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Structural, tectonic and geodynamic significance of Middle Triassic igneous activity in the Dolomites, NE Italy
Full text linkAt the Middle-Late Triassic boundary (~244-235 Ma) a diffuse igneous activity developed in Southern Alps, a wide area where the recently agglutinated Pangea super-continent had begun to disrupt. Sparse remnants of these products now crop out in the Brescian pre-Alps, the Vicentinian Alps (Recoaro-Schio-Posina), Non Valley, Dolomites and Tarvisian Alps. The igneous activity is concentred mainly in the Dolomites mostly as lava flow and pyroclastic successions, with rare intrusive bodies cropping out at Predazzo, Monzoni, and Cima Pape.
The Triassic igneous rocks show a wide compositional spectrum with compositions ranging from metaluminous (basalt/gabbros) to peraluminous (rhyolites/leucogranites) and including also cumulitic lithologies (cumulitic gabbros and clinopyroxenites).
The study of Triassic magmatism in the Southern Alps is the special interest due to contrasting models proposed to define the geodynamic and tectonic setting.
The petrographic, mineral chemistry and geochemical investigations have been performed for Triassic igneous rocks from different localities in the Dolomites and Vicentinian Alps to understand the origin of this magmatism and the main magmatic processes that controlled the evolution of these rocks.
We investigated the magnetic and magmatic fabric of Predazzo and Monzoni plutons by means of anisotropy of magnetic susceptibility (AMS) and microstructural data coupled with a field geological study. The AMS technique aimed at revealing the internal fabric of Predazzo and Monzoni plutons and defines the magnetic foliation and magnetic lineation (magmatic flow). Also, this technique is used to study magma migration and emplacement in the upper crust and define the model of emplacement of igneous bodies. Furthermore, the AMS method is aimed to constraining and define the relationship between magma emplacement and Middle Triassic tectonics.
Finally, the integration between structural and petrological analyses allowed to constrain the geodynamic and tectonic setting of Middle Triassic magmatism in the Dolomites and Southern Alps.
The major findings and contribution of this study are the following: 1) The Triassic magmatism in the Southern Alps has mainly shoshonitic affinity followed by high-K calcalkaline. 2) The studied rocks show a sharp correlation (SiO2, Na2O+K2O) and negative correlation (TiO2, Fe2O3tot, MnO, MgO, CaO, CaO/Al2O3) with differentiation index (D.I.). 3) The Dolomites lavas exhibit enrichment of large ion lithophile elements (LILE) relative to high field strength elements (HFSE) and shows high Ba/Nb (32.8-93.9), low Ce/Pb (1.8-10.4) and low U/Nb (0.11-0.33) coupled with low HFSE (e.g., Nb = 6-12 ppm) with low Nb/Nb* [(Nb/0.46)/((O980/0.023)*(U980/0.017))^0.5] ratio (0.1-0.35), resembling the typical characteristics of magmas generated by subduction-modified mantle sources. 4) The fractional crystallization of Mg-bearing phases such as olivine and clinopyroxene with only a minor role of plagioclase controlled Dolomites volcanic rocks evolution. 5) The 87Sr/86Sr for the Dolomites volcanic rocks ranges from 0.70432 to 0.70577 and do not show any correlation with D.I., with SiO2 or MgO which indicates that the mantle sources, only little modified, if any, by interaction with the local crust. 6) The 143Nd/144Nd(i) ranges from 0.51227 to 0.51237, with Nd(i) values slightly lower to slightly higher than ChUR(230 Ma) (from -1.4 to +0.5). The Pb isotopic compositions are homogeneous, with 206Pb/204Pb clustered around 18.26 and 18.41, 207Pb/204Pb from 15.62 to 15.67 and 208Pb/204Pb from 38.36 to 38.89. 7) The isotopic variation of the Southern Alps Triassic rocks is related to mantle source heterogeneities rather than interaction with upper crustal lithologies. 8) The mildly to strongly evolved rocks are genetically linked with the least differentiated terms by closed system fractional crystallization of gabbroic to monzonitic assemblages. 9) According to results of ABS5 software modelings of the less evolved basaltic sample, the origin of these rocks is a peridotitic mantle wedge source at typical subduction settings. 10) Finally, the mantle sources of Triassic igneous rocks reflect previous subduction metasomatism (likely developed during Hercynian times) when continental rifting caused raising of the geotherms and passive upwelling of asthenospheric mantle. 