Petrogenesis and tectonic significance of the early Paleozoic Delenuoer
ophiolite in the Central Qilian Shan, northeastern Tibetan Plateau
-
Abstract
The newly discovered early Paleozoic Delenuoer ophiolite, in the western margin of the Central Qilian Shan, is
composed of serpentinized peridotite, cumulate gabbro, diabase, massive basalt, and pillow basalt. This study
presents geochronological and geochemical data for the cumulate gabbro and basalt. LA–ICP–MS U–Pb dating of
zircons from the cumulate gabbro yielded a magmatic crystallization age of 472 4 Ma. The basalts have normal
mid-ocean ridge basalt (N-MORB) compositions and a narrow range of εNd(t) values (þ4.5 to þ5.3), which indicates
they were derived from a depleted mantle source. On the basis of regional geological constraints, it is
proposed that the Delenuoer ophiolite is a westward extension of the South Ophiolite Belt (Yushigou–
Youhulugou–Donggou–Dongcaohe Ophiolite Belt) in the North Qilian Shan. The Delenuoer ophiolite, along
with the Gulangxia–Delenuoer fault, defines the westernmost part of the tectonic boundary between the North
and Central Qilian Shan. This ophiolite may have formed during southward subduction of the Qilian Ocean slab
during the early Paleozoic.
-
-