Southwest Indian Research Articles

Impact of river discharge and suspended sediments on the nearshore benthic environment along the Indian southwest coast

River discharge into the sea and its implications on the environmental setting and fauna in the nearshore represent the intricate interactions among the atmosphere, hydrosphere, lithosphere, and biosphere. This study, based on in-situ and satellite data, presents how spatially varying river discharge laden with suspended sediments structure the hydrography and the nearshore benthic environment over a 590 km southwest (Kerala) coast of India. The 41 rivers that discharge along the Kerala coast are monsoon-driven; they are small but swift and cumulatively supply huge amounts of freshwater and suspended sediments into the Southeastern Arabian Sea (SEAS) during the Southwest Monsoon (SWM) when around 70 % (1925 mm) of the yearly rainfall occurs. These rivers are distributed unevenly along the coastline, with twenty-four of them discharging in the northern region (10.9–12.5°N), nine in the central (9.2–10.9°N), and eight in the south (8–9.2°N). During the SWM, plumes of low salinity (<32) with high clay content were widespread in the northern and central regions of the study area due to heavy river discharge and the presence of crystalline rocks and laterite deposits. In contrast, the low salinity plumes and suspended sediments were markedly low in the southern region due to limited river discharge and a predominance of sedimentary rocks and coastal alluvium that supported sandy sediments. This resulted in a spatial change in benthic sediment texture as well, with the central and northern regions more silty or clayey, while the south was sandy. Interestingly, the sandy south section had a noticeably higher faunal abundance than the rest of the region with an increased abundance of sensitive fauna of molluscs and echinoderms. This is a clear case of how spatially varying river discharge and sediment flux impact the nearshore environment and fauna.

Spatiotemporal dynamics of stable isotopes of different water sources in western Himalayas: Insights into regional hydrological processes

The spatiotemporal variations in stable isotope ratios are primarily related to atmospheric moisture transport. However, the isotopic composition of stream water is significantly influenced by the diverse landscape of glaciated and snow-dominated basins. The present study investigates the spatiotemporal variation of the isotopic composition of stream water and potential water sources such as rain, snowmelt, glacier melt, lakes, and groundwater in the Upper Jhelum River Basin (UJRB). Our findings reveal that the significant seasonal variability of precipitation is mainly associated with the transition between westerlies (WDs) and the Indian Southwest Monsoon (ISWM), each conveying distinct moisture to the UJRB. The isotopic signature in rain is actively controlled by the combined effect of temperature (T) and relative humidity (RH) during WDs. However, the impact of “amount effect” with lower condensation temperature is dominant during the latter half of ISWM. Seasonal variations in δ18O and d-excess in stream water are distinct, influenced by different contributing sources and topographic controls. A linear relationship is observed between δ18O vs. altitude and glacier area ratio (GAR). Lower δ18O in stream water and higher d-excess values are observed in the southwest at higher elevations in glacier-fed tributaries. On the northern side, higher δ18O in stream water indicates contributions from non-glacier fed tributaries and enhanced groundwater contributions rather than merely following the lower δ18O of precipitation along the strengthened WDs gradient. The δ18O isotopic lapse rate (ILR) of rain (−0.19‰/100 m) is higher compared to ILR for the river (−0.05‰/100 m), reflecting the mixing of water sources in river water. However, both are lower than the global average (−0.28‰/100 m). This study helps in understanding the influence of meteorological, topographic factors, and other water sources on stream water, a prerequisite for projecting a potential future change in the complex Himalayan region.

