The eruption characteristics of the Tarim flood basalt

Abstract

Integration of field investigation, regional stratigraphic comparison, remote sensing and image interpretation allow us to divide the Tarim Permian flood basalt province into three eruptive cycles listed by decreasing age; Kupukuziman flood basalt (KP), Felsic pyroclastic rocks (FP), Kaipaizileike flood basalt (KZ). KP features flood basalt and tuff; in the outcrop in Keping and Yingmaili areas, it can be differentiated into two units containing three thick layers of basaltic lava flows. These three layers decrease to one layer of basaltic lava flow in the Halahatang area; however, felsic pyroclastic rocks and lava layer thicknesses increase in the Halahatang area. FP in the outcrop in Keping area consists of ash fall tuff, ignimbrite, resedimented pyroclastic rocks, and the tuff layer interbedded with the normal elastic rocks section from top to bottom. This section is comparable to the tuff layer in the Yingmaili and Halahatang area, thus reveals one layer of lava flow covering an extensive area clue to a unit of the eruption of the FP. KZ mainly features flood basalt in its Kaipaizileike section, identifications of 4 eruptive units, 8 layers of flood basalt, and I layer of andesitic basalt were made. Traces of elastic rocks were found between eruption units, but no FP interlayers were found. This characteristic is different from Yingmaili and Halahatang volcanic se.quences, but similar to the flood basalt in Tazhong area. The differentiation between these three volcanic cycles reveals that Tarim flood basalt underwent a "flood basalt-felsic pyroclastic rocks-flood basalt " transformation, and is similar to Afro-Arabian large igneous province; thus, a comparative study between these two regions is merited.

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