Neogene faulting and volcanism in the Victoria Land Basin of the Ross Sea, Antarctica

The Neogene Terror Rift in the Antarctic Victoria Land Basin(VLB)of the Ross Sea,Antarctica,is composed of the Discovery Graben and the Lee Arch.Many Neogene volcanoes are aligned in the north-south direction in the southern VLB,belonging to the McMurdo Volcanic Group.However,due to multiple glaciations and limited seismic data,the volcanic processes are still unclear in the northern VLB,especially in the Terror Rift.Multichannel seismic profiles were collected at the VLB from the 32nd Chinese National Antarctic Research Expedition(CHINARE).We utilized four seismic profiles from the CHINARE and additional historical profiles,along with gravity and magnetic anomalies,to analyze faults and stratigraphic characteristics in the northern Terror Rift and volcanism in the VLB.Negative flower structures found in the northern Terror Rift suggest that the Terror Rift was affected by dextral strike-slip faults extending from the northern Victoria Land(NVL).After the initial orthogonal tension,the rift transited into an oblique extension,forming a set of downward concaving normal faults and accommodation zones in the Terror Rift.On the Lee Arch,several imbricated normal faults formed and converged into a detachment fault.Under gravitational forces,the strata bent upward and formed a rollover anticline.Many deep faults and thin strata subjected to erosion facilitated volcanic activity.A brittle volcanic region in the VLB was affected by dextral strike-slip movements and east-west extension,resulting in two Neogene volcanic chains that connect three igneous provinces in the VLB:the Hallett,Melbourne,and Erebus Provinces.These two chains contain mud volcanoes with magnetic nuclei,volcanic intrusions,and late-stage volcanic eruptions.Volcanisms have brought about opposite polarities of magnetic anomalies in Antarctica,indicating the occurrence of multiple volcanic activities.

Spectral programmable mid-infrared optical parametric oscillator

A spectral programmable,continuous-wave mid-infrared(MIR)optical parametric oscillator(OPO),enabled by a self-developed high-power spectral tailorable fiber laser,was proposed and realized.While operating at a singlewavelength,the maximum idler power reached 5.53 W at 3028 nm,with a corresponding pump-to-idler conversion efficiency of 14.7%.The wavelength number switchable output was available from one to three.The single idler was tunable in a range of 528 nm(2852–3380 nm).In a dual-wavelength operation,the interval between two idlers could be flexibly tuned for 470 nm(53–523 nm),and the intensity of each channel was controllable.Triplewavelength idler emission was realized,meanwhile exhibiting spectral custom-tailored characteristics.Furthermore,we balanced the parametric gain through the pre-modulating broadband multi-peak pump spectra,enabling a 10 d B bandwidth adjustment of the idler emission from 20 to 125 nm.This versatile mid-infrared laser,simultaneously featuring wide tuning,multi-wavelength operation,and broad bandwidth manipulation,has great application potential in composition detection,terahertz generation,and speckle-free imaging.