bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrahigh‐pressure metamorphism in the forbidden zone: the Xugou garnet peridotite, Sulu terrane, eastern China
Authors: Zhang R. Y. , Liou J. G. , Yang J. S. , Ye K. 
Published: July 2003

AbstractThe Xugou garnet peridotite body of the southern Sulu ultrahigh‐pressure (UHP) terrane is enclosed in felsic gneiss, bounded by faults, and consists of harzburgite and lenses of garnet clinopyroxenite and eclogite. The peridotite is composed of variable amounts of olivine (Fo91), enstatite (En92−93), garnet (Alm20−23Prp53−58Knr6−9Grs12−18), diopside and rare chromite. The ultramafic protolith has a depleted residual mantle composition, indicated by a high‐Mg number, very low CaO, Al2O3 and total REE contents compared to primary mantle and other Sulu peridotites. Most garnet (Prp44−58) clinopyroxenites are foliated. Except for rare kyanite‐bearing eclogitic bands, most eclogites contain a simple assemblage of garnet (Alm29−34Prp32−50Grs15−39) + omphacite (Jd24−36) + minor rutile. Clinopyroxenite and eclogite exhibit LREE‐depleted and LREE‐enriched patterns, respectively, but both have flat HREE patterns. Normalized La, Sm and Yb contents indicate that both eclogite and garnet clinopyroxenite formed by high‐pressure crystal accumulation (+ variable trapped melt) from melts resulting from two‐stage partial melting of a mantle source.Recrystallized textures and P–T estimates of 780–870 °C, 5–7 GPa and a metamorphic age of 231 ± 11 Ma indicate that both mafic and ultramafic protoliths experienced Triassic UHP metamorphism in the P–T forbidden zone with an extremely low thermal gradient (< 5 °C km−1), and multistage retrograde recrystallization during exhumation. Develop of prehnite veins in clinopyroxenite, eclogite, felsic blocks and country rock gneiss, and replacements of eclogitic minerals by prehnite, albite, white mica, and K‐feldspar indicate low‐temperature metasomatism.
SHRIMP U–Pb dating of coesite‐bearing zircon from the ultrahigh‐pressure metamorphic rocks, Sulu terrane, east China
Authors: Yang J. S. , Wooden J. L. , Wu C. L. , Liu F. L. , Xu Z. Q. , Shi R. D. , Katayama I. , Liou J. G. , Maruyama S. 
Published: July 2003

AbstractThis paper provides further evidence for the ongoing discussion as to whether the Dabie UHPM belt formed in Triassic or Palaeozoic time, and whether the Sulu UHPM belt formed in Triassic or Neoproterozoic time. Combined use of laser Raman spectrometer (LR), cathodoluminescence imaging (CL), and ion probe U–Pb in‐situ dating (SHRIMP) provided accurate ages of UHPM from rocks collected from Weihai, NE Sulu UHPM belt. LR was used to identify coesite and other UHP minerals as inclusions in zircon separates from an amphibolized peridotite and an eclogite. CL was used to examine the zoning structure of these zircon, and SHRIMP dating was performed on specific spots on zircon to obtain ages of different geological events. An age of 221 ± 12 Ma was obtained for coesite‐bearing zircon from the amphibolized peridotite; an age of 228 ± 29 Ma for eclogite was obtained from the lower intercept of a concordia plot. These ages are interpreted as the time of UHPM in the Weihai region. Ultramafic rocks to the east of Weihai yield a magmatic age at 581 ± 44 Ma. The zircon in the ultramafic rocks possibly also records a thermal event at c. 400 Ma, but no independent geological evidence for this event has been found. The eclogite protolith formed in the Middle Proterozoic (1821 ± 19 Ma), which is similar to the age of country rock gneisses of 1847–1744 Ma. The new geochronological data confirm that UHPM occurred in the Triassic in the Sulu area when subduction took the ultramafic body and the eclogite protolith, together with the adjacent supracrustal rocks, to mantle depths.
Remnants of premetamorphic fluid and oxygen isotopic signatures in eclogites and garnet clinopyroxenite from the Dabie‐Sulu terranes, eastern China
Authors: Fu B. , Touret J. L. R. , Zheng Y.‐F. 
Published: July 2003

