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Copyright of Reviews of Geophysics & Planetary Physics is the property of Editorial Office of Reviews of Geophysics & Planetary Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At the altitude of low-Earth-orbiting satellites, most details of lithospheric magnetic anomalies observed near surface are attenuated, and only slowly decaying long-wavelength magnetic anomalies can be detected. Long-wavelength magnetic anomalies are generated by large-scale magnetized rocks in the Earth's crust and uppermost mantle at depths shallower than the Curie depth. Interpretation of such lithospheric magnetic anomalies has been used in geological mapping, crustal composition and structure studies, plate tectonic reconstruction, and geodynamics. To introduce the origin of long-wavelength magnetic anomalies at a global scale, we first reviewed satellite magnetic anomaly maps in early periods and calculated anomaly maps using four main lithospheric magnetic field models, including the CHAOS-7, CM6, MF7, and CSES models. Then, based on the result of the CHAOS-7 model at 500 km altitude, 29 long-wavelength magnetic anomalies with amplitudes greater than 4 nT were identified and their geological origins were reviewed. Among these, there were twenty magnetic anomalies over continents and nine over the ocean. The long-wavelength magnetic anomalies over continental areas were mostly located in Precambrian basements related to the Archean nuclei, Proterozoic terrane, and iron-rich formations, with a few located in the orogenic background. The long-wavelength magnetic anomalies in the ocean region were all located in oceanic plateau, generally related to the breakup of Gondwana during the Cretaceous Period, and have the characteristics of thickened crust. Hence, the long-wavelength magnetic anomalies reveal a significant magnetization difference in the deep crust during crustal growth, a key issue that requires further study. Compared to satellite magnetic surveys in some other nations, detecting lithospheric magnetic anomalies by satellite started relatively late in China. The China Seismo-Electromagnetic Satellite (CSES) was launched in February 2018. It was China's first satellite designed to monitor earthquakes with multiple geophysical payloads, including magnetometers capable of measuring weak signals from the lithosphere. The Macau Science Satellite-1 (MSS-1) was launched in 2023 and is specially used for monitoring the geomagnetic field in low latitudes. Furthermore, a subsequent CSES-02 satellite is planned to be launched in 2024. With the vigorous development of satellite magnetic surveys in China, it is expected that progressively more Chinese researchers will pay attention to long-wavelength magnetic anomalies and promote the study of their origin.

Copyright of Advances in Earth Science (1001-8166) is the property of Advances in Earth Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As one of the largest Phanerozoic orogens in the world, the Central Asian Orogenic Belt ( CAOB) is an excellent place for studying accretionary orogenic process and continental crust growth. It is widely accepted that the CAOB formed by long-lived evolution of the Paleo-Asian Ocean (PAO) from Neoproterozoic to Early Mesozoic, comprises various allochthonous fragments, such as micro continents, island arcs, seamounts/ oceanic plateaus, accretionary prisms, and ophiolitic melanges. The composition of ophiolitic melange is almost same in the western CAOB. Except the typical ophiolite components, the ophiolitic melanges contain pillow basalt, volcanic breccia, reef limestone, olistostrome, and terrestrial elastic rocks. Geochemically, the mafic rocks in ophiolitic melange can be divided into two groups of MORBand OIB-type. The MORB-type belongs to tholeiitic basalt series and shows subduction characteristics; the OIB-type belongs to alkaline basalt series, and is formed in seamount/ oceanic plateau affinity. The age, property and distribution of ophiolitic melanges and metamorphic rocks in the western CAOB indicate that the subduction initiation time of the PAO is no later than Early Neoproterozoic, and the locat ion should be on the southern margin of Siberia plate and gradually develop southward. In the early development of the PAO, the mechanism of subduction initiation should be mantle plume-induced dominant. However, in the later period, the seamount/ oceanic plateau may block the subduction channel, causing the subduction polarity reversal and transition, and the subduction initiation occurs. Initiation of new subduction zone is a difficult problem of Earth's plate tectonics regime. The reason is that the subduction initiation is an extremely short process, scarcity of geological record, and there are few cases of subduction initiation that are happening on Earth today. Therefore, it is necessary for geologists to work together to reveal the past and present lives of the PAO, and to solve the mystery of the subduction initiation of plate tectonics. [ABSTRACT FROM AUTHOR]