Lithological Markers and Bio-indicators of Deep-water Environments During Paleozoic Siliceous Sedimentation (Gorny Altai Segment of the Paleo-Asian Ocean)

Geochemical diversity in oceanic basalts hosted by the Zasur’ya accretionary complex, NW Russian Altai, Central Asia: Implications from trace elements and Nd isotopes

“…A similar structure of the accretionary wedge was deduced for younger accretionary complexes in the Western Pacific, Japan (Wakita, 2000;Isozaki et al, 2010). Another evidence for the oceanic island environment for the alkaline basalts comes from their spatial association with seamount slope-type radiolarian cherts and other siliceous beds (Sennikov et al, 2003(Sennikov et al, , 2004.…”

“…Such a tendency was noted before between the older (Detroit and Meiji; 81-83 Ma) and younger (Nintoku, Daikakuji; 55-42 Ma) seamounts of the EHCS in the Pacific Ocean (Regelous et al, 2003) and between the older Kurai (600 Ma) and younger Katun (540 Ma) Paleoseamounts of the PAO . However, taking into account the average velocity of oceanic subduction and the growth of the oceanic lithosphere thickness (e.g., Parsons and Sclater, 1977;Reid and Jackson, 1981) the age difference between more depleted (transitional in our case) and enriched basalts erupted over one hot-spot and one oceanic plate, like in the EHCS, must be at least 30 Ma, i.e., approximately equal to the time interval between the Late Cambrian and Early Ordovician, which was estimated by micropaleontological data (Sennikov et al, 2003(Sennikov et al, , 2004. Therefore, for our interpretations we suggest that the older seamount could ne early Late Cambrian with an average age of 500 Ma and the younger seamount could ne Latest Cambrian to Early Ordovician with an average age of 470 Ma.…”

“…Based on the detailed analysis of geochemical data, previously reported geological and lithological data (Sennikov et al, 2003(Sennikov et al, , 2004 and tectonic implications (Buslov et al, 1999(Buslov et al, , 2000 we propose the following tectonic model for the formation of the oceanic basalts of the Zasur'ya accretionary complex (Fig. 13).…”

“…The basalts are associated with the sediments of Oceanic Plate Stratigraphy (OPS; Isozaki et al, 1990) such as pelagic radiolarian/ribbon chert, hemipelagic siliceous shale, mudstone, and other epiclastic slope facies. Biostratigraphy of associated oceanic siliceous sedimentary rocks was reported in Iwata et al (1997) and Sennikov et al (2003Sennikov et al ( , 2004.…”

“…This paper reviews few already published geochemical data (Sennikov et al, 2003(Sennikov et al, , 2004Safonova et al, 2004) and presents new high-precision ICP-MS trace element data for compositionally diverse basalts from the Zasur'ya unit or accretionary complex (Late Cambrian-Early Ordovician) of the Charysh-Terekta strikeslip zone located in Rudny Altai (Figs. 1 and 2).…”