AbstractA combined oxygen‐isotope and fluid‐inclusion study has been carried out on high‐ and ultrahigh‐pressure metamorphic (HP/UHPM) eclogites and garnet clinopyroxenite from the Dabie‐Sulu terranes in eastern China. Coesite‐bearing eclogites/garnet clinopyroxenite and quartz eclogites have a wide range in whole‐rock δ18OVSMOW, from 0 to 11‰. The high‐T oxygen‐isotope fractionations preserved between quartz and garnet preclude significant retrograde isotope exchange during exhumation, and the wide range in whole‐rock oxygen‐isotope composition is thought to be a presubduction signature of the precursors. Aqueous fluids with variable salinities and gas species (N2‐, CO2‐, or CH4‐rich), are trapped as primary inclusions in garnet, omphacite and epidote, and in quartz blebs enclosed within eclogitic minerals. In high‐δ18O HP/UHPM rocks from Hujialin and Shima, high‐salinity brine and/or N2 inclusions occur in garnet porphyroblasts, which also contain inclusions of coesite, Cl‐rich blue amphibole and dolomite. In contrast, in low‐δ18O eclogites from Qinglongshan and Huangzhen, the Cl concentrations in amphibole are very low, < 0.2 wt.%, and low‐salinity aqueous inclusions occur in quartz inclusions in epidote porphyroblasts and in epidote cores. These low‐salinity fluid inclusions are believed to be remnants of meteoric water, although the fluid composition was modified during pre‐ and syn‐peak HP/UHPM. Eclogites at Houshuichegou and Hetang contain CH4‐rich fluid inclusions, coexisting with high‐salinity brine inclusions. Methane was probably formed under the influence of CO2‐rich aqueous fluids during serpentinisation of mantle‐derived peridotites prior to or during plate subduction. Remnants of premetamorphic low‐ to high‐salinity aqueous fluid with minor N2 and/or other gas species preserved in the Dabie‐Sulu HP/UHPM eclogites and garnet clinopyroxenite indicate a great diversity of initial fluid composition in the precursors, implying very limited fluid–rock interaction during syn‐ and post‐peak HP/UHPM.
Low δ18O eclogites from the Kokchetav massif, northern Kazakhstan
Authors: Masago H. , Rumble D. , Ernst W. G. , Parkinson C. D. , Maruyama S. 
Published: July 2003

AbstractOxygen isotopic compositions of silicates in eclogites and whiteschists from the Kokchetav massif were analyzed by whole‐grain CO2‐laser fluorination methods. Systematic analyses yield extremely low δ18O for eclogites, as low as −3.9‰ for garnet; these values are comparable with those reported for the Dabie‐Sulu UHP eclogites. Oxygen isotopic compositions are heterogeneous in samples of eclogite, even on an outcrop scale. Schists have rather uniform oxygen isotope values compared to eclogites, and low δ18O is not observed. Isotope thermometry indicates that both eclogites and schists achieved high‐temperature isotopic equilibration at 500–800 °C. This implies that retrograde metamorphic recrystallization barely modified the peak‐metamorphic oxygen isotopic signatures. A possible geological environment to account for the low‐δ18O basaltic protolith is a continental rift, most likely subjected to the conditions of a cold climate. After the basalt interacted with low δ18O meteoric water, it was tectonically inserted into the surrounding sedimentary units prior to, or during subduction and UHP metamorphism.
Timing of Himalayan ultrahigh‐pressure metamorphism: sinking rate and subduction angle of the Indian continental crust beneath Asia
Authors: Kaneko Y. , Katayama I. , Yamamoto H. , Misawa K. , Ishikawa M. , Rehman H. U. , Kausar A. B. , Shiraishi K. 
Published: July 2003

AbstractCoesite relics were discovered as inclusions in clinopyroxene in eclogite and as inclusions in zircon in felsic and pelitic gneisses from Higher Himalayan Crystalline rocks in the upper Kaghan Valley, north‐west Himalaya. The metamorphic peak conditions of the coesite‐bearing eclogites are estimated to be 27–32 kbar and 700–770 °C, using garnet–pyroxene–phengite geobarometry and garnet–pyroxene geothermometry, respectively. Cathodoluminescence (CL) and backscattered electron (BSE) imaging distinguished three different domains in zircon: inner detrital core, widely spaced euhedral oscillatory zones, and thin, broadly zoned outermost rims. Each zircon domain contains a characteristic suite of micrometre‐sized mineral inclusions which were identified by in situ laser Raman microspectroscopy. Core and mantle domains contain quartz, apatite, plagioclase, muscovite and rutile. In contrast, the rim domains contain coesite and minor muscovite. Quartz inclusions were identified in all coesite‐bearing zircon grains, but not coexisting with coesite in the same growth domain (rim domain). 206Pb/238U zircon ages reveal that the quartz‐bearing mantle domains and the coesite‐bearing rim were formed at c. 50 Ma and 46.2 ± 0.7 Ma, respectively. These facts demonstrate that the continental materials were buried to 100 km within 7–9 Myr after initiation of the India–Asia collision (palaeomagnetic data from the Indian oceanic floor supports an initial India‐Asia contact at 55–53 Ma). Combination of the sinking rate of 1.1–1.4 cm year−1 with Indian plate velocity of 4.5 cm year−1 suggests that the Indian continent subducted to about 100 km depth at an average subduction angle of 14–19°.
The timing of stabilisation and the exhumation rate for ultra‐high pressure rocks in the Western Gneiss Region of Norway
Authors: Carswell D. A. , Brueckner H. K. , Cuthbert S. J. , Mehta K. , O'Brien P. J. 
Published: July 2003

