张裂

张裂（英语：Rift）是岩石圈被拉开的线性区域^[1] ^[2] ，是伸展构造的一种^[3]。

典型的张裂特征在中央有线状的断陷洼地，称为地堑，但更常见的是半地堑。半地堑的正断层和张裂侧隆起都在一侧，另一侧缺失^[4] 。张裂若保持在海平面以上，它们形成一个板块裂谷，若被水填满，就形成一个裂谷湖。张裂区的轴心可能含有火山岩，但不是张裂都有火山活动。

大多数大洋中脊的中心轴都有张裂，是两块板块之间的分离板块边缘，也是新生洋壳和岩石圈的地区。

衰退张裂（英语：Failed Rift）是大陆在分裂时未能达到分开扩张。通常从张裂活动到扩张的过渡期常发生在三叉汇接区，此区有三条张裂集聚在一个热点 (地质学)。其中两条张裂持续发展到海底扩张的地步，而第三条中途停止发展，形成拗拉槽。

张裂发展

张裂起始

张裂成熟度可由对局部应变反应而形成的张裂盆地变化来分期。在裂陷开始形成时，岩石圈上部发展一系列不连通的正断层，形成孤立的盆地^[5]。若在陆上形成张裂，此期的排水通常是内部的。

成熟张裂阶段

随著张裂的发展，一些单独的断层会增长，最终连接在一起形成边界断层。随后的扩张运动都集中在这些边界断层。断层的延长和断层间距的加宽，导致沿张裂轴的沉降区域更加连续。此阶段张裂肩的发育有明显隆升，对张裂盆地的排水和沉积有强烈的影响^[5]。

在张裂活动的高潮期，地壳会变薄，地表下沉，莫霍面相应升高。与此同时，因地幔岩石圈（英语：mantle lithosphere）变薄，导致软流圈顶部上升。这将使高热流从上升的软流圈带入到变薄的岩石圈，导致岩石圈进行脱水熔融，通常在这种大于 30 °C 的高热梯度下，引起极端变质作用。在碰撞造山带中，变质产物为的高温至超高温的麻粒岩及其伴生的混合岩和花岗岩。在大陆张裂带可能有变质核杂岩，而在扩张脊中可能有洋核杂岩。这就形成一种在伸展构造中的造山运动，称为裂谷造山运动（英语：Rift orogeny）^[6]。

张裂后期沉降

一旦张裂停止活动，张裂下面的地幔就会冷却，并伴随著大面积的张裂后期沉降。沉降量与张裂期地壳减薄量直接有关，以β因子来计算（初始地壳厚度除以最终地壳厚度）。沉降量也受张裂盆地在每个阶段的填充程度及物质的影响，因为沉积物的密度比水更大。 “McKenzie 模型”是一种简单的张裂形成模型，它假设张裂形成阶段是瞬时的。根据张裂后期沉降量的观察，来估计地壳变薄量^[7] ^[8]。另一种模型为“弯曲悬臂模型” 'flexural cantilever model'，该模型考虑了张裂断层的几何形状和地壳上部的弯曲均衡flexural isostasy ^[9]。

张裂多期活动

一些张裂显示出复杂而漫长的张裂历史，具几个不同的成长阶段。北海张裂就是一个实列，从二叠纪到最早白垩纪，超过 1 亿年的时期，经历了的几个独立的张裂发展阶段^[10]。

分裂到分开

张裂可能导致大陆分开和海洋盆地的形成。张裂演变到大陆分开时，海底会沿著大洋中脊而扩张，造成洋盆，并分隔两侧共轭大陆边缘。^[11]。张裂活动可能是主动的，受地幔对流控制。它也可能是被动的，被远场拉伸岩石圈的构造力驱动。受拉伸变形阶段之间的空间和时间影响，造成不同边缘区结构的发展。边缘区的分割最终导致形成莫霍面不同变化的张裂域，包括近端张裂域，具有由断层旋转的地壳块、颈缩张裂带，其地壳基底变薄、远端张裂域，具有深凹陷盆地、洋-陆过渡张裂带和大洋张裂带域^[12]。

