Early Southwest Research Articles

Maastrichtian–Rupelian paleoclimates in the southwest Pacific – a critical re-evaluation of biomarker paleothermometry and dinoflagellate cyst paleoecology at Ocean Drilling Program Site 1172

Abstract. Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT'5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX86-based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX86-based SST and MBT'5me-based MAAT estimates remain without definitive explanation.

Evaluation of Clifton beach by using macrobenthic assemblages for beach management

Spatio-temporal variations in macrobenthic assemblages were investigated at two tidal levels along sandy beach of Clifton with reference to environmental factors and anthropogenic activities in this study. Two stations were selected considering the local disturbances, Clifton station C1 and C2 where C2 is among the most common visiting site of thickly populated Karachi city and also receive untreated sewage waste from nearby areas. The samples were collected in replicates from quadrates of 0.25 m2 and a sum of 5066 specimens belonged to 49 species were recorded. The highest species diversity (H = 8.702) was recorded in pre southwest and lowest (0.1673) in early southwest monsoon. The average Bray-Curtis dissimilarity between C1 and C2 is 62% and is made up of 7.52% by Donax cuneatus which was the most abundant organism at C2. Analysis of similarity (ANOSIM) showed significant differences between C1 and C2 in environmental variables (R = 0.91; p < 0.02) and macrobenthos assemblages (R = 0.7; p < 0.02). PC1 accounted approximate variability of 77.1% and PC2 of 13.2% between environmental variables and monsoon seasons. Nutrients, sediment grain size and organic matter was responsible for the disparity between stations during monsoon season. The present study shows that benthic community structure at Clifton is regulated by shift in monsoon, environmental variables and human disturbances. The comparison of the data with earlier reports exhibited that those species which tolerate polluted and organically rich habitats has become more abundant in last decade at studied site. The abundance of Donax cuneatus can be used in the evaluation and management of this beach in future.

Noctiluca and copepods grazing on the phytoplankton community in a nutrient-enriched coastal environment along the southwest coast of India

The relative grazing impact of Noctiluca scintillans (hereafter referred only Noctiluca) and copepods (Acrocalanus gracilis, Paracalanus parvus, Acartia danae and Oithona similis) on the phytoplankton community in an upwelling-mudbank environment along the southwest coast India is presented here. This study was carried out during the Pre-Southwest Monsoon (April-May) to the Late Southwest Monsoon (August) period in 2014. During the sampling period, large hydrographical transformation was evident in the study area (off Alappuzha, Southwest coast of India); warmer Pre-Southwest Monsoon water column condition got transformed into cooler and nitrate-rich hypoxic waters during the Southwest Monsoon (June-August) due to intense coastal upwelling. Copepods were present in the study area throughout the sampling period with a noticeable increase in their abundance during the Southwest Monsoon. On the other hand, the first appearance of Noctiluca in the sampling location was during the Early Southwest Monsoon (mid-June) and thereafter their abundance increased towards the Peak Southwest Monsoon. The grazing experiments carried out as per the food removal method showed noticeable differences in the feeding preferences of Noctiluca and copepods, especially on the different size fractions of phytoplankton. Noctiluca showed the highest positive electivity for the phytoplankton micro-fraction (av. 0.49±0.04), followed by nano-fraction (av. 0.17±0.04) and a negative electivity for the pico-fraction (av. -0.66±0.06). In total ingestion of Noctiluca, micro-fraction contribution (83.7%) was significantly higher compared to the nano- (15.7%) and pico-fractions (0.58%). On the other hand, copepods showed the highest positive electivity for the phytoplankton nano-fraction (av. 0.38±0.04) followed by micro- (av. -0.17±0.05) and pico-fractions (av. -0.35±0.05). Similarly, in total ingestion of copepods, nano-fraction (69.7%) was the highest followed by micro- (28.9%) and pico-fractions (1.37%). The grazing pressure of Noctiluca on the total phytoplankton was found to be 27.7% of the standing stock and 45.6% of the production, whereas in the case of copepods, it was 9.95% of the standing stock and 16.6% of the production. The study showed that the grazing pressure of Noctiluca on the total phytoplankton as well as larger phytoplankton fraction was 2.8- and 8-folds higher than that of the copepods. This suggests the leading role of Noctiluca as an effective grazer of larger phytoplankton along the southwest west coast of India, especially during the Peak/Late Southwest Monsoon.

