scholarly journals Two-End-Member Mixing in the Fluids Emitted From Mud Volcano Lei-Gong-Huo, Eastern Taiwan: Evidence From Sr Isotopes

2022 ◽  
Vol 9 ◽  
Author(s):  
Hung-Chun Chao ◽  
Chen-Feng You ◽  
In-Tian Lin ◽  
Hou-Chun Liu ◽  
Ling-Ho Chung ◽  
...  
Keyword(s):  
Igneous Rock ◽  
Subduction Zones ◽  
Sedimentary Rock ◽  
Source Region ◽  
Sedimentary Basins ◽  
Mud Volcano ◽  
Chemical Compositions ◽  
Sr Isotopes ◽  
Strong Negative Correlation ◽  
Rock Interaction

Mud volcano is one of the most important conduits for deep seated materials to migrate upward in sedimentary basins, convergent margins, and subduction zones. Understanding their temporal and spatial characteristics and variations provides us the important information on fluid sources and chemical compositions at depth. Mud volcano Lei-Gong-Huo (MV LGH) is a unique mud volcano, which is located on the mélange formation lying on the andesitic volcanic arc. Fluids emitted from 46 mud pools in MV LGH in eastern Taiwan were sampled and their major trace constitutes as well as H, O, and Sr isotopes (87Sr/86Sr and δ88Sr) were measured. Major constitutes of the fluids are Cl−, Na, and Ca. Compared with seawater, LGH fluids have lower Cl−, δD, δ18O, Na/Cl, K/Cl, and Mg/Cl but higher Ca/Cl ratios, indicating water–rock interaction of igneous rock and the ancient seawater at the source region. This interpretation is further supported by Sr isotopes, which show low value of 87Sr/86Sr ratio down to 0.70708. The result of spatial distribution showing strong negative correlation between Na and Ca concentration as well as Ca and 87Sr/86Sr ratios indicates that two end-member mixing is the major chemical characteristic. The fluids interacting with igneous rock carry high Ca, high δ88Sr, low Na, and low 87Sr/86Sr ratio, while those interacting with sedimentary rock carry low Ca, low δ88Sr, high Na, and high 87Sr/86Sr ratio. The source from the igneous region dominates the eastern and southeastern parts of the mud pools while sedimentary source dominates the western and northwestern parts. Most mud pools show mixing behavior between the two sources. Some of the sedimentary-dominated mud pools reveal existence of residual ancient water as indicated by 87Sr/86Sr. The major factor to fractionate the stable Sr isotopes in LGH waters is the source lithology. In summary, fluids emitted by mud pools in LGH originate from two sources, which are water–rock interactions of igneous rock with the ancient seawater from the east and sedimentary rock from the west at depth, resulting from the complex geologic background of mélange formation.

Effect of rock strength on exhumation and the thermochronologic record: The south-central Colorado example

2021 ◽  
Author(s):  
Sabrina Kainz ◽  
Lon Abbott ◽  
Rebecca Flowers ◽  
James Metcalf
Keyword(s):  
Low Temperature ◽  
Sedimentary Rock ◽  
Rock Strength ◽  
Sedimentary Rocks ◽  
Sedimentary Basins ◽  
Crystalline Basement ◽  
Precambrian Basement ◽  
The West ◽  
South Central ◽  
Sangre De Cristo

