Hao Lulu

Chinese Academy of Sciences | CAS · Guangzhou Institute of Geochemistry

Numerous studies have argued that the andesitic model (i.e., the arc directly produces andesitic magmas) rather than the basaltic-input model (i.e., andesitic magmas were derived by fractionation from basaltic magmas) better explains the composition of continental crust. However, it remains controversial as to how andesitic magmas are directly prod...

High-MgO (>9 wt %) basaltic rocks can be primary magmas and are used to constrain the geochemistry and temperature of the mantle. However, high MgO contents can also result from mixing between evolved melts and antecrysts or xenocrysts, and thus, the whole-rock composition might not represent the solidified equivalents of primary magma. Whether suc...

Plain Language Summary The convergence and collision of India and Asia leading to the formation of the Himalayan Mountains and Tibetan Plateau (“the roof of the world”) is one of the most significant geological events of the Cenozoic Era. Geophysical data show that rocks of the Indian continent lie beneath southern Tibet, but the early subduction h...

Plain Language Summary Mo isotope systematics have been widely applied in the study of tracing recycled crustal materials, and abundant researches have proposed that heavy Mo isotopic compositions of arc‐mafic magma can be ascribed to slab‐dehydrated fluids. However, in continental subduction zones, the origin of the light Mo isotopes of post‐colli...

Despite their close temporal and spatial relationships, the effects of tectono-thermal events on ore formation remain obscure. To better understand this process, a comprehensive geochemical investigation on paleofluids from syn-tectonic felsic and quartz veins associated with the Devonian subduction and Permian collision of the Chinese Altai was co...

Andesitic rocks have similar compositions to average continental crust and have played a central role in improving our understanding of the formation and evolution of the continental crust. Here we present data for andesites from the Jiaqiong area of the Bangong–Nujiang suture zone (BNSZ), Central Tibet. LA–ICP–MS zircon U–Pb ages demonstrate that...

Constraints on mantle heterogeneity are important for understanding geochemical differentiation and recycling in Earth’s interior. Alkali basalts are of particular interest in this context due to the clear signatures of recycled components that they yield. Previous studies have focused more on oceanic basalts than on continental mafic rocks because...

The timing and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain disputed. Here, we report zircon U–Pb geochronological and O isotopic and whole-rock geochemical and Sr–Nd isotopic data for Eocene (41–37 Ma) granite porphyries and quartz monzonites from the Qoima Co area of the northern Qiangtang Block, centra...

Partial melting of granulites generates melts, which causes the modification of continental crust. However, the detailed mechanisms of this partial melting and related magmatic processes are debated. In this study, we investigated how crustal melting of granulites generated late Miocene (ca. 6.0 Ma) silicic volcanic rocks in the Chibuzhangcuo area...

Adakitic rocks at continental collisional zones have important implications for understanding the mechanism of crustal reworking. The Himalayan–Tibetan orogen, built by India–Asia collision and Indian continental plate subduction, is one of the most prominent Cenozoic continent–continent collision zones, and Cenozoic post-collisional adakitic rocks...

The role played by felsic igneous magmatism in crustal differentiation is of importance for the evolution and habitability of Earth system. However, the petrogenesis of felsic rocks and their genetic links to mafic magmas remain controversial, hindering our understanding of crustal differentiation processes. Cenozoic post-collisional felsic potassi...

A world-class Sn province in South China contains granite- and porphyry-related Sn deposits. In this paper, we investigate the source of Sn, based on a study of Early Cretaceous (145–134 Ma) ore-barren granites and granite porphyries, ore-barren rhyolites, and Sn-bearing granite porphyries in the Mikengshan (MKS)–Qingxixiang (QXX)–Yanbei (YB) area...

Understanding the subduction and recycling of continental crust is crucial for reconstructing the long-term evolutionary history of Earth's mantle and crust. The Himalaya-Tibet orogen is arguably the world's best natural laboratory for investigating these processes. Cenozoic post-collisional ultrapotassic volcanic rocks are common in the Lhasa bloc...

As one of the most important parts of the eastern Tethys, the evolution of the Bangong–Nujiang Tethyan Ocean (BNTO) has important geological implications for paleogeographic reconstructions of the Tethyan Realm. However, the closure time of the BNTO remains highly debated. Here, we report geochronological, petrological and geochemical data from thr...

In recent years, the mélange model has been increasingly considered as an important way to transfer slab components to arc sources in modern subduction zones. This model differs from the classic slab fluid/melt metasomatism model in that it invokes physical mixing of bulk sediment, altered oceanic crust (AOC), serpentinite, and mantle wedge at the...

Subduction zones are the main sites of material exchange between the crust and mantle. Sediments subducted at these zones are widely considered to play a key role in generating arc magmas. Here we report whole-rock Nd–Hf isotopic compositions of late Mesozoic intermediate–felsic igneous rocks from the southern Qiangtang Block, central Tibet. The la...

Recent experimental and natural studies have shown that igneous crystals can start to crystallize through skeletal or dendritic growth, and then backfill progressively to form polyhedral crystal morphologies, in contrast to the traditional tree-ring model of crystal growth. Identifying the growth mechanism of crystal is fundamental to understand cr...

Northward drift of the Cimmerian microcontinents and opening of the Neo-Tethys Ocean in Early Permian are prominent events in northern Gondwana's protracted breakup history. However, the geodynamic setting responsible for these events is controversial. The dispersal of the eastern Cimmerian microcontinents was accompanied by the emplacement of Qian...

