Occurrence of the ammonite Goodhallites goodhalli (J. Sowerby) in the Eromanga Basin,Queensland: an index species for the late Albian (Cretaceous)

Mortoniceratid ammonites of the Eromanga Basin of Queensland, although uncommon, are reviewed and reassessed utilising all known collections. Representatives of this group are restricted to the Allaru Formation and almost all specimens are Goodhallites goodhalli, a well-known species from the English Gault. The Allaru Formation overlies the Toolebuc Formation, widely considered to be an essentially isochronous unit because of its unusual sedimentary and geochemical character. Using G. goodhalli, the middle and upper Allaru Formation can be directly correlated with the early late Albian orbignyi and auritus Subzones of the Mortoniceras inflatum Zone as recognized in the reference ammonite zonation embedded in the standard Cretaceous time scale. Overlapping ranges of G. goodhalli and Labeceras and Myloceras allow these common Austral heteromorph genera to be also confidently assigned a late Albian age in Australia, matching their biostratigraphic occurrence in South Africa.     

Prosperity,power, and change: Modeling maize at Postclassic Xaltocan,Mexico

Documenting the relationship between agriculture and political economy occupies the center of much research and debate in anthropological archaeology. This study examines this issue by focusing on maize at Xaltocan, a Postclassic community located in the northern Basin of Mexico. We consider how different mechanisms of distribution, circulation, and production can influence maize variation. We analyze maize variability through time at Xaltocan and the community’s chinampa system and interpret patterns of variation in relation to its historical trajectory. This methodological and interpretive approach offers an innovative means to understand how agricultural practices transformed in relation to changing conditions of prosperity and power, especially the links between tribute, market exchange, conflict, and regional demography. Our study also speaks to broader, dichotomous perspectives that model the organization of agricultural systems, revealing that the strategies of both agriculturalists and the state often converge at local levels.     

Generation and accumulation of oil and condensates in the Wenchang A Sag, western Pearl River Mouth Basin, South China Sea

The Pearl River Mouth (PRM) Basin is one of four Cenozoic basins in the South China Sea, and the Wenchang A Sag is a secondary depression in the western part of the basin. Both the Wenchang and Enping formations contain good source rocks in the western PRM Basin; however, only the latter has been considered a likely source of the discovered oil and gas. New data from fluid inclusions and the analysis of oil–source rock correlations for the WC10-3 oil and gas pools indicate two stages of petroleum charging, the earlier originating from the Wenchang Formation and the later from the Enping Formation. Kinetics of petroleum generation and structural evolution modeling were employed to further investigate the mechanism of formation of the WC10-3 oil and gas pools. It was shown that the crucial condition for the formation of pools is the time of development of the structural trap. The Wenchang Formation source rocks generated oil from 25 to 14 Ma in the possible source area of the WC10-3 oil and gas pools in the Wenchang A Sag, so that only traps formed earlier than this period could capture oil sourced by the Wenchang Formation. The Enping Formation source rock experienced its oil window from 18 Ma to the present with the main stage of oil generation from 15 to 5 Ma. During this period structural traps in the sag continued to form until movements became weak, so that most pools in the Wenchang A Sag originated from the Enping Formation source rock. The likely dissipation of oil and gas from the earlier stage of charging should be taken into account in assessing the oil potential of the Wenchang A Sag.     

A case of treponematosis from pre‐Columbian Chaco Canyon,New Mexico

Although numerous cases of treponemal infection have been identified in prehispanic New World skeletal remains, none has been reported from Chaco Canyon, New Mexico. Chaco Canyon was the epicentre of a broad culture system that spanned the Four Corners region of the pre‐Columbian Southwestern United States. A burial recovered from the central Great House of Chaco Canyon, Pueblo Bonito, exhibits lesions indicative of treponematosis. However, the pathological condition of this individual has heretofore been only tentatively diagnosed because the skeleton was collected from a commingled context and distributed across four separate catalogue numbers. Now reassociated, these remains exhibit a pattern of pathological changes strongly indicative of treponemal disease. This case not only adds to the growing body of literature on the clinical expression and geographic distribution of pre‐Columbian treponematosis, but also demonstrates the utility of painstaking reassociation of commingled human remains. Copyright © 2009 John Wiley & Sons, Ltd.     

