Mechanisms and biogeochemical implications of Cenomanian/Turonian black shale formation in North Africa:An integrated geochemical, millennial-scale study from theTarfaya-LaAyoune Basin in SW Morocco

Cenomanian/Turonian (C/T; ~94 Ma ago) black shale successions from various N African basins, in particular from the Tarfaya-LaAyoune Basin (SW Morocco), have been studied in great detail using data from the field (including gamma-ray resistivity logging), sedimentology and advanced geochemical trace metal, biomarker and stable isotope methods. Deposition of these black shale units in most of the region was restricted to a short time envelope termed the C/T oceanic anoxic event (OAE2). During this short period, a favourable combination of factors existed which led to the development of exceptionally strong oxygen-deficiency in the N African Tethys and in particular in the southern proto-North Atlantic oceans. The C/T black shales in N Africa are laterally discontinuous and their distribution and thickness were controlled by the palaeorelief. The thickest and regionally most extensive C/T organic-rich shales in N Africa occur in Morocco namely in the Atlantic Tarfaya-LaAyoune Basin. The laminated biogenic sediments from this NW African shallow marine basin were deposited with very high sedimentation rates (av. 5-10 cm/ka) enabling the investigation of mid-Cretaceous paleoceanographic events at high temporal resolution with respect to rapid climate change and associated hydrocarbon source-rock formation. The low level of thermal maturity and the high degree of sulphurisation of the organic matter (kerogen) makes these black shale successions suitable for advanced inorganic and organic geochemical investigations

Lenalidomide induced good clinical response in a patient with multiple relapsed and refractory Hodgkin's lymphoma

<p>Abstract</p> <p>Background</p> <p>A 24-year-old female patient was diagnosed with classic Hodgkin's lymphoma in clinical stage II, and combination chemotherapy followed by radiotherapy was initiated. During the following 5 years, the disease progressed despite several standard therapeutic approaches, including autologous and allogeneic stem cell transplantation.</p> <p>Methods</p> <p>Lenalidomide (25 mg daily) treatment was then initiated in a continuous dosing schedule. Positron emission tomography scans were performed before and during lenalidomide treatment. Hematologic and laboratory values, as well as physical condition were also assessed before and during lenalidomide treatment.</p> <p>Results</p> <p>Four months after continuous lenalidomide treatment, tumor load was significantly reduced, B symptoms had resolved, and the patient's physical condition had improved, allowing her to resume normal daily-living activities. Evaluations after 15 months of lenalidomide treatment indicated limited disease progression. Nevertheless, the patient was feeling well and maintaining a normal active life. Treatment was well tolerated, allowing the patient to remain on continuous dosing, which has now been maintained for 18 months.</p> <p>Conclusion</p> <p>Daily, long-term lenalidomide treatment provided clinical benefit and was well tolerated in a patient with relapsed, advanced classic Hodgkin's lymphoma.</p

NEOANGIOGENESIS AND MICROVASCULAR DENSITY IN MYELODYSPLASTIC SYNDROME – A SINGLE CENTER EXPERIENCE

Angiogenesis has a significant part in the pathogenesis of hematological malignancies, such as leukemia and myelodysplastic syndromes (MDS). We evaluated the relationship between morphometric, morphological and clinical features of MDS. Blood vessels of 31 newly diagnosed MDS bone marrow biopsies were immunohistochemically analyzed using CD34 and compared with 8 controls and 13 chronic myelomonocytic leukemias (CMML). MDS were categorized into three risk groups: low-, intermediate- and high-risk MDS. Microvascular density (MVD) and major and minor axis length were analyzed using digital image analysis. Overall, MDS had significantly higher MVD and lower minor axis values than the control group and CMML. High-risk MDS had significantly higher MVD compared to the controls, while all MDS risk groups had lower minor axis values than the control group. Increased minor and major axis values were prognostic predictors of shorter overall survival in all MDS risk groups and CMML patients. In conclusion, angiogenesis presents one of the essential factors in MDS pathogenesis and progression characterized by descriptive marrow microvascular network transformation. The size-related features are powerful indicators of survival in MDS patients

Methane seepage in a Cretaceous greenhouse world recorded by an unusual carbonate deposit from the Tarfaya Basin, Morocco

During the Cretaceous major episodes of oceanic anoxic conditions triggered large scale deposition of marine black shales rich in organic carbon. Several oceanic anoxic events (OAEs) have been documented including the Cenomanian to Turonian OAE 2, which is among the best studied examples to date. This study reports on a large limestone body that occurs within a black shale succession exposed in a coastal section of the Tarfaya Basin, Morocco. The black shales were deposited in the aftermath of OAE 2 in a shallow continental sea. To decipher the mode and causes of carbonate formation in black shales, a combination of element geochemistry, palaeontology, thin section petrography, carbon and oxygen stable isotope geochemistry and lipid biomarkers are used. The ¹³C-depleted biphytanic diacids reveal that the carbonate deposit resulted, at least in part, from microbially-mediated anaerobic oxidation of methane in the shallow subseafloor at a hydrocarbon seep. The lowest obtained δ¹³Ccarbonate values of −23.5‰ are not low enough to exclude other carbon sources than methane apart from admixed marine carbonate, indicating a potential contribution from in situ remineralization of organic matter contained in the black shales. Nannofossil and trace metal inventories of the black shales and the macrofaunal assemblage of the carbonate body reveal that environmental conditions became less reducing during the deposition of the background shales that enclose the carbonate body, but the palaeoenvironment was overall mostly characterized by high productivity and episodically euxinic bottom waters. This study reconstructs the evolution of a hydrocarbon seep that was situated within a shallow continental sea in the aftermath of OAE 2, and sheds light on how these environmental factors influenced carbonate formation and the ecology at the seep site

