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Cretaceous mafic–felsic intrusions are extensively distributed in the West Burma terrane (Myanmar), but their petrogenesis and tectonic setting still remain unclear. In this study, whole-rock geochemical and Sr–Nd as well as zircon U–Pb and Hf isotopic data for the Cretaceous mafic–felsic intrusions from the Banmauk–Kawlin area (northern Myanmar) are presented. Precise zircon U–Pb dating results indicate that they emplaced at Cretaceous (~ 110–90 Ma) and likely belong to an eastward extension of the coeval Gangdese magmatic belt in the southern Lhasa terrane (Tibet). The studied Cretaceous intrusions (SiO2 = 41.97 to 74.54 wt%) mostly have calc-alkaline and Na-rich characteristics, and strong enrichments in large ion lithophile elements (e.g., Cs, Rb, and K), depletions in Nb and Ta on primitive mantle-normalized diagrams, consistent with geochemical characteristics of arc-type magmas. Most of Cretaceous gabbroic and dioritic intrusions with relatively depleted mantle Sr–Nd–Hf isotopic compositions (87Sr/86Sri = 0.7041–0.7048, εNd(t) = 0.2–6.8, and εHf(t) = 4.3–15.1) and high Ba/La ratios were possibly derived from partial melting of mantle wedge metasomatized by slab-derived fluids and underwent a certain degree of fractional crystallization. Whereas Cretaceous granodiorite and granite probably formed by partial melting of juvenile arc lower crust on the basis of positive εNd(t)–εHf(t) values (− 2.4 to 6.6 and − 2.8 to 15.3) and low initial Sr isotopic ratios (87Sr/86Sri = 0.7045–0.7063). A wide range of Th/Nb ratios and Sr–Nd–Hf isotopic values in these intrusions suggests that their juvenile arc lower crust possibly formed by melting of slab-derived fluids and/or sediment melts metasomatized mantle. Overall, Cretaceous (~ 110–90 Ma) mafic–felsic intrusions in the West Burma terrane may have formed in an arc setting during subduction of the Neo-Tethyan oceanic lithosphere, suggesting a prolonged Neo-Tethyan magmatic arc system from southern Tibet to Southeast Asia. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Molybdenite Re–Os and zircon U–Pb ages indicate the Dapingba Mo–W deposit formed at Cretaceous (∼119 Ma and ∼114 Ma). • Cassiterite U–Pb ages of ∼60 Ma suggest the Bawapin and Kalonta Sn–W deposits in southern Myanmar formed at Paleocene. • Molybdenite Re–Os age for the Shangalon porphyry Cu–Au deposit indicates that this deposit formed at Eocene (∼39 Ma). • A comprehensive Mesozoic-Cenozoic tectono-magmatic and metallogenic model in Myanmar are proposed. Abstract It is well known that there are many Sn–W–Mo and Cu–Au metal resources in Myanmar. However, the absence of precise mineralization ages for these deposits significantly hinders to understand the close genetic relationship among metallogeny, ore-bearing intrusions, and tectonic evolution. In this study, two groups of consistent molybdenite Re–Os and zircon U–Pb ages indicate that the Dapingba Mo–W deposit in northern Myanmar (Tengchong terrane) formed at Early Cretaceous (∼119 Ma and ∼114 Ma). The Dapingba ore-bearing granitic magmas were mainly derived from melting of ancient Tengchong crust on the basis of zircon Hf isotopic compositions (εHf(t) = −9.3 to 2.5). Moreover, the first reported cassiterite U–Pb ages of ∼60 Ma for the Bawapin and Kalonta Sn–W deposits in southern Myanmar (western Sibumasu terrane) suggest that the two deposits formed at Paleocene. Whereas the precise molybdenite Re–Os age for the Shangalon porphyry Cu–Au deposit in the West Burma terrane indicates that this deposit formed at Eocene (∼39 Ma). Importantly, combined with previous studies on tectonic evolution and magmatic petrogenesis in Myanmar and southwest China, a comprehensive Mesozoic-Cenozoic tectono-magmatic and metallogenic model are proposed. Two periods of Early Cretaceous (∼120–114 Ma) and Late Cretaceous (∼75–70 Ma) crust-derived felsic melts and related Mo–Sn–W deposits from the Tengchong and western Sibumasu terranes likely formed in a continental arc during subduction of the Meso- and Neo-Tethys oceanic lithosphere, respectively. Subsequently, Paleocene-Eocene (∼60–50 Ma) Sn–W deposits and coeval ore-bearing granites in the western Sibumasu terrane possibly formed during roll-back of the Neo-Tethys oceanic slab. After ∼50 Ma India–Asia collision, Eocene (∼41–39 Ma) porphyry Cu–Au (West Burma terrane) and Sn–W deposits (western Sibumasu terrane) likely formed during the Neo-Tethys oceanic slab tear and break-off in a collisional setting. Whereas Miocene (∼19–14 Ma) high sulfidation epithermal Cu deposit in the West Burma terrane possibly formed in an arc setting during oblique subduction of the Indian oceanic lithosphere. [ABSTRACT FROM AUTHOR]