AbstractNew petrographic evidence and a review of the latest radiometric age data are taken to indicate that formation of the ultra‐high pressure (UHP) eclogites within the Western Gneiss Region of Norway probably occurred within the 400–410 Ma time frame. Thus, this event took place significantly later than the previous, widely accepted age of c. 425 Ma for the timing of the high pressure metamorphism in this part of the Scandinavian Caledonides. Garnet growth under UHP (coesite‐stable) conditions is recognised as a discrete, younger event following on from earlier garnet formed under firstly amphibolite facies then quartz‐stable, eclogite facies conditions. Currently, the best constrained and most precise age, specifically for UHP mineral growth, is the 402 ± 2 Ma U–Pb age for metamorphic zircon (some of which retain coesite inclusions) from the Hareidland eclogite. Exhumation must have followed shortly thereafter and, based on synoptic pressure–temperature and depth–time curves, must have been very fast. Our data and those of others indicate an initial fast exhumation to about 35 km depth by about 395 Ma at a mean rate of about 10 mm a−1. This rapid exhumation rate may have been driven by the appreciable residual buoyancy of the deeply subducted continental crustal slab due to incomplete eclogitization of the dominant Proterozoic orthogneisses during the short‐lived UHP event. Subsequent exhumation to 8–10 km depth by about 375 Ma occurred at a much slower mean rate of about 1.3 mm a−1 with the late‐stage extensional collapse of the Caledonian orogen playing an increasingly important role, especially in the final unroofing of the Western Gneiss Region with some remarkably preserved UHP rocks.
Exhumation of high‐pressure rocks beneath the Solund Basin, Western Gneiss Region of Norway
Authors: Hacker B. R. , Andersen T. B. , Root D. B. , Mehl L. , Mattinson J. M. , Wooden J. L. 
Published: July 2003

AbstractThe Solund–Hyllestad–Lavik area affords an excellent opportunity to understand the ultrahigh‐pressure Scandian orogeny because it contains a near‐complete record of ophiolite emplacement, high‐pressure metamorphism and large‐scale extension. In this area, the Upper Allochthon was intruded by thec. 434 Ma Sogneskollen granodiorite and thrust eastward over the Middle/Lower Allochthon, probably in the Wenlockian. The Middle/Lower Allochthon was subducted to c. 50 km depth and the structurally lower Western Gneiss Complex was subducted to eclogite facies conditions at c. 80 km depth by c. 410–400 Ma. Within < 5–10 Myr, all these units were exhumed by the Nordfjord–Sogn detachment zone, producing shear strains > 100. Exhumation to upper crustal levels was complete by c. 403 Ma. The Solund fault produced the last few km of tectonic exhumation, bringing the near‐ultrahigh‐pressure rocks to within c. 3 km vertical distance from the low‐grade Solund Conglomerate.
Metamorphic evolution of the coesite‐bearing ultrahigh‐pressure terrane in the North Qaidam, Northern Tibet, NW China
Authors: Song S. G. , Yang J. S. , Xu Z. Q. , Liou J. G. , Shi R. D. 
Published: July 2003