Bias correction of CMIP6 simulations of precipitation over Indian monsoon core region using deep learning algorithms

AbstractGeneral Circulation Models or Global Climate Models (GCMs) output consists of inevitable bias due to insufficient knowledge about parameterization schemes and other mathematical computations that involve thermodynamical and physical laws while designing climate models. Indian summer monsoon (southwest monsoon) accounts for 75%–90% of the annual rainfall over most climatic zones of India during the months, June, July, August, and September, which has a direct impact on the agricultural economy of India. The aim of this study is to bias correct the Coupled Model Intercomparison Project Phase – 6 (CMIP6) GCMs' precipitation data for the historical period from 1985 to 2014 and two Shared Socioeconomic Pathways (SSP) SSP1‐2.6 and SSP5‐8.5, from the period 2015 to 2100, with reference to the India Meteorological Department (IMD) observed rainfall gridded dataset. The datasets used are for the rain‐bearing Indian southwest monsoon season from the months, June to September. Monsoon Core Region is selected to carry out the bias correction using a couple of deep learning algorithms, namely one‐dimensional Convolutional Neural Network (CNN1D) and Long Short‐Term Memory Encoder‐Decoder (LSTM‐ED) Neural Network. The performance of both algorithms is evaluated with metrics. The LSTM‐ED algorithm yielded better results with least error output. The bias‐corrected data obtained using the LSTM‐ED algorithm is then compared with IMD observed rainfall data for the climatic events such as ENSO (El Niño and La Niña) and Positive and Negative IOD (Indian Ocean Dipole).

Exploring Temporal Rainfall Variability and Trends Over a Tropical Region Using Tropical Rainfall Measurement Mission (TRMM) and Observatory Data

Kerala is the gateway of the Indian southwest monsoon. The Tropical Rainfall Measurement Mission (TRMM) rainfall data is an efficient approach to rainfall measurement. This study explores the temporal variability in rainfall and trends over Kerala from 1998-2019 using TRMM data and observatory data procured from India Meteorological Department (IMD). Direct comparison with observatory data at various time scales proved the reliability of the TRMM data (monthly, seasonal and annual). The temporal rainfall converted by averaging the data on an annual, monthly and seasonal time scale, and the results have confirmed that the rainfall estimated based on satellite data is dependable. The station wise comparison of rainfall in monsoon season provides satisfactory results. However, estimation of rainfall in mountainous areas is challenging task using the TRMM. In the basins of humid tropical regions, TRMM data can be a valuable source of rainfall data for water resource management and monitoring with some vigilance. In Kerala, the study found an insignificant increase in the southwest monsoon and winter season rainfall during last two decades. The rainfall over Kerala showed uncertainty in the distribution of monthly, seasonal and yearly time scales. This study provides a preview of recent weather patterns that would enable us to make better decisions and improve public policy against climate change.

Counter-clockwise epochal shift of the Indian Monsoon Sparse Zone

The Indian southwest monsoon season is considered the lifeline of the region's socioeconomic wellbeing. It is recognized that even small variations often lead to notable impacts on the regional economy and agricultural productivity. As a precursor to droughts, this study identifies from century-long data, Monsoon Sparse Zone (MSZ) as a locale with less seasonal rainfall compared to the long-term average climatology. Identifying the MSZ is crucial to understand the spread and propagation of drought-prone areas. The present study investigates the nature of the major MSZ shift in India during the past 116 years (1901–2016) and probable meteorological factors responsible for that transitions. For this purpose, the high-resolution daily rainfall analysis from India Meteorological Department (IMD) and other surface and upper air meteorological parameters from, the NOAA, CRU, and NCEP-NCAR are used. Two drought indices are used to study the MSZ and its epochal shifts during the past century over India. The MSZ locales follow the counter-clockwise shift from west to north-central India through the peninsular region from one to another epoch (each of 29 years) that is statistically significant. The MSZ shifting is insensitive to epochal duration selection. Large-scale and regional processes that may impact the shift of MSZ are analyzed. The El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) have strong influences on the MSZ shift. Additional synergistic effect of large-scale – factors such as westward shifting of subsidence branch of the Walker circulation, the orientation of IOD and local-scale phenomena like the increased surface temperature, moisture flux inflow from the Bay of Bengal, also have shifts aligning to cause this detectable and significant change in the MSZ locales. The presence of MSZ conforms to the drought-prone area over India and has a direct influence on water resources, agriculture, and allied sectors.