Subduction of the Indian continental lithosphere in the eastern Tibet-Himalaya orogenic belt remains unclear. Newly reported zircon U-Pb ages in this study indicate that the Shangalon intermediate-felsic magmatic rocks in northern Myanmar formed at Eocene-Oligocene (∼ 40–32 Ma). They have calc-alkaline to shoshonitic characteristics, LREE-enriched patterns, enrichments in LILE (e.g., Rb, Cs), and depletions in HFSE (e.g., Nb). Obviously, they show the higher initial Sr and lower Nd-Hf isotopic compositions (87Sr/86Sr i = 0.7054–0.7082, εNd(t) = −5.3 to −0.4, and εHf(t) = −3.4 to 10.8) than Cretaceous arc-related mafic-felsic rocks in the West Burma terrane. A positive correlation between Nd isotopic compositions and SiO 2 contents indicates that the Eocene Shangalon diorite and andesite with the lowest εNd(t) values (−5.3 to −4.0) likely derived from a mantle source contaminated by the subducted Indian continental lithosphere. Coupled with regional coeval OIB-like mafic melts and high temperature metamorphism, the Eocene-Oligocene Shangalon magma might have formed in the Neo-Tethyan oceanic slab break-off setting after the India-Asia collision. In addition, Eocene granodioritic rocks have the adakitic features, which possibly resulted by fractional crystallization of hornblende. The hornblende-dominated crystallization in the Shangalon ore-bearing granodioritic rocks is well consistent with magma evolution of H 2 O-rich melts, which play an important role in the formation of the Eocene Shangalon porphyry Cu-Au deposit. • The Shangalon magmatic rocks in northern Myanmar formed at Eocene-Oligocene (∼ 40–32 Ma). • Eocene intrusions were derived from a metasomatized mantle by the Indian continental lithosphere. • The Shangalon intrusions formed in a slab break-off setting after the India-Asia collision. [ABSTRACT FROM AUTHOR]

• Zircon U–Pb dating shows that granites in southern Myanmar formed in Late Cretaceous–Eocene. • The granites belong to fractionated I-type magmas and derived from the Sibusima crust. • The granites formed during subduction of the Neo-Tethyan oceanic lithosphere. • Fractional crystallization and fluid exsolution are the fundamental processes for Sn metallogeny. The geochronology, petrogenesis and tectonic setting of granites associated with tin–tungsten mineralization in southern Myanmar remain unclear. This work presents whole-rock geochemical, Sr–Nd isotopic, and zircon U–Pb and Hf isotopic data for felsic intrusions in the Sibusima terrane. Zircon U–Pb dating indicates formation in the Late Cretaceous–Early Eocene (~84–48 Ma) and suggests that these intrusions likely represent a southward extension of the coeval magmatic belt in the Tengchong terrane. Primarily classified as high-K calc-alkaline, the granites show strong enrichments in large ion lithophile elements (e.g., Cs, Rb, and K), depletions in Nb, Ta, P, and Ti, and negative Ba and Sr anomalies on primitive mantle-normalized diagrams. P 2 O 5 , CaO, Al 2 O 3 , MgO, TiO 2 contents, and Nb/Ta ratios decrease with increasing SiO 2 contents, possibly consistent with evolution trends in fractionated I-type granitic magmas. In addition, these intrusions display a wide range of negative ε Nd (t) (−14.6–−5.5) and zircon ε Hf (t) values (–22.7–5.7), suggesting a dominant Sibusimacrustal source with a minor mantle contribution. Notably, the Eocene and a few Paleocene granites show more contribution of mantle material based on higher ε Nd (t) (−8.5–−5.5) and zircon ε Hf (t) (−11.0–−3.2) values. Large variations in zircon Hf isotopic compositions within an individual Eocene granitic intrusion (e.g., −15.2–5.7) and corresponding biotite-rich enclave (−17.8–0.2) likely indicate magma mixing. Considering the spatial-temporal distribution of magmatism in the West Burma and Sibusima terranes, the studied Late Cretaceous–Eocene felsic magmas likely formed in a continental arc setting during normal subduction (~100–60 Ma) and subsequent roll-back of the Neo-Tethyan oceanic lithosphere (~60–50 Ma). Additionally, most of granites have the elevated Sn with increasing Rb/Sr ratios, and decreasing TiO 2 contents and Nb/Ta ratios, suggesting Sn enrichment is primarily controlled by magmatic fractionation. Meanwhile, Sn and Li depletions in some granites deviate from the magmatic evolution trend, likely as a result of fluid exsolution. The exsolved Sn-rich fluids could have made a genetic contribution to hydrothermal Sn mineralization in southern Myanmar. [ABSTRACT FROM AUTHOR]