線性脊狀網

線性脊狀網格(Linear ridge networks)在火星各處的隕坑內外都有發現[1],這些特徵也被稱為「多邊形脊狀網格」、「箱形脊」和「網狀脊」等[2]。脊線通常顯示為格子狀相交的大段直線,它們長數百米,高幾十米,寬數米。據認為,撞擊會在地表形成裂縫,後來這些裂縫又充當了流體通道,液體使結構膠結凝固。隨着時間的推移,周圍的材料被侵蝕掉,從而留下了堅硬的凸脊。有理由認為,火星上的撞擊會產生裂縫,因為地球上的斷層常形成於撞擊坑中。可以猜測這些脊狀網格是岩脈,但與這些方向變化不定的凸脊相比,岩脈的走向或多或少是相同的。由於脊線出現在有粘土的地方,這些地層可作為粘土的標誌,粘土的形成需要水[3][4][5],這裏的水可以支持這些地方過去的生命,粘土也可以保存化石或其他曾經的生命痕跡。

這些山脊線可能產生於大型撞擊時,由熔融岩石和/或碎石(角礫岩)構成的裂縫、斷層或岩脈[6]。2017年,奎因(Quinn)和埃爾曼(Ehlmann)提出了一種沉積物堆積的形成機制,沉積物最終經歷成岩作用,導致體積縮小和斷裂,在侵蝕暴露出裂縫後,裂縫中灌滿了可能為酸性硫酸鹽流體的礦物。更多的侵蝕去除了較鬆軟的地層,留下了更耐侵蝕的凸脊[[7]。如果撞擊造成的岩脈是由撞擊熱量產生的純熔岩構成,則它也被稱為「假玄武玻璃」(pseudotachylite)[8]。此外,由於撞擊中產生的熱量,可能還涉及到熱液作用[9]。一組研究奧基隕擊坑的科研人員報告了熱液作的有力證據,該隕石坑中的脊線可能是在撞擊產生的裂縫之後形成的。他們通過火星勘測軌道飛行器上的儀器,發現了蒙脫石二氧化矽沸石蛇紋石碳酸鹽以及地球上撞擊誘發的熱液系統中常見的綠泥石[10] [11] [12] [13] [14] [15]。其他研究火星隕石坑的科學家也提供了火星撞擊後熱液系統的另外證據[16] [17] [18][19]

由於凸脊線似乎只發現於較舊的地殼中,據信,它們發生在火星地質史的早期,當時有更多更大的小行星撞擊該行星[20],這些早期撞擊可能導致早期地殼中佈滿了相互連接的通道[21] [22]。這些網格在包括阿拉伯高地阿拉伯區)、子午線高原北部、太陽高原諾亞高地挪亞區)、亞特蘭提斯混沌內彭西斯桌山群第勒尼安海區)等火星許多區域都有發現[23]

梅杜莎槽溝層東部發現了一處稍有不同的山脊地層;這些深色的凸脊有50米高並被侵蝕成黑色的巨石。有人認為,在被熔岩流包圍的梅杜莎槽溝地層中存在熔岩填塞的裂縫[20]