<p>Past work has used the Southern Rocky Mountains (SRM) in the U.S. state of Colorado to illustrate the important role that rock strength plays in the histories recorded by the apatite fission track (AFT) and apatite (U-Th)/He (AHe) low-temperature thermochronometers (Flowers & Ehlers, 2018). The SRM were initially raised during the Laramide Orogeny, ca. 70-45 Ma, but consensus exists that the region also experienced a later, post-Laramide exhumation event. Flowers & Ehlers (2018) pointed to the low erosion potential of the Precambrian crystalline basement rocks that crop out in most SRM ranges as a primary reason for the abundance of 55-70 Ma “Laramide” AFT and AHe dates in the region, compared to a paucity of younger dates that would presumably be produced through erosion triggered by the post-Laramide exhumation event. South-central Colorado offers a test of this hypothesis, due to lateral variations in rock erodibility provided by the presence here of both sedimentary and crystalline Laramide ranges and adjacent sedimentary basins. The combination of our ongoing AHe study with previous south-central Colorado AFT and AHe work reveals kilometer-scale post-Laramide (Oligo-Miocene) exhumation has occurred in areas that possess thick sedimentary rock sequences whereas exhumation has been negligible where crystalline basement comprises the land surface. </p><p>South-central Colorado’s Sangre de Cristo Mountains consist of an imbricate stack of thrust sheets composed of Permian sedimentary rock. About 30 km farther east stand the Wet Mountains, another Laramide range – but one composed of Precambrian basement rock. The Raton Basin, a SRM foreland basin filled with 2 km of synorogenic fill underlain by a thick sequence of marine shale, lies south and east of the two ranges. The Wet Mountains thus form a peninsula of strong crystalline rock surrounded by more erodible sedimentary rocks to the west, south, and east. </p><p>Our study and that of Landman (2018) records at least 2 km of erosion in the Raton Basin east and south of the Wet Mountains since 25 Ma. Lindsey et al (1986) obtained 24-15 Ma AFT dates from the Paleozoic sedimentary rocks of the Sangre de Cristo Mountains, demonstrating that kilometer-scale Oligo-Miocene exhumation occurred just west of the Wet Mountains. By contrast, Kelley and Chapin (2004) obtained only pre-Laramide AFT ages between 228-110 Ma for 17 samples of Precambrian basement from the crest of the Wet Mountains. A 32 Ma ash flow tuff unconformably overlies Precambrian basement on Greenhorn Mountain, the Wet Mountains’ highest and southernmost peak. Its presence reinforces the conclusion, based on the AFT dates, that Oligo-Miocene erosion of the Wet Mountain massif has been minimal simultaneous with kilometer-scale exhumation to the west, south, and east. These results illustrate the important role that rock strength plays in determining the dates recorded in low-temperature thermochronologic studies.</p>

Seismic Structure and Tectonic Evolution of Borneo and Sulawesi

2021 ◽  
Author(s):  
Harry Telajan Linang ◽  
Amy Gilligan ◽  
Jennifer Jenkins ◽  
Tim Greenfield ◽  
Felix Tongkul ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Receiver Function ◽  
Leading Edge ◽  
Sedimentary Basins ◽  
Crustal Thickness ◽  
The Philippines ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Seismic Stations ◽  
Preliminary Results

<div> <div> <div> <p>Borneo is located at the centre of Southeast Asia, which is one of the most active tectonic regions on Earth due to the subduction of the Indo-Australian plate in the south and the Philippines Sea plate in the east. Borneo resides on the leading edge of the Sundaland block of the Eurasian plate and exhibits lower rates of seismicity when compared to the surrounding regions due to its intraplate setting. Sulawesi, an island which lies just southeast of Borneo, is characterised by intense seismicity due to multiple subduction zones in its vicinity. The tectonic relationship between the two islands is poorly understood, including the provenance of their respective lithospheres, which may have Eurasian and/or East Gondwana origin.</p> <p>Here, we present recent receiver function (RF) results from temporary and permanent broadband seismic stations in the region, which can be used to help improve our understanding of the crust and mantle lithosphere beneath Borneo and Sulawesi. We applied H-K stacking, receiver function migration and inversion to obtain reliable estimates of the crustal thickness beneath the seismic stations. Our preliminary results indicate that the crust beneath Sabah (in northern Borneo), which is a post-subduction setting, appears to be much more complex and is overall thicker (more than 35 km) than the rest of the island. In addition, we find that crustal thickness varies between different tectonic blocks defined from previous surface mapping, with the thinnest crust (23 to 25 km) occurring beneath Sarawak in the west-northwest as well as in the east of Kalimantan.</p> <p>We also present preliminary results from Virtual Deep Seismic Sounding (VDSS) in northern Borneo, where from the RF results we know that there is thick and complex crust. VDSS is able to produce well constrained crustal thickness results in regions where the RF analysis has difficulty recovering the Moho, likely due to complexities such as thick sedimentary basins and obducted ophiolite sequences.</p> </div> </div> </div>

