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Exceptionally well-preserved Eocene plant fossils occurring in leafy litter mats from the Buchanan Lake Formation, Canadian Arctic, make it possible to estimate the accumulation rate of the lignite. This method is based on the assumption that the projected leaf-surface area of individual tree species per unit of ground-surface area (leaf-area index) is more or less constant. The calculated accumulation rate of 1.6 mm/year has been corrected to the minimum accumulation rate of 0.8 mm/year by considering the effects of organic decomposition. Since the compaction ratio of the leaf lignite is difficult to estimate, correct comparison with accumulation rates of modern and Quaternary peats that have been determined by using 14C ages is impossible. However, the accumulation rate calibrated in the peat stage of coalification by using the compaction ratio of woods embedded in the leaf lignite is within the range of accumulation rates determined for modern and Quaternary peats.

Fossil forests, where petrified stumps were preserved in growth position, have been found within Early Tertiary sediments near Strathcona Fiord, Ellesmere Island, Canadian Arctic Archipelago. These fossil forests are obvious evidence for Early Tertiary climate much warmer than that of today. We analyzed the growth rings of petrified woods from two fossil forest sites (one in middle Paleocene, and the other in late Early Eocene) to extract information on climate change. The woods consist most abundantly of Metasequoia and cf. Glyptostrobus, suggesting that these forests grew in similar environments of warm to cool temperate climates. Mean ring width, mean sensitivity and power spectrum were calculated for ring-width sequences. Although significant difference in the mean ring width between the two forests was found, a comparison with living trees suggests that the difference can be attributed to the specific difference between the forests, so that a significant climate change may not necessarily be invoked. We found little significant difference in the mean sensitivity and power spectrum between the forests, neither did we find any strong indication of periodicities. Consideration of all features suggests that there was no significant difference in climate of middle Paleocene and late Early Eocene time in the High Arctic. However, the mean ring-widths of these forests were significantly smaller than that reported for mid-Cretaceous High Arctic fossil forest.

The Nadanhada Range in Northeast China is composed of upper Paleozoic limestone, greenstone, middle to late Triassic bedded chert, and middle Jurassic siliceous shale; these rocks are enclosed in post-middle Jurassic clastic rocks. The lithologic association, ages, radiolarian assemblages and geologic structure of the Nadanhada Range are very similar to those of the Tamba-Mino-Ashio terrane in Southwest Japan. This indicates that the Nadanhada Range is the northern extension of the Tamba-Mino-Ashio terrane. Mesozoic tectonostratigraphic terranes identified in Northeast China, Sikhote-Alin and Southwest Japan are: the Khanka terrane (a micro-continent composed of Precambrian metamorhic rocks and Paleozoic to Mesozoic sedimentary and volcanic covers), the Nadanhada-Western Sikhote-Alin terrane (a disrupted terrane composed of upper Paleozoic to Jurassic sedimentary rocks), the Eastern Sikhote-Alin terrane (a terrane composed mainly of early Cretaceous clastics), the Tetyukhe terrane (a disrupted terrane composed of upper Paleozoic to early Cretaceous sedimentary rocks), the Hida terrane (a continent-type stratigraphic terrane composed of Precambrian and upper Paleozoic basement covered with Jurassic to Cretaceous coarse clastics), and the Tamba-Mino-Ashio terrane (a disrupted terrane composed of upper Paleozoic to earliest Cretaceous sedimentary rocks). Accretionary history of these terranes is discussed on the basis of paleomagnetic and paleobiogeographic data.