Calcareous nannoplankton response to early Eocene warmth, Southwest Pacific Ocean

Episodes of pronounced climatic warming in the early Eocene (56–48 Ma) provide insights into how biological systems might respond to future climate changes. Eocene climate reconstructions for the Southwest (SW) Pacific have proved challenging due to some disparities between geochemical proxy-based estimates for sea temperatures and estimates derived from climate models. Changes in marine phytoplankton populations through the early Eocene provide a means to evaluate model and proxy-based approaches and also reveal how climatic changes affected the ocean ecosystem. This study documents early to middle Eocene calcareous nannofossil assemblages from legacy Deep Sea Drilling Project (DSDP) sites in the SW Pacific. We integrate nannofossil assemblage changes with foraminiferal-based stable isotopes and other microfossil data to provide updated age models for DSDP Sites 207 (Lord Howe Rise) and 277 (Campbell Plateau), and to infer past environmental change through the early to mid-Eocene in the SW Pacific. Although these sites record a short hiatus in the earliest Eocene, deposition resumed by ~54 Ma, prior to the onset of the Early Eocene Climate Optimum (EECO). Both sites show an increase in warm-water taxa from the onset of the EECO until approximately 50.5 Ma. Abundance of warm-water taxa was higher (~23%) at the EECO onset at the more northerly Site 207 and increased only slightly to ~27%, whereas at Site 277 warm-water taxa comprised only ~3% at the EECO onset but increased to ~31% by 50.5 Ma. Cool-water taxa at both sites were present in very sparse numbers (<3%) through much of the EECO and only began to increase in abundance after 50 Ma, concomitant with a decrease in warm-water taxa. These results are similar to other mid-latitude sites in the SW Pacific and Indian Ocean, including mid-Waipara River (Canterbury Basin, New Zealand) and ODP Site 762 (Exmouth Plateau), and indicate assemblages during the EECO are best described as warm temperate. Benthic δ18O records from both sites show good agreement with nannofossil trends and, despite the possibility of recrystallization at Site 277, sea surface temperatures (SSTs) indicated by planktic foraminifera also imply warm temperate conditions. This suggests that a warm proto-East Australian Current extended to at least 55°S during the EECO, displacing the proto-Tasman Front southward, which migrated northward after termination of the EECO possibly due to expansion of a proto-Ross Sea Gyre.

Culturally tailored evidence-based substance use disorder treatments are efficacious with an American Indian Southwest tribe: an open-label pilot-feasibility randomized controlled trial.

Many evidence-based treatments (EBTs) for substance use disorder (SUD) exist, yet few are tailored to Indigenous patients. This trial tested the efficacy of a culturally tailored EBT that combined Motivational Interviewing and the Community Reinforcement Approach (MICRA) versus treatment as usual (TAU). A mixed efficacy/effectiveness randomized controlled trial of MICRA (n=38) and TAU (n=41) using a parallel design with follow-up assessments at 4-, 8-, and 12-months post baseline. United States, reservation-based outpatient, addiction specialty care treatment program. 79 (68% male) American Indian and Alaska Native (AI/AN) Tribal members meeting criteria for SUD and seeking SUD treatment. MICRA (individual therapy sessions beginning with MI for 2-3 sessions) compared with TAU (individual and group counseling sessions in a didactic style with Twelve-Step philosophy and elements of relapse prevention). Demographics, percent days abstinent (PDA; the primary outcome at 12months assessed by Form 90D), Inventory of Drug Use Consequences, Alcohol and Drug Use Self-Efficacy Scale, Native American Spirituality Scale, and SCID-DSM-IV-TR. There was no evidence for the benefit of MICRA over TAU (MICRA PDA=72.63%, TAU=73.62%, treatment effect: B = -4.04 (SE=5.47); 95% CI = -14.941, 6.866; BF=3.44) in the primary outcome. Both groups showed improvements in PDA, SUD severity, and negative consequences from baseline to the 12-month follow-up. Neither self-efficacy nor spirituality were significant mediators of MICRA. There were no treatment group differences between culturally tailored evidence-based treatments for substance use disorder and treatment as usual in this randomized controlled trial with American Indian and Alaska Native participants. Nonetheless, participants improved over time on several substance-related outcomes.