Determination of oil charge timing in the Ordovician carbonate reservoir of the Tahe Oilfield, Tarim Basin, NW China

2021 ◽  
Author(s):  
Jiaxu Chen ◽  
Xiaowen Guo
Keyword(s):  
Tarim Basin ◽  
Sedimentary Basins ◽  
Carbonate Reservoir ◽  
Rock Interaction ◽  
Tahe Oilfield ◽  
Petroleum Systems ◽  
Calcite Veins ◽  
Homogenization Temperatures ◽  
Two Phases ◽  
Northern Tarim Basin

<p>Determining the timings of oil charge in sedimentary basins are essential to understand the evolutionary histories of petroleum systems, especially in sedimentary basins with complicated tectonic evolution and thermal histories. The Ordovician carbonate reservoir in the Tahe Oilfield, which is located in the northern Tarim Basin, comprises the largest marine reservoirs in China with reserves up to 3.2×10<sup>8</sup> t. This study aims to determine the timings of oil charge in the Ordovician carbonate reservoir in the Tahe Oilfield, Tarim Basin, which basin is subjected to multiple phases of tectonic deformations and oil charge. The phases of calcite veins that contain oil inclusions were systematically investigated by cathodoluminescence observation, in situ rare earth element, C, O, and Sr isotope analyses. The homogenization temperatures of aqueous inclusions that are coeval with oil inclusions were measured to determine the timings of oil charge by combining the burial and geothermal histories. Two phases of calcite veins were judged by the differences in cathodoluminescence color, Ce anomaly, δ<sup>18</sup>O, and <sup>87</sup>Sr/<sup>86</sup>Sr values, which might be caused by variations in the water-rock interaction processes during different calcite phases. Primary oil inclusions with yellow fluorescence were observed in the two phases of calcite veins, suggesting two phases of oil charge. By combining the homogenization temperatures of aqueous inclusions with the burial and geothermal histories, the timing of phase I oil charge was inferred to be 336–312 Ma, and the timing of phase II oil charge was inferred to be 237–217 Ma.</p>

Influences of natural and anthropogenic processes on the groundwater quality in the Dagujia River Basin in Yantai, China

2019 ◽  
Vol 69 (2) ◽  
pp. 184-196 ◽  
Author(s):  
Henghua Zhu ◽  
Jianwei Zhou ◽  
Tingting Song ◽  
Haibo Feng ◽  
Zhizheng Liu ◽  
...  
Keyword(s):  
Groundwater Quality ◽  
Seawater Intrusion ◽  
Human Activities ◽  
Industrial Development ◽  
Anthropogenic Activities ◽  
Total Hardness ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Rock Interaction ◽  
Natural Processes

Abstract Groundwater plays an important role in water supply and economic development for Yantai city, China. However, the groundwater quality has degraded due to the increase and expansion of agricultural and industrial development. It is urgent to acquire groundwater characteristics and distinguish impacts of natural factors and anthropogenic activities on the groundwater quality. Forty-six groundwater samples collected from different wells showed a great variation of chemical components across the study area. Most wells with higher total dissolved solids, total hardness, K+, Na+, Ca2+, Mg2+, Cl− and SO42− concentrations were located relatively close to the coastal zone. The factor analysis (FA) and hierarchical cluster analysis results displayed that seawater intrusion was the primary mechanism controlling the groundwater quality in the coastal areas. A three-factor model was proposed based on the FA and explained over 85% of the total groundwater quality variation: Factor 1, the seawater intrusion; Factor 2, the water–rock interaction and Factor 3 (NO3−), the human activities. Furthermore, the geographical maps of the factor scores clearly described the spatial distributions of wells affected by natural processes or human activities. The study indicated that both natural processes and human activities are the major factors affecting the chemical compositions of groundwater.

scholarly journals Effects of Cenozoic subduction along the outboard margin of the Northern Cordillera: Derived from e-book on the Northern Cordillera (Alaska and Western Canada) and adjacent marine areas

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 33-61
Author(s):  
Warren J. Nokleberg ◽  
David W. Scholl ◽  
Thomas K. Bundtzen ◽  
David B. Stone
Keyword(s):  
Continental Margin ◽  
Subduction Zones ◽  
Hot Springs ◽  
Sedimentary Basins ◽  
Oceanic Lithosphere ◽  
Popular Science ◽  
Strike Slip ◽  
Western Canada ◽  
Regional Effects ◽  
Marine Areas