A shifting rift—Geophysical insights into the evolution of Rio Grande rift margins and the Embudo transfer zone near Taos, New Mexico

We present a detailed example of how a subbasin develops adjacent to a transfer zone in the Rio Grande rift. The Embudo transfer zone in the Rio Grande rift is considered one of the classic examples and has been used as the inspiration for several theoretical models. Despite this attention, the history of its development into a major rift structure is poorly known along its northern extent near Taos, New Mexico. Geologic evidence for all but its young rift history is concealed under Quaternary cover. We focus on under­standing the pre-Quaternary evidence that is in the subsurface by integrating diverse pieces of geologic and geophysical information. As a result, we present a substantively new understanding of the tectonic configuration and evolution of the northern extent of the Embudo fault and its adjacent subbasin. We integrate geophysical, borehole, and geologic information to interpret the subsurface configuration of the rift margins formed by the Embudo and Sangre de Cristo faults and the geometry of the subbasin within the Taos embayment. Key features interpreted include (1) an imperfect D-shaped subbasin that slopes to the east and southeast, with the deepest point ∼2 km below the valley floor located northwest of Taos at ∼36° 26′N latitude and 105° 37′W longitude; (2) a concealed Embudo fault system that extends as much as 7 km wider than is mapped at the surface, wherein fault strands disrupt or truncate flows of Pliocene Servilleta Basalt and step down into the subbasin with a minimum of 1.8 km of vertical displacement; and (3) a similar, wider than expected (5–7 km) zone of stepped, west-down normal faults associated with the Sangre de Cristo range front fault. From the geophysical interpretations and subsurface models, we infer relations between faulting and flows of Pliocene Servilleta Basalt and older, ­buried basaltic rocks that, combined with geologic mapping, suggest a revised rift history involving shifts in the locus of fault activity as the Taos subbasin developed. We speculate that faults related to north-striking grabens at the end of Laramide time formed the first west-down master faults. The Embudo fault may have initiated in early Miocene southwest of the Taos region. Normal-oblique slip on these early fault strands likely transitioned in space and time to dominantly left-lateral slip as the Embudo fault propagated to the northeast. During and shortly after eruption of Servilleta Basalt, proto-­Embudo fault strands were active along and parallel to the modern, NE-aligned Rio Pueblo de Taos, ∼4–7 km basinward of the modern, mapped Embudo fault zone. Faults along the northeastern subbasin margin had northwest strikes for most of the period of subbasin formation and were located ∼5–7 km basinward of the modern Sangre de Cristo fault. The locus of fault activity shifted to more northerly striking faults within 2 km of the modern range front sometime after Servilleta volcanism had ceased. The northerly faults may have linked with the northeasterly proto-Embudo faults at this time, concurrent with the development of N-striking Los Cordovas normal faults within the interior of the subbasin. By middle Pleistocene(?) time, the Los Cordovas faults had become inactive, and the linked Embudo–Sangre de Cristo fault system migrated to the south, to the modern range front.

Review: Contesting the Borderlands: Interviews on the Early Southwest by Deborah Lawrence and Jon Lawrence

Book Review| February 01 2017 Review: Contesting the Borderlands: Interviews on the Early Southwest by Deborah Lawrence and Jon Lawrence Contesting the Borderlands: Interviews on the Early Southwest. By Deborah Lawrence and Jon Lawrence. (Norman: University of Oklahoma Press, 2016. 280 pp. $24.95 paper). Raphael Folsom Raphael Folsom Professor Folsom is a scholar of colonial Latin America, focusing on native peoples and imperial borderlands in New Spain. His first book, The Yaquis & The Empire: Violence, Spanish Imperial Power, and Native Resilience in Colonial Mexico (Yale University Press, 2014), deals with the history of one of Mexico’s most famous native peoples and their negotiations with Jesuit missionaries, Spanish officials, and their indigenous neighbors in colonial Sonora. Search for other works by this author on: This Site PubMed Google Scholar Southern California Quarterly (2017) 99 (1): 92–94. https://doi.org/10.1525/scq.2017.99.1.92 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Search Site Citation Raphael Folsom; Review: Contesting the Borderlands: Interviews on the Early Southwest by Deborah Lawrence and Jon Lawrence. Southern California Quarterly 1 February 2017; 99 (1): 92–94. doi: https://doi.org/10.1525/scq.2017.99.1.92 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentSouthern California Quarterly Search This content is only available via PDF. © 2017 by The Historical Society of Southern California2017 Article PDF first page preview Close Modal You do not currently have access to this content.

