Structural Control of the Getang Carlin-Type Gold Deposit in Southwest China

The Getang is a representative Carlin-type gold deposit in Southwest China.It has a proven reserve of about 30 tonnes at an average grade of 5.1 g/t Au.The orebodies occur as strat-abound lenses,and are structurally controlled by shallow NWW-and NE-trending fold-fault systems and the unconformity between the Upper and Middle Permian.In this study,the regional-and deposit-scale structural investigations,joints and finite strain measurements,and stress and dynamic analysis were conducted with an aim to reveal the structural process of the Getang gold deposit and clarify the relationship between the gold mineralization and structures.Three phases of deformation were identified in the deposit:(1)paleokarst was generated by a crustal uplift when the Youjiang Basin experienced extension at the end of the Middle Permian,laying the foundation for the unconformity;(2)the NW-trending structures were formed under a NNE-SSW compression during the Indochina-South China collision(Indosinian orogeny)in Triassic;(3)the NE-trending structures were generated or reactivated under a NW-SE-oriented compression during the Yanshanian intracontinental orogeny.The unconformity recorded two episodes of tectonic evolution in the NNE-SSW and NW-SE directions.Structural analyses and geochronology data suggest that the Getang gold deposit was formed as a result of tectonic transition from compression to extension during the Yanshanian intracontinental orogeny.

Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite

As China’s first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band(1-250 ke V) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 Me V. It was designed to perform pointing, scanning and gamma-ray burst(GRB)observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed.Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.

The High Energy X-ray telescope (HE) onboard the Insight-HXMT astronomy satellite

The Insight-Hard X-ray Modulation Telescope(Insight-HXMT) is a broadband X-ray and γ-ray(1-3000 ke V) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope(HE). The main detector plane of HE comprises 18 Na I(Tl)/Cs I(Na) phoswich detectors, where Na I(Tl) is used as the primary detector to measure ~ 20-250 ke V photons incident from the field of view(FOV) defined by collimators, and Cs I(Na) is used as the active shielding detector to Na I(Tl) by pulse shape discrimination. Additionally, Cs I(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV,i.e. 1.1°×5.7°(15 units), 5.7°×5.7°(2 units), and blocked(1 unit). Therefore, the combined FOV of HE is approximately5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 ke V. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the deadtime is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20-250 ke V band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 Me V band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments.

Insight-HXMT observations of the first binary neutron star merger GW170817

Finding the electromagnetic （EM） counterpart of binary compact star merger, especially the binary neutron star （BNS） merger, is critically important for gravitational wave （GW） astronomy, cosmology and fundamental physics. On Aug. 17, 2017, Advanced LIGO and Fermi/GBM independently triggered the first BNS merger, GW170817, and its high energy EM counterpart, GRB 170817A, respectively, resulting in a global observation campaign covering gamma-ray, X-ray, UV, optical, IR, radio as well as neutrinos. The High Energy X-ray telescope （HE） onboard Insight-HXMT （Hard X-ray Modulation Telescope） is the unique high-energy gamma-ray telescope that monitored the entire GW localization area and especially the optical counterpart （SSS17a/AT2017gfo） with very large collection area （M000 cm2） and microsecond time resolution in 0.2-5 MeV. In addition, Insight-HXMT quickly implemented a Target of Opportunity （TOO） observation to scan the GW localization area for potential X-ray emission from the GW source. Although Insight-HXMT did not detect any significant high energy （0.2-5 MeV） radiation from GW170817, its observation helped to confirm the unexpected weak and soft nature of GRB 170817A. Meanwhile, Insight-HXMT/HE provides one of the most stringent constraints （-10-7 to 104 erg/cm2/s） for both GRB170817A and any other possible precursor or extended emissions in 0.2-5 MeV, which help us to better understand the properties of EM radiation from this BNS merger. Therefore the observation of Insight-HXMT constitutes an important chapter in the full context of multi-wavelength and multi-messenger observation of this historical GW event.