Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)

The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion.

Download Full-text

Socioeconomic and lifestyle determinants of the prevalence of hypertension among elderly individuals in rural southwest China: a structural equation modelling approach

BMC Cardiovascular Disorders ◽

10.1186/s12872-021-01885-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Li Xiao ◽

Cai Le ◽

Gui-Yi Wang ◽

Lu-Ming Fan ◽

Wen-Long Cui ◽

...

Keyword(s):

Family History ◽

Sleep Quality ◽

Body Fat ◽

Physical Inactivity ◽

Structural Equation ◽

Southwest China ◽

Fat Distribution ◽

Body Fat Distribution ◽

History Of ◽

Family History Of Hypertension

Abstract Background This study examines the association between socioeconomic and lifestyle factors and the prevalence of hypertension among elderly individuals in rural Southwest China. Methods A cross-sectional survey of 4833 consenting adults aged ≥ 60 years in rural regions of Yunnan Province, China, was conducted in 2017. Data on individual socioeconomic status, sleep quality, physical activity level, and family history of hypertension were collected with a standardized questionnaire. Blood pressure, fasting blood glucose, height, weight, and waist circumference were also measured. An individual socioeconomic position (SEP) index was constructed using principal component analysis. Structural equation modelling (SEM) was applied to analyse the association between socioeconomic and lifestyle factors and the prevalence of hypertension. Results The overall prevalence of hypertension was 50.6% in the study population. Body fat distribution, including measures of obesity and central obesity, had the greatest total effect on hypertension (0.21), followed by family history of hypertension (0.14), biological sex (0.08), sleep quality (− 0.07), SEP (− 0.06), physical inactivity (0.06), and diabetes (0.06). Body fat distribution, SEP, and family history of hypertension had both direct and indirect effects on hypertension, whereas physical inactivity, diabetes, and sleep quality were directly associated with the prevalence of hypertension. Biological sex was indirectly associated with the prevalence of hypertension. Conclusions SEP, body fat distribution, physical inactivity, diabetes, and sleep quality critically influence the prevalence of hypertension. Future interventions to prevent and control hypertension should give increased attention to individuals with low SEP and should focus on controlling diabetes and obesity, increasing physical activity levels, and improving quality of sleep among older adults aged ≥ 60 years in rural Southwest China.

Download Full-text

Neotectonic evolution and sediment budget of the Meuse catchment in the Ardennes and the Roer Valley Rift System

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s0016774600022459 ◽

2002 ◽

Vol 81 (2) ◽

pp. 211-215 ◽

Cited By ~ 7

Author(s):

R.T. Van Balen ◽

R.F. Houtgast ◽

F.M. Van der Wateren ◽

J. Vandenberghe

Keyword(s):

Digital Terrain Model ◽

River System ◽

Sediment Budget ◽

Middle Pleistocene ◽

Rift System ◽

Terrain Model ◽

Fluvial Terraces ◽

Digital Terrain ◽

History Of ◽

Planation Surfaces

AbstractUsing marine planation surfaces, fluvial terraces and a digital terrain model, the amount of eroded rock volume versus time for the Meuse catchment has been computed. A comparison of the amount of eroded volume with the volume of sediment preserved in the Roer Valley Rift System shows that 12% of the eroded volume is trapped in this rift. The neotectonic uplift evolution of the Ardennes is inferred from the incision history of the Meuse River system and compared to the subsidence characteristics of the Roer Valley Rift System. Both areas are characterized by an early Middle Pleistocene uplift event.

Download Full-text

A review of the non-lyctine powder-post beetles of Yunnan (China) with a new genus and new species (Coleoptera: Bostrichidae)

Zootaxa ◽

10.11646/zootaxa.5091.4.1 ◽

2022 ◽

Vol 5091 (4) ◽

pp. 501-545

Author(s):

YI-FENG ZHANG ◽

LING-ZENG MENG ◽

ROGER A. BEAVER

Keyword(s):