Upper ocean oxygenation dynamics from I/Ca ratios during the Cenomanian-Turonian OAE 2

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 30 (2015): 510–526, doi:10.1002/2014PA002741.Global warming lowers the solubility of gases in the ocean and drives an enhanced hydrological cycle with increased nutrient loads delivered to the oceans, leading to increases in organic production, the degradation of which causes a further decrease in dissolved oxygen. In extreme cases in the geological past, this trajectory has led to catastrophic marine oxygen depletion during the so-called oceanic anoxic events (OAEs). How the water column oscillated between generally oxic conditions and local/global anoxia remains a challenging question, exacerbated by a lack of sensitive redox proxies, especially for the suboxic window. To address this problem, we use bulk carbonate I/Ca to reconstruct subtle redox changes in the upper ocean water column at seven sites recording the Cretaceous OAE 2. In general, I/Ca ratios were relatively low preceding and during the OAE interval, indicating deep suboxic or anoxic waters exchanging directly with near-surface waters. However, individual sites display a wide range of initial values and excursions in I/Ca through the OAE interval, reflecting the importance of local controls and suggesting a high spatial variability in redox state. Both I/Ca and an Earth System Model suggest that the northeast proto-Atlantic had notably higher oxygen levels in the upper water column than the rest of the North Atlantic, indicating that anoxia was not global during OAE 2 and that important regional differences in redox conditions existed. A lack of correlation with calcium, lithium, and carbon isotope records suggests that neither enhanced global weathering nor carbon burial was a dominant control on the I/Ca proxy during OAE 2.Z.L. thanks NSF OCE 1232620. J.D.O. is supported by an Agouron Postdoctoral Fellowship. T.W.L. acknowledges support from the NSF-EAR and NASA-NAI. A.R. thanks the support of NERC via NE/J01043X/1.2015-11-1

Why are the δ 13 C org values in Phanerozoic black shales more negative than in modern marine organic matter?

The δ 13 C org values of Phanerozoic black shales average −27‰, whereas those of modern marine organic matter average −20‰. The black shale isotopic values mimic those of continental organic matter, yet their organic geochemical properties mandate that they contain predominantly marine organic matter. Hypotheses that proposed to explain the low δ 13 C values of black shales include diagenetic losses of isotopically heavier organic matter components, releases of isotopically light carbon from methane clathrates or extensive magmatic events, greater photosynthetic discrimination against 13 C during times of higher atmospheric p CO 2 , and greenhouse climate stratification of the surface ocean that magnified photic zone recycling of isotopically light organic matter. Although the last possibility seems contrary to the vertical mixing that leads to the high productivity of modern oceanic upwelling systems, it is consistent with the strongly stratified conditions that accompanied deposition of the organic carbon‐rich Pliocene‐Pleistocene sapropels of the Mediterranean Sea. Because most Phanerozoic black shales contain evidence of photic zone anoxia similar to the sapropels, well‐developed surface stratification of the oceans was likely involved in their formation. Existence of isotopically light land plant organic matter during several episodes of extensive magmatism that accompanied black shale deposition implies massive release of mantle CO 2 that added to the greenhouse conditions that favored oceanic stratification. The 13 C depletion common to most Phanerozoic black shales apparently resulted from a greenhouse climate associated with elevated atmospheric p CO 2 that led to a strongly stratified ocean and photic zone recycling of organic matter in, augmented by magmatic CO 2 releases. Key Points Photic zone recycling of organic carbon is responsible for their low δ 13 C values Black shales deposited during periods of strong surface ocean stratification Periods of greenhouse climate established conditions for black shale depositionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108327/1/ggge20506.pd

Steuerungsmechanismen und biogeochemische Auswirkungen von Schwarzschiefergenese an der Cenoman/Turon-Wende in Nordafrika: Ein integrierte hochauflösender geochemische Studie aus dem Tarfaya-LaAyoune Becken in SW-Marokko

Cenomanian/Turonian (C/T; ~94 Ma ago) black shale successions from various N African basins, in particular from the Tarfaya-LaAyoune Basin (SW Morocco), have been studied in great detail using data from the field (including gamma-ray resistivity logging), sedimentology and advanced geochemical trace metal, biomarker and stable isotope methods. Deposition of these black shale units in most of the region was restricted to a short time envelope termed the C/T oceanic anoxic event (OAE2). During this short period, a favourable combination of factors existed which led to the development of exceptionally strong oxygen-deficiency in the N African Tethys and in particular in the southern proto-North Atlantic oceans. The C/T black shales in N Africa are laterally discontinuous and their distribution and thickness were controlled by the palaeorelief. The thickest and regionally most extensive C/T organic-rich shales in N Africa occur in Morocco namely in the Atlantic Tarfaya-LaAyoune Basin. The laminated biogenic sediments from this NW African shallow marine basin were deposited with very high sedimentation rates (av. 5-10 cm/ka) enabling the investigation of mid-Cretaceous paleoceanographic events at high temporal resolution with respect to rapid climate change and associated hydrocarbon source-rock formation. The low level of thermal maturity and the high degree of sulphurisation of the organic matter (kerogen) makes these black shale successions suitable for advanced inorganic and organic geochemical investigations