Influence of tropical cyclones on the 100‐year return period wave height—A study based on 39‐year long ERA5 reanalysis data

AbstractVarious engineering activities in a coastal and offshore environment require detailed assessment about the probable extreme wave characteristics in its lifetime to prevent human as well as property loss. The accurate estimation of wave height with a 100‐year return period not only contribute to the level of protection but also the scale of investments. In this study, significant wave height return levels for a northwestern Bay of Bengal location are estimated using extreme value models; generalized extreme value (GEV) and generalized Pareto distribution (GPD). Both block maxima and initial distribution methods are used in the GEV and GPD incorporated with peak over threshold (POT) series. The study is based on the European Centre for Medium‐Range Weather Forecasts ERA5 reanalysis hourly data at 0.25° × 0.25° spatial resolution from 1979 to 2017. The GPD estimates show that the return levels do not follow prevailing seasonality over the location since the return levels greatly depend upon the extreme events and most of the extreme events are during the northeast monsoon season (October–January). The POT with October–January data gives 9.08 m as 100‐year return level, and corresponding Indian southwest monsoon (June–September) return level is only 5.41 m. When different block periods ranging from 15 to 39 years are considered, the 50‐year return levels range from 5.12 to 8.67 m for GEV with annual maxima. The influence of tropical cyclones (TCs) on return levels are examined considering different case studies, and the results show that the strength of a TC alters the return levels more significantly than the number of TCs in the observation. The 100‐year return level decreases by ~30% when wave height during the two cyclones; Phailin and Hudhud are removed from the data set.

Evolution of the Great Whirl Using an Altimetry‐Based Eddy Tracking Algorithm

AbstractTwenty‐three years of Archiving, Validation, and Interpretation of Satellite Oceanographic data absolute dynamic topography and HYbrid Coordinate Ocean Model sea surface height were analyzed with a focus on interannual variability of the Indian Southwest Monsoon in the southwest Arabian Sea. A new algorithm for identification and tracking of the Great Whirl (GW) is presented, which better accounts for the gyre's embedded environment than traditional mesoscale eddy tracking algorithms that use sea level observations. Based on this algorithm, the GW exhibits an average life span of 198 days, which is considerably longer than previous estimates, attributed primarily to a later termination date. A climatology of the GW evolution is created, peaking in early September. This study suggests a possible periodicity of the upper ocean structure during the mature phase of the GW and also highlights the sporadic nature of the decay phase.

Magmatic process beneath the ultra-slow spreading ridge: Petrological studies of a Plagioclase Ultra-phyric Basalt (PUB) from 63.9&amp;#176;E, Southwest Indian Ridge

人们对超慢速扩张洋中脊深部岩浆过程的了解至今仍十分模糊。我们对西南印度洋洋中脊（Southwest Indian Ridge，SWIR）63.9°E处采集到的斜长石超斑状玄武岩（Plagioclase Ultra-Phyric Basalt，PUB）进行了岩石学和地球化学研究。样品具有以下几个特征：斜长石斑晶的体积分数高达~25%，而橄榄石斑晶的体积分数约1%；尽管该样品中玻璃的成分与同一洋脊段玄武岩的成分基本一致，但高Fo橄榄石斑晶与玻璃基质的成分不平衡；不同类型的斜长石晶体之间存在成分差异，单个斜长石大斑晶中的An值也呈现出与正常的结晶分异过程不符的环带；斜长石斑晶中发育溶蚀、筛状等不平衡结构。因此，我们认为，斜长石超斑状玄武岩经历了多期次熔体的作用，是由通过密度分选聚集在岩浆房顶部的斜长石斑晶被之后的火山喷发带出海底形成。尽管斜长石超斑状玄武岩与同一洋脊段的非斑状玄武岩之间并不存在母熔体成分上的差别，但超斑状玄武岩的出现进一步反映了超慢速扩张洋壳岩浆活动的多样性。

