superplume contributed to the snowball Earth event near the Vendian–Cambrian boundary; this was one of the most dramatic events in Earth's history. The scale of the Pacific superplume activity roughly corresponds to the scale of drastic environmental change.     

Syntectonic Mobility of Supergene Nickel Ores of New Caledonia (Southwest Pacific). Evidence from Garnierite Veins and Faulted Regolith

Supergene nickel deposits of New Caledonia that have been formed in the Neogene by weathering of obducted ultramafic rocks are controlled by fracture development. The relationship of tropical weathering and tectonic structures, faults and tension gashes, have been investigated in order to determine whether fractures play a passive role only, as previously thought; or alternatively, if brittle tectonics was acting together with alteration. Observation of time‐relationship, textures, and mineralogy of various fracture fills and fault gouges shows that active faulting has played a prominent role not only in facilitating drainage and providing room for synkinematic crystallization of supergene nickel silicate, but also in mobilizing already formed sparse nickel ore, producing the very high grade ore nicknamed “green gold”.     

High heat flow anomalies on an old oceanic plate observed seaward of the Japan Trench

Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most prominent anomaly with the highest value of 114 mW/m² is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope of the trench, heat flow is variable: high (70–90 mW/m²) at some locations and normal for the seafloor age (about 50 mW/m²) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer. Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that discovered recently on the Pacific plate east of the Japan Trench.     

The Epi－continental arc of Southeast China and relevant earthquakes

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Diversity and stages in evolution of conodontophorids and bivalve mollusks in Triassic seas of Siberia and the Far East

Comparative analysis of taxonomic diversity dynamics of condontophorids from Boreal (Arctic regions of Russia) and Tethyan (Northwest Pacific) paleobasins showed that they had most favorable habitat environments in tropical seas. In the Boreal realm, condontophorids went through three stages of evolution comprising probably four substages and four phases, whereas three stages with six substages and twelve phases are distinguished in the Tethyan realm. The most important abiotic factors that controlled development of conodontophorids are paleotemperature of seawater and paleogeographic settings. Renewals in taxonomic composition conodontophorids and diversification of their assemblages have been confined to moments of paleotemperature and/or sea level rise. The comparative analysis of stages in evolution of conodontophorid and bivalve assemblages has been carried out. As is established, the peak taxonomic diversity of bivalves in Boreal seas was in the Late Triassic after the diversity minimum of the Early Triassic time. In contrast, conodontophorids were most diverse in the Olenekian Age.