第勒尼安海區的線性脊狀網

其中一些可能形成於撞擊後產生的熱液系統。

卡西烏斯區的線性脊狀網

大瑟提斯區的線性脊狀網

法厄同區的線性脊狀網

亞馬遜區的線性脊狀網

阿拉伯區的線性脊狀網

阿耳卡狄亞區的線性脊狀網

另請查看

參引文獻

  1. ^ Head, J., J. Mustard. 2006. Breccia dikes and crater-related faults in impact craters on Mars: Erosion and exposure on the floor of a crater 75 km in diameter at the dichotomy boundary, Meteorit. Planet Science: 41, 1675-1690.
  2. ^ Moore, J., D. Wilhelms. 2001. Hellas as a possible site of ancient ice-covered lakes on Mars. Icarus: 154, 258-276.
  3. ^ Mangold et al. 2007. Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 2. Aqueous alteration of the crust. J. Geophys. Res., 112, doi:10.1029/2006JE002835.
  4. ^ Mustard et al., 2007. Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 1. Ancient impact melt in the Isidis Basin and implications for the transition from the Noachian to Hesperian, J. Geophys. Res., 112.
  5. ^ Mustard et al., 2009. Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis Basin, J. Geophys. Res., 114, doi:10.1029/2009JE003349.
  6. ^ Pascuzzo, A., J. Mustard. 2017. ONGOING CRISM INVESTIGATION OF RIDGE NETWORKS AND THEIR PHYLLOSILICATEBEARING HOST UNIT IN THE NILI FOSSAE AND NORTHEAST SYRTIS REGIONS. Lunar and Planetary Science XLVIII (2017). 2807. pdf.
  7. ^ Quinn, D., B. Ehlmann. 2017. THE DEPOSITION AND ALTERATION HISTORY OF THE NORTHEAST SYRTIS LAYERED SULFATES. Lunar and Planetary Science XLVIII (2017). 2932.pdf.
  8. ^ 存档副本. [2021-08-18]. (原始內容存檔於2021-08-18). 
  9. ^ Osinski, G., et al. 2013. Impact-generated hydrothermal systems on Earth and Mars. Icarus: 224, 347-363.
  10. ^ Carrozzo, F. et al. 2017. Geology and mineralogy of the Auki Crater, Tyrrhena Terra, Mars: A possible post impact-induced hydrothermal system. 281: 228-239
  11. ^ Loizeau, D. et al. 2012. Characterization of hydrated silicate-bearing outcrops in tyrrhena Terra, Mars: implications to the alteration history of Mars. Icarus: 219, 476-497.
  12. ^ Naumov, M. 2005. Principal features of impact-generated hydrothermal circulation systems: mineralogical and geochemical evidence. Geofluids: 5, 165-184.
  13. ^ Ehlmann, B., et al. 2011. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on Mars from phyllosilicate mineral assemblages. Clays Clay Miner: 59, 359-377.
  14. ^ Osinski, G. et al. 2013. Impact-generated hydrothermal systems on Earth and Mars. Icarus: 224, 347-363.
  15. ^ Schwenzer, S., D. Kring. 2013. Alteration minerals in impact-generated hydrothermal systems – Exploring host rock variability. Icarus: 226, 487-496.
  16. ^ Marzo, G., et al. 2010. Evidence for hesperian impact-induced hydrothermalism on Mars. Icarus: 667-683.
  17. ^ Mangold, N., et al. 2012. Hydrothermal alteration in a late hesperian impact crater on Mars. 43th Lunar and Planetary Science. #1209.
  18. ^ Tornabene, L., et al. 2009. Parautochthonous megabreccias and possible evidence of impact-induced hydrothermal alteration in holden crater, Mars. 40th LPSC. #1766.
  19. ^ Pascuzzo, A., et al. 2018. THE ORIGIN OF ENIGMATIC RIDGE NETWORKS, NILI FOSSAE, MARS: IMPLICATIONS FOR EXTENSIVE SUBSURFACE FLUID FLOW IN THE NOACHIAN. 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083). 2268.pdf
  20. ^ 20.0 20.1 Kerber, L., et al. 2017. Polygonal ridge networks on Mars: Diversity of morphologies and the special case of the Eastern Medusae Fossae Formation. Icarus: 281, 200-219.
  21. ^ Ehlmann, G. et al. 2011. Subsurface water and clay mineral formation during the early history of Mars. Nature: 479, 53-61.
  22. ^ E. K. Ebinger E., J. Mustard. 2015. LINEAR RIDGES IN THE NILOSYRTIS REGION OF MARS: IMPLICATIONS FOR SUBSURFACE FLUID FLOW. 46th Lunar and Planetary Science Conference (2015) 2034.pdf
  23. ^ Saper, L., J. Mustard. 2013. Extensive linear ridge networks in Nili Fossae and Nilosyrtis, Mars: implications for fluid flow in the ancient crust. Geophysical Research letters: 40, 245-249.

外部連結