We investigate the relationship between climate change and hydrate stability in two peri-Antarctic areas: Antarctic Peninsula and South Chile. We consider these areas because the polar and subpolar areas are the most sensitive about global change. The zone, where the methane can be easily released by hydrate melting, is the shallow water, that is, in proximity of the intersection between the BSR and the sea bottom. In order to simulate the effect of climate change on hydrate stability, we consider the following seven scenarios for both areas: present environmental condition; sea bottom temperature increase/decrease of <svg style="vertical-align:-0.17554pt;width:22.8125px;" id="M1" height="11.0375" version="1.1" viewBox="0 0 22.8125 11.0375" width="22.8125"  xmlns="http://www.w3.org/2000/svg">
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 water depth increase/decrease of 100&#x2009;m; sea bottom temperature and water depth increase/decrease of <svg style="vertical-align:-0.17554pt;width:22.8125px;" id="M2" height="11.0375" version="1.1" viewBox="0 0 22.8125 11.0375" width="22.8125"  xmlns="http://www.w3.org/2000/svg">
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 and 100&#x2009;m, respectively. On the basis of our result, we can draw the conclusion that the modeling is a useful tool to understand the effect of the climate change on hydrate stability. Moreover, in these areas where the sea bottom temperature is influenced by temperature increase, slides could be easily triggered by hydrate dissociation.

U. Tinivella

M. Giustiniani

D. Accettella

BSR versus Climate Change and Slides

Very abundant remains of <i>Bos primigenius</i> have been recovered in the early Late Pleistocene site of Avetrana (southern Italy). The site is characterized by a karst filling originated from a series of almost coeval depositional events. This discovery represents a rare record in the early Late Pleistocene of southern Europe. Biometrical analysis of the metapodial bones of aurochs from Avetrana gave the cue to examine the evolutive trend of the species in southern Europe, from the Middle Pleistocene to Holocene. This trend is characterized by an increase in size of the metapodial bones from Middle Pleistocene to early Late Pleistocene and to a decrease in size of the same during the late Late Pleistocene and Holocene. Also, the variations in size are competed by change in shape of the metapodial bones. These variations seem to be related with climatic fluctuations and competitions with <i>Homo</i> and <i>Bison</i>. At least, five evolutive stages are recognized; they constitute an important tool for the biochronological correlations among the Pleistocene sites of southern Europe.

Luca Pandolfi

Carmelo Petronio

Leonardo Salari

<i>Bos primigenius</i> Bojanus, 1827 from the Early Late Pleistocene Deposit of Avetrana (Southern Italy) and the Variation in Size of the Species in Southern Europe: Preliminary Report

The Indian monsoon activity, coinciding with the Inter-Tropical Convective Zone (ITCZ), progresses from the southern Indian Ocean during the boreal summer and withdraws towards the south in winter. Islands situated to the south of India receive, therefore, the first and last showers of the monsoon; speleothems in such islands have not yet been explored for their potential to reconstruct past monsoon rainfall. Here, we present the first measurements of stable carbon and oxygen isotopic compositions (<i>&#x3b4;</i><sup>13</sup>C and <i>&#x3b4;</i><sup>18</sup>O) of a stalagmite collected from the Baratang Island of Andamans, along with new data on <i>&#x3b4;</i><sup>18</sup>O of modern monsoon precipitation (May to July 2010). The aim was to detect (i) whether these samples are amenable to dating using <sup>14</sup>C, (ii) whether their oxygen isotopes indicate precipitation under isotopic equilibrium, and (iii) if (i) and (ii) above are true, can we reconstruct monsoon activity during the past few millennia? Our results indicate that while <i>&#x3b4;</i><sup>18</sup>O of speleothem does show evidence for precipitation under isotopic equilibrium; dating by <sup>14</sup>C shows inversions due to varying contributions from dead carbon. The present work highlights the problems and prospects of speleothem paleomonsoon research in these islands.

Amzad H. Laskar

S. Raghav

M. G. Yadava

R. A. Jani

A. C. Narayana

R. Ramesh

Potential of Stable Carbon and Oxygen Isotope Variations of Speleothems from Andaman Islands, India, for Paleomonsoon Reconstruction

A structural analysis of Cretaceous alkaline dykes swarm associated with the central segment of the Asunción Rift is reported here. Dykes are generally single near-vertical tabular bodies, less than 5 m wide, although multiple and composite intrusions also occur. Many of these small bodies have been emplaced into Paleozoic sedimentary rocks and exhibit a regional NW-SE orientation pattern. Petrographical and geochemical data allow recognition of two different lineages of potassic dykes: a silica-undersaturated suite ranging from basanite to phonolite (B-P) and a silica-saturated suite ranging from alkali basalt to trachyte (AB-T). The morphological features, the regional en-échelon distribution, and the NW-SE orientation pattern suggest that the dykes were injected along fractures and faults, under a transtensional tectonic regime with σ1 NW/horizontal, σ2/vertical, and σ3 NE/horizontal. Detailed analysis, combining dyke petrography, orientation pattern, and relative chronology reveals a rotation from WNW toward NNW during dyke emplacement. In terms of the paleostress field orientation, the evidence indicates that the dykes were diachronically formed under a similar stress condition. Finally, the pattern of orientation documented for the Cretaceous alkaline dykes of the Asunción Rift is consistent, temporally and spatially, with the phases of regional deformation that occurred during the process of the Atlantic Ocean opening.