Tracing ionic sources and geochemical evolution of groundwater in the Intermountain Una basin in outer NW Himalaya, Himachal Pradesh, India

The present research aims to identify sources of ions and factors controlling the geochemical evolution of groundwater in an intermountain basin, comprising hill and valley fill region, of Outer Himalaya in Himachal Pradesh, India. The groundwater samples collected from 81 tubewells and handpumps are analyzed for major ions, trace metals and stable isotopes (δ18O and δD). Geochemically the dominant hydrochemical facies in the Una basin are Ca–HCO3, Ca–Mg–HCO3 and Na–Cl types at few locations. A relatively lower ionic concentration in the valley fills indicates dilution and low residence time of water to interact with the aquifer mass due to high porosity and permeability. The ionic ratios of 0.9, 0.8 and 3.8 to 5.7, respectively, for (Ca + Mg): HCO3, (Ca + Mg): (HCO3 + SO4) and Na: Cl, suggests that ionic composition of groundwater is mainly controlled by rock weathering of, particularly by dissolution/precipitation of calcrete and calcite hosted in rock veins and Ca–Na feldspar hosted in conglomerate deposits derived from the Higher and Lesser Himalaya during the formation of Siwalik rocks. Although Na, K, NO3 and SO4 are introduced in the groundwater through agricultural practices, Na has also been introduced through ion exchange processes that have occurred during water–rock interaction, as indicated by negative CAI values. Factor analysis further suggests three major factors affecting the water chemistry of the area. The first two factors are associated with rock weathering while the third is anthropogenic processes associated with high nitrate and iron concentration. High concentrations of Fe and Mn ions that are exceeded that of WHO and BIS standards are also present at few locations. The recharge of groundwater in the Outer Himalaya is entirely through Indian Southwest Monsoon (ISM) and depleted ratios of δ18O/δD in valley region indicate infiltration from irrigation in recharging the groundwater and fractionation of isotopes of precipitation due to evaporation before infiltration. High d-excess values and inverse relation with δ18O are indicative of secondary evaporation of precipitation during recharge of groundwater.

New spatial and temporal indices of Indian summer monsoon rainfall

The overall yearly seasonal performance of Indian southwest monsoon rainfall (ISMR) for the whole Indian land mass is presently expressed by the India Meteorological Department (IMD) by a single number, the total quantum of rainfall. Any particular year is declared as excess/deficit or normal monsoon rainfall year on the basis of this single number. It is well known that monsoon rainfall also has high interannual variability in spatial and temporal scales. To account for these aspects in ISMR, we propose two new spatial and temporal indices. These indices have been calculated using the 115 years of IMD daily 0.25° × 0.25° gridded rainfall data. Both indices seem to go in tandem with the in vogue seasonal quantum index. The anomaly analysis indicates that the indices during excess monsoon years behave randomly, while for deficit monsoon years the phase of all the three indices is the same. Evaluation of these indices is also studied with respect to the existing dynamical indices based on large-scale circulation. It is found that the new temporal indices have better link with circulation indices as compared to the new spatial indices. El Nino and Southern Oscillation (ENSO) especially over the equatorial Pacific Ocean still have the largest influence in both the new indices. However, temporal indices have much better remote influence as compared to that of spatial indices. Linkages over the Indian Ocean regions are very different in both the spatial and temporal indices. Continuous wavelet transform (CWT) analysis indicates that the complete spectrum of oscillation of the QI is shared in the lower oscillation band by the spatial index and in the higher oscillation band by the temporal index. These new indices may give some extra dimension to study Indian summer monsoon variability.

