Here we present one of the world's oldest examples of large-scale and formalized water management, in the case of the Liangzhu culture of the Yangtze Delta, dated at 5,300-4,300 years cal B.P. The Liangzhu culture represented a peak of early cultural and social development predating the historically recorded Chinese dynasties; hence, this study reveals more about the ancient origins of hydraulic engineering as a core element of social, political, and economic developments. Archaeological surveys and excavations can now portray the impressive extent and structure of dams, levees, ditches, and other landscape-transforming features, supporting the ancient city of Liangzhu, with an estimated size of about 300 ha. The results indicate an enormous collective undertaking, with unprecedented evidence for understanding how the city, economy, and society of Liangzhu functioned and developed at such a large scale. Concurrent with the evidence of technological achievements and economic success, a unique relationship between ritual order and social power is seen in the renowned jade objects in Liangzhu elite burials, thus expanding our view beyond the practicalities of water management and rice farming.

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Remanent magnetization complicates the inversion of magnetic data due to altering the strength and direction of the magnetization vector. To deal with the problem, we have developed a 2D sequential inversion method of successively recovering the distributions of magnetization intensity and susceptibility and estimating the magnetization direction. The magnetization intensity distribution is first recovered from the total magnitude anomaly that is frequently transformed from the observed total-field anomaly and is invariant with the magnetization direction. With the recovered magnetization intensity distribution, we forward model the total-field anomalies caused by sources with different magnetization directions and calculate the correlations between the observed and predicted data. The orientation when the correlations attain a peak of maximum is defined as the optimal magnetization direction. Finally, the estimated magnetization direction helps to recover the susceptibility distribution by further inverting for total-field data. This method was tested by use of synthetic data and field data of two iron-ore deposits involving significant remanence, and all tests returned favorable results. The method obtaining the magnetization intensity and susceptibility distributions and an averaged magnetization direction made full use of the amplitude and phase information of magnetic anomalies, and it was more applicable for scenarios with a homogeneous magnetization direction.

Extension and rifting of the lithosphere is fundamental to the evolution of the continents, but the mechanism by which the lithosphere thins remains enigmatic. Using new dense magnetotelluric array data collected within the rifted margin and adjacent areas of Southeast China (Figure 1), we resolve the three-dimensional electrical structure of the lithosphere to constrain the process of rifting and thinning. Our measurements discover a brittle-ductile transition zone featuring low electrical resistivity and low seismic velocity in the Cathaysia Block. A southeast-directed dip is resolved for the Jiangshan-Shaoxing Fault that documents the Neoproterozoic suturing of the Yangtze and Cathaysia Blocks, and has been reactivated by the Early Paleozoic and Early Mesozoic intracontinental orogenies. It acted as a low-angle detachment fault during the Mesozoic extension and rifting. Given the asymmetries of topography, electrical resistivity, Bouguer gravity anomaly and Mesozoic volcanism across the Gan-Hang Rift, an asymmetric simple shear extension model is proposed for the South China Mesozoic rift system. Water content of up to 0.1 wt% and melt fraction of up to 1% are estimated at 70 km depth beneath the central Wuyi Mountains, suggesting hydration of the mantle lithosphere. The hydration weakening of the mantle lithosphere promoted both the gravitational instability and convective removal of the lowermost lithosphere in South China.

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