在张裂演化过程中，常见变形和岩浆相互作用^[12]。具岩浆活动的边缘有主要的火山活动特征。此种火山边缘均在被动大陆边缘^[13]。缺乏岩浆活动的张裂边缘，一般会受到大规模断层和地壳超伸展的影响^[14]，在海底伸展滑脱带，常具有被蛇纹石化的上地幔的橄榄岩和辉长岩。

参考文献

[1]
Rift valley: definition and geologic significance, Giacomo Corti, The Ethiopian Rift Valley
[2]
Decompressional Melting During Extension of Continental Lithosphere, Jolante van Wijk, MantlePlumes.org
[3]
Plate Tectonics: Lecture 2, Geology Department at University of Leicester
[4]
Leeder, M.R.; Gawthorpe, R.L. (1987). "Sedimentary models for extensional tilt-block/half-graben basins" (PDF). In Coward, M.P.; Dewey, J.F.; Hancock, P.L. (eds.). Continental Extensional Tectonics. Geological Society, Special Publications. Vol. 28. pp. 139–152. ISBN 9780632016051.
[5]
Withjack, M.O.; Schlische R.W.; Olsen P.E. (2002). "Rift-basin structure and its influence on sedimentary systems" (PDF). In Renaut R.W. & Ashley G.M. (ed.). Sedimentation in Continental Rifts. Special Publications. Vol. 73. Society for Sedimentary Geology. Retrieved 28 October 2012
[6]
Zheng, Y.-F.; Chen, R.-X. (2017). "Regional metamorphism at extreme conditions: Implications for orogeny at convergent plate margins". Journal of Asian Earth Sciences. 145: 46–73. Bibcode:2017JAESc.145...46Z. doi:10.1016/j.jseaes.2017.03.009
[7]
McKenzie, D. (1978). "Some remarks on the development of sedimentary basins" (PDF). Earth and Planetary Science Letters. 40 (1): 25–32. Bibcode:1978E&PSL..40...25M. CiteSeerX 10.1.1.459.4779. doi:10.1016/0012-821x(78)90071-7. Archived from the original (PDF) on 1 March 2014. Retrieved 25 October 2012
[8]
Kusznir, N.J.; Roberts A.M.; Morley C.K. (1995). "Forward and reverse modelling of rift basin formation". In Lambiase J.J. (ed.). Hydrocarbon habitat in rift basins. Special Publications. Vol. 80. London: Geological Society. pp. 33–56. ISBN 9781897799154. Retrieved 25 October 2012
[9]
Nøttvedt, A.; Gabrielsen R.H.; Steel R.J. (1995). "Tectonostratigraphy and sedimentary architecture of rift basins, with reference to the northern North Sea". Marine and Petroleum Geology. 12 (8): 881–901. doi:10.1016/0264-8172(95)98853-W.
[10]
Ravnås, R.; Nøttvedt A.; Steel R.J.; Windelstad J. (2000). "Syn-rift sedimentary architectures in the Northern North Sea". Dynamics of the Norwegian Margin. Special Publications. Vol. 167. London: Geological Society. pp. 133–177. ISBN 9781862390560. Retrieved 28 October 2012
[11]
Ziegler P.A.; Cloetingh S. (2003). "Dynamic processes controlling evolution of rifted basins". 64. Earth-Science Reviews
[12]
Péron-Pinvidic G.; Manatschal G.; Osmundsen P.T. (2013). "Structural comparison of archetypal Atlantic rifted margins: a review of observations and concepts". 43. Marine and Petroleum Geology
[13]
Reston T.J.; Manatschal G. (2011). "Arc-Continent Collision". In Brown D. & Ryan P.D. (ed.). Building blocks of later collision. Frontiers in Earth Sciences
[14]
Péron-Pinvidic G.; Manatschal G. (2009). "The final rifting evolution at deep magma-poor passive margins from Iberia-Newfoundland: a new point of view". 98. International Journal of Earth Sciences