Contesting the Borderlands: Interviews on the Early Southwest by Deborah Lawrence and Jon Lawrence

Reviewed by: Contesting the Borderlands: Interviews on the Early Southwest by Deborah Lawrence and Jon Lawrence Jennifer Koshatka Seman Contesting the Borderlands: Interviews on the Early Southwest. By Deborah Lawrence and Jon Lawrence. (Norman: University of Oklahoma Press, 2016. Pp. 280. Illustrations, notes, bibliography, index.) Contesting the Borderlands: Interviews on the Early Southwest is a collection of interviews with nine prominent scholars of the southwestern borderlands that provides insight into some of the most important and provocative scholarship on this region. Organized chronologically, the volume starts with the prehistoric period, continues through Spanish colonization, covers the Mexican era, and ends with the U.S. takeover in 1848. The interviews illuminate the contested historical issues defining the Southwest, such as violence between Native peoples and the negotiation of power between Europeans and Indians. Sparked by probing questions from the authors, the interviews reveal not only how these scholars came to their interpretations of the past—their questions, methodologies, and use of evidence—but also how their analyses fit into the larger historical debates in the study of the Southwest. The first interview is with archaeologist Steven LeBlanc. His work proposes that the early Southwest was far more violent than previously believed, a conclusion he reached based on his research of ancestral Puebloan sites. The authors ask LeBlanc for his thoughts on the differing [End Page 387] scholarly assessments of this period in the Southwest, many suggesting this period was peaceful. LeBlanc explains how his methodology—the examination of multiple, independent strands of evidence that all point to the same conclusion—convinces him of the soundness of his conclusions. Among the book’s most interesting features are the interviewees’ responses to contradicting scholarship and, in some cases, defenses of their own. The interview with Juliana Barr will likely be the most compelling to Texas historians and enthusiasts. Her scholarship focuses on the colonial history of Texas, in particular the history of Native peoples and women. Barr explains how she came to the interpretation of Native peoples as powerful and dominant in the colonial encounter. Barr also focuses on the role of women and gender in Native cultures, something that readers of her excellent Peace Came in the Form of a Woman: Indians and Spaniards in the Texas Borderlands (UNC Press, 2007) will be familiar with in tone and substance. Barr’s interview is a significant addition to Contesting the Borderlands as she is the only scholar interviewed who utilizes in-depth gender analysis in her work. Another highlight is the interview with eminent historian David J. Weber (1940–2010), whose work on the Spanish and Mexican borderlands emphasizes both conflict and accommodation among the various groups of people in the Southwest. In this interview, Weber manages to include all regions of the Southwest—including Texas, New Mexico, California, and northern Mexico—in his answers to questions about Spanish missions, Indian slavery, and the myth of the frontier. Contesting the Borderlands offers both a clear introductory overview of the increasingly broad and diverse scholarship on the Southwest and an in-depth discussion of specific issues and interpretations. The authors provide short introductions outlining pertinent historical context before each interview so that the specialist will be reminded of the essential details of the subject to be discussed while the novice will also have just enough background to engage meaningfully with the interview. This volume is enriched with maps, illustrations, and extensive notes. Jennifer Koshatka Seman Brookhaven College Copyright © 2015 The Texas State Historical Association

Rainfall Distributions in Sri Lanka in Time and Space: An Analysis Based on Daily Rainfall Data

Daily rainfall totals are analyzed for the main agro-climatic zones of Sri Lanka for the period 1976–2006. The emphasis is on daily rainfall rather than on longer-period totals, in particular the number of daily falls exceeding given threshold totals. For one station (Mapalana), where a complete daily series is available from 1950, a longer-term perspective on changes over half a century is provided. The focus here is particularly on rainfall in March and April, given the sensitivity of agricultural decisions to early southwest monsoon rainfall at the beginning of the Yala cultivation season but other seasons are also considered, in particular the northeast monsoon. Rainfall across Sri Lanka over three decades is investigated in relation to the main atmospheric drivers known to affect climate in the region: sea surface temperatures in the Pacific and Indian Oceans, of which the former are shown to be more important. The strong influence of El Niño and La Niña phases on various aspects of the daily rainfall distribution in Sri Lanka is confirmed: positive correlations with Pacific sea-surface temperatures during the north east monsoon and negative correlations at other times. It is emphasized in the discussion that Sri Lanka must be placed in its regional context and it is important to draw on regional-scale research across the Indian subcontinent and the Bay of Bengal.

Geographies of Power: Mapping Indian Borders in the “Borderlands” of the Early Southwest

Geographies of Power: Mapping Indian Borders in the “Borderlands” of the Early Southwest

Early Southwest Ornithologists, 1528–1900

Early Southwest Ornithologists, 1528–1900

Early Southwest Ornithologists, 1528-1900 Dan L. Fischer

Early Southwest Ornithologists, 1528-1900 Dan L. Fischer

Early Southwest Ornithologists, 1528–1900

Early Southwest Ornithologists, 1528–1900

Analysis of 210Pb in sediment trap samples and sediments from the northern Arabian Sea: evidence for boundary scavenging

