Geochemistry data from the Toupugol volcanogenic complex

A large fragment of a paleovolcano of Silurian to Early Devonian age was discovered in the Voikar volcanic belt suggesting an ensimatic island are as its geodynamic environment. Formationally, the rocks under study are comparable to Pleistocene island arc volcanites and their paleo-analogues. The volcanites of the Toupugol complex underwent strong hydrothermal-metasomatic alteration: propylites, acid metasomatic rocks and quartz-carbonate veins, which must have resulted from hydrothermal-metasomatic alteration of andesitoids. Both volcanites and apovolcanic hydrothermal rocks in Toupugol were found to host noble metal mineralisation. It is found in close association with sulphides, particularly pyrite. Free gold was discovered in all investigated volcanites and hydrothermal rocks and is characterised by low mercury content and an unusual set of microimpurities (Pt, Pd, Cu, Fe, S) suggesting its links to the mantle substrate.

Climate and total tree cover reconstructions based on the 43.7-kyr fossil pollen record from Khoe (NW Sakhalin Island) and modern climate variables of 236 modern surface pollen sampling sites

A late Quaternary pollen record from northern Sakhalin Island (51.34°N, 142.14°E, 15 m a.s.l.) spanning the last 43.7 ka was used to reconstruct regional climate dynamics and vegetation distribution by using the modern analogue technique (MAT). The long-term trends of the reconstructed mean annual temperature (TANN) and precipitation (PANN), and total tree cover are generally in line with key palaeoclimate records from the North Atlantic region and the Asian monsoon domain. TANN largely follows the fluctuations in solar summer insolation at 55°N. During Marine Isotope Stage (MIS) 3, TANN and PANN were on average 0.2 °C and 700 mm, respectively, thus very similar to late Holocene/modern conditions. Full glacial climate deterioration (TANN = -3.3 °C, PANN = 550 mm) was relatively weak as suggested by the MAT-inferred average climate parameters and tree cover densities. However, error ranges of the climate reconstructions during this interval are relatively large and the last glacial environments in northern Sakhalin could be much colder and drier than suggested by the weighted average values. An anti-phase relationship between mean temperature of the coldest (MTCO) and warmest (MTWA) month is documented during the last glacial period, i.e. MIS 2 and 3, suggesting more continental climate due to sea levels that were lower than present. Warmest and wettest climate conditions have prevailed since the end of the last glaciation with an optimum (TANN = 1.5 °C, PANN = 800 mm) in the middle Holocene interval (ca 8.7-5.2 cal. ka BP). This lags behind the solar insolation peak during the early Holocene. We propose that this is due to continuous Holocene sea level transgression and regional influence of the Tsushima Warm Current, which reached maximum intensity during the middle Holocene. Several short-term climate oscillations are suggested by our reconstruction results and correspond to Northern Hemisphere Heinrich and Dansgaard-Oeschger events, the Bølling-Allerød and the Younger Dryas. The most prominent fluctuation is registered during Heinrich 4 event, which is marked by noticeably colder and drier conditions and the spread of herbaceous taxa.

(Table 1) Organic geochemistry at DSDP Leg 71 Holes

Forty-three core samples from Sites 511 through 514 of DSDP Leg 71 were analyzed geochemically. The black shales at the bottom of Hole 511, in the basin province of the Falkland Plateau, contain an average of 1590 ppm extractable organic matter (EOM) and 120 ppm hydrocarbons. Whereas molecular type-carbon number distributions of mono- and polynuclear aromatic hydrocarbons and their sulphur and oxygen analogues in the black shale "aromatic hydrocarbon" fractions are very similar to those of many crude oils, other data - gas chromatography (GC) fingerprint, pyrolysis GC, visual kerogen analysis, H/C ratio - suggest the black shale section is thermally immature. Together, these observations imply that many of the hydrocarbons were deposited with the original sediments or are diagenetic products of other biological compounds. Pyrograms of the humic acid and kerogen fractions from the black shale interval are typical of geopolymers derived from marine algal material. It appears that these humic acids and kerogens are derived from the same lipid stock.

(Table 1) Summary statistics of taxa in samples of ODP Hole 181-1123B

Planktonic foraminifera are used to identify late Pliocene-Quaternary near surface water masses on the northeastern flank of Chatham Rise by comparison with faunas in core-tops east of New Zealand. In an overview study, distance measures, ordinations, and discriminant analysis are applied to 32 faunas from Site 1123B to identify similar faunas among 35 core-tops between 35 and 61°S east of New Zealand. Many Site 1123B faunas in the 2.72 myr interval sampled compare with those in core-tops on the northern side of Chatham Rise from a similar latitude, and are identified as transitional zone assemblages now associated with the subtropical gyre. This result is consistent with studies of late Quaternary planktonic foraminifera from this region and suggests that, typically, the Subtropical Front was locked to Chatham Rise through glacial and interglacial periods, at least back to the late Pliocene. However, a fauna at ca. 1.17 Ma compares with subpolar assemblages in core-tops between 44 and 48°S and identifies cooler surface water. Expectedly, closer sampling may reveal additional periods when southern water moved over the northeastern flank of Chatham Rise. Although the dominance of Globorotalia inflata, a species typical of the southern margin of subtropical gyres, is a principal feature of Site 1123B faunas, in a minority it is replaced as the most abundant species by dextral populations of Neogloboquadrina pachyderma, particularly about the time of the middle Pleistocene transition. Close analogues of these variant transitional assemblages are not present in core-tops about Chatham Rise but sediment trap and coretop data from other regions suggest that they identify high fertility in the mixed layer associated with upwelling or mixing of water masses. The proportion of sinistrally coiled Neogloboquadrina pachyderma rises to ca. 0.6 between ca. 2.45 and 2.57 Ma, soon after the intensification of Northern Hemisphere glaciation. Although the coiling data indicate subantarctic near surface water, the species remains rare. As the faunas retain their transitional zone character, only minor entrainment of subantarctic water may have occurred.