New Species ◽

Southeast Asia ◽

Yunnan Province ◽

New Genus ◽

Southwest China ◽

Geological History ◽

Yunnan Region ◽

Palearctic Region ◽

History Of ◽

First Time

The powder post beetles (Coleoptera: Bostrichidae) (except Lyctinae) of Yunnan Province in Southwest China are reviewed for the first time. Keys to twenty-six genera and fifty-two species from the Yunnan region are provided. One new genus and seven new species are described: Dinoderus (Dinoderastes) hongheensis sp. nov., Dinoderus (Dinoderastes) nanxiheensis sp. nov., Gracilenta yingjiangensis gen. nov., sp. nov., Calonistes vittatus sp. nov., Calophagus colombiana sp. nov., Xylodrypta guochuanii sp. nov. and Xylodrypta zhenghei sp. nov.. Fourteen species are recorded in China for the first time. The bostrichid fauna of Yunnan is compared with those of the neighbouring bio-geographically related Southeast Asian and Himalayan regions. The fauna has a close affinity with that of tropical Southeast Asia and a much weaker relationship with the Palearctic region. The differences with the Himalayas may reflect the separate evolutionary and complex geological history of the two areas.

Download Full-text

COASTAL GEOLOGY OF BLUEFIELDS BAY, WESTMORELAND PARISH, JAMAICA: SUCCESSIONS OF NON-MARINE TO MARGINAL-MARINE DEBRIS FLOWS IN AN ACTIVE TECTONIC SETTING

10.1130/abs/2018am-317629 ◽

2018 ◽

Author(s):

Kevin Ray Evans ◽

◽

Brett M. Kenning ◽

Toby J. Dogwiler ◽

Robert T. Pavlowsky

Keyword(s):

Debris Flows ◽

Tectonic Setting ◽

Marine Debris ◽

Coastal Geology ◽

Active Tectonic

Download Full-text

Moisture content variations in soil and plant of post-fire regenerating forests in central Yunnan Plateau, Southwest China

Journal of Geographical Sciences ◽

10.1007/s11442-019-1652-8 ◽

2019 ◽

Vol 29 (7) ◽

pp. 1179-1192 ◽

Cited By ~ 1

Author(s):

Lifang Chen ◽

Qun Dou ◽

Zhiming Zhang ◽

Zehao Shen

Keyword(s):

Moisture Content ◽

Southwest China ◽

Yunnan Plateau

Download Full-text

Towards assessing the influence of sediment loading on Last Interglacial sea level

Geophysical Journal International ◽

10.1093/gji/ggz447 ◽

2019 ◽

Vol 220 (1) ◽

pp. 384-392

Author(s):

T Pico

Keyword(s):

Sea Level ◽

Tectonic Uplift ◽

Sediment Loading ◽

Glacial Cycle ◽

Last Interglacial ◽

Isostatic Adjustment ◽

Uplift Rates ◽

History Of ◽

The Impact ◽

The Last Glacial

SUMMARY Locally, the elevation of last interglacial (LIG; ∼122 ka) sea level markers is modulated by processes of vertical displacement, such as tectonic uplift or glacial isostatic adjustment, and these processes must be accounted for in deriving estimates of global ice volumes from geological sea level records. The impact of sediment loading on LIG sea level markers is generally not accounted for in these corrections, as it is assumed that the impact is negligible except in extremely high depositional settings, such as the world's largest river deltas. Here we perform a generalized test to assess the extent to which sediment loading may impact global variability in the present-day elevation of LIG sea level markers. We numerically simulate river sediment deposition using a diffusive model that incorporates a migrating shoreline to construct a global history of sedimentation over the last glacial cycle. We then calculate sea level changes due to this sediment loading using a gravitationally self-consistent model of glacial isostatic adjustment, and compare these predictions to a global compilation of LIG sea level data. We perform a statistical analysis, which accounts for spatial autocorrelation, across a global compilation of 1287 LIG sea level markers. Though limited by uncertainties in the LIG sea level database and the precise history of river deposition, this analysis suggests there is not a statistically significant global signal of sediment loading in LIG sea level markers. Nevertheless, at sites where LIG sea level markers have been measured, local sea level predicted using our simulated sediment loading history is perturbed up to 16 m. More generally, these predictions establish the relative sensitivity of different regions to sediment loading. Finally, we consider the implications of our results for estimates of tectonic uplift rates derived from LIG marine terraces; we predict that sediment loading causes 5–10 m of subsidence over the last glacial cycle at specific locations along active margin regions such as California and Barbados, where deriving long-term tectonic uplift rates from LIG shorelines is a common practice.

Download Full-text