The prevalence of tooth wear and its associated risk factors in Indian South West coastal population: An epidemiological study

Background: The aim of the study was to estimate the prevalence of tooth wear in South West Coastal population of India and to investigate the risk factors associated with it. Materials and Methods: This study was conducted in the Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Mangalore, and the rural satellite centers during June 2016–August 2016. A total of 1000 patients were evaluated for the presence of attrition, abrasion, erosion, and abfraction followed by the questionnaire to evaluate risk factors associated with it. The data were statistically analyzed using SPSS version 22.0 software. Statistical analysis was carried out by applying Chi-square test for linear trend. Results: Total prevalence of tooth wear in the study population was 40.6% of which attrition (29%), abrasion (23.7%), erosion (4.6%), and abfraction (6.3%) were observed. The tooth wear was more prevalent in the age group of 40–60 years. Males and urban population showed higher tooth wear compared to females and rural population, respectively. Erosion lesions were higher in people consuming alcohol and soft drinks and with the gastric regurgitation compared to their counterparts. Attrition lesions were significantly higher among tobacco chewers and in patients with parafunctional habits such as bruxism compared to their counterparts. Conclusions: This study throws a light on the prevalence of tooth wear in South West Coastal population of India, and its associated risks, which can be utilized for patient education and increasing the awareness regarding tooth wear as timely intervention is vital for arresting irreversible disease process and the well-being of the patient.

Cloud Condensation Nuclei activity in the tropical marine regions during Indian southwest monsoon

This paper presents the first onboard measurements of cloud condensation nuclei (CCN) distributions at super-saturations (ss) less than 0.5% (0.2% and 0.4%) and more than 0.5% (0.6% and 0.8%) as a function of prevailing winds during July and August over south to southeastern head-Bay region of Bay of Bengal (BoB). During monsoon season of 2012, the cross equatorial flow (CEF) along the belt 50°N–50°S was towards north and prevailing winds were stronger than normal by 2.6ms−1 and 5.14ms−1 respectively. Also, 2 and 5 low-pressure systems were formed during July and August 2012 respectively. Due to the strength of CEF, winds and low-pressure systems, mean value of wind speeds (U) observed onboard the ship during August was found to be stronger than that for July by 28%. As a result, mean values of CCN concentrations in August when winds were above 10ms−1 were higher in magnitude by 9.5%, 15.6%, 13.4%, 12.13% and 11.9% for supersaturations of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% respectively compared to corresponding means of CCN concentration during July when winds were below 10ms−1. Wind-driven (U above 10ms−1) CCN activity is found to be of high CCN concentrations at ss more than 0.5% despite active monsoonal cloud-aerosol interaction in the tropical marine environment. Relationships between CCN concentration and U when winds were above 10ms−1 are found to be log10CCN = 0.057U + 2.4 and log10CCN = 0.047U + 2.6 at ss of 0.6% (R = 0.43) and 0.8% (R = 0.4) respectively, slopes of which appear to be reasonable climatic regulators for wind-induced CCN activity over south to southeastern head-Bay region of BoB.

The role of climate and tectonics in aggradation and incision of the Indus River in the Ladakh Himalaya during the late Quaternary

AbstractThe geomorphic evolution of the upper Indus River that traverses across the southwest (SW) edge of Tibet, and the Ladakh and Zanskar ranges, was examined along a ~350-km-long stretch of its reaches. Based on the longitudinal river profile, stream length gradient index, and river/strath terraces, this stretch of the river is divided into four segments. Valley fill river terraces are ubiquitous, and strath terraces occur in the lower reaches where the Indus River cuts through deformed Indus Molasse. Optically stimulated luminescence ages of river/strath terraces suggest that valley aggradation occurred in three pulses, at ~52, ~28, and ~16 ka, and that these broadly coincide with periods of stronger SW Indian summer monsoon. Reconstructed longitudinal river profiles using strath terraces provide an upper limit on the bedrock and provide incision rates ranging from 1.0±0.3 to 2.2±0.9 mm/a. These results suggested that rapid uplift of the western syntaxes aided by uplift along the local faults led to the formation of strath terraces and increased fluvial incision rates along this stretch of the river.