[”Rift”-1] [1]
Rift valley: definition and geologic significance, Giacomo Corti, The Ethiopian Rift Valley

[Decom”-2] [2]
Decompressional Melting During Extension of Continental Lithosphere, Jolante van Wijk, MantlePlumes.org

[”Plate”-3] [3]
Plate Tectonics: Lecture 2, Geology Department at University of Leicester

[”Leeder”-4] [4]
Leeder, M.R.; Gawthorpe, R.L. (1987). "Sedimentary models for extensional tilt-block/half-graben basins" (PDF). In Coward, M.P.; Dewey, J.F.; Hancock, P.L. (eds.). Continental Extensional Tectonics. Geological Society, Special Publications. Vol. 28. pp. 139–152. ISBN 9780632016051.

[”Withjack”-5] [5]
Withjack, M.O.; Schlische R.W.; Olsen P.E. (2002). "Rift-basin structure and its influence on sedimentary systems" (PDF). In Renaut R.W. & Ashley G.M. (ed.). Sedimentation in Continental Rifts. Special Publications. Vol. 73. Society for Sedimentary Geology. Retrieved 28 October 2012

[”Zheng”-6] [6]
Zheng, Y.-F.; Chen, R.-X. (2017). "Regional metamorphism at extreme conditions: Implications for orogeny at convergent plate margins". Journal of Asian Earth Sciences. 145: 46–73. Bibcode:2017JAESc.145...46Z. doi:10.1016/j.jseaes.2017.03.009

[”McKenzie”-7] [7]
McKenzie, D. (1978). "Some remarks on the development of sedimentary basins" (PDF). Earth and Planetary Science Letters. 40 (1): 25–32. Bibcode:1978E&PSL..40...25M. CiteSeerX 10.1.1.459.4779. doi:10.1016/0012-821x(78)90071-7. Archived from the original (PDF) on 1 March 2014. Retrieved 25 October 2012

[”Kusznir”-8] [8]
Kusznir, N.J.; Roberts A.M.; Morley C.K. (1995). "Forward and reverse modelling of rift basin formation". In Lambiase J.J. (ed.). Hydrocarbon habitat in rift basins. Special Publications. Vol. 80. London: Geological Society. pp. 33–56. ISBN 9781897799154. Retrieved 25 October 2012

[”Nøttvedt”-9] [9]
Nøttvedt, A.; Gabrielsen R.H.; Steel R.J. (1995). "Tectonostratigraphy and sedimentary architecture of rift basins, with reference to the northern North Sea". Marine and Petroleum Geology. 12 (8): 881–901. doi:10.1016/0264-8172(95)98853-W.

[”Ravnås”-10] [10]
Ravnås, R.; Nøttvedt A.; Steel R.J.; Windelstad J. (2000). "Syn-rift sedimentary architectures in the Northern North Sea". Dynamics of the Norwegian Margin. Special Publications. Vol. 167. London: Geological Society. pp. 133–177. ISBN 9781862390560. Retrieved 28 October 2012

[”Ziegler”-11] [11]
Ziegler P.A.; Cloetingh S. (2003). "Dynamic processes controlling evolution of rifted basins". 64. Earth-Science Reviews

[”Péron”-12] [12]
Péron-Pinvidic G.; Manatschal G.; Osmundsen P.T. (2013). "Structural comparison of archetypal Atlantic rifted margins: a review of observations and concepts". 43. Marine and Petroleum Geology

[”Reston”-13] [13]
Reston T.J.; Manatschal G. (2011). "Arc-Continent Collision". In Brown D. & Ryan P.D. (ed.). Building blocks of later collision. Frontiers in Earth Sciences

[”Pinvidic”-14] [14]
Péron-Pinvidic G.; Manatschal G. (2009). "The final rifting evolution at deep magma-poor passive margins from Iberia-Newfoundland: a new point of view". 98. International Journal of Earth Sciences

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]