Victor F. Velázquez

Claudio Riccomini

Celso de Barros Gomes

Jason Kirk

The Cretaceous Alkaline Dyke Swarm in the Central Segment of the Asunción Rift, Eastern Paraguay: Its Regional Distribution, Mechanism of Emplacement, and Tectonic Significance

The prediction of oil cracked gas resources is necessary and urgent in the gas exploration of these basins at high to over stage in China. A marine crude oil sample was pyrolyzed using sealed gold tubes system in our study. The pyrolysates including gas, liquid, and solid were quantitatively analyzed. Based on the pyrolysis data and kinetic calculation, the yield correlativity among gas, liquid, and solid products was regressed with high correlative coefficients to establish a prediction model suitable for the resource estimation of oil cracked gas. The verification formula for this model was also established on the principle of mass conservation. The affecting factors and the application preconditions of this model were discussed. Finally the model was extrapolated to the prediction of oil cracked gas resources of Feixianguan formation in NE Sichuan basin, SW China. The prediction value of oil cracked resources is about <svg style="vertical-align:-0.1638pt;width:74.375px;" id="M1" height="16.049999" version="1.1" viewBox="0 0 74.375 16.049999" width="74.375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,15.775)"><path id="x36" d="M137 343l67 33q37 17 63 17q79 0 129.5 -53t50.5 -131q0 -92 -58 -156.5t-147 -64.5t-147 68t-58 182q0 63 17 119t43 95.5t61.5 72t69 52t67.5 31.5q62 22 128 33l6 -32q-56 -11 -108 -35q-149 -71 -184 -231zM227 337q-47 0 -95 -27q-6 -23 -6 -70q0 -93 36 -155.5&#xA;t96 -62.5q53 0 78 45.5t25 105.5q0 68 -35 116t-99 48z" /></g><g transform="matrix(.017,-0,0,-.017,8.222,15.775)"><path id="x2E" d="M113 -12q-24 0 -39.5 16t-15.5 42q0 24 16 40.5t40 16.5t40 -16.5t16 -40.5q0 -26 -16 -42t-41 -16z" /></g><g transform="matrix(.017,-0,0,-.017,12.098,15.775)"><path id="x38" d="M249 635q70 0 116 -43t46 -105q0 -46 -28 -80q-22 -25 -80 -64q62 -35 97 -75t35 -99q0 -81 -63 -131t-135 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d="M241 635q53 0 94 -28.5t63.5 -76t33.5 -102.5t11 -116q0 -58 -11 -112.5t-34 -103.5t-63.5 -78.5t-94.5 -29.5t-95 28t-64.5 75t-34.5 102.5t-11 118.5q0 58 11.5 112.5t34.5 103t64.5 78t95.5 29.5zM238 602q-32 0 -55.5 -25t-35.5 -68t-17.5 -91t-5.5 -105&#xA;q0 -76 10 -138.5t37 -107.5t69 -45q32 0 55.5 25t35.5 68.5t17.5 91.5t5.5 105t-5.5 105.5t-18 92t-36 68t-56.5 24.5z" /></g><g transform="matrix(.012,-0,0,-.012,62.262,7.613)"><use xlink:href="#x31" /></g><g transform="matrix(.012,-0,0,-.012,67.974,7.613)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g></svg> m<sup>3</sup>, and generation intensity of oil cracked gas is about <svg style="vertical-align:-0.20474pt;width:68.662498px;" id="M2" height="16.1" version="1.1" viewBox="0 0 68.662498 16.1" width="68.662498" 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110t-121.5 41q-53 0 -102 -20l38 305h286l6 -8&#xA;l-26 -65h-233z" /></g><g transform="matrix(.017,-0,0,-.017,32.19,15.775)"><use xlink:href="#xD7" /></g><g transform="matrix(.017,-0,0,-.017,45.942,15.775)"><use xlink:href="#x31" /></g><g transform="matrix(.017,-0,0,-.017,54.102,15.775)"><use xlink:href="#x30" /></g><g transform="matrix(.012,-0,0,-.012,62.262,7.613)"><use xlink:href="#x38" /></g></svg> m<sup>3</sup>/km<sup>2</sup>, and the paleo-oil reserves is about <svg style="vertical-align:-0.20474pt;width:56.625px;" id="M3" height="16.1" version="1.1" viewBox="0 0 56.625 16.1" width="56.625" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,15.775)"><use xlink:href="#x39" /></g><g transform="matrix(.017,-0,0,-.017,8.222,15.775)"><use xlink:href="#x37" /></g><g transform="matrix(.017,-0,0,-.017,20.155,15.775)"><use xlink:href="#xD7" /></g><g transform="matrix(.017,-0,0,-.017,33.907,15.775)"><use xlink:href="#x31" 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The verifying value for this prediction is approximately equal to 1, indicating the model is reliable in the resource estimation of oil cracked gas.

Tongshan Wang

Ansng Geng

Xia Li

Hongjun Wang

Zecheng Wang

Li Qiufen

A Prediction Model of Oil Cracked Gas Resources and Its Application in the Gas Pools of Feixianguan Formation in NE Sichuan Basin, SW China

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