Temperature‐dependent Li isotope ratios in Appalachian Plateau and Gulf Coast Sedimentary Basin saline water

Lithium (Li) concentrations of produced water from unconventional (horizontally drilled and hydraulically fractured shale) and conventional gas wells in Devonian reservoirs in the Appalachian Plateau region of western Pennsylvania range from 0.6 to 17 mmol kg^?1, and Li isotope ratios, expressed as in δ⁷Li, range from +8.2 to +15‰. Li concentrations are as high as 40 mmol kg^?1 in produced waters from Plio‐Pleistocene through Jurassic‐aged reservoirs in the Gulf Coast Sedimentary Basin analyzed for this study, and δ⁷Li values range from about +4.2 to +16.6‰. Because of charge‐balance constraints and rock buffering, Li concentrations in saline waters from sedimentary basins throughout the world (including this study) are generally positively correlated with chloride (Cl), the dominant anion in these fluids. Li concentrations also vary with depth, although the extent of depth dependence differs among sedimentary basins. In general, Li concentrations are higher than expected from seawater or evaporation of seawater and therefore require water–mineral reactions that remove lithium from the minerals. Li isotope ratios in these produced waters vary inversely with temperature. However, calculations of temperature‐dependent fractionation of δ⁷Li between average shale δ⁷Li (?0.7‰) and water result in δ⁷Li_water that is more positive than that of most produced waters. This suggests that aqueous δ⁷Li may reflect transport of water from depth and/or reaction with rocks having δ⁷Li lighter than average shale.     

Between colonising waters and extracting forest fronts: Entangled eco-frontiers in the Usumacinta River Basin

The eco-frontier concept has addressed the processes of certain territories that are subject to ecological concern and appropriation of different actors. This study approaches the underexplored interaction with the frontier. The article sharpens the focus on the relations between the eco-frontier and the frontier as both a naturally rich periphery with importance to political centres and as an advancing front. The research discusses empirical results in the case of the transboundary Usumacinta River Basin (URB), which extends from Guatemala's highlands and lowlands through three Mexican states to the Gulf of Mexico. Three historical stages of eco-frontiers—exploratory, epistemic, and institutionalised—are identified in the URB. Its entangled eco-frontiers transform wildernesses and waters to forest ecosystems with inhabitants both spatially and mentally, yet contain some colonial, geopolitical, and global components. This article suggests that the eco-frontiers are fundamentally created because of contemporary frontier dynamics.     

Seismic Response of the Central Part of Indo-Gangetic Plain

In spite of high seismic risk, there is no numerical model of Indo-Gangetic Plain. In this paper, seismic response of the central part of Indo-Gangetic Plain, i.e., Ganga Plain is studied using a two-dimensional plane strain finite element model. Seismic source is assumed to be located beneath the Himalayas near Himalayan Frontal Thrust. Basin response is simulated for a hypothetical M_w 8.0 Himalayan earthquake. Ground motion amplification and sensitive frequency band of the basin, obtained from the numerical simulation, show that the sediment depth and epicentral distance at a site play significant role in the seismic response of the site.     

