Tholeiite–Boninite terrane in the North Qilian suture zone: Implications for subduction initiation and back-arc basin development

A tholeiite–boninite terrane occurs as a ~ 4.5-km-thick massif with lavas and intrusions in the Dachadaban (DCDB) area, the middle part of the North Qilian oceanic-type suture zone. It comprises two distinct lithological groups: the lower tholeiite unit and the upper boninite unit. The lower tholeiite unit consists of massive lava flows and subordinate gabbro intrusions with MORB-like characteristics that could represent 5–6% melting of an...