**3.3. Third stage: 101–99 Myr**

The third stage of the history of geological development of the Bureya-Jiamusi was the shortest one. Apparently, some catastrophic events took place at that period. They evoke the formation of the volcanic-plutonic complex of rhyolites-alkaline trachydacytes (Solonechny). The complex is represented with the rocks of the cover, vent, subvolcanic facies and plutonic comagmates. They are depleted in Ba and Sr. and are enriched in Rb, Th, Nb, Hf, and Zr. The age of the volcanites determined by the 40Ar /39Ar method is 99–101 Myr [8, 36], which corresponds to the alb.

#### **3.4. Forth stage: 56 Myr to Cenozoic**

In the interval 99–56 Myr, the territory of Bureya-Jiamusi superterrane is in a state of rest; in fact, it is a platform where coarse clastic terrigenous deposits accumulate. Impulsive outpouring of volcanites, predominantly of basic composition, occurs about 56 Myr ago and, in fact, up to our time—260 years ago (bass Nemarhe river—mineral spring Udalyanchi, China). Herewith, typical adakites were formed in the frames of the southern flank of the superterrane—on the border with the orogenic belt of Wundurmiao [2]. The age of adakitic rocks is 55 Myr. All the following magmatites (less than 20 Myr) correlate with the intraplate formations by their geochemical characteristics.

**5. Geodynamic evolution of the Bureya-Jiamusi superterrane**

rane during the interval of 120–99 Myr actually [4, 5, 30, 38].

power and rigidity.

(**Figure 3**).

The Bureya-Jiamusi superterrane tectonic development scheme for the territory of China was developed back in 1994 by Liu Zhaojun with co-authors [47]. According to this scheme, the stretching prevailed in the region in late Jurassic-early Chalk. It was triggered by changes in the movement of the Izanagi ocean plate. As a result, rift-like structures were formed about 135 Myr ago. These structures were filled with of coal-bearing precipitates and volcanites of acid composition. In the territory of Russia, within the Bureya-Jiamusi superterrane, a similar volcanic complex with an age of magmatic component of 136–135 Myr [4, 37] is formed during this period. The territory of Bureya-Jiamusi superterrane represented a passive continental margin and, probably, was at rest approximately 135–120 Myr. According to palinspastic reconstructions (Bretshtein and Klimov [16] and Didenko with coauthors [9]), Bureya-Jiamusi superterrane was an independent geological body during this period. It drifted on the Izanagi oceanic plate in the northwestern (close to northern) direction with a speed of 30–20 cm per year [23]. Magmatic activity occurred throughout the territory of Bureya-Jiamusi superter-

Bureya-Jiamusi Superterrane: Tectonic and Geodynamic Processes in Late Mesozoic - Cenozoic

http://dx.doi.org/10.5772/intechopen.72538

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According to the palinspastic data of Bretshtein and Klimov [16], the Bureya-Jiamusi superterrane accretion to the Badzhal terrain occurred in post-Jurassic. It was shown that the formation of volcanites with geochemical marks of the suprasubduction type took place 120–105 Myr [2, 4, 5, 7]. Based on the data, it can be assumed that the subduction processes covered almost the entire territory of the Bureya-Jiamusi superterrane during this period. We can consider the following as one of the possible tectonic scenarios: subduction processes are caused by the displacement of a younger and, therefore, more plastic Badzhal terrain to older formations of the Bureya-Jiamusi superterrane, which has more

What was the cause of this? According to paleomagnetic definitions [23], the Izanagi plate reversed its direction from north-west to northeast 119 Myr. And although the angle of rotation was insignificant, and the speed changed by only 0.6 cm per year (from 21.1 to 20.5 cm/year), it could be enough for the interaction of these geological objects to occur. Proceeding from such a tectonic scenario, the next stage of magmatic activity will be more understandable. Catastrophic events that were accompanied by the formation of an intraplate volcano-plutonic complex of acidic-alkaline rocks at the contact of Bureya-Jiamusi superterrane and Badzhal terrain occurred about 101–99 Myr [8, 36]. Therefore, it is assumed as the most likely scenario, that during the subduction process a sharp break (breakage) and a plunge of the slab of Badzhal terrain into the asthenospheric "window" occurred. This was, naturally, accompanied by an active and short-term formation of the rocks of the intraplate volcano-plutonic complex [4, 8, 36]

According to paleomagnetic data, for the main tectonic units of the Far East south [16] in the Jurassic-Neogenic interval, the Bureya-Jiamusi superterrane was at a very considerable distance from the continental margin of Asia. Similar research works [18] prove that the width of the Mongolo-Okhotsk paleobasin in the late Jurassic was about 3000 km. Paleomagnetic