Abstract This article describes the regional effects of Cenozoic subduction along the outboard margin of the Northern Cordillera (Alaska, USA, and Western Canada), and thereby acquaints the reader with several chapters of the e-book Dynamic Geology of the Northern Cordillera (Alaska, Western Canada, and Adjacent Marine Areas). This article and the e-book are written for earth-science students and teachers. The level of writing for the article and the source e-book is that of popular science magazines, and readers are encouraged to share this article with students and laypersons. The main thrust of the article is to present and describe a suite of ten regional topographic, bathymetric, and geologic maps, and two figures portraying deep-crustal sections that illustrate the regional effects of Cenozoic subduction along the outboard margin of the North American Cordillera. The regional maps and cross sections are described in a way that a teacher might describe a map to students. Cenozoic subduction along the margin of the Northern Cordillera resulted in the formation of the following: (1) underthrusting of terranes and oceanic lithosphere beneath Southern Alaska; (2) landscapes, including narrow continental shelves along Southern and Southeastern Alaska and Western Canada (the Canadian Cordillera) and continental-margin mountain ranges, including the Alaska Peninsula, Chugach Range, Saint Elias Mountains, and Cascade Mountains; (3) sedimentary basins; (4) an array of active continental strike-slip and thrust faults (inboard of subduction zones); (5) earthquake belts related to subduction of terranes and oceanic plates; (6) active volcanoes, including continental-margin arcs (the Aleutian, Wrangell, and Cascade Arcs) linked to subduction zones, and interior volcanic belts related to strike-slip faulting or to hot spots; (7) lode and placer mineral deposits related to continental margin arcs or subduction of oceanic ridges; (8) hot springs related to continental-margin arcs; (9) plate movements as recorded from GPS measurements; and (10) underthrusting of terranes and oceanic lithosphere beneath the Northern Cordillera.

scholarly journals New constraints on the 1922 Atacama, Chile, earthquake from Historical seismograms

2019 ◽  
Vol 219 (1) ◽  
pp. 645-661 ◽  
Author(s):  
Hiroo Kanamori ◽  
Luis Rivera ◽  
Lingling Ye ◽  
Thorne Lay ◽  
Satoko Murotani ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Source Region ◽  
Plate Boundary ◽  
Spatial Proximity ◽  
Motion Data ◽  
Megathrust Earthquakes ◽  
Great Earthquakes ◽  
Chile Earthquake ◽  
Earthquake Research ◽  
Earthquake Research Institute

SUMMARY We recently found the original Omori seismograms recorded at Hongo, Tokyo, of the 1922 Atacama, Chile, earthquake (MS = 8.3) in the historical seismogram archive of the Earthquake Research Institute (ERI) of the University of Tokyo. These recordings enable a quantitative investigation of long-period seismic radiation from the 1922 earthquake. We document and provide interpretation of these seismograms together with a few other seismograms from Mizusawa, Japan, Uppsala, Sweden, Strasbourg, France, Zi-ka-wei, China and De Bilt, Netherlands. The 1922 event is of significant historical interest concerning the cause of tsunami, discovery of G wave, and study of various seismic phase and first-motion data. Also, because of its spatial proximity to the 1943, 1995 and 2015 great earthquakes in Chile, the 1922 event provides useful information on similarity and variability of great earthquakes on a subduction-zone boundary. The 1922 source region, having previously ruptured in 1796 and 1819, is considered to have significant seismic hazard. The focus of this paper is to document the 1922 seismograms so that they can be used for further seismological studies on global subduction zones. Since the instrument constants of the Omori seismographs were only incompletely documented, we estimate them using the waveforms of the observed records, a calibration pulse recorded on the seismogram and the waveforms of better calibrated Uppsala Wiechert seismograms. Comparison of the Hongo Omori seismograms with those of the 1995 Antofagasta, Chile, earthquake (Mw = 8.0) and the 2015 Illapel, Chile, earthquake (Mw = 8.3) suggests that the 1922 event is similar to the 1995 and 2015 events in mechanism (i.e. on the plate boundary megathrust) and rupture characteristics (i.e. not a tsunami earthquake) with Mw = 8.6 ± 0.25. However, the initial fine scale rupture process varies significantly from event to event. The G1 and G2, and R1 and R2 of the 1922 event are comparable in amplitude, suggesting a bilateral rupture, which is uncommon for large megathrust earthquakes.