AbstractWidespread evidence for ultrahigh‐pressure (UHP) metamorphism is reported in the Dulan eclogite‐bearing terrane, the North Qaidam–Altun HP–UHP belt, northern Tibet. This includes: (1) coesite and associated UHP mineral inclusions in zircon separates from paragneiss and eclogite (identified by laser Raman spectroscopy); (2) inclusions of quartz pseudomorphs after coesite and polycrystalline K‐feldspar + quartz in eclogitic garnet and omphacite; and (3) densely oriented SiO2lamellae in omphacitic clinopyroxene. These lines of evidence demonstrate that the Dulan region is a UHP metamorphic terrane. In the North Dulan Belt (NDB), eclogites are characterized by the peak assemblage Grt + Omp + Rt + Phn + Coe (pseudomorph) and retrograde symplectites of Cpx + Ab and Hbl + Pl. The peak conditions of the NDB eclogites areP= 2.9–3.2 GPa, andT= 631–687 °C; the eclogite shows a near‐isothermal decompressionP–Tpath suggesting a fast exhumation. In the South Dulan Belt (SDB), three metamorphic stages are recognized in eclogites: (1) a peak eclogite facies stage with the assemblage Grt + Omp + Ky + Rt + Phn atP= 2.9–3.3 GPa andT= 729–746 °C; (2) a high‐pressure granulite facies stage with Grt + Cpx (Jd < 30) + Pl (An24–29) + Scp atP= 1.9–2.0 GPa,T= 873–948 °C; and (3) an amphibolite facies stage with the assemblage Hbl + Pl + Ep/Czo atP= 0.7–0.9 GPa andT= 660–695 °C. The clockwiseP–Tpath of the SDB eclogites is different from the near‐isothermal decompressionP–Tpath from the NDB eclogites, which suggests that the SDB was exhumed to a stable crustal depth at a slower rate. In essence these two sub‐belts formed in different tectonic settings; they both subducted to mantle depths of around 100 km, but were exhumed to the Earth's surface separately along different paths. This UHP terrane plays an important role in understanding continental collision in north‐western China.
2003 Wolff Award: Possible Parasympathetic Contributions to Peripheral and Central Sensitization During Migraine
Authors: Yarnitsky David , Goor‐Aryeh Itay , Bajwa Zahid H. , Ransil Bernard I. , Cutrer F. Michael , Sottile Anna , Burstein Rami 
Published: July 2003

Background.—Neurologic signs of increased parasympathetic outflow to the head often accompany migraine attacks. Because increased parasympathetic outflow to the cranial cavity induces vasodilation of cerebral and meningeal blood vessels, it can enhance plasma protein extravasation and the release of proinflammatory mediators that activate perivascular nociceptors. We recently showed that activation of intracranial perivascular nociceptors induces peripheral and central sensitization along the trigeminovascular pathway and proposed that these sensitizations mediate the intracranial hypersensitivity and the cutaneous allodynia of migraine.Methods.—The present study investigates possible parasympathetic contributions to the generation of peripheral and central sensitization during migraine by applying intranasal lidocaine to reduce cranial parasympathetic outflow through the sphenopalatine ganglion.Results.—In the absence of migraine, patients were pain‐free, and their skin sensitivity was normal. Their mean baseline pain thresholds were less than 15°C for cold, more than 45°C for heat, and more than 100 g for mechanical pressure. Their mean pain score was 7.5 of 10 (standard deviation, 1.4) during untreated migraine and 3.5 of 10 (standard deviation, 2.4) after the nasal lidocaine‐induced sphenopalatine ganglion block (P < .0001). Most patients developed cutaneous allodynia during migraine, and their mean pain thresholds changed to more than 25°C for cold, less than 40°C for heat, and less than 10 g for mechanical pressure. Following the nasal lidocaine administration (sphenopalatine ganglion block), this allodynia remained unchanged in spite of the pain relief.Conclusion.—These findings suggest that cranial parasympathetic outflow contributes to migraine pain by activating or sensitizing (or both) intracranial nociceptors, and that these events induce parasympathetically independent allodynia by sensitizing the central nociceptive neurons in the spinal trigeminal nucleus.
Headache Management Program Improves Outcome for Chronic Headache
Authors: Harpole Linda H. , Samsa Gregory P. , Jurgelski Annette E. , Shipley Janice L. , Bernstein Allan , Matchar David B. 
Published: July 2003