The Cotoncello Shear Zone (Elba Island, Italy): The deep root of a fossil oceanic detachment fault in the Ligurian ophiolites

The ophiolite sequences in the western Elba Island are classically interpreted as a well-exposed ocean-floor section emplaced during the Apennines orogeny at the top of the tectonic nappe-stack. Stratigraphic, petrological and geochemical features indicate that these ophiolite sequences are remnants of slow-ultraslow spreading oceanic lithosphere analogous to the present-day Mid-Atlantic Ridge and Southwest Indian Ridge.Within the oceanward section of Tethyan lithosphere exposed in the Elba Island, we investigated for the first time a ​10s of meters-thick structure, the Cotoncello Shear Zone (CSZ), that records high-temperature ductile deformation. We used a multidisciplinary approach to document the tectono-metamorphic evolution of the shear zone and its role during spreading of the western Tethys. In addition, we used zircon U–Pb ages to date formation of the gabbroic lower crust in this sector of the Apennines. Our results indicate that the CSZ rooted below the brittle–ductile transition at temperature above 800°C. A high-temperature ductile fabric was overprinted by fabrics recorded during progressive exhumation up to shallower levers under temperature <500°C. We suggest that the CSZ may represent the deep root of a detachment fault that accomplished exhumation of an ancient oceanic core complex (OCC) in between two stages of magmatic accretion. We suggest that the CSZ represents an excellent on-land example enabling to assess relationships between magmatism and deformation when extensional oceanic detachments are at work.

The Oxford Handbook of American Indian History ed. by Frederick E. Hoxie

Reviewed by: The Oxford Handbook of American Indian History ed. by Frederick E. Hoxie Steven J. Peach The Oxford Handbook of American Indian History. Edited by Frederick E. Hoxie. ( New York and other cities: Oxford University Press, 2016. Pp. xvi, 644. $150.00, ISBN 978-0-19-985889-7.) As The Oxford Handbook of American Indian History makes clear, American Indian history has blossomed into a mature field of historical inquiry. Gone are the days when Frederick Jackson Turner's frontier thesis subsumed North America's indigenous peoples within a westward-moving narrative where heroic settlers triumphed over "static and backward" Indians (p. 2). Until the dawn of the New Indian History of the late 1960s, as editor Frederick E. Hoxie points out, scholars drew on Turner to interpret Indians as "primitive" and Europeans as "cultured" (p. 2). Yet the civil rights movement, the advent of social history, and Indian activists and intellectuals birthed American Indian history and studies, fields that elevate Indians as "dynamic actors" who have adapted, accommodated, and resisted European colonization since 1492 (p. 5). This volume captures the chronologies, geographies, and themes of the field. Divided into three parts, the volume presents eight contributions covering the "Major Chapters in the Native American Past" from 1492 to the twenty-first century, eleven chapters on "Regional and Tribal Histories," and another eleven on "Big Themes." Each author marshals publications that debuted in the late 1980s or early 1990s when questions first posed in the 1970s began receiving sustained scholarly attention. Hoxie offers the overarching argument that American Indian history is "Indigenous History," anchoring indigenous people in the American historical narrative (p. 10). The collection reflects a coalition of Native and non-Native scholars: at least nine of the thirty-two total authors hail from such sovereign polities as the Round Valley Indian reservation and the Akwesasne Mohawk Nation. Part 1 canvasses scholarly trends in specific periods and stresses the endurance, complexity, and resilience of American Indians since first contact with Europeans. New diseases, new trade goods, and new patterns of warfare prompted Indians to adapt as best as they could. Some, like the Osages and Comanches, manipulated access to firearms, horses, and other technologies to expand their influence. On the Pacific coast, according to Claudio Saunt, [End Page 758] Russian and Spanish colonization exercised a "calamitous impact" on Native populations who, nonetheless, incorporated Spanish Catholicism into preexisting spiritual customs (p. 80). As the United States consolidated its hold over the continent in the twentieth century, an extremely diverse population of Native Americans blended "Indian and American thinking and practices," laying the foundation for a post-1960 "Indian Renaissance" in politics, law, language, and the arts (pp. 112, 129). Even today, according to Wisconsin Oneida Paul DeMain, Indians face the future by "reaching backward" for strength in traditions (p. 165). Part 2 historicizes specific regions up to the present day. Many chapters probe those areas that have received little attention, such as the Pacific Northwest, Alaska, and the Great Basin, while also covering familiar ground in chapters on the Southeast, the Great Lakes, and Iroquoia. Some chapters interrogate key themes, such as relationship building in the Great Lakes or the geographic and cultural "world of movement" of the Indian Southwest (p. 217). Andrew H. Fisher combats stereotypes of the vanishing Indian personified by Chief Joseph and Chief Seattle by focusing on how the Northwest Indians adapted their cultures, identities, and lands to colonial pressures. Still other scholars write compelling narratives of continuity and adaptation in places like Native California, Native Alaska, and the Native South. Furthermore, more and more work charts the built environment. In the Great Basin and Great Plains, Indians adapted their economies, polities, and traditions to arid landscapes and the wild fluctuations in weather patterns. Finally, Part 3 unpacks eleven major themes in American Indian history, ranging from treaty making and intellectual history to the expressive arts and Indians in popular culture. Many essays embrace an interdisciplinary approach and provide a model for interdisciplinary collaboration. Red Lake Ojibwe Brenda J. Child's essay on gender and family highlights both men and women in their struggle to work and survive in twentieth-century Ojibwe country. Other Native...

