Abstract: The petrogenesis and geodynamic setting of Cretaceous magmatic rocks in the middle and northern Gangdese (i.e., the northern part of the Lhasa Terrane), Tibet remain debated so far. In order to explore these issues, this paper reports the data of bulk-rock major element, trace element, Sr-Nd isotopes and zircon Hf isotopes of the magmatic rocks exposed in the Baerda region of the northern Gangdese, Tibet. These rocks consist of granodiorite porphyry and andesite porphyrite. Zircon U-Pb age dating indicates that they were emplaced at ca. 114Ma, and can be considered as representing one of the Early Cretaceous magmatic rock bodies in the northern Gangdese. All samples in Baerda are high-K calc-alkaline, in which granodiorite porphyry samples that exhibit SiO2 contents of 64.45%~67.52%, total alkali (K2O+Na2O) contents of 6.23%~7.47% with A/CNK values of 0.98~1.22, are consistent with S-type granite (although features of I-type granite are also present). Andesite porphyrite samples have SiO2 contents of 57.50%~62.15%, K2O content of 2.30%~3.60%, MgO content of 2.27%~4.40%. Both the granodiorite porphyries and andesite porphyrites are enriched in large-ion lithophile element (LILE) and Pb, and depleted in high field strength elements (HFSE) and Ba. The Baerda magmatic rocks have higher εNd(t) values ( -7.8~-6.8 ) and lower initial 87Sr/86Sr> ratios ( 0.7094~0.7105) relative to melts derived from mature continental crust in the Gangdese. The Baerda magmatic rocks are heterogeneous in zircon εHf(t) values (-4.2~+3.3), yielding younger zircon Hf crustal modal ages of 639(975Ma. Both zircon Hf isotopic data and bulk-rock zircon saturation temperature (768~818℃) indicate that mantle-derived materials may have played an important role in the generation of the Baerda magmatic rocks. We propose that the Baerda magmatic rocks were most likely generated in a setting associated with the slab breakoff of the southward subduction of the Bangong-Nujiang ocean floor, where rising asthenosphere may have provided the heat and material for the melting of lithosphere mantle to generate basaltic magmas. Such basaltic magmas are capable of causing anatexis of upper crust and then mixed with crust-derived melts to form hybrid melts (i.e., lithosphere mantle-derived basaltic magmas+crust-derived felsic magmas) parent to the Baerda magmatism. We attribute the shift from S- to I-type melts observed in Baerda region to the enhanced contributions of mantle-derived melts during magma mixing.