Diverse rock types and contrasting geochemical compositions of post-collisional mafic rocks across the Tibetan Plateau indicate that the underlying enriched lithospheric mantle is heterogeneous; however, how these enriched mantle sources were formed is still debated. The accreted terranes within the Tibetan Plateau experienced multiple stages of ev...

Subduction erosion is important for crustal material recycling and is widespread in modern active convergent margins. However, such a process is rarely identified in fossil convergent systems, which casts doubt on the importance of subduction erosion through the geological record. We report on ca. 155 Ma Kangqiong (pluton) intrusive rocks of a Meso...

The nature and timing of post-collisional crustal thickening and its link to surface uplift in the eastern Lhasa block of the southern Tibetan plateau remain controversial. Here we report on Cenozoic magmatism in the Wuyu area of the eastern Lhasa block. The Eocene (ca. 46 Ma) trachyandesites and trachydacites show slight fractionation of rare eart...

Adakitic rocks are intermediate-acid magmatic rocks characterized by enrichment in light rare-earth elements, depletion in heavy rare-earth elements, positive to negligible Eu and Sr anomalies, and high La/Yb and Sr/Y ratios. Cenozoic adakitic rocks generated by partial melting of subducted oceanic crust (slab) under eclogite-facies conditions (i.e...

We report on a ca. 239 Ma mafic dike swarm intruded in the Southern Qiangtang terrane, central Tibet, that was generated on the passive continental margin of a subducting lower plate. The dikes are tholeiitic basalts and exhibit light rare earth element enrichment, modest negative anomalies in Nb and Ta, and enriched isotopic signatures. The dikes...

Modern oceans contain large bathymetric highs (spreading oceanic ridges, aseismic ridges or oceanic plateaus and inactive arc ridges) that, in total, constitute more than 20–30% of the total area of the world’s ocean floor. These bathymetric highs may be subducted, and such processes are commonly referred to as ridge subduction. Such ridge subducti...

A Late Jurassic–Late Cretaceous magmatic belt extends for >800 km along the southern margin of the southern Qiangtang Block (SQB) in central Tibet. However, the Mesozoic tectonic setting of these igneous rocks remains uncertain. Here, we report new in situ zircon U–Pb ages and Hf–O isotopes as well as whole-rock major- and trace-element composition...

Identification of arc magmatic rock associations in a subduction zone has important implications for specifically revealing the geodynamic evolution of the subduction system. The closure time of the Bangong-Nujiang Tethyan Ocean and the detailed subduction processes have been hotly debated, hindering our understanding of the tectonic evolution of c...

Collisional zones are commonly considered as important regions for crustal reworking, but the reworking mechanism remains debated. The well-known Himalayan-southern Tibetan orogen, built by India-Asia collision and convergence, has the thickest continental crust on Earth and is therefore an ideal region for studying crustal reworking during collisi...

Late Early Oligocene mantle-derived potassium (K)-rich lavas occur widely in the Qiangtang Block, central Tibet. However, it remains ambiguous whether partial melting of crust beneath central Tibet occurred in the Oligocene. Here, we report the newly identified trachytes in the Gemuchaka area of central Qiangtang Block. Zircon U-Pb and biotite ⁴⁰Ar...

A-type magmatism is commonly generated in extensional settings. Cenozoic postcollisional extensional structures and magmatism widely occur in the well-known Himalayan-Tibetan orogen (HTO). So far, however, no Cenozoic A-type magmatism has been identified in the orogen. Here, we report on newly identified 24-23 Ma felsic lavas (trachytes + rhyolites...

The history of Indian continental subduction beneath Asian plate remains unclear. Miocene ultrapotassic rocks in southern Tibet, with extremely enriched isotopes, have often been used to trace mantle metasomatism and geodynamic processes associated with Indian continental subduction. These rocks, however, may have been contaminated by Lhasa ancient...

Recognizing the early-developed intra-oceanic arc is important in revealing the early evolution of East Paleo-Tethys Ocean. In this study, new SIMS zircon U-Pb dating, O-Hf isotopes, and whole-rock geochemical data are reported for the newly-discovered Late Devonian-Early Carboniferous arc in Qiangtang, central Tibet. New dating results reveal that...

The Pianshishan eclogites discovered in central Qiangtang are a key piece of evidence constraining the main suture of the Paleo-Tethys Ocean in Tibet. Based on the eclogite-facies metamorphic inclusions found in them, a previous study interpreted the zircon grains as metamorphic in origin, although their catholuminescence images were similar to zir...

The time and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain highly controversial. Here, we report on zircon U-Pb age, and mineral, element, and Sr-Nd isotope composition data for Eocene adakitic porphyries in the Laorite Co area of central-northern Qiangtang Block, central Tibet. LA-ICPMS zircon U-Pb age da...

Deciphering the petrogenesis of andesitic/dioritic rocks is fundamental to understanding the formation of the continental crust. Here we present detailed petrology, geochronology, major and trace element, Sr–Nd–Hf–O isotope data for the Early Cretaceous (∼122 Ma) dioritic rocks in the Bizha area in southern Qiangtang, Tibet. The dioritic rocks are...

Phanerozoic growth of continental crust has widely been considered as an important geological phenomenon and mainly occurs in an arc setting. However, the crustal growth models (mantle-derived basalt underplating or accretion of island or intra-oceanic arc complexes or oceanic plateau) have been disputed. Here we present new zircon LA-ICPMS U-Pb ag...