186Os–187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os-rich alloys

Abyssal peridotites are oceanic mantle fragments that were recently processed through ridges and represent residues of both modern and ancient melting. To constrain the nature and timing of melt depletion processes, and the composition of the mantle, we report high-precision Os isotope data for abyssal peridotites from three ocean basins, as well as for Os-rich alloys, primarily from Mesozoic ophiolites. These data are complemented by whole-rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), trace- and major-element abundances for the abyssal peridotites, which are from the Southwest Indian (SWIR), Central Indian (CIR), Mid-Atlantic (MAR) and Gakkel Ridges. The results reveal a limited role for melt refertilization or secondary alteration processes in modifying abyssal peridotite HSE compositions. The abyssal peridotites examined have experienced variable melt depletion (2% to >16%), which occurred >0.5Ga ago for some samples. Abyssal peridotites typically exhibit low Pd/Ir and, combined with high-degrees of estimated total melt extraction, imply that they were relatively refractory residues prior to incorporation into their present ridge setting. Recent partial melting processes and mid-ocean ridge basalt (MORB) generation therefore played a limited role in the chemical evolution of their precursor mantle domains. The results confirm that many abyssal peridotites are not simple residues of recent MORB source melting, having a more complex and long-lived depletion history.Peridotites from the Gakkel Ridge, SWIR, CIR and MAR indicate that the depleted MORB mantle has 186Os/188Os of 0.1198356±21 (2SD). The Phanerozoic Os-rich alloys yield an average 186Os/188Os within uncertainty of abyssal peridotites (0.1198361±20). Melt depletion trends defined between Os isotopes and melt extraction indices (e.g., Al2O3) allow an estimate of the primitive mantle (PM) composition, using only abyssal peridotites. This yields 187Os/188Os (0.1292±25), and 186Os/188Os of 0.1198388±29, both of which are within uncertainty of previous primitive mantle estimates. The 186Os/188Os composition of the PM is less radiogenic than for some plume-related lavas, with the latter requiring sources with high long-term time-integrated Pt/Os. Estimates of primitive mantle HSE concentrations using abyssal peridotites define chondritic Pd/Ir, which differs from previous supra-chondritic estimates for Pd/Ir based on peridotites from a range of tectonic settings. By contrast, estimates of PM yield supra-chondritic Ru/Ir. The cause of enhanced Ru in the mantle remains enigmatic, but may reflect variable partitioning behavior of Ru at high pressure and temperature.

Underwater navigation and calibration of Jiaolong manned submersible in the Southwest Indian Ridge hydrothermal vents

Underwater navigation and calibration of Jiaolong manned submersible in the Southwest Indian Ridge hydrothermal vents

Evaluation Methodology and Indicator System of Polymetallic Sulfide Mineral Resources in the Southwest Indian Ocean

Evaluation Methodology and Indicator System of Polymetallic Sulfide Mineral Resources in the Southwest Indian Ocean