Origin of the Piché Structural Complex and implications for the early evolution of the Archean crustal-scale Cadillac – Larder Lake Fault Zone, Canada

2018 ◽  
Vol 55 (8) ◽  
pp. 905-922 ◽  
Author(s):  
Pierre Bedeaux ◽  
Lucie Mathieu ◽  
Pierre Pilote ◽  
Silvain Rafini ◽  
Réal Daigneault
Keyword(s):  
Fault Zone ◽  
Cross Sections ◽  
Volcanic Rocks ◽  
Sedimentary Basins ◽  
Drill Hole ◽  
Gold Deposits ◽  
Ductile Deformation ◽  
Chemical Compositions ◽  
Abitibi Subprovince ◽  
Felsic Volcanic

The Piché Structural Complex (PSC) extends over 150 km within the Cadillac – Larder Lake Fault Zone (CLLFZ), a gold-endowed, east-trending, and high-strain corridor located along the southern edge of the Archean Abitibi Subprovince. The PSC consists of discontinuous units of volcanic rocks (<1 km thick) that host multiple gold deposits. It is spatially associated with molasse-type Timiskaming sedimentary basins. This study describes and interprets the origin of structures and lithologies within the poorly understood PSC to unravel the tectonic evolution of the CLLFZ. Field mapping, chemical analyses, as well as interpretations of cross-sections from drill-hole data, were used to interpret the geometry and structure of the PSC. The PSC is subdivided into six homogeneous fault-bounded segments or slivers. These slivers consist mostly of ultramafic to intermediate volcanic rocks and include some felsic volcanic flows and intrusions. Volcanic facies, chemical compositions, and isotopic ages confirm that these slivers are derived from the early volcanic units of the southern Abitibi greenstone belt, which are located north of the CLLFZ. Cross-cutting relationships between volcanic rocks of the PSC and the Timiskaming-aged intrusions suggest that the slivers were inserted into the CLLFZ during the early stages of the accretion-related deformation (<2686 Ma) and prior to Timiskaming sedimentation and ductile deformation (>2676 Ma). The abundant ultramafic rocks located within the CLLFZ may have focused strain, thereby facilitating the nucleation of the fault as well as the displacements along this crustal-scale structure.

scholarly journals Study on Fluid-Rock Interaction and Reuse of Flowback Fluid for Gel Fracturing in Desert Area

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Tianbo Liang ◽  
Linjie Shao ◽  
Erdong Yao ◽  
Jie Zuo ◽  
Xiongfei Liu ◽  
...  
Keyword(s):  
Ph Value ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Reservoir Rock ◽  
Chemical Compositions ◽  
Desert Area ◽  
Rock Interaction ◽  
Flowback Water ◽  
Reservoir Conditions

Hydraulic fracturing requires a large volume of fresh water, which is difficult and expensive to obtain in the desert area such as Tarim Basin. Currently, flowback fluid is typically transported to the sewage treatment plant and then discharged after reaching environmental requirements; however, this is not only costly, but also a waste of water resource. Therefore, it is imperative to understand the potential interactions between fracturing fluid and reservoir rock, and then find solutions to reuse the flowback water for subsequent fracturing. In this study, once flowback fluid was directly collected from the field, its chemical compositions were analyzed; then, filtering, decoloring, and chelating methods were chosen to effectively remove or shield the unfavorable reintroduced components. Moreover, pH value was further tuned during different stages of the recycling process to ensure good gelation and cross-linking properties of guar. Cross-linked guar synthesized with the flowback fluid was evaluated in the lab through shear resistance tests and coreflood tests under the reservoir conditions; results indicated the recycled gel behaved similarly as the original gel, or even better. From this work, a cheap and effective treatment process was proposed to reuse the flowback fluid in the desert area.

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