11) The study is a new evidence of the validity of the AMS method for unraveling the mode of emplacement of igneous bodies. 12) AMS, microstructural and petrographic data from the Predazzo body are consistent with a multistage ring-dyke emplacement mode. 13) The Predazzo sheets were emplaced via either upward magma flow or along-strike lateral magma transport. 14) The ENE-WSW elongated shape of the Monzoni body was controlled by the occurrence of strike-slip faults associated with Ladinian-tectonics. 15) The feeder zones are located at the NE and SW part of the Predazzo intrusion and at the NE edge of the Monzoni intrusion. 16) The low degree of anisotropy (Pj) values indicate the existence of low strain during the emplacement of Predazzo and Monzoni. 17) The Predazzo and Monzoni plutons emplacement followed the main Triassic tectonic phase (post-tectonic). 18) Ladinian strike-slip tectonics providing a preferential pathway for post-tectonic magma
Emerging drugs for endometriosis
No full textMedical treatment of endometriosis relies on drugs that suppress ovarian steroids and induce an hypoestrogenic state that causes atrophy of ectopic endometrium. Gonadotrophin-releasing hormone (GnRH) analogues, danazol, progestogens and oestrogen-progestin combinations have all proven effective in relieving pain and reducing the extent of endometriotic implants. However, symptoms often recur after discontinuation of therapy and hypoestrogenism-related side effects limit the long-term use of most medications. Furthermore, these therapies are of limited value in patients with a desire to become pregnant because they inhibit ovulation. An important target for current research is to identify effective therapies that can be safely administered in the long term. GnRH analogues with add-back therapy, progestogens and continuous oral contraceptive are options available for a medium or long-term systemic treatment. Mifepristone, an antiprogestogen, may constitute an alternative if encouraging preliminary data on its effectiveness and tolerability are confirmed. A very appealing area of interest is the possibility of treating endometriosis without suppressing ovarian function. Aromatase inhibitors might have such characteristics as they have been shown to inhibit oestrogen production selectively in endometriotic lesions, without affecting ovarian function; the clinical role of these drugs in the treatment of endometriosis is under evaluation. Levonorgestrel medicated intrauterine device has proven effective in relieving dysmenorrhoea associated with endometriosis, as well as pain associated with rectovaginal endometriosis. Although a systemic absorption is present determining side effects, this approach is promising in the long-term management of this condition. A fundamental objective of research in endometriosis treatment is to develop new therapeutic approaches based on the findings from experimental studies on the aetiopathogenesis of the disease; current research is focusing on anti-inflammatory drugs and modulators of the immune system. TNF-binding protein-1 and IL-12 have proved effective in reducing endometriotic lesions in animal models, while pentoxifylline and INF-alpha 2b have shown encouraging results in clinical studies. This area may be of paramount importance in the near future in order to develop a therapy that could prevent or eradicate endometriosis rather than merely relieving the symptoms
Hormonal treatments for adenomyosis
No full textLike endometriosis and uterine myomas, adenomyosis presents the typical characteristics of oestrogen-dependent diseases. The medical treatment of adenomyosis is based on the hormonal dependency of the disease and its strongly debated similarities with endometriosis. Infact, despite the evident differences between the two conditions, the therapies that treat endometriosis effectively have also been successful for the treatment of adenomyosis. Although the two diseases have distinct epidemiological features, they have the same 'target tissue' for hormonal therapy, namely ectopic endometrium. Recognized approaches are systemic hormonal treatments, which are generally used for endometriosis and are capable of suppressing the oestrogenic induction of the disease, and local hormonal treatment that targets the ectopic endometrium directly. Gonadotropin-releasing hormone agonists, danazol and intrauterine levonorgestrel- or danazol-releasing devices have been used in the treatment of adenomyosis. Despite the solid rational basis for its hormonal treatment, few studies have been performed on medical therapy for adenomyosis