The concentrations of 210Pb were measured in particles intercepted by sediment traps deployed at 1024 m and 3024 m in the northern Arabian Sea for a period of 1 year from November 1986 to October 1987. The 210Pb activity in the biweekly samples varied from 11 to 108 dpm g −1 at 1024 m and 58 dpm g −1 to 588 dpm g −1 at 3024 m. The mean annual 210Pb flux increased from 0.27 dpm cm −2 yr −1 in the 1024 m trap to 0.65 dpm cm −2 yr −1 in the 3024 m trap. The 210Pb flux exhibited a strong seasonal pattern associated with variations in the sediment mass flux and organic carbon (C org) flux except during early southwest monsoon in the 3024 m trap. This could be due to enhanced scavenging of 210Pb on inorganic phases consisting mostly of Fe–Mn oxides. 210Pb concentrations were dependent on particle composition, indicating that 210Pb scavenging from the water column is directly coupled to the type of settling particles. Organic matter does not appear to be the dominant carrier phase for 210Pb as shown by the poor 210Pb–C org correlation. The fraction of 210Pb removed from the ocean by settling particles F/ P ( 210Pb Flux / 210Pb production) cannot be used as a proxy to determine the C org flux in this region. The excess 210Pb inventories in 13 sediment cores in the Arabian Sea ranged from 11 to 211 dpm cm −2. Such highly variable spatial distribution of the excess 210Pb inventory reflects a non-uniform deposition of 210Pb in this region. The measured excess 210Pb inventories (124–211 dpm cm −2) for the sea floor sediments below the Western Arabian Sea Trap and from other locations in the vicinity of the sediment trap mooring lend support to boundary scavenging within the northwestern Arabian Sea as a sink for 210Pb.

Mavericks on the Border: The Early Southwest in Historical Fiction and Film; The Medicine Line: Life and Death on a North American Borderland

Mavericks on the Border: The Early Southwest in Historical Fiction and Film; The Medicine Line: Life and Death on a North American Borderland

Early Southwest Ornithologists, 1528-1900

Early Southwest Ornithologists, 1528-1900

Mavericks on the Border: The Early Southwest in Historical Fiction and Film

The American Southwest, especially as it existed from the time of the Mexican-American War to World War I, has long fascinated audiences. Authors and filmmakers of the 20th century have created a pantheon of mavericks - some macho, others angst-ridden - who often cross a metaphorical boundary among the literal ones of Anglo, Native American and Hispanic cultures. In this text, the author focuses on such border crossings as a key feature of novels and films about the region. Alongside such works as "The Wild Bunch", "Broken Arrow", "Blood Meridian", "Gringo Viejo" and "Go Down, Moses", the author discusses lesser-known novels and films that tell equally compelling stories of the region. He analyzes unfamiliar mavericks as well as familiar ones, including Geronimo, Doc Holliday and Billy the Kid, as they struggle for identity, purpose and justice.

The Kachina and the Cross: Indians and Spaniards in the Early Southwest. By Carroll L. Riley (Salt Lake City: University of Utah Press, 1999. xvi plus 336pp. $34.95)

The Kachina and the Cross: Indians and Spaniards in the Early Southwest. By Carroll L. Riley (Salt Lake City: University of Utah Press, 1999. xvi plus 336pp. $34.95)

The Kachina and the Cross: Indians and Spaniards in the Early Southwest

Journal Article The Kachina and the Cross: Indians and Spaniards in the Early Southwest. By Carroll L. Riley. (Salt Lake City: University of Utah Press, 1999. xvi, 336 pp. $34.95, ISBN 0-87480-610-0.) Get access Oakah L. Jones Oakah L. Jones Emeritus, Purdue University, West Lafayette, Indiana Search for other works by this author on: Oxford Academic Google Scholar Journal of American History, Volume 88, Issue 1, June 2001, Pages 180–181, https://doi.org/10.2307/2674937 Published: 01 June 2001

Mavericks on the border: the early Southwest in historical fiction and film

American Southwest, especially as it existed from the time of the Mexican-American War to World War I, has long fascinated audiences. Authors and filmmakers of the 20th century have created a pantheon of mavericks - some macho, others angst-ridden - who often cross a metaphorical boundary among the literal ones of Anglo, Native American and Hispanic cultures. In this text, the author focuses on such border crossings as a key feature of novels and films about the region. Alongside such works as The Wild Bunch, Broken Arrow, Blood Meridian, Gringo Viejo and Go Down, Moses, the author discusses lesser-known novels and films that tell equally compelling stories of the region. He analyzes unfamiliar mavericks as well as familiar ones, including Geronimo, Doc Holliday and Billy the Kid, as they struggle for identity, purpose and justice.

Mavericks on the Border: The Early Southwest in Historical Fiction and Film (review)

Mavericks on the Border: The Early Southwest in Historical Fiction and Film (review)

The kachina and the cross: Indians and Spaniards in the early Southwest

The kachina and the cross: Indians and Spaniards in the early Southwest