Objective.—To determine the feasibility of developing a headache management program and to assess the outcomes of patients referred to the program for treatment of chronic headache.Background.—Effective headache treatment requires that the patient receives the correct headache diagnosis; that appropriate acute and, if indicated, preventive medications be prescribed; and that the patient receives adequate education, including headache self‐management skills.Design/Methods.—A headache management program was established at a northern California staff‐model health maintenance organization. Fifty‐four patients were enrolled in the program and followed for 6 months. Patients participated in a structured program of group and individual sessions with the program manager. Data collection at baseline and 6 months included the Migraine Disability Assessment (MIDAS), the Short Form‐36 Health Survey (SF‐36), a patient satisfaction survey, and 2 additional short surveys—one that assessed patient worries about their headaches and another that queried patients on their problems with headache management.Results.—All enrolled patients participated in the initial group visit; 74% had at least one additional visit. All but one patient suffered from more than one headache type. Sixty‐one percent of patients suffered from migraine headache and 98% from tension‐type headache. At baseline, patients were severely disabled, with a mean MIDAS score of 41. At 6 months, MIDAS scores decreased an average of 21.2 points (P < .005). Patients reported 14.5 fewer days with headache over the preceding 3 months (P < .0001) and experienced clinically significant improvements in 6 of the SF‐36 subscales. Patients were significantly more satisfied with their headache care (P < .0001), reported less problems with their headache management (P < .0001), and were less worried about their headaches (P < .01). During the intervention, emergency department visits for headache decreased (P < .02).Conclusions.—A headache management program was successfully established. Patients referred to the program experienced significant improvement in headache‐related disability and functional health status and reported greater satisfaction with care. Even so, these results were obtained at one site and in a small sample that was not randomized. We currently are conducting a randomized controlled trial to better evaluate the clinical and financial impact of a headache management program for patients with chronic headache.
Prevalence of Atrial Septal Aneurysm in Patients With Migraine: An Echocardiographic Study
Authors: Carerj S. , Narbone M. C. , Zito C. , Serra S. , Coglitore S. , Pugliatti P. , Luzza F. , Arrigo F. , Oreto G. 
Published: July 2003

Objective.—To evaluate the prevalence of atrial septal aneurysm in patients with migraine.Background.—Migraine has long been considered a risk factor for stroke. Atrial septal aneurysm is often observed in young patients with ischemic stroke and is frequently associated with other conditions potentially leading to embolism.Methods.—We performed a transthoracic echocardiogram in 90 consecutive patients (65 women and 25 men; mean age, 35.3 years [standard deviation, 9]) with migraine but free from cerebral and cardiovascular disease and in 53 control subjects (37 women and 16 men; mean age, 34 years [standard deviation, 10]). The diagnosis of atrial septal aneurysm was performed according to Olivares‐Reyes criteria. A transesophageal echocardiogram also was performed in 75 patients with migraine (83.3%).Results.—The prevalence of isolated atrial septal aneurysm was higher in patients with migraine with aura (28.5%) than in patients with migraine without aura (3.6%) (P < .005) or in control subjects (1.9%) (P < .005).Conclusions.—Our data suggest a role of atrial septal aneurysm in the genesis of aura in patients with migraine.
Sumatriptan Plus Metoclopramide in Triptan‐Nonresponsive Migraineurs
Authors: Schulman Elliott A. , Dermott Kathleen F. 
Published: July 2003

Objectives.—We evaluated the effectiveness of combination treatment using sumatriptan plus metoclopramide versus sumatriptan alone for the treatment of acute migraine. The patients who were treated had failed to respond to triptans in the past despite adequate doses on at least 2 separate trials of the same triptan or 2 trials involving different triptans.Background.—There is limited evidence that dopaminergic antagonists may benefit the migraineur by relieving migraine pain and associated symptoms. The exact mechanism of action in migraine is unknown. The postulated action is the inhibition of dopaminergic overactivity. A dopaminergic antagonist, metoclopramide, may improve the efficacy of a 5‐HT1B/1D agonist, sumatriptan.Methods.—In this double‐blind, randomized, crossover study, 16 adult migraineurs fulfilling International Headache Society (IHS) criteria for migraine with or without aura who had failed to receive adequate relief from triptans treated one migraine with each treatment: sumatriptan 50 mg plus metoclopramide 10 mg or sumatriptan 50 mg plus placebo to match metoclopramide. Patients treated their migraines when they were moderate or severe in intensity and recorded pain severity and symptoms prior to treatment and 30, 60, 90, and 120 minutes and 24 hours after treatment.Results.—Thirteen women and 3 men (mean age, 40 years) completed the study; ie, treated 2 migraines (a total of 32 migraines), one attack with each treatment. Meaningful relief was attained in 10 (63%) of 16 migraines treated with the combination of sumatriptan 50 mg plus metoclopramide 10 mg compared with 5 (31%) of 16 migraines treated with sumatriptan 50 mg plus placebo. Headache response (moderate or severe to mild or no pain at 2 hours) was achieved in 7 (44%) of 16 migraines with the combination of sumatriptan 50 mg plus metoclopramide 10 mg compared with 5 (31%) of 16 migraines treated with sumatriptan 50 mg plus placebo. There did not appear to be a difference between treatment groups with respect to associated symptoms. The combination of sumatriptan 50 mg plus metoclopramide 10 mg was well tolerated.Conclusions.—Combining sumatriptan with metoclopramide provided relief in some migraineurs who failed to achieve adequate relief with a triptan alone. It remains unknown whether initiating therapy when pain was mild or using a higher dose of sumatriptan (ie, 100 mg) would have provided additional benefit. Further studies are indicated.