Laparoscopic ovarian puncture for correct staging of endometriosis
No full textSmall, deep ovarian endometriomas are not easily diagnosed. In 52 infertile patients, laparoscopy demonstrated enlarged ovaries (maximum diameter 3.5 to 5 cm) with a smooth whitish surface and no mature follicles, corpora lutea, or other cysts. Ovarian puncture was performed, and endometriotic material aspirated in 25 women (48.0%). Cyst diameter was calculated using the geometric formula r = 3 square root of 3V/4 pi where r = radius and V = volume of liquid aspirated. Eight patients with apparently normal pelvis had endometriosis, and 14 with apparent minimal or mild endometriotic lesions were restaged. Laparoscopic ovarian puncture of enlarged ovaries was important for correct diagnosis and staging of endometriosis
A possible mechanism for non replication of allelic association between a SNP of the human beta T cell receptor and autoimmune diseases
No full textGene polymorphisms, in particular single nucleotide polymorphisms (SNP), have been associated to multi-factorial diseases such as cancer, inflammation and autoimmunity. Indeed for some autoimmune diseases it has been possible to identify critical residues that play a major role in susceptibility to disease.
The association of a common T/C polymorphism in the promoter region of the beta 2 constant chain of the T cell receptor with autoimmune diseases as insulin-dependent diabetes, autoimmune hepatitis, IgA nephropathy, membranous nephropathy, Graves’disease and Hashimoto’s thyroiditis, was described in the ninenties. These reports have not be confirmed in last few years. Indeed an interesting difference of allelic frequency in male e female was observed in some studies, this finding led us to make an allele frequency study of this single nucleotide polymorphism between sexes in a new series of patients. We studied 165 subjects, 80 males and 85 females, and we found a significant difference between sexes especially for the CC homozygous genotype: 34% of females versus 14% of males (p = 0.008). If the higher frequency in females of CC homozygous genotype (that is associated with an increased risk of autoimmune diseases) would be confirmed in normal population, this could be a explanation of the controversial results obtained in association study made between this SNP and autoimmune disease
Septums and synechiae: Approaches to surgical correction
No full textIf the Mullerian ducts fail to fuse, or, if the wall which is the result of fusion is not adequately resorbed, the result is a spectrum of uterine abnormalities called Mullerian fusion and absorption defects. The impact of these abnormalities on fertility is a subject for debate, but at least a subset seems to have a negative impact on reproductive performance manifesting in recurrent abortion and/or premature labor. Previous surgical interventions required laparotomy, but, with careful application of imaging techniques, a group of patients can be identified with a uterine septum amenable to removal under hysteroscopic direction with little morbidity. Intrauterine adhesions or synechiae are usually secondary to curettage in the context of missed abortion or pregnancy-related hemorrhage. These lesions cover a spectrum that ranges from minor and insignificant to severe cohesive adhesions that affect menstrual function and fertility. Surgical repair of the endometrial cavity affected with such adhesions presents a challenge to the hysteroscopic surgeon. Appropriate management is controversial but may include second loop hysteroscopy and the use of postoperative adjuvants such as systemic estrogens and intrauterine devices or systems designed to impede the development of adhesions
Laparotomy versus laparoscopy in the surgical treatment of endometriosis : the end of an era?
No full textThe Authors compare the efficiency of laparoscopic treatment with laparotomic surgical management of endometriosis. When the disease causes mechanical distortions and adnexal adhesions, there is an obvious explanation for infertility; in these cases laparotomic surgery has so far proved the only treatment to produce significantly valid results. No findings have yet been reported to demonstrate that cytoreduction, either pharmacological, laparoscopic or laparotomic, offers concrete advantages compared with simple observation when the disease is in the early stage
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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