Fluid environment for preservation of pore spaces in a deep dolomite reservoir

Well TS1 reveals many uncemented pores and vugs at depths of more than 8000 m in a deep Cambrian dolomite reservoir in the Tarim Basin, northwestern China. The fluid environment and mechanism required for the preservation of reservoir spaces have yet not been well constrained. Carbon, oxygen, and strontium isotope compositions and fluid inclusion data suggest two types of fluids, meteoric water and hydrothermal fluid, affecting the Lower Paleozoic carbonate reservoirs in the Tarim Basin. Based on simulation using a thermodynamic model for H₂O‐CO₂‐NaCl‐CaCO₃ system, meteoric water has the ability to continuously dissolve carbonate minerals during downward migration from the surface to deep strata until it reaches a transition depth, below which it will begin to precipitate carbonate minerals to fill preexisting pore spaces. In contrast, hydrothermal fluid has the ability to dissolve carbonate in deep strata and precipitate carbonate in shallow strata during upward migration. Based on the dissolution–precipitation characteristics of the two types of fluids, the ideal fluid environment for the preservation of preexisting reservoir spaces occurs when carbonate reservoir is neither in the CaCO₃ precipitation domain of meteoric water nor in the CaCO₃ precipitation domain of hydrothermal fluid. Taking the Lower Paleozoic carbonate reservoirs in the north uplift area as an example, the spaces in the deep Cambrian dolomite reservoir near well TS1 were seldom filled because thick Ordovician deposits blocked meteoric water from migrating downward into the Cambrian dolomite reservoir and because the Cambrian dolomite reservoir has been in the domain of hydrothermal dissolution since the Permian. The deep carbonate layers in basins elsewhere with a similar fluid environment may have high uncemented porosity and consequently have good hydrocarbon exploration potential.     

First record of the trace fossil Protovirgularia from the Middle Permian of southeastern Gondwana (southern Sydney Basin,Australia)

LUO, M. &; SHI G.R., February 2017. First record of the trace fossil Protovirgularia from the Middle Permian of southeastern Gondwana (southern Sydney Basin, Australia). Alcheringa 0, 000–000. ISSN 0311-5518.

This study reports the first examples of well-preserved chevronate trails referable to Protovirgularia longespicata De Stefani, 1885 Stefani, DE.C., 1885. Studi paleozoologici sulle creta superiore e media dell' Apennino settentionale. Atti della Reale Accademia dea Lincei, Memorie 22, 101?134. [Google Scholar] from the early Middle Permian (Roadian) upper Wandrawandian Siltstone of the southern Sydney Basin, southeastern Australia. The highly meandering trace with closely spaced, papillate chevrons is interpreted to have been produced by the locomotion-feeding behaviour of certain protobranch bivalves in an offshore environment. The dense trails occurring on the upper bedding planes of pebbly siltstone may represent a gregarious lifestyle, where junior and senior individuals of the trace-maker bivalves coexisted while moving within sediments. The Wandrawandian Protovirgularia also represents the first known occurrence of this ichnotaxon from a glaciomarine environment in the Permian eastern Gondwana. The global record of Protovirgularia occurrences suggests that these trails had a wide environmental distribution since the Cambrian, and there is no obvious difference in the environmental distribution of Protovirgularia after the Permian?Triassic transition.

Mao Luo [m.luo@deakin.edu.au] and G.R. Shi [guang.shi@deakin.edu.au], Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood Campus, 221 Burwood Highway, VIC 3125, Australia.     

Morphometric Analysis of Camelid Remains from the Alero Deodoro Roca (ADR) Site (Córdoba,Argentina). An Attempt to Characterise Body‐Size Variability in Sierras Pampeanas Australes Region

This paper focuses in the morphometric analyses of Lama guanicoe remains recovered from the hunter–gatherer archaeological site Alero Deodoro Roca, located at Sierras Pampeanas Australes region (Córdoba Argentina), an area that has little information on the body‐size variability of these artiodactyls. Because of the sparse osteometric data in the region, we focused on determining inter‐intraspecific differentiation of wild camelids through corroborated osteometric techniques and multivariate statistical analyses of proximal phalanges. Our results showed a clear interspecific differentiation between modern vicuñas and archaeological specimens. We could also distinguish at least three guanaco size groups (small, medium and large) with the archaeological remains from the late Holocene (3000–3600 bp ) of the site, presenting medium‐size characteristics. Finally this paper aims at establishing a first approach in the characterisation of guanaco body size in the mountainous region of Córdoba. Copyright © 2016 John Wiley & Sons, Ltd.